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• Pointers to Derived Class Objects Losing vfptr

  - by duckworthd

  To begin, I am trying to write a run-of-the-mill, simple Ray Tracer. In my Ray Tracer, I have multiple types of geometries in the world, all derived from a base class called "SceneObject". I've included the header for it here. /** Interface for all objects that will appear in a scene */ class SceneObject { public: mat4 M, M_inv; Color c; SceneObject(); ~SceneObject(); /** The transformation matrix to be applied to all points of this object. Identity leaves the object in world frame. */ void setMatrix(mat4 M); void setMatrix(MatrixStack mStack); void getMatrix(mat4& M); /** The color of the object */ void setColor(Color c); void getColor(Color& c); /** Alter one portion of the color, leaving the rest as they were. */ void setDiffuse(vec3 rgb); void setSpecular(vec3 rgb); void setEmission(vec3 rgb); void setAmbient(vec3 rgb); void setShininess(double s); /** Fills 'inter' with information regarding an intersection between this object and 'ray'. Ray should be in world frame. */ virtual void intersect(Intersection& inter, Ray ray) = 0; /** Returns a copy of this SceneObject */ virtual SceneObject* clone() = 0; /** Print information regarding this SceneObject for debugging */ virtual void print() = 0; }; As you can see, I've included a couple virtual functions to be implemented elsewhere. In this case, I have only two derived class -- Sphere and Triangle, both of which implement the missing member functions. Finally, I have a Parser class, which is full of static methods that do the actual "Ray Tracing" part. Here's a couple snippets for relevant portions void Parser::trace(Camera cam, Scene scene, string outputFile, int maxDepth) { int width = cam.getNumXPixels(); int height = cam.getNumYPixels(); vector<vector<vec3>> colors; colors.clear(); for (int i = 0; i< width; i++) { vector<vec3> ys; for (int j = 0; j<height; j++) { Intersection intrsct; Ray ray; cam.getRay(ray, i, j); vec3 color; printf("Obtaining color for Ray[%d,%d]\n", i,j); getColor(color, scene, ray, maxDepth); ys.push_back(color); } colors.push_back(ys); } printImage(colors, width, height, outputFile); } void Parser::getColor(vec3& color, Scene scene, Ray ray, int numBounces) { Intersection inter; scene.intersect(inter,ray); if(inter.isIntersecting()){ Color c; inter.getColor(c); c.getAmbient(color); } else { color = vec3(0,0,0); } } Right now, I've forgone the true Ray Tracing part and instead simply return the color of the first object hit, if any. As you have no doubt noticed, the only way the computer knows that a ray has intersected an object is through Scene.intersect(), which I also include. void Scene::intersect(Intersection& i, Ray r) { Intersection result; result.setDistance(numeric_limits<double>::infinity()); result.setIsIntersecting(false); double oldDist; result.getDistance(oldDist); /* Cycle through all objects, making result the closest one */ for(int ind=0; ind<objects.size(); ind++){ SceneObject* thisObj = objects[ind]; Intersection betterIntersect; thisObj->intersect(betterIntersect, r); double newDist; betterIntersect.getDistance(newDist); if (newDist < oldDist){ result = betterIntersect; oldDist = newDist; } } i = result; } Alright, now for the problem. I begin by creating a scene and filling it with objects outside of the Parser::trace() method. Now for some odd reason, I cast Ray for i=j=0 and everything works wonderfully. However, by the time the second ray is cast all of the objects stored in my Scene no longer recognize their vfptr's! I stepped through the code with a debugger and found that the information to all the vfptr's are lost somewhere between the end of getColor() and the continuation of the loop. However, if I change the arguments of getColor() to use a Scene& instead of a Scene, then no loss occurs. What crazy voodoo is this?

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• SSL confirmation dialog popup auto closes in IE8 when re-accessing a JNLP file

  - by haylem

  I'm having this very annoying problem to troubleshoot and have been going at it for way too many days now, so have a go at it. The Environment We have 2 app-servers, which can be located on either the same machine or 2 different machines, and use the same signing certificate, and host 2 different web-apps. Though let's say, for the sake of our study case here, that they are on the same physical machine. So, we have: https://company.com/webapp1/ https://company.com/webapp2/ webapp1 is GWT-based rich-client which contains on one of its screens a menu with an item that is used to invoke a Java WebStart Client located on webapp2. It does so by performing a simple window.open call via this GWT call: Window.open("https://company.com/webapp2/app.jnlp", "_blank", null); Expected Behavior User merrilly goes to webapp1 User navigates to menu entry to start the WebStart app and clicks on it browser fires off a separate window/dialog which, depending on the browser and its security settings, will: request confirmation to navigate to this secure site, directly download the file, and possibly auto-execute a javaws process if there's a file association, otherwise the user can simply click on the file and start the app (or go about doing whatever it takes here). If you close the app, close the dialog, and re-click the menu entry, the same thing should happen again. Actual Behavior On Anything but God-forsaken IE 8 (Though I admit there's also all the god-forsaken pre-IE8 stuff, but the Requirements Lords being merciful we have already recently managed to make them drop these suckers. That was close. Let's hold hands and say a prayer of gratitude.) Stuff just works. JNLP gets downloaded, app executes just fine, you can close the app and re-do all the steps and it will restart happily. People rejoice. Puppies are safe and play on green hills in the sunshine. Developers can go grab a coffee and move on to more meaningful and rewarding tasks, like checking out on SO questions. Chrome doesn't want to execute the JNLP, but who cares? Customers won't get RSI from clicking a file every other week. On God-forsaken IE8 On the first visit, the dialog opens and requests confirmation for the user to continue to webapp2, though it could be unsafe (here be dragons, I tell you). The JNLP downloads and auto-opens, the app start. Your breathing is steady and slow. You close the app, close that SSL confirmation dialog, and re-click the menu entry. The dialog opens and auto-closes. Nothing starts, the file wasn't downloaded to any known location and Fiddler just reports the connection was closed. If you close IE and reach that menu item to click it again, it is now back to working correctly. Until you try again during the same session, of course. Your heart-rate goes up, you get some more coffee to make matters worse, and start looking for plain tickets online and a cheap but heavy golf-club on an online auction site to go clubbing baby polar seals to avenge your bloodthirst, as the gates to the IE team in Redmond are probably more secured than an ice block, as one would assume they get death threats often. Plus, the IE9 and IE10 teams are already hard at work fxing the crap left by their predecessors, so maybe you don't want to be too hard on them, and you don't have money to waste on a PI to track down the former devs responsible for this mess. Added Details I have come across many problems with IE8 not downloading files over SSL when it uses a no-cache header. This was indeed one of our problems, which seems to be worked out now. It downloads files fine, webapp2 uses the following headers to serve the JNLP file: response.setHeader("Cache-Control", "private, must-revalidate"); // IE8 happy response.setHeader("Pragma", "private"); // IE8 happy response.setHeader("Expires", "0"); // IE8 happy response.setHeader("Access-Control-Allow-Origin", "*"); // allow to request via cross-origin AJAX response.setContentType("application/x-java-jnlp-file"); // please exec me As you might have inferred, we get some confirmation dialog because there's something odd with the SSL certificate. Unfortunately I have no control over that. Assuming that's only temporary and for development purposes as we usually don't get our hands on the production certs. So the SSL cert is expired and doesn't specify the server. And the confirmation dialog. Wouldn't be that bad if it weren't for IE, as other browsers don't care, just ask for confirmation, and execute as expected and consistantly. Please, pretty please, help me, or I might consider sacrificial killings as an option. And I think I just found a decently prized stainless steel golf-club, so I'm right on the edge of gore. Side Notes Might actually be related to IE8 window.open SSL Certificate issue. Though it doesn't explain why the dialog would auto-close (that really is beyong me...), it could help to not have the confirmation dialog and not need the dialog at all. For instance, I was thinking that just having a simple URL in that menu instead of have it entirely managed by GWT code to invoke a Window.open would solve the problem. But I don't have control on that menu, and also I'm very curious how this could be fixed otherwise and why the hell it happens in the first place...

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• Why can't I retrieve the entities I've just persisted?

  - by felipecao

  I've got this web service that basically queries the database and returns all persisted entities. For testing purposes, I've created a TestDataManager that persists 2 example entities after Spring context is loaded (BTW, I'm using JAX-WS, Spring, Hibernate and HSQLDB). My TestDataManager looks like this: @Component public class TestDataManager { @Resource private SessionFactory sf; @PostConstruct @Transactional(readOnly = false, propagation = Propagation.REQUIRES_NEW) public void insertTestData(){ sf.openSession(); sf.openSession().beginTransaction(); sf.openSession().persist(new Site("site one")); sf.openSession().persist(new Site("site two")); sf.openSession().flush(); } } My JAX-WS endpoint looks like this: @WebService public class SmartBrickEndpoint { @Resource private WebServiceContext context; public Set<Site> getSitesForUser(String user){ return getSiteService().findByUser(new User(user)); } private ISiteService getSiteService(){ ServletContext servletContext = (ServletContext) context.getMessageContext().get("javax.xml.ws.servlet.context"); return (ISiteService) BeanRetriever.getBean(servletContext, ISiteService.class); } } This my Service class: @Component @Transactional(readOnly = true) public class SiteService implements ISiteService { @Resource private ISiteDao siteDao; @Override public Set<Site> findByUser(User user) { return siteDao.findByUser(user); } } This is my DAO: @Component @Transactional(readOnly = true) public class SiteDao implements ISiteDao { @Resource private SessionFactory sessionFactory; @Override public Set<Site> findByUser(User user) { Set<Site> sites = new LinkedHashSet<Site>(sessionFactory.getCurrentSession().createCriteria(Site.class).list()); return sites; } } This is my applicationContext.xml: <context:annotation-config /> <context:component-scan base-package="br.unirio.wsimxp.dao"/> <context:component-scan base-package="br.unirio.wsimxp.service"/> <context:component-scan base-package="br.unirio.wsimxp.spring"/> <bean id="applicationDS" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="org.hsqldb.jdbcDriver"/> <property name="url" value="jdbc:hsqldb:file:sites"/> </bean> <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> <property name="dataSource" ref="applicationDS" /> <property name="configLocation"> <value>classpath:hibernate.cfg.xml</value> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">org.hibernate.dialect.HSQLDialect</prop> <prop key="hibernate.show_sql">true</prop> <prop key="hibernate.format_sql">true</prop> <prop key="hibernate.connection.release_mode">on_close</prop> <!--<prop key="hibernate.current_session_context_class">thread</prop>--> <prop key="hibernate.query.factory_class">org.hibernate.hql.classic.ClassicQueryTranslatorFactory</prop> <prop key="hibernate.hbm2ddl.auto">create-drop</prop> </props> </property> </bean> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean> <tx:annotation-driven transaction-manager="transactionManager" /> This is what's going on now: when the app is deployed, TestDataManager#insertTestData kicks-in (due to @PostConstruct) and persist does not raise any exception. I should have 2 entities in the DB by now. Afterwards, I invoke the endpoint by a SOAP client, and the request goes all the way up to the DAO. The Hibernate invocation does not raise any exception, but the returned list is empty. The odd thing is, in TestDataManager, if I switch from sf.openSession() to sf.getCurrentSession(), I get an error message: "No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here". What I am doing wrong here? Why is the query "not seeing" the persisted entities? Why do I need to invoke sf.openSession() on TestDataManager although it's annotated with @Transactional? I have done some tests with hibernate.current_session_context_class=thread in application.xml, but then I just switch problems in each class. I'd like not needing to manually invoke sf.openSession() and leave that for Hibernate to take care. Thanks a lot for any help!

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• Cocos2d-iPhone: CCSprite positions differ between Retina & non-Retina Screens

  - by bobwaycott

  I have a fairly simple app built using cocos2d-iphone, but a strange positioning problem that I've been unable to resolve. The app uses sprite sheets, and there is a Retina and non-Retina sprite sheet within the app that use the exact same artwork (except for resolution, of course). There are other artwork within the app used for CCSprites that are both standard and -hd suffixed. Within the app, a group of sprites are created when the app starts. These initially created CCSprites always position identically (and correctly) on Retina & non-Retina screens. // In method called to setup sprites when app launches // Cache & setup app sprites [[CCSpriteFrameCache sharedSpriteFrameCache] addSpriteFramesWithFile: @"sprites.plist"]; sprites = [CCSpriteBatchNode batchNodeWithFile: @"sprites.png"]; hill = [CCSprite spriteWithSpriteFrameName: @"hill.png"]; hill.position = ccp( 160, 75 ); [sprites addChild: hill z: 1]; // ... [create more sprites in same fashion] // NOTE: All sprites created here have correct positioning on Retina & non-Retina screens When a user taps the screen a certain way, a method is called that creates another group of CCSprites (on- and off-screen), animating them all in. One of these sprites, hand, is always positioned identically (and correctly) on Retina & non-Retina screens. The others (a group of clouds) successfully create & animate, but their positions are correct only on Retina displays. On a non-Retina display, each cloud has incorrect starting positions (incorrect for x, y, or sometimes both), and their ending positions after animation are also wrong. I've included the responsible code below from the on-touch method that creates the new sprites and animates them in. Again, it works as expected on a Retina display, but incorrectly on non-Retina screens. The CCSprites used are created in the same way at app-start to setup all the initial sprites in the app, which always have correct positions. // Elsewhere, in a method called on touch // Create clouds cloud1 = [CCSprite spriteWithSpriteFrameName: @"cloud_1.png"]; cloud1.position = ccp(-150, 320); cloud1.scale = 1.2f; cloud2 = [CCSprite spriteWithSpriteFrameName: @"cloud_2.png"]; cloud2.position = ccp(-150, 335); cloud2.scale = 1.3f; cloud3 = [CCSprite spriteWithSpriteFrameName: @"cloud_4.png"]; cloud3.position = ccp(-150, 400); cloud4 = [CCSprite spriteWithSpriteFrameName: @"cloud_5.png"]; cloud4.position = ccp(-150, 420); cloud5 = [CCSprite spriteWithSpriteFrameName: @"cloud_3.png"]; cloud5.position = ccp(400, 350); cloud6 = [CCSprite spriteWithSpriteFrameName: @"cloud_1.png"]; cloud6.position = ccp(400, 335); cloud6.scale = 1.1f; cloud7 = [CCSprite spriteWithSpriteFrameName: @"cloud_2.png"]; cloud7.flipY = YES; cloud7.flipX = YES; cloud7.position = ccp(400, 380); // Create hand hand = [CCSprite spriteWithSpriteFrameName:@"hand.png"]; hand.position = ccp(160, 650); [sprites addChild: cloud1 z: 10]; [sprites addChild: cloud2 z: 9]; [sprites addChild: cloud3 z: 8]; [sprites addChild: cloud4 z: 7]; [sprites addChild: cloud5 z: 6]; [sprites addChild: cloud6 z: 10]; [sprites addChild: cloud7 z: 8]; [sprites addChild: hand z: 10]; // ACTION!! [cloud1 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(70, 320)]]; [cloud2 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(60, 335)]]; [cloud3 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(100, 400)]]; [cloud4 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(80, 420)]]; [cloud5 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(250, 350)]]; [cloud6 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(250, 335)]]; [cloud7 runAction:[CCMoveTo actionWithDuration: 1.0f position: ccp(270, 380)]]; [hand runAction: handIn]; It may be worth mentioning that I see this incorrect positioning behavior in the iOS Simulator when running the app and switching between the standard iPhone and iPhone (Retina) hardware options. I have not been able to verify this occurs or does not occur on an actual non-Retina iPhone because I do not have one. However, this is the only time I see this odd positioning behavior occur (the incorrect results obtained after user touch), and since I'm creating all sprites in exactly the same way (i.e., [CCSprite spriteWithSpriteFrameName:] and then setting position with cpp()), I would be especially grateful for any help in tracking down why this single group of sprites are always incorrect on non-Retina screens. Thank you.

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• Building a jQuery Plug-in to make an HTML Table scrollable

  - by Rick Strahl

  Today I got a call from a customer and we were looking over an older application that uses a lot of tables to display financial and other assorted data. The application is mostly meta-data driven with lots of layout formatting automatically driven through meta data rather than through explicit hand coded HTML layouts. One of the problems in this apps are tables that display a non-fixed amount of data. The users of this app don't want to use paging to see more data, but instead want to display overflow data using a scrollbar. Many of the forms are very densely populated, often with multiple data tables that display a few rows of data in the UI at the most. This sort of layout does not lend itself well to paging, but works much better with scrollable data. Unfortunately scrollable tables are not easily created. HTML Tables are mangy beasts as anybody who's done any sort of Web development knows. Tables are finicky when it comes to styling and layout, and they have many funky quirks, especially when it comes to scrolling both of the table rows themselves or even the child columns. There's no built-in way to make tables scroll and to lock headers while you do, and while you can embed a table (or anything really) into a scrolling div with something like this: <div style="position:relative; overflow: hidden; overflow-y: scroll; height: 200px; width: 400px;"> <table id="table" style="width: 100%" class="blackborder" > <thead> <tr class="gridheader"> <th>Column 1</th> <th>Column 2</th> <th>Column 3</th> <th >Column 4</th> </tr> </thead> <tbody> <tr> <td>Column 1 Content</td> <td>Column 2 Content</td> <td>Column 3 Content</td> <td>Column 4 Content</td> </tr> <tr> <td>Column 1 Content</td> <td>Column 2 Content</td> <td>Column 3 Content</td> <td>Column 4 Content</td> </tr> … </tbody> </table> </div> </div> that won't give a very satisfying visual experience: Both the header and body scroll which looks odd. You lose context as soon as the header scrolls off the top and when you reach the bottom of the list the bottom outline of the table shows which also looks off. The the side bar shows all the way down the length of the table yet another visual miscue. In a pinch this will work, but it's ugly. What's out there? Before we go further here you should know that there are a few capable grid plug-ins out there already. Among them: Flexigrid (can work of any table as well as with AJAX data) jQuery Scrollable Table Plug-in (feature similar to what I need but not quite) jqGrid (mostly an Ajax Grid which is very powerful and works very well) But in the end none of them fit the bill of what I needed in this situation. All of these require custom CSS and some of them are fairly complex to restyle. Others are AJAX only or work better with AJAX loaded data. However, I need to actually try (as much as possible) to maintain the original styling of the tables without requiring extensive re-styling. Building the makeTableScrollable() Plug-in To make a table scrollable requires rearranging the table a bit. In the plug-in I built I create two <div> tags and split the table into two: one for the table header and one for the table body. The bottom <div> tag then contains only the table's row data and can be scrolled while the header stays fixed. Using jQuery the basic idea is pretty simple: You create the divs, copy the original table into the bottom, then clone the table, clear all content append the <thead> section, into new table and then copy that table into the second header <div>. Easy as pie, right? Unfortunately it's a bit more complicated than that as it's tricky to get the width of the table right to account for the scrollbar (by adding a small column) and making sure the borders properly line up for the two tables. A lot of style settings have to be made to ensure the table is a fixed size, to remove and reattach borders, to add extra space to allow for the scrollbar and so forth. The end result of my plug-in is a table with a scrollbar. Using the same table I used earlier the result looks like this: To create it, I use the following jQuery plug-in logic to select my table and run the makeTableScrollable() plug-in against the selector: $("#table").makeTableScrollable( { cssClass:"blackborder"} ); Without much further ado, here's the short code for the plug-in: (function ($) { $.fn.makeTableScrollable = function (options) { return this.each(function () { var $table = $(this); var opt = { // height of the table height: "250px", // right padding added to support the scrollbar rightPadding: "10px", // cssclass used for the wrapper div cssClass: "" } $.extend(opt, options); var $thead = $table.find("thead"); var $ths = $thead.find("th"); var id = $table.attr("id"); var cssClass = $table.attr("class"); if (!id) id = "_table_" + new Date().getMilliseconds().ToString(); $table.width("+=" + opt.rightPadding); $table.css("border-width", 0); // add a column to all rows of the table var first = true; $table.find("tr").each(function () { var row = $(this); if (first) { row.append($("<th>").width(opt.rightPadding)); first = false; } else row.append($("<td>").width(opt.rightPadding)); }); // force full sizing on each of the th elemnts $ths.each(function () { var $th = $(this); $th.css("width", $th.width()); }); // Create the table wrapper div var $tblDiv = $("<div>").css({ position: "relative", overflow: "hidden", overflowY: "scroll" }) .addClass(opt.cssClass); var width = $table.width(); $tblDiv.width(width).height(opt.height) .attr("id", id + "_wrapper") .css("border-top", "none"); // Insert before $tblDiv $tblDiv.insertBefore($table); // then move the table into it $table.appendTo($tblDiv); // Clone the div for header var $hdDiv = $tblDiv.clone(); $hdDiv.empty(); var width = $table.width(); $hdDiv.attr("style", "") .css("border-bottom", "none") .width(width) .attr("id", id + "_wrapper_header"); // create a copy of the table and remove all children var $newTable = $($table).clone(); $newTable.empty() .attr("id", $table.attr("id") + "_header"); $thead.appendTo($newTable); $hdDiv.insertBefore($tblDiv); $newTable.appendTo($hdDiv); $table.css("border-width", 0); }); } })(jQuery); Oh sweet spaghetti code :-) The code starts out by dealing the parameters that can be passed in the options object map: height The height of the full table/structure. The height of the outside wrapper container. Defaults to 200px. rightPadding The padding that is added to the right of the table to account for the scrollbar. Creates a column of this width and injects it into the table. If too small the rightmost column might get truncated. if too large the empty column might show. cssClass The CSS class of the wrapping container that appears to wrap the table. If you want a border around your table this class should probably provide it since the plug-in removes the table border. The rest of the code is obtuse, but pretty straight forward. It starts by creating a new column in the table to accommodate the width of the scrollbar and avoid clipping of text in the rightmost column. The width of the columns is explicitly set in the header elements to force the size of the table to be fixed and to provide the same sizing when the THEAD section is moved to a new copied table later. The table wrapper div is created, formatted and the table is moved into it. The new wrapper div is cloned for the header wrapper and configured. Finally the actual table is cloned and cleared of all elements. The original table's THEAD section is then moved into the new table. At last the new table is added to the header <div>, and the header <div> is inserted before the table wrapper <div>. I'm always amazed how easy jQuery makes it to do this sort of re-arranging, and given of what's happening the amount of code is rather small. Disclaimer: Your mileage may vary A word of warning: I make no guarantees about the code above. It's a first cut and I provided this here mainly to demonstrate the concepts of decomposing and reassembling an HTML layout :-) which jQuery makes so nice and easy. I tested this component against the typical scenarios we plan on using it for which are tables that use a few well known styles (or no styling at all). I suspect if you have complex styling on your <table> tag that things might not go so well. If you plan on using this plug-in you might want to minimize your styling of the table tag and defer any border formatting using the class passed in via the cssClass parameter, which ends up on the two wrapper div's that wrap the header and body rows. There's also no explicit support for footers. I rarely if ever use footers (when not using paging that is), so I didn't feel the need to add footer support. However, if you need that it's not difficult to add - the logic is the same as adding the header. The plug-in relies on a well-formatted table that has THEAD and TBODY sections along with TH tags in the header. Note that ASP.NET WebForm DataGrids and GridViews by default do not generate well-formatted table HTML. You can look at my Adding proper THEAD sections to a GridView post for more info on how to get a GridView to render properly. The plug-in has no dependencies other than jQuery. Even with the limitations in mind I hope this might be useful to some of you. I know I've already identified a number of places in my own existing applications where I will be plugging this in almost immediately. Resources Download Sample and Plug-in code Latest version in the West Wind Web & AJAX Toolkit Repository © Rick Strahl, West Wind Technologies, 2005-2011Posted in jQuery  HTML  ASP.NET  

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• eBooks on iPad vs. Kindle: More Debate than Smackdown

  - by andrewbrust

  When the iPad was presented at its San Francisco launch event on January 28th, Steve Jobs spent a significant amount of time explaining how well the device would serve as an eBook reader. He showed the iBooks reader application and iBookstore and laid down the gauntlet before Amazon and its beloved Kindle device. Almost immediately afterwards, criticism came rushing forth that the iPad could never beat the Kindle for book reading. The curious part of that criticism is that virtually no one offering it had actually used the iPad yet. A few weeks later, on April 3rd, the iPad was released for sale in the United States. I bought one on that day and in the few additional weeks that have elapsed, I’ve given quite a workout to most of its capabilities, including its eBook features. I’ve also spent some time with the Kindle, albeit a first-generation model, to see how it actually compares to the iPad. I had some expectations going in, but I came away with conclusions about each device that were more scenario-based than absolute. I present my findings to you here.   Vital Statistics Let’s start with an inventory of each device’s underlying technology. The iPad has a color, backlit LCD screen and an on-screen keyboard. It has a battery which, on a full charge, lasts anywhere from 6-10 hours. The Kindle offers a monochrome, reflective E Ink display, a physical keyboard and a battery that on my first gen loaner unit can go up to a week between charges (Amazon claims the battery on the Kindle 2 can last up to 2 weeks on a single charge). The Kindle connects to Amazon’s Kindle Store using a 3G modem (the technology and network vary depending on the model) that incurs no airtime service charges whatsoever. The iPad units that are on-sale today work over WiFi only. 3G-equipped models will be on sale shortly and will command a $130 premium over their WiFi-only counterparts. 3G service on the iPad, in the U.S. from AT&T, will be fee-based, with a 250MB plan at $14.99 per month and an unlimited plan at $29.99. No contract is required for 3G service. All these tech specs aside, I think a more useful observation is that the iPad is a multi-purpose Internet-connected entertainment device, while the Kindle is a dedicated reading device. The question is whether those differences in design and intended use create a clear-cut winner for reading electronic publications. Let’s take a look at each device, in isolation, now.   Kindle To me, what’s most innovative about the Kindle is its E Ink display. E Ink really looks like ink on a sheet of paper. It requires no backlight, it’s fully visible in direct sunlight and it causes almost none of the eyestrain that LCD-based computer display technology (like that used on the iPad) does. It’s really versatile in an all-around way. Forgive me if this sounds precious, but reading on it is really a joy. In fact, it’s a genuinely relaxing experience. Through the Kindle Store, Amazon allows users to download books (including audio books), magazines, newspapers and blog feeds. Books and magazines can be purchased either on a single-issue basis or as an annual subscription. Books, of course, are purchased singly. Oddly, blogs are not free, but instead carry a monthly subscription fee, typically $1.99. To me this is ludicrous, but I suppose the free 3G service is partially to blame. Books and magazine issues download quickly. Magazine and blog subscriptions cause new issues or posts to be pushed to your device on an automated basis. Available blogs include 9000-odd feeds that Amazon offers on the Kindle Store; unless I missed something, arbitrary RSS feeds are not supported (though there are third party workarounds to this limitation). The shopping experience is integrated well, has an huge selection, and offers certain graphical perks. For example, magazine and newspaper logos are displayed in menus, and book cover thumbnails appear as well. A simple search mechanism is provided and text entry through the physical keyboard is relatively painless. It’s very easy and straightforward to enter the store, find something you like and start reading it quickly. If you know what you’re looking for, it’s even faster. Given Kindle’s high portability, very reliable battery, instant-on capability and highly integrated content acquisition, it makes reading on whim, and in random spurts of downtime, very attractive. The Kindle’s home screen lists all of your publications, and easily lets you select one, then start reading it. Once opened, publications display in crisp, attractive text that is adjustable in size. “Turning” pages is achieved through buttons dedicated to the task. Notes can be recorded, bookmarks can be saved and pages can be saved as clippings. I am not an avid book reader, and yet I found the Kindle made it really fun, convenient and soothing to read. There’s something about the easy access to the material and the simplicity of the display that makes the Kindle seduce you into chilling out and reading page after page. On the other hand, the Kindle has an awkward navigation interface. While menus are displayed clearly on the screen, the method of selecting menu items is tricky: alongside the right-hand edge of the main display is a thin column that acts as a second display. It has a white background, and a scrollable silver cursor that is moved up or down through the use of the device’s scrollwheel. Picking a menu item on the main display involves scrolling the silver cursor to a position parallel to that menu item and pushing the scrollwheel in. This navigation technique creates a disconnect, literally. You don’t really click on a selection so much as you gesture toward it. I got used to this technique quickly, but I didn’t love it. It definitely created a kind of anxiety in me, making me feel the need to speed through menus and get to my destination document quickly. Once there, I could calm down and relax. Books are great on the Kindle. Magazines and newspapers much less so. I found the rendering of photographs, and even illustrations, to be unacceptably crude. For this reason, I expect that reading textbooks on the Kindle may leave students wanting. I found that the original flow and layout of any publication was sacrificed on the Kindle. In effect, browsing a magazine or newspaper was almost impossible. Reading the text of individual articles was enjoyable, but having to read this way made the whole experience much more “a la carte” than cohesive and thematic between articles. I imagine that for academic journals this is ideal, but for consumer publications it imposes a stripped-down, low-fidelity experience that evokes a sense of deprivation. In general, the Kindle is great for reading text. For just about anything else, especially activity that involves exploratory browsing, meandering and short-attention-span reading, it presents a real barrier to entry and adoption. Avid book readers will enjoy the Kindle (if they’re not already). It’s a great device for losing oneself in a book over long sittings. Multitaskers who are more interested in periodicals, be they online or off, will like it much less, as they will find compromise, and even sacrifice, to be palpable.   iPad The iPad is a very different device from the Kindle. While the Kindle is oriented to pages of text, the iPad orbits around applications and their interfaces. Be it the pinch and zoom experience in the browser, the rich media features that augment content on news and weather sites, or the ability to interact with social networking services like Twitter, the iPad is versatile. While it shares a slate-like form factor with the Kindle, it’s effectively an elegant personal computer. One of its many features is the iBook application and integration of the iBookstore. But it’s a multi-purpose device. That turns out to be good and bad, depending on what you’re reading. The iBookstore is great for browsing. It’s color, rich animation-laden user interface make it possible to shop for books, rather than merely search and acquire them. Unfortunately, its selection is rather sparse at the moment. If you’re looking for a New York Times bestseller, or other popular titles, you should be OK. If you want to read something more specialized, it’s much harder. Unlike the awkward navigation interface of the Kindle, the iPad offers a nearly flawless touch-screen interface that seduces the user into tinkering and kibitzing every bit as much as the Kindle lulls you into a deep, concentrated read. It’s a dynamic and interactive device, whereas the Kindle is static and passive. The iBook reader is slick and fun. Use the iPad in landscape mode and you can read the book in 2-up (left/right 2-page) display; use it in portrait mode and you can read one page at a time. Rather than clicking a hardware button to turn pages, you simply drag and wipe from right-to-left to flip the single or right-hand page. The page actually travels through an animated path as it would in a physical book. The intuitiveness of the interface is uncanny. The reader also accommodates saving of bookmarks, searching of the text, and the ability to highlight a word and look it up in a dictionary. Pages display brightly and clearly. They’re easy to read. But the backlight and the glare made me less comfortable than I was with the Kindle. The knowledge that completely different applications (including the Web and email and Twitter) were just a few taps away made me antsy and very tempted to task-switch. The knowledge that battery life is an issue created subtle discomfort. If the Kindle makes you feel like you’re in a library reading room, then the iPad makes you feel, at best, like you’re under fluorescent lights at a Barnes and Noble or Borders store. If you’re lucky, you’d be on a couch or at a reading table in the store, but you might also be standing up, in the aisles. Clearly, I didn’t find this conducive to focused and sustained reading. But that may have more to do with my own tendency to read periodicals far more than books, and my neurotic . And, truth be known, the book reading experience, when not explicitly compared to Kindle’s, was still pleasant. It is also important to point out that Kindle Store-sourced books can be read on the iPad through a Kindle reader application, from Amazon, specific to the device. This offered a less rich experience than the iBooks reader, but it was completely adequate. Despite the Kindle brand of the reader, however, it offered little in terms of simulating the reading experience on its namesake device. When it comes to periodicals, the iPad wins hands down. Magazines, even if merely scanned images of their print editions, read on the iPad in a way that felt similar to reading hard copy. The full color display, touch navigation and even the ability to render advertisements in their full glory makes the iPad a great way to read through any piece of work that is measured in pages, rather than chapters. There are many ways to get magazines and newspapers onto the iPad, including the Zinio reader, and publication-specific applications like the Wall Street Journal’s and Popular Science’s. The New York Times’ free Editors’ Choice application offers a Times Reader-like interface to a subset of the Gray Lady’s daily content. The completely Web-based but iPad-optimized Times Skimmer site (at www.nytimes.com/timesskimmer) works well too. Even conventional Web sites themselves can be read much like magazines, given the iPad’s ability to zoom in on the text and crop out advertisements on the margins. While the Kindle does have an experimental Web browser, it reminded me a lot of early mobile phone browsers, only in a larger size. For text-heavy sites with simple layout, it works fine. For just about anything else, it becomes more trouble than it’s worth. And given the way magazine articles make me think of things I want to look up online, I think that’s a real liability for the Kindle.   Summing Up What I came to realize is that the Kindle isn’t so much a computer or even an Internet device as it is a printer. While it doesn’t use physical paper, it still renders its content a page at a time, just like a laser printer does, and its output appears strikingly similar. You can read the rendered text, but you can’t interact with it in any way. That’s why the navigation requires a separate cursor display area. And because of the page-oriented rendering behavior, turning pages causes a flash on the display and requires a sometimes long pause before the next page is rendered. The good side of this is that once the page is generated, no battery power is required to display it. That makes for great battery life, optimal viewing under most lighting conditions (as long as there is some light) and low-eyestrain text-centric display of content. The Kindle is highly portable, has an excellent selection in its store and is refreshingly distraction-free. All of this is ideal for reading books. And iPad doesn’t offer any of it. What iPad does offer is versatility, variety, richness and luxury. It’s flush with accoutrements even if it’s low on focused, sustained text display. That makes it inferior to the Kindle for book reading. But that also makes it better than the Kindle for almost everything else. As such, and given that its book reading experience is still decent (even if not superior), I think the iPad will give Kindle a run for its money. True book lovers, and people on a budget, will want the Kindle. People with a robust amount of discretionary income may want both devices. Everyone else who is interested in a slate form factor e-reading device, especially if they also wish to have leisure-friendly Internet access, will likely choose the iPad exclusively. One thing is for sure: iPad has reduced Kindle’s market, and may have shifted its mass market potential to a mere niche play. If Amazon is smart, it will improve its iPad-based Kindle reader app significantly. It can then leverage the iPad channel as a significant market for the Kindle Store. After all, selling the eBooks themselves is what Amazon should care most about.

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• Sorting Algorithms

  - by MarkPearl

  General Every time I go back to university I find myself wading through sorting algorithms and their implementation in C++. Up to now I haven’t really appreciated their true value. However as I discovered this last week with Dictionaries in C# – having a knowledge of some basic programming principles can greatly improve the performance of a system and make one think twice about how to tackle a problem. I’m going to cover briefly in this post the following: Selection Sort Insertion Sort Shellsort Quicksort Mergesort Heapsort (not complete) Selection Sort Array based selection sort is a simple approach to sorting an unsorted array. Simply put, it repeats two basic steps to achieve a sorted collection. It starts with a collection of data and repeatedly parses it, each time sorting out one element and reducing the size of the next iteration of parsed data by one. So the first iteration would go something like this… Go through the entire array of data and find the lowest value Place the value at the front of the array The second iteration would go something like this… Go through the array from position two (position one has already been sorted with the smallest value) and find the next lowest value in the array. Place the value at the second position in the array This process would be completed until the entire array had been sorted. A positive about selection sort is that it does not make many item movements. In fact, in a worst case scenario every items is only moved once. Selection sort is however a comparison intensive sort. If you had 10 items in a collection, just to parse the collection you would have 10+9+8+7+6+5+4+3+2=54 comparisons to sort regardless of how sorted the collection was to start with. If you think about it, if you applied selection sort to a collection already sorted, you would still perform relatively the same number of iterations as if it was not sorted at all. Many of the following algorithms try and reduce the number of comparisons if the list is already sorted – leaving one with a best case and worst case scenario for comparisons. Likewise different approaches have different levels of item movement. Depending on what is more expensive, one may give priority to one approach compared to another based on what is more expensive, a comparison or a item move. Insertion Sort Insertion sort tries to reduce the number of key comparisons it performs compared to selection sort by not “doing anything” if things are sorted. Assume you had an collection of numbers in the following order… 10 18 25 30 23 17 45 35 There are 8 elements in the list. If we were to start at the front of the list – 10 18 25 & 30 are already sorted. Element 5 (23) however is smaller than element 4 (30) and so needs to be repositioned. We do this by copying the value at element 5 to a temporary holder, and then begin shifting the elements before it up one. So… Element 5 would be copied to a temporary holder 10 18 25 30 23 17 45 35 – T 23 Element 4 would shift to Element 5 10 18 25 30 30 17 45 35 – T 23 Element 3 would shift to Element 4 10 18 25 25 30 17 45 35 – T 23 Element 2 (18) is smaller than the temporary holder so we put the temporary holder value into Element 3. 10 18 23 25 30 17 45 35 – T 23   We now have a sorted list up to element 6. And so we would repeat the same process by moving element 6 to a temporary value and then shifting everything up by one from element 2 to element 5. As you can see, one major setback for this technique is the shifting values up one – this is because up to now we have been considering the collection to be an array. If however the collection was a linked list, we would not need to shift values up, but merely remove the link from the unsorted value and “reinsert” it in a sorted position. Which would reduce the number of transactions performed on the collection. So.. Insertion sort seems to perform better than selection sort – however an implementation is slightly more complicated. This is typical with most sorting algorithms – generally, greater performance leads to greater complexity. Also, insertion sort performs better if a collection of data is already sorted. If for instance you were handed a sorted collection of size n, then only n number of comparisons would need to be performed to verify that it is sorted. It’s important to note that insertion sort (array based) performs a number item moves – every time an item is “out of place” several items before it get shifted up. Shellsort – Diminishing Increment Sort So up to now we have covered Selection Sort & Insertion Sort. Selection Sort makes many comparisons and insertion sort (with an array) has the potential of making many item movements. Shellsort is an approach that takes the normal insertion sort and tries to reduce the number of item movements. In Shellsort, elements in a collection are viewed as sub-collections of a particular size. Each sub-collection is sorted so that the elements that are far apart move closer to their final position. Suppose we had a collection of 15 elements… 10 20 15 45 36 48 7 60 18 50 2 19 43 30 55 First we may view the collection as 7 sub-collections and sort each sublist, lets say at intervals of 7 10 60 55 – 20 18 – 15 50 – 45 2 – 36 19 – 48 43 – 7 30 10 55 60 – 18 20 – 15 50 – 2 45 – 19 36 – 43 48 – 7 30 (Sorted) We then sort each sublist at a smaller inter – lets say 4 10 55 60 18 – 20 15 50 2 – 45 19 36 43 – 48 7 30 10 18 55 60 – 2 15 20 50 – 19 36 43 45 – 7 30 48 (Sorted) We then sort elements at a distance of 1 (i.e. we apply a normal insertion sort) 10 18 55 60 2 15 20 50 19 36 43 45 7 30 48 2 7 10 15 18 19 20 30 36 43 45 48 50 55 (Sorted) The important thing with shellsort is deciding on the increment sequence of each sub-collection. From what I can tell, there isn’t any definitive method and depending on the order of your elements, different increment sequences may perform better than others. There are however certain increment sequences that you may want to avoid. An even based increment sequence (e.g. 2 4 8 16 32 …) should typically be avoided because it does not allow for even elements to be compared with odd elements until the final sort phase – which in a way would negate many of the benefits of using sub-collections. The performance on the number of comparisons and item movements of Shellsort is hard to determine, however it is considered to be considerably better than the normal insertion sort. Quicksort Quicksort uses a divide and conquer approach to sort a collection of items. The collection is divided into two sub-collections – and the two sub-collections are sorted and combined into one list in such a way that the combined list is sorted. The algorithm is in general pseudo code below… Divide the collection into two sub-collections Quicksort the lower sub-collection Quicksort the upper sub-collection Combine the lower & upper sub-collection together As hinted at above, quicksort uses recursion in its implementation. The real trick with quicksort is to get the lower and upper sub-collections to be of equal size. The size of a sub-collection is determined by what value the pivot is. Once a pivot is determined, one would partition to sub-collections and then repeat the process on each sub collection until you reach the base case. With quicksort, the work is done when dividing the sub-collections into lower & upper collections. The actual combining of the lower & upper sub-collections at the end is relatively simple since every element in the lower sub-collection is smaller than the smallest element in the upper sub-collection. Mergesort With quicksort, the average-case complexity was O(nlog2n) however the worst case complexity was still O(N*N). Mergesort improves on quicksort by always having a complexity of O(nlog2n) regardless of the best or worst case. So how does it do this? Mergesort makes use of the divide and conquer approach to partition a collection into two sub-collections. It then sorts each sub-collection and combines the sorted sub-collections into one sorted collection. The general algorithm for mergesort is as follows… Divide the collection into two sub-collections Mergesort the first sub-collection Mergesort the second sub-collection Merge the first sub-collection and the second sub-collection As you can see.. it still pretty much looks like quicksort – so lets see where it differs… Firstly, mergesort differs from quicksort in how it partitions the sub-collections. Instead of having a pivot – merge sort partitions each sub-collection based on size so that the first and second sub-collection of relatively the same size. This dividing keeps getting repeated until the sub-collections are the size of a single element. If a sub-collection is one element in size – it is now sorted! So the trick is how do we put all these sub-collections together so that they maintain their sorted order. Sorted sub-collections are merged into a sorted collection by comparing the elements of the sub-collection and then adjusting the sorted collection. Lets have a look at a few examples… Assume 2 sub-collections with 1 element each 10 & 20 Compare the first element of the first sub-collection with the first element of the second sub-collection. Take the smallest of the two and place it as the first element in the sorted collection. In this scenario 10 is smaller than 20 so 10 is taken from sub-collection 1 leaving that sub-collection empty, which means by default the next smallest element is in sub-collection 2 (20). So the sorted collection would be 10 20 Lets assume 2 sub-collections with 2 elements each 10 20 & 15 19 So… again we would Compare 10 with 15 – 10 is the winner so we add it to our sorted collection (10) leaving us with 20 & 15 19 Compare 20 with 15 – 15 is the winner so we add it to our sorted collection (10 15) leaving us with 20 & 19 Compare 20 with 19 – 19 is the winner so we add it to our sorted collection (10 15 19) leaving us with 20 & _ 20 is by default the winner so our sorted collection is 10 15 19 20. Make sense? Heapsort (still needs to be completed) So by now I am tired of sorting algorithms and trying to remember why they were so important. I think every year I go through this stuff I wonder to myself why are we made to learn about selection sort and insertion sort if they are so bad – why didn’t we just skip to Mergesort & Quicksort. I guess the only explanation I have for this is that sometimes you learn things so that you can implement them in future – and other times you learn things so that you know it isn’t the best way of implementing things and that you don’t need to implement it in future. Anyhow… luckily this is going to be the last one of my sorts for today. The first step in heapsort is to convert a collection of data into a heap. After the data is converted into a heap, sorting begins… So what is the definition of a heap? If we have to convert a collection of data into a heap, how do we know when it is a heap and when it is not? The definition of a heap is as follows: A heap is a list in which each element contains a key, such that the key in the element at position k in the list is at least as large as the key in the element at position 2k +1 (if it exists) and 2k + 2 (if it exists). Does that make sense? At first glance I’m thinking what the heck??? But then after re-reading my notes I see that we are doing something different – up to now we have really looked at data as an array or sequential collection of data that we need to sort – a heap represents data in a slightly different way – although the data is stored in a sequential collection, for a sequential collection of data to be in a valid heap – it is “semi sorted”. Let me try and explain a bit further with an example… Example 1 of Potential Heap Data Assume we had a collection of numbers as follows 1[1] 2[2] 3[3] 4[4] 5[5] 6[6] For this to be a valid heap element with value of 1 at position [1] needs to be greater or equal to the element at position [3] (2k +1) and position [4] (2k +2). So in the above example, the collection of numbers is not in a valid heap. Example 2 of Potential Heap Data Lets look at another collection of numbers as follows 6[1] 5[2] 4[3] 3[4] 2[5] 1[6] Is this a valid heap? Well… element with the value 6 at position 1 must be greater or equal to the element at position [3] and position [4]. Is 6 > 4 and 6 > 3? Yes it is. Lets look at element 5 as position 2. It must be greater than the values at [4] & [5]. Is 5 > 3 and 5 > 2? Yes it is. If you continued to examine this second collection of data you would find that it is in a valid heap based on the definition of a heap.

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• CodePlex Daily Summary for Tuesday, November 13, 2012

  CodePlex Daily Summary for Tuesday, November 13, 2012Popular ReleasesSymphony Framework: Symphony Framework v2.0.0.6: Symphony Framework version 2.0.0.6. has just been released General note: If you install Symphony Framework 2.0.0.6 you must re-generate all your code-generated source files, resource files, controls and windows. Failure to regenerate will cause your applications to fail. Symphony Framework requires at least version 4.2.3 of CodeGen due to some new functionality that has been added. Please ensure that you download and install the latest version of CodeGen. You can review the full release ...AcDown?????: AcDown????? v4.3: ??●AcDown??????????、??、??、???????。????，????，?????????????????????????。???????????Acfun、????(Bilibili)、??、??、YouTube、??、???、??????、SF????、????????????。 ●??????AcPlay?????，??????、????????????????。 ● AcDown??????????????????，????????????????????????????。 ● AcDown???????C#??，????.NET Framework 2.0??。?????"Acfun?????"。 ????32??64? Windows XP/Vista/7/8 ???? 32??64? ???Linux ????(1)????????Windows XP???，????????.NET Framework 2.0???(x86)，?????"?????????"??? (2)???????????Linux???，????????Mono?? ??2...WallSwitch: WallSwitch 1.2.1: Version 1.2.1 Changes: Improved collage image distribution to overlap older images first. Set default collage background blur distance to 4 (provides a more gradual effect). Fixed issue where wallpaper not displayed on Windows Vista when Cross-Fade transitions enabled. Fixed issue with duplicated themes not updating history view correctly.????: ???? 1.0: ????ALinq Dynamic (Entity SQL for Linq to SQL): ALinq Dynamic v1.1: 1. Fix a few bugs about aggregate function. 2. Supports more functions. 3. Append more samples.Unicode IVS Add-in for Microsoft Office: Unicode IVS Add-in for Microsoft Office: Unicode IVS Add-in for Microsoft Office ??? ?????、Unicode IVS?????????????????Unicode IVS???????????????。??、??????????????、?????????????????????????????。Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.74: fix for issue #18836 - sometimes throws null-reference errors in ActivationObject.AnalyzeScope method. add back the Context object's 8-parameter constructor, since someone has code that's using it. throw a low-pri warning if an expression statement is == or ===; warn that the developer may have meant an assignment (=). if window.XXXX or window"XXXX" is encountered, add XXXX (as long as it's a valid JavaScript identifier) to the known globals so subsequent references to XXXX won't throw ...Home Access Plus+: v8.3: Changes: Fixed: A odd scroll bar showing up for no reason Changed: Added some code to hopefully sort out the details view when there is a small number of files Fixed: Where the details toolbar shows in the wrong place until you scroll Fixed: Where the Help Desk live tile shows all open tiles, instead of user specific tiles (admins still see all) Added: Powerpoint Files Filter Added: Print style for Booking System Added: Silent check for the logon tracker Updated: Logon Tracker I...???????: Monitor 2012-11-11: This is the first releaseVidCoder: 1.4.5 Beta: Removed the old Advanced user interface and moved x264 preset/profile/tune there instead. The functionality is still available through editing the options string. Added ability to specify the H.264 level. Added ability to choose VidCoder's interface language. If you are interested in translating, we can get VidCoder in your language! Updated WPF text rendering to use the better Display mode. Updated HandBrake core to SVN 5045. Removed logic that forced the .m4v extension in certain ...ImageGlass: Version 1.5: http://i1214.photobucket.com/albums/cc483/phapsuxeko/ImageGlass/1.png v1.5.4401.3015 Thumbnail bar: Increase loading speed Thumbnail image with ratio Support personal customization: mouse up, mouse down, mouse hover, selected item... Scroll to show all items Image viewer Zoom by scroll, or selected rectangle Speed up loading Zoom to cursor point New background design and customization and others... v1.5.4430.483 Thumbnail bar: Auto move scroll bar to selected image Show / Hi...Building Windows 8 Apps with C# and XAML: Full Source Chapters 1 - 10 for Windows 8 Fix 002: This is the full source from all chapters of the book, compiled and tested on Windows 8 RTM. Includes: A fix for the Netflix example from Chapter 6 that was missing a service reference A fix for the ImageHelper issue (images were not being saved) - this was due to the buffer being inadequate and required streaming the writeable bitmap to a buffer first before encoding and savingmyCollections: Version 2.3.2.0: New in this version : Added TheGamesDB.net API for Games and NDS Added Support for Windows Media Center Added Support for myMovies Added Support for XBMC Added Support for Dune HD Added Support for Mede8er Added Support for WD HDTV Added Fast search options Added order by Artist/Album for music You can now create covers and background for games You can now update your ID3 tag with the info of myCollections Fixed several provider Performance improvement New Splash ...Draw: Draw 1.0: Drawing PadPlayer Framework by Microsoft: Player Framework for Windows 8 (v1.0): IMPORTANT: List of breaking changes from preview 7 Ability to move control panel or individual elements outside media player. more info... 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Pored novosti vezanih uz (sitne) izmjene u spomenutoj novoj verziji Tehnicke dokumentacije, projekt smo prošili sa nekim dodatnim feature-ima od kojih je vecina proizašla iz vaših prijedloga - hvala :) Novosti u v1.2. su: - Neusuglašenost zahtjeva (http://fiskalizacija.codeplex.com/workitem/645) - Sample projekt - iznosi se množe sa 100 (http://fiskalizacija.codeplex.c...New Projects3jidi IPTV App: 3jidi IPTV application on microsoft mediaroomAX 2012 Custom Operating Units: With this tool, non technical users can create custom operating units, link them with existing org model, model custom units as financial dimensions etc.BASE32 Encoder: This awesome app let you convert all your music, pictures and video to brand new BASE32 encoding! BilgeAdam.ChannelShow: BilgeAdam.ChannelShowBlueset Studio Opensource Projects: Only for Opensource projects form Blueset Studio.Bubble Trouble: This is a game where you are trapped in a room with lethal bubbles bouncing around the rooms. You must use your special vine gun to shoot and pop the bubbles!ClomibepASP (Suspended): PL: Zaawansowany system zarzadzania trescia ClomibepASP. EN: Advenced content managment system ClomibepASP.CoBaS - Contract Based Serializer: The serialization framework that cares for bits and speed :)DelegateDuck: New stub library for C#. You can build with it any object using delegates and such an object can be casted to any compatible interface.Demir Yayincilik: Ulusal arastirmacilarin ana dilleri ile yaptiklari yayinlarin kolay dagitilmasi ve izlenmesi gereksiniminden hareketle kurulan Demir yayincilik...DNN LiveEvents: DotNetNuke Live Events ModuleFamFamFam Silk Icons Atlas (CSS Sprites): A CSS/Image generator for CSS Sprites (Atlas) for FamFamFam Silk iconsGuid Finder Solution for Microsoft Dynamics CRM 2011: Guid Finder Solution for Microsoft Dynamics CRM 2011. This Solution helps to find any record "GUID" across all entities in Dynamics CRM. hyd: a game demoJogo do Galo: JOGO DO GALO REGRAS •O tabuleiro é a matriz de três linhas em três colunas. •Dois jogadores escolhem três peças cada um. •Os jogadores jogam alternadamente, uma peça de cada vez, num espaço que esteja vazio. •O objectivo é conseguir três peças iguais em linha, quer horizontal, vjQCalendarPart: jQCalendarPart is a JS application which when added to a CEWP in SP 2010 will display a jQuery Calendar control with the upcoming events from the Calendar list.Kinect Table Tennis: A 2D Top-down Kinect table tennis game! Booyeah!MathNullable: The example of the Nullable Mathematics.Metro Launch: Metro Launch is a new Start menu inspired by Windows 8's.Monoxide.Diagnostics: This is Systems.Diagnostics source code extracted from Mono so that people on any platform (Windows, too!) can extend more of the tracing framework.new1325: hellonew1327: helloPizza-Service: School Project of a Pizza-Service application.ProjectOnElance: SomeProjectOnElanceRemote Controller for Trackmania: Evzrecon is a remote controller for Trackmania Forever dedicated servers, much like XASECO but written in Java.SoftRenderer: a software rendererStripeOne ShortenUrl: Projeto de estudo para encurtar urls, com cms para o usuário (caso seja registrado ou por sessão) e cms administrativo com estatisticas de urls mais usadas.testtom11122012git01: htesttom11122012hg01: fdstesttom11122012tfs01: fdstesttom11122012tfs03: rewThe new Basecamp API C# Wrapper: This project aims to be a complete C# wrapper around the new Basecamp API. Direct API call support in addition to convenience methods are provided.TVendas: Este projeto surgiu com a necessidade de se ter um software de gerenciamento de vendas web e gratuito. Então surgiu o TVendas.WDTVHUBLIVE Companion: Intitial summary : This is a project to learn C# and to create an application to manage media on a WDTVLiveHub. WordTrending: ECE 275 Assignment #4Yet another SharePoint 2010 Deployment Script: The following PowerShell script is intended to help operations staff as well as developers to automate the base installation of SharePoint 2010 Server. Zytonic Hotkeys: Zytonic Hotkeys Is a User Library That Aims to defeat The hassle of creating User Hotkeys for your .NET Applications.????: ????

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• Using Deployment Manager

  - by Jess Nickson

  One of the teams at Red Gate has been working very hard on a new product: Deployment Manager. Deployment Manager is a free tool that lets you deploy updates to .NET apps, services and databases through a central dashboard. Deployment Manager has been out for a while, but I must admit that even though I work in the same building, until now I hadn’t even looked at it. My job at Red Gate is to develop and maintain some of our community sites, which involves carrying out regular deployments. One of the projects I have to deploy on a fairly regular basis requires me to send my changes to our build server, TeamCity. The output is a Zip file of the build. I then have to go and find this file, copy it across to the staging machine, extract it, and copy some of the sub-folders to other places. In order to keep track of what builds are running, I need to rename the folders accordingly. However, even after all that, I still need to go and update the site and its applications in IIS to point at these new builds. Oh, and then, I have to repeat the process when I deploy on production. Did I mention the multiple configuration files that then need updating as well? Manually? The whole process can take well over half an hour. I’m ready to try out a new process. Deployment Manager is designed to massively simplify the deployment processes from what could be lots of manual copying of files, managing of configuration files, and database upgrades down to a few clicks. It’s a big promise, but I decided to try out this new tool on one of the smaller ASP.NET sites at Red Gate, Format SQL (the result of a Red Gate Down Tools week). I wanted to add some new functionality, but given it was a new site with no set way of doing things, I was reluctant to have to manually copy files around servers. I decided to use this opportunity as a chance to set the site up on Deployment Manager and check out its functionality. What follows is a guide on how to get set up with Deployment Manager, a brief overview of its features, and what I thought of the experience. To follow along with the instructions that follow, you’ll first need to download Deployment Manager from Red Gate. It has a free ‘Starter Edition’ which allows you to create up to 5 projects and agents (machines you deploy to), so it’s really easy to get up and running with a fully-featured version. The Initial Set Up After installing the product and setting it up using the administration tool it provides, I launched Deployment Manager by going to the URL and port I had set it to run on. This loads up the main dashboard. The dashboard does a good job of guiding me through the process of getting started, beginning with a prompt to create some environments. 1. Setting up Environments The dashboard informed me that I needed to add new ‘Environments’, which are essentially ways of grouping the machines you want to deploy to. The environments that get added will show up on the main dashboard. I set up two such environments for this project: ‘staging’ and ‘live’.   2. Add Target Machines Once I had created the environments, I was ready to add ‘target machine’s to them, which are the actual machines that the deployment will occur on.   To enable me to deploy to a new machine, I needed to download and install an Agent on it. The ‘Add target machine’ form on the ‘Environments’ page helpfully provides a link for downloading an Agent.   Once the agent has been installed, it is just a case of copying the server key to the agent, and the agent key to the server, to link them up.   3. Run Health Check If, after adding your new target machine, the ‘Status’ flags an error, it is possible that the Agent and Server keys have not been entered correctly on both Deployment Manager and the Agent service.     You can ‘Check Health’, which will give you more information on any issues. It is probably worth running this regardless of what status the ‘Environments’ dashboard is claiming, just to be on the safe side.     4. Add Projects Going back to the main Dashboard tab at this point, I found that it was telling me that I needed to set up a new project.   I clicked the ‘project’ link to get started, gave my new project a name and clicked ‘Create’. I was then redirected to the ‘Steps’ page for the project under the Projects tab.   5. Package Steps The ‘Steps’ page was fairly empty when it first loaded.   Adding a ‘step’ allowed me to specify what packages I wanted to grab for the deployment. This part requires a NuGet package feed to be set up, which is where Deployment Manager will look for the packages. At Red Gate, we already have one set up, so I just needed to tell Deployment Manager about it. Don’t worry; there is a nice guide included on how to go about doing all of this on the ‘Package Feeds’ page in ‘Settings’, if you need any help with setting these bits up.    At Red Gate we use a build server, TeamCity, which is capable of publishing built projects to the NuGet feed we use. This makes the workflow for Format SQL relatively simple: when I commit a change to the project, the build server is configured to grab those changes, build the project, and spit out a new NuGet package to the Red Gate NuGet package feed. My ‘package step’, therefore, is set up to look for this package on our feed. The final part of package step was simply specifying which machines from what environments I wanted to be able to deploy the project to.     Format SQL Now the main Dashboard showed my new project and environment in a rather empty looking grid. Clicking on my project presented me with a nice little message telling me that I am now ready to create my first release!   Create a release Next I clicked on the ‘Create release’ button in the Projects tab. If your feeds and package step(s) were set up correctly, then Deployment Manager will automatically grab the latest version of the NuGet package that you want to deploy. As you can see here, it was able to pick up the latest build for Format SQL and all I needed to do was enter a version number and description of the release.   As you can see underneath ‘Version number’, it keeps track of what version the previous release was given. Clicking ‘Create’ created the release and redirected me to a summary of it where I could check the details before deploying.   I clicked ‘Deploy this release’ and chose the environment I wanted to deploy to and…that’s it. Deployment Manager went off and deployed it for me.   Once I clicked ‘Deploy release’, Deployment Manager started to automatically update and provide continuing feedback about the process. If any errors do arise, then I can expand the results to see where it went wrong. That’s it, I’m done! Keep in mind, if you hit errors with the deployment itself then it is possible to view the log output to try and determine where these occurred. You can keep expanding the logs to narrow down the problem. The screenshot below is not from my Format SQL deployment, but I thought I’d post one to demonstrate the logging output available. Features One of the best bits of Deployment Manager for me is the ability to very, very easily deploy the same release to multiple machines. Deploying this same release to production was just a case of selecting the deployment and choosing the ‘live’ environment as the place to deploy to. Following on from this is the fact that, as Deployment Manager keeps track of all of your releases, it is extremely easy to roll back to a previous release if anything goes pear-shaped! You can view all your previous releases and select one to re-deploy. I needed this feature more than once when differences in my production and staging machines lead to some odd behavior.     Another option is to use the TeamCity integration available. This enables you to set Deployment Manager up so that it will automatically create releases and deploy these to an environment directly from TeamCity, meaning that you can always see the latest version up and running without having to do anything. Machine Specific Deployments ‘What about custom configuration files?’ I hear you shout. Certainly, it was one of my concerns. Our setup on the staging machine is not in line with that on production. What this means is that, should we deploy the same configuration to both, one of them is going to break. Thankfully, it turns out that Deployment Manager can deal with this. Given I had environments ‘staging’ and ‘live’, and that staging used the project’s web.config file, while production (‘live’) required the config file to undergo some transformations, I simply added a web.live.config file in the project, so that it would be included as part of the NuGet package. In this file, I wrote the XML document transformations I needed and Deployment Manager took care of the rest. Another option is to set up ‘variables’ for your project, which allow you to specify key-value pairs for your configuration file, and which environment to apply them to. You’ll find Variables as a full left-hand submenu within the ‘Projects’ tab. These features will definitely be of interest if you have a large number of environments! There are still many other features that I didn’t get a chance to play around with like running PowerShell scripts for more personalised deployments. Maybe next time! Also, let’s not forget that my use case in this article is a very simple one – deploying a single package. I don’t believe that all projects will be equally as simple, but I already appreciate how much easier Deployment Manager could make my life. I look forward to the possibility of moving our other sites over to Deployment Manager in the near future.   Conclusion In this article I have described the steps involved in setting up and configuring an instance of Deployment Manager, creating a new automated deployment process, and using this to actually carry out a deployment. I’ve tried to mention some of the features I found particularly useful, such as error logging, easy release management allowing you to deploy the same release multiple times, and configuration file transformations. If I had to point out one issue, then it would be that the releases are immutable, which from a development point of view makes sense. However, this causes confusion where I have to create a new release to deploy to a newly set up environment – I cannot simply deploy an old release onto a new environment, the whole release needs to be recreated. I really liked how easy it was to get going with the product. Setting up Format SQL and making a first deployment took very little time. Especially when you compare it to how long it takes me to manually deploy the other site, as I described earlier. I liked how it let me know what I needed to do next, with little messages flagging up that I needed to ‘create environments’ or ‘add some deployment steps’ before I could continue. I found the dashboard incredibly convenient. As the number of projects and environments increase, it might become awkward to try and search them and find out what state they are in. Instead, the dashboard handily keeps track of the latest deployments of each project and lets you know what version is running on each of the environments, and when that deployment occurred. Finally, do you remember my complaint about having to rename folders so that I could keep track of what build they came from? This is yet another thing that Deployment Manager takes care of for you. Each release is put into its own directory, which takes the name of whatever version number that release has, though these can be customised if necessary. If you’d like to take a look at Deployment Manager for yourself, then you can download it here.

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• Entity Framework 4.3.1 Code based Migrations and Connector/Net 6.6

  - by GABMARTINEZ

   Code-based migrations is a new feature as part of the Connector/Net support for Entity Framework 4.3.1. In this tutorial we'll see how we can use it so we can keep track of the changes done to our database creating a new application using the code first approach. If you don't have a clear idea about how code first works we highly recommend you to check this subject before going further with this tutorial. Creating our Model and Database with Code First  From VS 2010  1. Create a new console application 2.  Add the latest Entity Framework official package using Package Manager Console (Tools Menu, then Library Package Manager -> Package Manager Console). In the Package Manager Console we have to type  Install-Package EntityFramework This will add the latest version of this library.  We will also need to make some changes to your config file. A <configSections> was added which contains the version you have from EntityFramework.  An <entityFramework> section was also added where you can set up some initialization. This section is optional and by default is generated to use SQL Express. Since we don't need it for now (we'll see more about it below) let's leave this section empty as shown below. 3. Create a new Model with a simple entity. 4. Enable Migrations to generate the our Configuration class. In the Package Manager Console we have to type  Enable-Migrations; This will make some changes in our application. It will create a new folder called Migrations where all the migrations representing the changes we do to our model.  It will also create a Configuration class that we'll be using to initialize our SQL Generator and some other values like if we want to enable Automatic Migrations.  You can see that it already has the name of our DbContext. You can also create you Configuration class manually. 5. Specify our Model Provider. We need to specify in our Class Configuration that we'll be using MySQLClient since this is not part of the generated code. Also please make sure you have added the MySql.Data and the MySql.Data.Entity references to your project. using MySql.Data.Entity;   // Add the MySQL.Data.Entity namespace public Configuration() { this.AutomaticMigrationsEnabled = false; SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());    // This will add our MySQLClient as SQL Generator } 6. Add our Data Provider and set up our connection string <connectionStrings> <add name="PersonalContext" connectionString="server=localhost;User Id=root;database=Personal;" providerName="MySql.Data.MySqlClient" /> </connectionStrings> <system.data> <DbProviderFactories> <remove invariant="MySql.Data.MySqlClient" /> <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.6.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" /> </DbProviderFactories> </system.data> * The version recommended to use of Connector/Net is 6.6.2 or earlier. At this point we can create our database and then start working with Migrations. So let's do some data access so our database get's created. You can run your application and you'll get your database Personal as specified in our config file. Add our first migration Migrations are a great resource as we can have a record for all the changes done and will generate the MySQL statements required to apply these changes to the database. Let's add a new property to our Person class public string Email { get; set; } If you try to run your application it will throw an exception saying  The model backing the 'PersonelContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269). So as suggested let's add our first migration for this change. In the Package Manager Console let's type Add-Migration AddEmailColumn Now we have the corresponding class which generate the necessary operations to update our database. namespace MigrationsFromScratch.Migrations { using System.Data.Entity.Migrations; public partial class AddEmailColumn : DbMigration { public override void Up(){ AddColumn("People", "Email", c => c.String(unicode: false)); } public override void Down() { DropColumn("People", "Email"); } } } In the Package Manager Console let's type Update-Database Now you can check your database to see all changes were succesfully applied. Now let's add a second change and generate our second migration public class Person   {       [Key]       public int PersonId { get; set;}       public string Name { get; set; }       public string Address {get; set;}       public string Email { get; set; }       public List<Skill> Skills { get; set; }   }   public class Skill   {     [Key]     public int SkillId { get; set; }     public string Description { get; set; }   }   public class PersonelContext : DbContext   {     public DbSet<Person> Persons { get; set; }     public DbSet<Skill> Skills { get; set; }   } If you would like to customize any part of this code you can do that at this step. You can see there is the up method which can update your database and the down that can revert the changes done. If you customize any code you should make sure to customize in both methods. Now let's apply this change. Update-database -verbose I added the verbose flag so you can see all the SQL generated statements to be run. Downgrading changes So far we have always upgraded to the latest migration, but there may be times when you want downgrade to a specific migration. Let's say we want to return to the status we have before our last migration. We can use the -TargetMigration option to specify the migration we'd like to return. Also you can use the -verbose flag. If you like to go  back to the Initial state you can do: Update-Database -TargetMigration:$InitialDatabase  or equivalent: Update-Database -TargetMigration:0  Migrations doesn't allow by default a migration that would ocurr in a data loss. One case when you can got this message is for example in a DropColumn operation. You can override this configuration by setting AutomaticMigrationDataLossAllowed to true in the configuration class. Also you can set your Database Initializer in case you want that these Migrations can be applied automatically and you don't have to go all the way through creating a migration and updating later the changes. Let's see how. Database Initialization by Code We can specify an initialization strategy by using Database.SetInitializer (http://msdn.microsoft.com/en-us/library/gg679461(v=vs.103)). One of the strategies that I found very useful when you are at a development stage (I mean not for production) is the MigrateDatabaseToLatestVersion. This strategy will make all the necessary migrations each time there is a change in our model that needs a database replication, this also implies that we have to enable AutomaticMigrationsEnabled flag in our Configuration class. public Configuration()         {             AutomaticMigrationsEnabled = true;             AutomaticMigrationDataLossAllowed = true;             SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());    // This will add our MySQLClient as SQL Generator          } In the new EntityFramework section of your Config file we can set this at a context level basis.  The syntax is as follows: <contexts> <context type="Custom DbContext name, Assembly name"> <databaseInitializer type="System.Data.Entity.MigrateDatabaseToLatestVersion`2[[ Custom DbContext name, Assembly name],  [Configuration class name, Assembly name]],  EntityFramework" /> </context> </contexts> In our example this would be: The syntax is kind of odd but very convenient. This way all changes will always be applied when we do any data access in our application. There are a lot of new things to explore in EF 4.3.1 and Migrations so we'll continue writing some more posts about it. Please let us know if you have any questions or comments, also please check our forums here where we keep answering questions in general for the community.  Hope you found this information useful. Happy MySQL/.Net Coding! 

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• Using FiddlerCore to capture HTTP Requests with .NET

  - by Rick Strahl

  Over the last few weeks I’ve been working on my Web load testing utility West Wind WebSurge. One of the key components of a load testing tool is the ability to capture URLs effectively so that you can play them back later under load. One of the options in WebSurge for capturing URLs is to use its built-in capture tool which acts as an HTTP proxy to capture any HTTP and HTTPS traffic from most Windows HTTP clients, including Web Browsers as well as standalone Windows applications and services. To make this happen, I used Eric Lawrence’s awesome FiddlerCore library, which provides most of the functionality of his desktop Fiddler application, all rolled into an easy to use library that you can plug into your own applications. FiddlerCore makes it almost too easy to capture HTTP content! For WebSurge I needed to capture all HTTP traffic in order to capture the full HTTP request – URL, headers and any content posted by the client. The result of what I ended up creating is this semi-generic capture form: In this post I’m going to demonstrate how easy it is to use FiddlerCore to build this HTTP Capture Form.  If you want to jump right in here are the links to get Telerik’s Fiddler Core and the code for the demo provided here. FiddlerCore Download FiddlerCore on NuGet Show me the Code (WebSurge Integration code from GitHub) Download the WinForms Sample Form West Wind Web Surge (example implementation in live app) Note that FiddlerCore is bound by a license for commercial usage – see license.txt in the FiddlerCore distribution for details. Integrating FiddlerCore FiddlerCore is a library that simply plugs into your application. You can download it from the Telerik site and manually add the assemblies to your project, or you can simply install the NuGet package via:       PM> Install-Package FiddlerCore The library consists of the FiddlerCore.dll as well as a couple of support libraries (CertMaker.dll and BCMakeCert.dll) that are used for installing SSL certificates. I’ll have more on SSL captures and certificate installation later in this post. But first let’s see how easy it is to use FiddlerCore to capture HTTP content by looking at how to build the above capture form. Capturing HTTP Content Once the library is installed it’s super easy to hook up Fiddler functionality. Fiddler includes a number of static class methods on the FiddlerApplication object that can be called to hook up callback events as well as actual start monitoring HTTP URLs. In the following code directly lifted from WebSurge, I configure a few filter options on Form level object, from the user inputs shown on the form by assigning it to a capture options object. In the live application these settings are persisted configuration values, but in the demo they are one time values initialized and set on the form. Once these options are set, I hook up the AfterSessionComplete event to capture every URL that passes through the proxy after the request is completed and start up the Proxy service:void Start() { if (tbIgnoreResources.Checked) CaptureConfiguration.IgnoreResources = true; else CaptureConfiguration.IgnoreResources = false; string strProcId = txtProcessId.Text; if (strProcId.Contains('-')) strProcId = strProcId.Substring(strProcId.IndexOf('-') + 1).Trim(); strProcId = strProcId.Trim(); int procId = 0; if (!string.IsNullOrEmpty(strProcId)) { if (!int.TryParse(strProcId, out procId)) procId = 0; } CaptureConfiguration.ProcessId = procId; CaptureConfiguration.CaptureDomain = txtCaptureDomain.Text; FiddlerApplication.AfterSessionComplete += FiddlerApplication_AfterSessionComplete; FiddlerApplication.Startup(8888, true, true, true); } The key lines for FiddlerCore are just the last two lines of code that include the event hookup code as well as the Startup() method call. Here I only hook up to the AfterSessionComplete event but there are a number of other events that hook various stages of the HTTP request cycle you can also hook into. Other events include BeforeRequest, BeforeResponse, RequestHeadersAvailable, ResponseHeadersAvailable and so on. In my case I want to capture the request data and I actually have several options to capture this data. AfterSessionComplete is the last event that fires in the request sequence and it’s the most common choice to capture all request and response data. I could have used several other events, but AfterSessionComplete is one place where you can look both at the request and response data, so this will be the most common place to hook into if you’re capturing content. The implementation of AfterSessionComplete is responsible for capturing all HTTP request headers and it looks something like this:private void FiddlerApplication_AfterSessionComplete(Session sess) { // Ignore HTTPS connect requests if (sess.RequestMethod == "CONNECT") return; if (CaptureConfiguration.ProcessId > 0) { if (sess.LocalProcessID != 0 && sess.LocalProcessID != CaptureConfiguration.ProcessId) return; } if (!string.IsNullOrEmpty(CaptureConfiguration.CaptureDomain)) { if (sess.hostname.ToLower() != CaptureConfiguration.CaptureDomain.Trim().ToLower()) return; } if (CaptureConfiguration.IgnoreResources) { string url = sess.fullUrl.ToLower(); var extensions = CaptureConfiguration.ExtensionFilterExclusions; foreach (var ext in extensions) { if (url.Contains(ext)) return; } var filters = CaptureConfiguration.UrlFilterExclusions; foreach (var urlFilter in filters) { if (url.Contains(urlFilter)) return; } } if (sess == null || sess.oRequest == null || sess.oRequest.headers == null) return; string headers = sess.oRequest.headers.ToString(); var reqBody = sess.GetRequestBodyAsString(); // if you wanted to capture the response //string respHeaders = session.oResponse.headers.ToString(); //var respBody = session.GetResponseBodyAsString(); // replace the HTTP line to inject full URL string firstLine = sess.RequestMethod + " " + sess.fullUrl + " " + sess.oRequest.headers.HTTPVersion; int at = headers.IndexOf("\r\n"); if (at < 0) return; headers = firstLine + "\r\n" + headers.Substring(at + 1); string output = headers + "\r\n" + (!string.IsNullOrEmpty(reqBody) ? reqBody + "\r\n" : string.Empty) + Separator + "\r\n\r\n"; BeginInvoke(new Action<string>((text) => { txtCapture.AppendText(text); UpdateButtonStatus(); }), output); } The code starts by filtering out some requests based on the CaptureOptions I set before the capture is started. These options/filters are applied when requests actually come in. This is very useful to help narrow down the requests that are captured for playback based on options the user picked. I find it useful to limit requests to a certain domain for captures, as well as filtering out some request types like static resources – images, css, scripts etc. This is of course optional, but I think it’s a common scenario and WebSurge makes good use of this feature. AfterSessionComplete like other FiddlerCore events, provides a Session object parameter which contains all the request and response details. There are oRequest and oResponse objects to hold their respective data. In my case I’m interested in the raw request headers and body only, as you can see in the commented code you can also retrieve the response headers and body. Here the code captures the request headers and body and simply appends the output to the textbox on the screen. Note that the Fiddler events are asynchronous, so in order to display the content in the UI they have to be marshaled back the UI thread with BeginInvoke, which here simply takes the generated headers and appends it to the existing textbox test on the form. As each request is processed, the headers are captured and appended to the bottom of the textbox resulting in a Session HTTP capture in the format that Web Surge internally supports, which is basically raw request headers with a customized 1st HTTP Header line that includes the full URL rather than a server relative URL. When the capture is done the user can either copy the raw HTTP session to the clipboard, or directly save it to file. This raw capture format is the same format WebSurge and also Fiddler use to import/export request data. While this code is application specific, it demonstrates the kind of logic that you can easily apply to the request capture process, which is one of the reasonsof why FiddlerCore is so powerful. You get to choose what content you want to look up as part of your own application logic and you can then decide how to capture or use that data as part of your application. The actual captured data in this case is only a string. The user can edit the data by hand or in the the case of WebSurge, save it to disk and automatically open the captured session as a new load test. Stopping the FiddlerCore Proxy Finally to stop capturing requests you simply disconnect the event handler and call the FiddlerApplication.ShutDown() method:void Stop() { FiddlerApplication.AfterSessionComplete -= FiddlerApplication_AfterSessionComplete; if (FiddlerApplication.IsStarted()) FiddlerApplication.Shutdown(); } As you can see, adding HTTP capture functionality to an application is very straight forward. FiddlerCore offers tons of features I’m not even touching on here – I suspect basic captures are the most common scenario, but a lot of different things can be done with FiddlerCore’s simple API interface. Sky’s the limit! The source code for this sample capture form (WinForms) is provided as part of this article. Adding Fiddler Certificates with FiddlerCore One of the sticking points in West Wind WebSurge has been that if you wanted to capture HTTPS/SSL traffic, you needed to have the full version of Fiddler and have HTTPS decryption enabled. Essentially you had to use Fiddler to configure HTTPS decryption and the associated installation of the Fiddler local client certificate that is used for local decryption of incoming SSL traffic. While this works just fine, requiring to have Fiddler installed and then using a separate application to configure the SSL functionality isn’t ideal. Fortunately FiddlerCore actually includes the tools to register the Fiddler Certificate directly using FiddlerCore. Why does Fiddler need a Certificate in the first Place? Fiddler and FiddlerCore are essentially HTTP proxies which means they inject themselves into the HTTP conversation by re-routing HTTP traffic to a special HTTP port (8888 by default for Fiddler) and then forward the HTTP data to the original client. Fiddler injects itself as the system proxy in using the WinInet Windows settings  which are the same settings that Internet Explorer uses and that are configured in the Windows and Internet Explorer Internet Settings dialog. Most HTTP clients running on Windows pick up and apply these system level Proxy settings before establishing new HTTP connections and that’s why most clients automatically work once Fiddler – or FiddlerCore/WebSurge are running. For plain HTTP requests this just works – Fiddler intercepts the HTTP requests on the proxy port and then forwards them to the original port (80 for HTTP and 443 for SSL typically but it could be any port). For SSL however, this is not quite as simple – Fiddler can easily act as an HTTPS/SSL client to capture inbound requests from the server, but when it forwards the request to the client it has to also act as an SSL server and provide a certificate that the client trusts. This won’t be the original certificate from the remote site, but rather a custom local certificate that effectively simulates an SSL connection between the proxy and the client. If there is no custom certificate configured for Fiddler the SSL request fails with a certificate validation error. The key for this to work is that a custom certificate has to be installed that the HTTPS client trusts on the local machine. For a much more detailed description of the process you can check out Eric Lawrence’s blog post on Certificates. If you’re using the desktop version of Fiddler you can install a local certificate into the Windows certificate store. Fiddler proper does this from the Options menu: This operation does several things: It installs the Fiddler Root Certificate It sets trust to this Root Certificate A new client certificate is generated for each HTTPS site monitored Certificate Installation with FiddlerCore You can also provide this same functionality using FiddlerCore which includes a CertMaker class. Using CertMaker is straight forward to use and it provides an easy way to create some simple helpers that can install and uninstall a Fiddler Root certificate:public static bool InstallCertificate() { if (!CertMaker.rootCertExists()) { if (!CertMaker.createRootCert()) return false; if (!CertMaker.trustRootCert()) return false; } return true; } public static bool UninstallCertificate() { if (CertMaker.rootCertExists()) { if (!CertMaker.removeFiddlerGeneratedCerts(true)) return false; } return true; } InstallCertificate() works by first checking whether the root certificate is already installed and if it isn’t goes ahead and creates a new one. The process of creating the certificate is a two step process – first the actual certificate is created and then it’s moved into the certificate store to become trusted. I’m not sure why you’d ever split these operations up since a cert created without trust isn’t going to be of much value, but there are two distinct steps. When you trigger the trustRootCert() method, a message box will pop up on the desktop that lets you know that you’re about to trust a local private certificate. This is a security feature to ensure that you really want to trust the Fiddler root since you are essentially installing a man in the middle certificate. It’s quite safe to use this generated root certificate, because it’s been specifically generated for your machine and thus is not usable from external sources, the only way to use this certificate in a trusted way is from the local machine. IOW, unless somebody has physical access to your machine, there’s no useful way to hijack this certificate and use it for nefarious purposes (see Eric’s post for more details). Once the Root certificate has been installed, FiddlerCore/Fiddler create new certificates for each site that is connected to with HTTPS. You can end up with quite a few temporary certificates in your certificate store. To uninstall you can either use Fiddler and simply uncheck the Decrypt HTTPS traffic option followed by the remove Fiddler certificates button, or you can use FiddlerCore’s CertMaker.removeFiddlerGeneratedCerts() which removes the root cert and any of the intermediary certificates Fiddler created. Keep in mind that when you uninstall you uninstall the certificate for both FiddlerCore and Fiddler, so use UninstallCertificate() with care and realize that you might affect the Fiddler application’s operation by doing so as well. When to check for an installed Certificate Note that the check to see if the root certificate exists is pretty fast, while the actual process of installing the certificate is a relatively slow operation that even on a fast machine takes a few seconds. Further the trust operation pops up a message box so you probably don’t want to install the certificate repeatedly. Since the check for the root certificate is fast, you can easily put a call to InstallCertificate() in any capture startup code – in which case the certificate installation only triggers when a certificate is in fact not installed. Personally I like to make certificate installation explicit – just like Fiddler does, so in WebSurge I use a small drop down option on the menu to install or uninstall the SSL certificate:   This code calls the InstallCertificate and UnInstallCertificate functions respectively – the experience with this is similar to what you get in Fiddler with the extra dialog box popping up to prompt confirmation for installation of the root certificate. Once the cert is installed you can then capture SSL requests. There’s a gotcha however… Gotcha: FiddlerCore Certificates don’t stick by Default When I originally tried to use the Fiddler certificate installation I ran into an odd problem. I was able to install the certificate and immediately after installation was able to capture HTTPS requests. Then I would exit the application and come back in and try the same HTTPS capture again and it would fail due to a missing certificate. CertMaker.rootCertExists() would return false after every restart and if re-installed the certificate a new certificate would get added to the certificate store resulting in a bunch of duplicated root certificates with different keys. What the heck? CertMaker and BcMakeCert create non-sticky CertificatesI turns out that FiddlerCore by default uses different components from what the full version of Fiddler uses. Fiddler uses a Windows utility called MakeCert.exe to create the Fiddler Root certificate. FiddlerCore however installs the CertMaker.dll and BCMakeCert.dll assemblies, which use a different crypto library (Bouncy Castle) for certificate creation than MakeCert.exe which uses the Windows Crypto API. The assemblies provide support for non-windows operation for Fiddler under Mono, as well as support for some non-Windows certificate platforms like iOS and Android for decryption. The bottom line is that the FiddlerCore provided bouncy castle assemblies are not sticky by default as the certificates created with them are not cached as they are in Fiddler proper. To get certificates to ‘stick’ you have to explicitly cache the certificates in Fiddler’s internal preferences. A cache aware version of InstallCertificate looks something like this:public static bool InstallCertificate() { if (!CertMaker.rootCertExists()) { if (!CertMaker.createRootCert()) return false; if (!CertMaker.trustRootCert()) return false; App.Configuration.UrlCapture.Cert = FiddlerApplication.Prefs.GetStringPref("fiddler.certmaker.bc.cert", null); App.Configuration.UrlCapture.Key = FiddlerApplication.Prefs.GetStringPref("fiddler.certmaker.bc.key", null); } return true; } public static bool UninstallCertificate() { if (CertMaker.rootCertExists()) { if (!CertMaker.removeFiddlerGeneratedCerts(true)) return false; } App.Configuration.UrlCapture.Cert = null; App.Configuration.UrlCapture.Key = null; return true; } In this code I store the Fiddler cert and private key in an application configuration settings that’s stored with the application settings (App.Configuration.UrlCapture object). These settings automatically persist when WebSurge is shut down. The values are read out of Fiddler’s internal preferences store which is set after a new certificate has been created. Likewise I clear out the configuration settings when the certificate is uninstalled. In order for these setting to be used you have to also load the configuration settings into the Fiddler preferences *before* a call to rootCertExists() is made. I do this in the capture form’s constructor:public FiddlerCapture(StressTestForm form) { InitializeComponent(); CaptureConfiguration = App.Configuration.UrlCapture; MainForm = form; if (!string.IsNullOrEmpty(App.Configuration.UrlCapture.Cert)) { FiddlerApplication.Prefs.SetStringPref("fiddler.certmaker.bc.key", App.Configuration.UrlCapture.Key); FiddlerApplication.Prefs.SetStringPref("fiddler.certmaker.bc.cert", App.Configuration.UrlCapture.Cert); }} This is kind of a drag to do and not documented anywhere that I could find, so hopefully this will save you some grief if you want to work with the stock certificate logic that installs with FiddlerCore. MakeCert provides sticky Certificates and the same functionality as Fiddler But there’s actually an easier way. If you want to skip the above Fiddler preference configuration code in your application you can choose to distribute MakeCert.exe instead of certmaker.dll and bcmakecert.dll. When you use MakeCert.exe, the certificates settings are stored in Windows so they are available without any custom configuration inside of your application. It’s easier to integrate and as long as you run on Windows and you don’t need to support iOS or Android devices is simply easier to deal with. To integrate into your project, you can remove the reference to CertMaker.dll (and the BcMakeCert.dll assembly) from your project. Instead copy MakeCert.exe into your output folder. To make sure MakeCert.exe gets pushed out, include MakeCert.exe in your project and set the Build Action to None, and Copy to Output Directory to Copy if newer. Note that the CertMaker.dll reference in the project has been removed and on disk the files for Certmaker.dll, as well as the BCMakeCert.dll files on disk. Keep in mind that these DLLs are resources of the FiddlerCore NuGet package, so updating the package may end up pushing those files back into your project. Once MakeCert.exe is distributed FiddlerCore checks for it first before using the assemblies so as long as MakeCert.exe exists it’ll be used for certificate creation (at least on Windows). Summary FiddlerCore is a pretty sweet tool, and it’s absolutely awesome that we get to plug in most of the functionality of Fiddler right into our own applications. A few years back I tried to build this sort of functionality myself for an app and ended up giving up because it’s a big job to get HTTP right – especially if you need to support SSL. FiddlerCore now provides that functionality as a turnkey solution that can be plugged into your own apps easily. The only downside is FiddlerCore’s documentation for more advanced features like certificate installation which is pretty sketchy. While for the most part FiddlerCore’s feature set is easy to work with without any documentation, advanced features are often not intuitive to gleam by just using Intellisense or the FiddlerCore help file reference (which is not terribly useful). While Eric Lawrence is very responsive on his forum and on Twitter, there simply isn’t much useful documentation on Fiddler/FiddlerCore available online. If you run into trouble the forum is probably the first place to look and then ask a question if you can’t find the answer. The best documentation you can find is Eric’s Fiddler Book which covers a ton of functionality of Fiddler and FiddlerCore. The book is a great reference to Fiddler’s feature set as well as providing great insights into the HTTP protocol. The second half of the book that gets into the innards of HTTP is an excellent read for anybody who wants to know more about some of the more arcane aspects and special behaviors of HTTP – it’s well worth the read. While the book has tons of information in a very readable format, it’s unfortunately not a great reference as it’s hard to find things in the book and because it’s not available online you can’t electronically search for the great content in it. But it’s hard to complain about any of this given the obvious effort and love that’s gone into this awesome product for all of these years. A mighty big thanks to Eric Lawrence  for having created this useful tool that so many of us use all the time, and also to Telerik for picking up Fiddler/FiddlerCore and providing Eric the resources to support and improve this wonderful tool full time and keeping it free for all. Kudos! Resources FiddlerCore Download FiddlerCore NuGet Fiddler Capture Sample Form Fiddler Capture Form in West Wind WebSurge (GitHub) Eric Lawrence’s Fiddler Book© Rick Strahl, West Wind Technologies, 2005-2014Posted in .NET  HTTP   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• A Taxonomy of Numerical Methods v1

  - by JoshReuben

  Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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• Red Gate Coder interviews: Robin Hellen

  - by Michael Williamson

  Robin Hellen is a test engineer here at Red Gate, and is also the latest coder I’ve interviewed. We chatted about debugging code, the roles of software engineers and testers, and why Vala is currently his favourite programming language. How did you get started with programming?It started when I was about six. My dad’s a professional programmer, and he gave me and my sister one of his old computers and taught us a bit about programming. It was an old Amiga 500 with a variant of BASIC. I don’t think I ever successfully completed anything! It was just faffing around. I didn’t really get anywhere with it.But then presumably you did get somewhere with it at some point.At some point. The PC emerged as the dominant platform, and I learnt a bit of Visual Basic. I didn’t really do much, just a couple of quick hacky things. A bit of demo animation. Took me a long time to get anywhere with programming, really.When did you feel like you did start to get somewhere?I think it was when I started doing things for someone else, which was my sister’s final year of university project. She called up my dad two days before she was due to submit, saying “We need something to display a graph!”. Dad says, “I’m too busy, go talk to your brother”. So I hacked up this ugly piece of code, sent it off and they won a prize for that project. Apparently, the graph, the bit that I wrote, was the reason they won a prize! That was when I first felt that I’d actually done something that was worthwhile. That was my first real bit of code, and the ugliest code I’ve ever written. It’s basically an array of pre-drawn line elements that I shifted round the screen to draw a very spikey graph.When did you decide that programming might actually be something that you wanted to do as a career?It’s not really a decision I took, I always wanted to do something with computers. And I had to take a gap year for uni, so I was looking for twelve month internships. I applied to Red Gate, and they gave me a job as a tester. And that’s where I really started having to write code well. To a better standard that I had been up to that point.How did you find coming to Red Gate and working with other coders?I thought it was really nice. I learnt so much just from other people around. I think one of the things that’s really great is that people are just willing to help you learn. Instead of “Don’t you know that, you’re so stupid”, it’s “You can just do it this way”.If you could go back to the very start of that internship, is there something that you would tell yourself?Write shorter code. I have a tendency to write massive, many-thousand line files that I break out of right at the end. And then half-way through a project I’m doing something, I think “Where did I write that bit that does that thing?”, and it’s almost impossible to find. I wrote some horrendous code when I started. Just that principle, just keep things short. Even if looks a bit crazy to be jumping around all over the place all of the time, it’s actually a lot more understandable.And how do you hold yourself to that?Generally, if a function’s going off my screen, it’s probably too long. That’s what I tell myself, and within the team here we have code reviews, so the guys I’m with at the moment are pretty good at pulling me up on, “Doesn’t that look like it’s getting a bit long?”. It’s more just the subjective standard of readability than anything.So you’re an advocate of code review?Yes, definitely. Both to spot errors that you might have made, and to improve your knowledge. The person you’re reviewing will say “Oh, you could have done it that way”. That’s how we learn, by talking to others, and also just sharing knowledge of how your project works around the team, or even outside the team. Definitely a very firm advocate of code reviews.Do you think there’s more we could do with them?I don’t know. We’re struggling with how to add them as part of the process without it becoming too cumbersome. We’ve experimented with a few different ways, and we’ve not found anything that just works.To get more into the nitty gritty: how do you like to debug code?The first thing is to do it in my head. I’ll actually think what piece of code is likely to have caused that error, and take a quick look at it, just to see if there’s anything glaringly obvious there. The next thing I’ll probably do is throw in print statements, or throw some exceptions from various points, just to check: is it going through the code path I expect it to? A last resort is to actually debug code using a debugger.Why is the debugger the last resort?Probably because of the environments I learnt programming in. VB and early BASIC didn’t have much of a debugger, the only way to find out what your program was doing was to add print statements. Also, because a lot of the stuff I tend to work with is non-interactive, if it’s something that takes a long time to run, I can throw in the print statements, set a run off, go and do something else, and look at it again later, rather than trying to remember what happened at that point when I was debugging through it. So it also gives me the record of what happens. I hate just sitting there pressing F5, F5, continually. If you’re having to find out what your code is doing at each line, you’ve probably got a very wrong mental model of what your code’s doing, and you can find that out just as easily by inspecting a couple of values through the print statements.If I were on some codebase that you were also working on, what should I do to make it as easy as possible to understand?I’d say short and well-named methods. The one thing I like to do when I’m looking at code is to find out where a value comes from, and the more layers of indirection there are, particularly DI [dependency injection] frameworks, the harder it is to find out where something’s come from. I really hate that. I want to know if the value come from the user here or is a constant here, and if I can’t find that out, that makes code very hard to understand for me.As a tester, where do you think the split should lie between software engineers and testers?I think the split is less on areas of the code you write and more what you’re designing and creating. The developers put a structure on the code, while my major role is to say which tests we should have, whether we should test that, or it’s not worth testing that because it’s a tiny function in code that nobody’s ever actually going to see. So it’s not a split in the code, it’s a split in what you’re thinking about. Saying what code we should write, but alternatively what code we should take out.In your experience, do the software engineers tend to do much testing themselves?They tend to control the lowest layer of tests. And, depending on how the balance of people is in the team, they might write some of the higher levels of test. Or that might go to the testers. I’m the only tester on my team with three other developers, so they’ll be writing quite a lot of the actual test code, with input from me as to whether we should test that functionality, whereas on other teams, where it’s been more equal numbers, the testers have written pretty much all of the high level tests, just because that’s the best use of resource.If you could shuffle resources around however you liked, do you think that the developers should be writing those high-level tests?I think they should be writing them occasionally. It helps when they have an understanding of how testing code works and possibly what assumptions we’ve made in tests, and they can say “actually, it doesn’t work like that under the hood so you’ve missed this whole area”. It’s one of those agile things that everyone on the team should be at least comfortable doing the various jobs. So if the developers can write test code then I think that’s a very good thing.So you think testers should be able to write production code?Yes, although given most testers skills at coding, I wouldn’t advise it too much! I have written a few things, and I did make a few changes that have actually gone into our production code base. They’re not necessarily running every time but they are there. I think having that mix of skill sets is really useful. In some ways we’re using our own product to test itself, so being able to make those changes where it’s not working saves me a round-trip through the developers. It can be really annoying if the developers have no time to make a change, and I can’t touch the code.If the software engineers are consistently writing tests at all levels, what role do you think the role of a tester is?I think on a team like that, those distinctions aren’t quite so useful. There’ll be two cases. There’s either the case where the developers think they’ve written good tests, but you still need someone with a test engineer mind-set to go through the tests and validate that it’s a useful set, or the correct set for that code. Or they won’t actually be pure developers, they’ll have that mix of test ability in there.I think having slightly more distinct roles is useful. When it starts to blur, then you lose that view of the tests as a whole. The tester job is not to create tests, it’s to validate the quality of the product, and you don’t do that just by writing tests. There’s more things you’ve got to keep in your mind. And I think when you blur the roles, you start to lose that end of the tester.So because you’re working on those features, you lose that holistic view of the whole system?Yeah, and anyone who’s worked on the feature shouldn’t be testing it. You always need to have it tested it by someone who didn’t write it. Otherwise you’re a bit too close and you assume “yes, people will only use it that way”, but the tester will come along and go “how do people use this? How would our most idiotic user use this?”. I might not test that because it might be completely irrelevant. But it’s coming in and trying to have a different set of assumptions.Are you a believer that it should all be automated if possible?Not entirely. So an automated test is always better than a manual test for the long-term, but there’s still nothing that beats a human sitting in front of the application and thinking “What could I do at this point?”. The automated test is very good but they follow that strict path, and they never check anything off the path. The human tester will look at things that they weren’t expecting, whereas the automated test can only ever go “Is that value correct?” in many respects, and it won’t notice that on the other side of the screen you’re showing something completely wrong. And that value might have been checked independently, but you always find a few odd interactions when you’re going through something manually, and you always need to go through something manually to start with anyway, otherwise you won’t know where the important bits to write your automation are.When you’re doing that manual testing, do you think it’s important to do that across the entire product, or just the bits that you’ve touched recently?I think it’s important to do it mostly on the bits you’ve touched, but you can’t ignore the rest of the product. Unless you’re dealing with a very, very self-contained bit, you’re almost always encounter other bits of the product along the way. Most testers I know, even if they are looking at just one path, they’ll keep open and move around a bit anyway, just because they want to find something that’s broken. If we find that your path is right, we’ll go out and hunt something else.How do you think this fits into the idea of continuously deploying, so long as the tests pass?With deploying a website it’s a bit different because you can always pull it back. If you’re deploying an application to customers, when you’ve released it, it’s out there, you can’t pull it back. Someone’s going to keep it, no matter how hard you try there will be a few installations that stay around. So I’d always have at least a human element on that path. With websites, you could probably automate straight out, or at least straight out to an internal environment or a single server in a cloud of fifty that will serve some people. But I don’t think you should release to everyone just on automated tests passing.You’ve already mentioned using BASIC and C# — are there any other languages that you’ve used?I’ve used a few. That’s something that has changed more recently, I’ve become familiar with more languages. Before I started at Red Gate I learnt a bit of C. Then last year, I taught myself Python which I actually really enjoyed using. I’ve also come across another language called Vala, which is sort of a C#-like language. It’s basically a pre-processor for C, but it has very nice syntax. I think that’s currently my favourite language.Any particular reason for trying Vala?I have a completely Linux environment at home, and I’ve been looking for a nice language, and C# just doesn’t cut it because I won’t touch Mono. So, I was looking for something like C# but that was useable in an open source environment, and Vala’s what I found. C#’s got a few features that Vala doesn’t, and Vala’s got a few features where I think “It would be awesome if C# had that”.What are some of the features that it’s missing?Extension methods. And I think that’s the only one that really bugs me. I like to use them when I’m writing C# because it makes some things really easy, especially with libraries that you can’t touch the internals of. It doesn’t have method overloading, which is sometimes annoying.Where it does win over C#?Everything is non-nullable by default, you never have to check that something’s unexpectedly null.Also, Vala has code contracts. This is starting to come in C# 4, but the way it works in Vala is that you specify requirements in short phrases as part of your function signature and they stick to the signature, so that when you inherit it, it has exactly the same code contract as the base one, or when you inherit from an interface, you have to match the signature exactly. Just using those makes you think a bit more about how you’re writing your method, it’s not an afterthought when you’ve got contracts from base classes given to you, you can’t change it. Which I think is a lot nicer than the way C# handles it. When are those actually checked?They’re checked both at compile and run-time. The compile-time checking isn’t very strong yet, it’s quite a new feature in the compiler, and because it compiles down to C, you can write C code and interface with your methods, so you can bypass that compile-time check anyway. So there’s an extra runtime check, and if you violate one of the contracts at runtime, it’s game over for your program, there’s no exception to catch, it’s just goodbye!One thing I dislike about C# is the exceptions. You write a bit of code and fifty exceptions could come from any point in your ten lines, and you can’t mentally model how those exceptions are going to come out, and you can’t even predict them based on the functions you’re calling, because if you’ve accidentally got a derived class there instead of a base class, that can throw a completely different set of exceptions. So I’ve got no way of mentally modelling those, whereas in Vala they’re checked like Java, so you know only these exceptions can come out. You know in advance the error conditions.I think Raymond Chen on Old New Thing says “the only thing you know when you throw an exception is that you’re in an invalid state somewhere in your program, so just kill it and be done with it!”You said you’ve also learnt bits of Python. How did you find that compared to Vala and C#?Very different because of the dynamic typing. I’ve been writing a website for my own use. I’m quite into photography, so I take photos off my camera, post-process them, dump them in a file, and I get a webpage with all my thumbnails. So sort of like Picassa, but written by myself because I wanted something to learn Python with. There are some things that are really nice, I just found it really difficult to cope with the fact that I’m not quite sure what this object type that I’m passed is, I might not ever be sure, so it can randomly blow up on me. But once I train myself to ignore that and just say “well, I’m fairly sure it’s going to be something that looks like this, so I’ll use it like this”, then it’s quite nice.Any particular features that you’ve appreciated?I don’t like any particular feature, it’s just very straightforward to work with. It’s very quick to write something in, particularly as you don’t have to worry that you’ve changed something that affects a different part of the program. If you have, then that part blows up, but I can get this part working right now.If you were doing a big project, would you be willing to do it in Python rather than C# or Vala?I think I might be willing to try something bigger or long term with Python. We’re currently doing an ASP.NET MVC project on C#, and I don’t like the amount of reflection. There’s a lot of magic that pulls values out, and it’s all done under the scenes. It’s almost managed to put a dynamic type system on top of C#, which in many ways destroys the language to me, whereas if you’re already in a dynamic language, having things done dynamically is much more natural. In many ways, you get the worst of both worlds. I think for web projects, I would go with Python again, whereas for anything desktop, command-line or GUI-based, I’d probably go for C# or Vala, depending on what environment I’m in.It’s the fact that you can gain from the strong typing in ways that you can’t so much on the web app. Or, in a web app, you have to use dynamic typing at some point, or you have to write a hell of a lot of boilerplate, and I’d rather use the dynamic typing than write the boilerplate.What do you think separates great programmers from everyone else?Probably design choices. Choosing to write it a piece of code one way or another. For any given program you ask me to write, I could probably do it five thousand ways. A programmer who is capable will see four or five of them, and choose one of the better ones. The excellent programmer will see the largest proportion and manage to pick the best one very quickly without having to think too much about it. I think that’s probably what separates, is the speed at which they can see what’s the best path to write the program in. More Red Gater Coder interviews

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• PTLQueue : a scalable bounded-capacity MPMC queue

  - by Dave

  Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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• Sniffing out SQL Code Smells: Inconsistent use of Symbolic names and Datatypes

  - by Phil Factor

  It is an awkward feeling. You’ve just delivered a database application that seems to be working fine in production, and you just run a few checks on it. You discover that there is a potential bug that, out of sheer good chance, hasn’t kicked in to produce an error; but it lurks, like a smoking bomb. Worse, maybe you find that the bug has started its evil work of corrupting the data, but in ways that nobody has, so far detected. You investigate, and find the damage. You are somehow going to have to repair it. Yes, it still very occasionally happens to me. It is not a nice feeling, and I do anything I can to prevent it happening. That’s why I’m interested in SQL code smells. SQL Code Smells aren’t necessarily bad practices, but just show you where to focus your attention when checking an application. Sometimes with databases the bugs can be subtle. SQL is rather like HTML: the language does its best to try to carry out your wishes, rather than to be picky about your bugs. Most of the time, this is a great benefit, but not always. One particular place where this can be detrimental is where you have implicit conversion between different data types. Most of the time it is completely harmless but we’re  concerned about the occasional time it isn’t. Let’s give an example: String truncation. Let’s give another even more frightening one, rounding errors on assignment to a number of different precision. Each requires a blog-post to explain in detail and I’m not now going to try. Just remember that it is not always a good idea to assign data to variables, parameters or even columns when they aren’t the same datatype, especially if you are relying on implicit conversion to work its magic.For details of the problem and the consequences, see here:  SR0014: Data loss might occur when casting from {Type1} to {Type2} . For any experienced Database Developer, this is a more frightening read than a Vampire Story. This is why one of the SQL Code Smells that makes me edgy, in my own or other peoples’ code, is to see parameters, variables and columns that have the same names and different datatypes. Whereas quite a lot of this is perfectly normal and natural, you need to check in case one of two things have gone wrong. Either sloppy naming, or mixed datatypes. Sure it is hard to remember whether you decided that the length of a log entry was 80 or 100 characters long, or the precision of a number. That is why a little check like this I’m going to show you is excellent for tidying up your code before you check it back into source Control! 1/ Checking Parameters only If you were just going to check parameters, you might just do this. It simply groups all the parameters, either input or output, of all the routines (e.g. stored procedures or functions) by their name and checks to see, in the HAVING clause, whether their data types are all the same. If not, it lists all the examples and their origin (the routine) Even this little check can occasionally be scarily revealing. ;WITH userParameter AS  ( SELECT   c.NAME AS ParameterName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  t.name + ' '     + CASE     --we may have to put in the length            WHEN t.name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.max_length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.name IN ('nchar', 'nvarchar')                      THEN c.max_length / 2 ELSE c.max_length                    END)                END + ')'         WHEN t.name IN ('decimal', 'numeric')             THEN '(' + CONVERT(VARCHAR(4), c.precision)                   + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = c.XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType]  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'   AND parameter_id>0)SELECT CONVERT(CHAR(80),objectName+'.'+ParameterName),DataType FROM UserParameterWHERE ParameterName IN   (SELECT ParameterName FROM UserParameter    GROUP BY ParameterName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY ParameterName   so, in a very small example here, we have a @ClosingDelimiter variable that is only CHAR(1) when, by the looks of it, it should be up to ten characters long, or even worse, a function that should be a char(1) and seems to let in a string of ten characters. Worth investigating. Then we have a @Comment variable that can't decide whether it is a VARCHAR(2000) or a VARCHAR(MAX) 2/ Columns and Parameters Actually, once we’ve cleared up the mess we’ve made of our parameter-naming in the database we’re inspecting, we’re going to be more interested in listing both columns and parameters. We can do this by modifying the routine to list columns as well as parameters. Because of the slight complexity of creating the string version of the datatypes, we will create a fake table of both columns and parameters so that they can both be processed the same way. After all, we want the datatypes to match Unfortunately, parameters do not expose all the attributes we are interested in, such as whether they are nullable (oh yes, subtle bugs happen if this isn’t consistent for a datatype). We’ll have to leave them out for this check. Voila! A slight modification of the first routine ;WITH userObject AS  ( SELECT   Name AS DataName,--the actual name of the parameter or column ('@' removed)  --and the qualified object name of the routine  OBJECT_SCHEMA_NAME(ObjectID) + '.' + OBJECT_NAME(ObjectID) AS ObjectName,  --now the harder bit: the definition of the datatype.  TypeName + ' '     + CASE     --we may have to put in the length. e.g. CHAR (10)           WHEN TypeName IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN MaxLength = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN TypeName IN ('nchar', 'nvarchar')                      THEN MaxLength / 2 ELSE MaxLength                    END)                END + ')'         WHEN TypeName IN ('decimal', 'numeric')--a BCD number!             THEN '(' + CONVERT(VARCHAR(4), Precision)                   + ',' + CONVERT(VARCHAR(4), Scale) + ')'         ELSE ''      END  --we've done with putting in the length      + CASE WHEN XML_collection_ID <> 0 --tush tush. XML         THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                    THEN 'DOCUMENT '                    ELSE 'CONTENT '                   END              + COALESCE(               (SELECT TOP 1 QUOTENAME(ss.name) + '.' + QUOTENAME(sc.Name)                FROM sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE sc.xml_collection_ID = XML_collection_ID),'NULL') + ')'          ELSE ''         END        AS [DataType],       DataObjectType  FROM   (Select t.name AS TypeName, REPLACE(c.name,'@','') AS Name,          c.max_length AS MaxLength, c.precision AS [Precision],           c.scale AS [Scale], c.[Object_id] AS ObjectID, XML_collection_ID,          is_XML_Document,'P' AS DataobjectType  FROM sys.parameters c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  AND parameter_id>0  UNION all  Select t.name AS TypeName, c.name AS Name, c.max_length AS MaxLength,          c.precision AS [Precision], c.scale AS [Scale],          c.[Object_id] AS ObjectID, XML_collection_ID,is_XML_Document,          'C' AS DataobjectType            FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID   WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys'  )f)SELECT CONVERT(CHAR(80),objectName+'.'   + CASE WHEN DataobjectType ='P' THEN '@' ELSE '' END + DataName),DataType FROM UserObjectWHERE DataName IN   (SELECT DataName FROM UserObject   GROUP BY DataName    HAVING MIN(Datatype)<>MAX(DataType))ORDER BY DataName     Hmm. I can tell you I found quite a few minor issues with the various tabases I tested this on, and found some potential bugs that really leap out at you from the results. Here is the start of the result for AdventureWorks. Yes, AccountNumber is, for some reason, a Varchar(10) in the Customer table. Hmm. odd. Why is a city fifty characters long in that view?  The idea of the description of a colour being 256 characters long seems over-ambitious. Go down the list and you'll spot other mistakes. There are no bugs, but just mess. We started out with a listing to examine parameters, then we mixed parameters and columns. Our last listing is for a slightly more in-depth look at table columns. You’ll notice that we’ve delibarately removed the indication of whether a column is persisted, or is an identity column because that gives us false positives for our code smells. If you just want to browse your metadata for other reasons (and it can quite help in some circumstances) then uncomment them! ;WITH userColumns AS  ( SELECT   c.NAME AS columnName,  OBJECT_SCHEMA_NAME(c.object_ID) + '.' + OBJECT_NAME(c.object_ID) AS ObjectName,  REPLACE(t.name + ' '   + CASE WHEN is_computed = 1 THEN ' AS ' + --do DDL for a computed column          (SELECT definition FROM sys.computed_columns cc           WHERE cc.object_id = c.object_id AND cc.column_ID = c.column_ID)     --we may have to put in the length            WHEN t.Name IN ('char', 'varchar', 'nchar', 'nvarchar')             THEN '('               + CASE WHEN c.Max_Length = -1 THEN 'MAX'                ELSE CONVERT(VARCHAR(4),                    CASE WHEN t.Name IN ('nchar', 'nvarchar')                      THEN c.Max_Length / 2 ELSE c.Max_Length                    END)                END + ')'       WHEN t.name IN ('decimal', 'numeric')       THEN '(' + CONVERT(VARCHAR(4), c.precision) + ',' + CONVERT(VARCHAR(4), c.Scale) + ')'       ELSE ''      END + CASE WHEN c.is_rowguidcol = 1          THEN ' ROWGUIDCOL'          ELSE ''         END + CASE WHEN XML_collection_ID <> 0            THEN --deal with object schema names             '(' + CASE WHEN is_XML_Document = 1                THEN 'DOCUMENT '                ELSE 'CONTENT '               END + COALESCE((SELECT                QUOTENAME(ss.name) + '.' + QUOTENAME(sc.name)                FROM                sys.xml_schema_collections sc                INNER JOIN Sys.Schemas ss ON sc.schema_ID = ss.schema_ID                WHERE                sc.xml_collection_ID = c.XML_collection_ID),                'NULL') + ')'            ELSE ''           END + CASE WHEN is_identity = 1             THEN CASE WHEN OBJECTPROPERTY(object_id,                'IsUserTable') = 1 AND COLUMNPROPERTY(object_id,                c.name,                'IsIDNotForRepl') = 0 AND OBJECTPROPERTY(object_id,                'IsMSShipped') = 0                THEN ''                ELSE ' NOT FOR REPLICATION '               END             ELSE ''            END + CASE WHEN c.is_nullable = 0               THEN ' NOT NULL'               ELSE ' NULL'              END + CASE                WHEN c.default_object_id <> 0                THEN ' DEFAULT ' + object_Definition(c.default_object_id)                ELSE ''               END + CASE                WHEN c.collation_name IS NULL                THEN ''                WHEN c.collation_name <> (SELECT                collation_name                FROM                sys.databases                WHERE                name = DB_NAME()) COLLATE Latin1_General_CI_AS                THEN COALESCE(' COLLATE ' + c.collation_name,                '')                ELSE ''                END,'  ',' ') AS [DataType]FROM sys.columns c  INNER JOIN sys.types t ON c.user_Type_ID = t.user_Type_ID  WHERE OBJECT_SCHEMA_NAME(c.object_ID) <> 'sys')SELECT CONVERT(CHAR(80),objectName+'.'+columnName),DataType FROM UserColumnsWHERE columnName IN (SELECT columnName FROM UserColumns  GROUP BY columnName  HAVING MIN(Datatype)<>MAX(DataType))ORDER BY columnName If you take a look down the results against Adventureworks, you'll see once again that there are things to investigate, mostly, in the illustration, discrepancies between null and non-null datatypes So I here you ask, what about temporary variables within routines? If ever there was a source of elusive bugs, you'll find it there. Sadly, these temporary variables are not stored in the metadata so we'll have to find a more subtle way of flushing these out, and that will, I'm afraid, have to wait!

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• How to shoot yourself in the foot (DO NOT Read in the office)

  - by TATWORTH

  Originally posted on: http://geekswithblogs.net/TATWORTH/archive/2013/06/21/how-to-shoot-yourself-in-the-foot-do-not-read.aspxLet me make it absolutely clear - the following is:merely collated by your Geek from http://www.codeproject.com/Lounge.aspx?msg=3917012#xx3917012xxvery, very very funny so you read it in the presence of others at your own riskso here is the list - you have been warned!C You shoot yourself in the foot.   C++ You accidently create a dozen instances of yourself and shoot them all in the foot. Providing emergency medical assistance is impossible since you can't tell which are bitwise copies and which are just pointing at others and saying "That's me, over there."   FORTRAN You shoot yourself in each toe, iteratively, until you run out of toes, then you read in the next foot and repeat. If you run out of bullets, you continue anyway because you have no exception-handling facility.   Modula-2 After realizing that you can't actually accomplish anything in this language, you shoot yourself in the head.   COBOL USEing a COLT 45 HANDGUN, AIM gun at LEG.FOOT, THEN place ARM.HAND.FINGER on HANDGUN.TRIGGER and SQUEEZE. THEN return HANDGUN to HOLSTER. CHECK whether shoelace needs to be retied.   Lisp You shoot yourself in the appendage which holds the gun with which you shoot yourself in the appendage which holds the gun with which you shoot yourself in the appendage which holds...   BASIC Shoot yourself in the foot with a water pistol. On big systems, continue until entire lower body is waterlogged.   Forth Foot yourself in the shoot.   APL You shoot yourself in the foot; then spend all day figuring out how to do it in fewer characters.   Pascal The compiler won't let you shoot yourself in the foot.   Snobol If you succeed, shoot yourself in the left foot. If you fail, shoot yourself in the right foot.   HyperTalk Put the first bullet of the gun into foot left of leg of you. Answer the result.   Prolog You tell your program you want to be shot in the foot. The program figures out how to do it, but the syntax doesn't allow it to explain.   370 JCL You send your foot down to MIS with a 4000-page document explaining how you want it to be shot. Three years later, your foot comes back deep-fried.   FORTRAN-77 You shoot yourself in each toe, iteratively, until you run out of toes, then you read in the next foot and repeat. If you run out of bullets, you continue anyway because you still can't do exception-processing.   Modula-2 (alternative) You perform a shooting on what might be currently a foot with what might be currently a bullet shot by what might currently be a gun.   BASIC (compiled) You shoot yourself in the foot with a BB using a SCUD missile launcher.   Visual Basic You'll really only appear to have shot yourself in the foot, but you'll have so much fun doing it that you won't care.   Forth (alternative) BULLET DUP3 * GUN LOAD FOOT AIM TRIGGER PULL BANG! EMIT DEAD IF DROP ROT THEN (This takes about five bytes of memory, executes in two to ten clock cycles on any processor and can be used to replace any existing function of the language as well as in any future words). (Welcome to bottom up programming - where you, too, can perform compiler pre-processing instead of writing code)   APL (alternative) You hear a gunshot and there's a hole in your foot, but you don't remember enough linear algebra to understand what happened. or @#&^$%&%^ foot   Pascal (alternative) Same as Modula-2 except that the bullet is not the right type for the gun and your hand is blown off.   Snobol (alternative) You grab your foot with your hand, then rewrite your hand to be a bullet. The act of shooting the original foot then changes your hand/bullet into yet another foot (a left foot).   Prolog (alternative) You attempt to shoot yourself in the foot, but the bullet, failing to find its mark, backtracks to the gun, which then explodes in your face.   COMAL You attempt to shoot yourself in the foot with a water pistol, but the bore is clogged, and the pressure build-up blows apart both the pistol and your hand. or draw_pistol aim_at_foot(left) pull_trigger hop(swearing)   Scheme As Lisp, but none of the other appendages are aware of this happening.   Algol You shoot yourself in the foot with a musket. The musket is aesthetically fascinating and the wound baffles the adolescent medic in the emergency room.   Ada If you are dumb enough to actually use this language, the United States Department of Defense will kidnap you, stand you up in front of a firing squad and tell the soldiers, "Shoot at the feet." or The Department of Defense shoots you in the foot after offering you a blindfold and a last cigarette. or After correctly packaging your foot, you attempt to concurrently load the gun, pull the trigger, scream and shoot yourself in the foot. When you try, however, you discover that your foot is of the wrong type. or After correctly packing your foot, you attempt to concurrently load the gun, pull the trigger, scream, and confidently aim at your foot knowing it is safe. However the cordite in the round does an Unchecked Conversion, fires and shoots you in the foot anyway.   Eiffel   You create a GUN object, two FOOT objects and a BULLET object. The GUN passes both the FOOT objects a reference to the BULLET. The FOOT objects increment their hole counts and forget about the BULLET. A little demon then drives a garbage truck over your feet and grabs the bullet (both of it) on the way. Smalltalk You spend so much time playing with the graphics and windowing system that your boss shoots you in the foot, takes away your workstation and makes you develop in COBOL on a character terminal. or You send the message shoot to gun, with selectors bullet and myFoot. A window pops up saying Gunpowder doesNotUnderstand: spark. After several fruitless hours spent browsing the methods for Trigger, FiringPin and IdealGas, you take the easy way out and create ShotFoot, a subclass of Foot with an additional instance variable bulletHole. Object Oriented Pascal You perform a shooting on what might currently be a foot with what might currently be a bullet fired from what might currently be a gun.   PL/I You consume all available system resources, including all the offline bullets. The Data Processing & Payroll Department doubles its size, triples its budget, acquires four new mainframes and drops the original one on your foot. Postscript foot bullets 6 locate loadgun aim gun shoot showpage or It takes the bullet ten minutes to travel from the gun to your foot, by which time you're long since gone out to lunch. The text comes out great, though.   PERL You stab yourself in the foot repeatedly with an incredibly large and very heavy Swiss Army knife. or You pick up the gun and begin to load it. The gun and your foot begin to grow to huge proportions and the world around you slows down, until the gun fires. It makes a tiny hole, which you don't feel. Assembly Language You crash the OS and overwrite the root disk. The system administrator arrives and shoots you in the foot. After a moment of contemplation, the administrator shoots himself in the foot and then hops around the room rabidly shooting at everyone in sight. or You try to shoot yourself in the foot only to discover you must first reinvent the gun, the bullet, and your foot.or The bullet travels to your foot instantly, but it took you three weeks to load the round and aim the gun.   BCPL You shoot yourself somewhere in the leg -- you can't get any finer resolution than that. Concurrent Euclid You shoot yourself in somebody else's foot.   Motif You spend days writing a UIL description of your foot, the trajectory, the bullet and the intricate scrollwork on the ivory handles of the gun. When you finally get around to pulling the trigger, the gun jams.   Powerbuilder While attempting to load the gun you discover that the LoadGun system function is buggy; as a work around you tape the bullet to the outside of the gun and unsuccessfully attempt to fire it with a nail. In frustration you club your foot with the butt of the gun and explain to your client that this approximates the functionality of shooting yourself in the foot and that the next version of Powerbuilder will fix it.   Standard ML By the time you get your code to typecheck, you're using a shoot to foot yourself in the gun.   MUMPS You shoot 583149 AK-47 teflon-tipped, hollow-point, armour-piercing bullets into even-numbered toes on odd-numbered feet of everyone in the building -- with one line of code. Three weeks later you shoot yourself in the head rather than try to modify that line.   Java You locate the Gun class, but discover that the Bullet class is abstract, so you extend it and write the missing part of the implementation. Then you implement the ShootAble interface for your foot, and recompile the Foot class. The interface lets the bullet call the doDamage method on the Foot, so the Foot can damage itself in the most effective way. Now you run the program, and call the doShoot method on the instance of the Gun class. First the Gun creates an instance of Bullet, which calls the doFire method on the Gun. The Gun calls the hit(Bullet) method on the Foot, and the instance of Bullet is passed to the Foot. But this causes an IllegalHitByBullet exception to be thrown, and you die.   Unix You shoot yourself in the foot or % ls foot.c foot.h foot.o toe.c toe.o % rm * .o rm: .o: No such file or directory % ls %   370 JCL (alternative) You shoot yourself in the head just thinking about it.   DOS JCL You first find the building you're in in the phone book, then find your office number in the corporate phone book. Then you have to write this down, then describe, in cubits, your exact location, in relation to the door (right hand side thereof). Then you need to write down the location of the gun (loading it is a proprietary utility), then you load it, and the COBOL program, and run them, and, with luck, it may be run tonight.   VMS   $ MOUNT/DENSITY=.45/LABEL=BULLET/MESSAGE="BYE" BULLET::BULLET$GUN SYS$BULLET $ SET GUN/LOAD/SAFETY=OFF/SIGHT=NONE/HAND=LEFT/CHAMBER=1/ACTION=AUTOMATIC/ LOG/ALL/FULL SYS$GUN_3$DUA3:[000000]GUN.GNU $ SHOOT/LOG/AUTO SYS$GUN SYS$SYSTEM:[FOOT]FOOT.FOOT   %DCL-W-ACTIMAGE, error activating image GUN -CLI-E-IMGNAME, image file $3$DUA240:[GUN]GUN.EXE;1 -IMGACT-F-NOTNATIVE, image is not an OpenVMS Alpha AXP image or %SYS-F-FTSHT, foot shot (fifty lines of traceback omitted) sh,csh, etc You can't remember the syntax for anything, so you spend five hours reading manual pages, then your foot falls asleep. You shoot the computer and switch to C.   Apple System 7 Double click the gun icon and a window giving a selection for guns, target areas, plus balloon help with medical remedies, and assorted sound effects. Click "shoot" button and a small bomb appears with note "Error of Type 1 has occurred."   Windows 3.1 Double click the gun icon and wait. Eventually a window opens giving a selection for guns, target areas, plus balloon help with medical remedies, and assorted sound effects. Click "shoot" button and a small box appears with note "Unable to open Shoot.dll, check that path is correct."   Windows 95 Your gun is not compatible with this OS and you must buy an upgrade and install it before you can continue. Then you will be informed that you don't have enough memory.   CP/M I remember when shooting yourself in the foot with a BB gun was a big deal.   DOS You finally found the gun, but can't locate the file with the foot for the life of you.   MSDOS You shoot yourself in the foot, but can unshoot yourself with add-on software.   Access You try to point the gun at your foot, but it shoots holes in all your Borland distribution diskettes instead.   Paradox Not only can you shoot yourself in the foot, your users can too.   dBase You squeeze the trigger, but the bullet moves so slowly that by the time your foot feels the pain, you've forgotten why you shot yourself anyway. or You buy a gun. Bullets are only available from another company and are promised to work so you buy them. Then you find out that the next version of the gun is the one scheduled to actually shoot bullets.   DBase IV, V1.0 You pull the trigger, but it turns out that the gun was a poorly designed hand grenade and the whole building blows up.   SQL You cut your foot off, send it out to a service bureau and when it returns, it has a hole in it but will no longer fit the attachment at the end of your leg. or Insert into Foot Select Bullet >From Gun.Hand Where Chamber = 'LOADED' And Trigger = 'PULLED'   Clipper You grab a bullet, get ready to insert it in the gun so that you can shoot yourself in the foot and discover that the gun that the bullets fits has not yet been built, but should be arriving in the mail _REAL_SOON_NOW_. Oracle The menus for coding foot_shooting have not been implemented yet and you can't do foot shooting in SQL.   English You put your foot in your mouth, then bite it off. (For those who don't know, English is a McDonnell Douglas/PICK query language which allegedly requires 110% of system resources to run happily.) Revelation [an implementation of the PICK Operating System] You'll be able to shoot yourself in the foot just as soon as you figure out what all these bullets are for.   FlagShip Starting at the top of your head, you aim the gun at yourself repeatedly until, half an hour later, the gun is finally pointing at your foot and you pull the trigger. A new foot with a hole in it appears but you can't work out how to get rid of the old one and your gun doesn't work anymore.   FidoNet You put your foot in your mouth, then echo it internationally.   PicoSpan [a UNIX-based computer conferencing system] You can't shoot yourself in the foot because you're not a host. or (host variation) Whenever you shoot yourself in the foot, someone opens a topic in policy about it.   Internet You put your foot in your mouth, shoot it, then spam the bullet so that everybody gets shot in the foot.   troff rmtroff -ms -Hdrwp | lpr -Pwp2 & .*place bullet in footer .B .NR FT +3i .in 4 .bu Shoot! .br .sp .in -4 .br .bp NR HD -2i .*   Genetic Algorithms You create 10,000 strings describing the best way to shoot yourself in the foot. By the time the program produces the optimal solution, humans have evolved wings and the problem is moot.   CSP (Communicating Sequential Processes) You only fail to shoot everything that isn't your foot.   MS-SQL Server MS-SQL Server’s gun comes pre-loaded with an unlimited supply of Teflon coated bullets, and it only has two discernible features: the muzzle and the trigger. If that wasn't enough, MS-SQL Server also puts the gun in your hand, applies local anesthetic to the skin of your forefinger and stitches it to the gun's trigger. Meanwhile, another process has set up a spinal block to numb your lower body. It will then proceeded to surgically remove your foot, cryogenically freeze it for preservation, and attach it to the muzzle of the gun so that no matter where you aim, you will shoot your foot. In order to avoid shooting yourself in the foot, you need to unstitch your trigger finger, remove your foot from the muzzle of the gun, and have it surgically reattached. Then you probably want to get some crutches and go out to buy a book on SQL Server Performance Tuning.   Sybase Sybase's gun requires assembly, and you need to go out and purchase your own clip and bullets to load the gun. Assembly is complicated by the fact that Sybase has hidden the gun behind a big stack of reference manuals, but it hasn't told you where that stack is. While you were off finding the gun, assembling it, buying bullets, etc., Sybase was also busy surgically removing your foot and cryogenically freezing it for preservation. Instead of attaching it to the muzzle of the gun, though, it packed your foot on dry ice and sent it UPS-Ground to an unnamed hookah bar somewhere in the middle east. In order to shoot your foot, you must modify your gun with a GPS system for targeting and hire some guy named "Indy" to find the hookah bar and wire the coordinates back to you. By this time, you've probably become so daunted at the tasks stand between you and shooting your foot that you hire a guy who's read all the books on Sybase to help you shoot your foot. If you're lucky, he'll be smart enough both to find your foot and to stop you from shooting it.   Magic software You spend 1 week looking up the correct syntax for GUN. When you find it, you realise that GUN will not let you shoot in your own foot. It will allow you to shoot almost anything but your foot. You then decide to build your own gun. You can't use the standard barrel since this will only allow for standard bullets, which will not fire if the barrel is pointed at your foot. After four weeks, you have created your own custom gun. It blows up in your hand without warning, because you failed to initialise the safety catch and it doesn't know whether the initial state is "0", 0, NULL, "ZERO", 0.0, 0,0, "0.0", or "0,00". You fix the problem with your remaining hand by nesting 12 safety catches, and then decide to build the gun without safety catch. You then shoot the management and retire to a happy life where you code in languages that will allow you to shoot your foot in under 10 days.FirefoxLets you shoot yourself in as many feet as you'd like, while using multiple great addons! IEA moving target in terms of standard ammunition size and doesn't always work properly with non-Microsoft ammunition, so sometimes you shoot something other than your foot. However, it's the corporate world's standard foot-shooting apparatus. Hackers seem to enjoy rigging websites up to trigger cascading foot-shooting failures. Windows 98 About the same as Windows 95 in terms of overall bullet capacity and triggering mechanisms. Includes updated DirectShot API. A new version was released later on to support USB guns, Windows 98 SE.WPF:You get your baseball glove and a ball and you head out to your backyard, where you throw balls to your pitchback. Then your unkempt-haired-cargo-shorts-and-sandals-with-white-socks-wearing neighbor uses XAML to sculpt your arm into a gun, the ball into a bullet and the pitchback into your foot. By now, however, only the neighbor can get it to work and he's only around from 6:30 PM - 3:30 AM. LOGO: You very carefully lay out the trajectory of the bullet. Then you start the gun, which fires very slowly. You walk precisely to the point where the bullet will travel and wait, but just before it gets to you, your class time is up and one of the other kids has already used the system to hack into Sony's PS3 network. Flash: Someone has designed a beautiful-looking gun that anyone can shoot their feet with for free. It weighs six hundred pounds. All kinds of people are shooting themselves in the feet, and sending the link to everyone else so that they can too. That is, except for the criminals, who are all stealing iOS devices that the gun won't work with.APL: Its (mostly) all greek to me. Lisp: Place ((gun in ((hand sight (foot then shoot))))) (Lots of Insipid Stupid Parentheses)Apple OS/X and iOS Once a year, Steve Jobs returns from sick leave to tell millions of unwavering fans how they will be able to shoot themselves in the foot differently this year. They retweet and blog about it ad nauseam, and wait in line to be the first to experience "shoot different".Windows ME Usually fails, even at shooting you in the foot. Yo dawg, I heard you like shooting yourself in the foot. So I put a gun in your gun, so you can shoot yourself in the foot while you shoot yourself in the foot. (Okay, I'm not especially proud of this joke.) Windows 2000 Now you really do have to log in, before you are allowed to shoot yourself in the foot.Windows XPYou thought you learned your lesson: Don't use Windows ME. Then, along came this new creature, built on top of Windows NT! So you spend the next couple days installing antivirus software, patches and service packs, just so you can get that driver to install, and then proceed to shoot yourself in the foot. Windows Vista Newer! Glossier! Shootier! Windows 7 The bullets come out a lot smoother. Active Directory Each bullet now has an attached Bullet Identifier, and can be uniquely identified. Policies can be applied to dictate fragmentation, and the gun will occasionally have a confusing delay after the trigger has been pulled. PythonYou try to use import foot; foot.shoot() only to realize that's only available in 3.0, to which you can't yet upgrade from 2.7 because of all those extension libs lacking support. Solaris Shoots best when used on SPARC hardware, but still runs the trigger GUI under Java. After weeks of learning the appropriate STOP command to prevent the trigger from automatically being pressed on boot, you think you've got it under control. Then the one time you ever use dtrace, it hits a bug that fires the gun. MySQL The feature that allows you to shoot yourself in the foot has been in development for about 6 years, and they are adding it into the next version, which is coming out REAL SOON NOW, promise! But you can always check it out of source control and try it yourself (just not in any environment where data integrity is important because it will probably explode.) PostgreSQLAllows you to have a smug look on your face while you shoot yourself in the foot, because those MySQL guys STILL don't have that feature. NoSQL Barrel? Who needs a barrel? Just put the bullet on your foot, and strike it with a hammer. See? It's so much simpler and more efficient that way. You can even strike multiple bullets in one swing if you swing with a good enough arc, because hammers are easy to use. Getting them to synchronize is a little difficult, though.Eclipse There are about a dozen different packages for shooting yourself in the foot, with weird interdependencies on outdated components. Once you finally navigate the morass and get one installed, you then have something to look at while you shoot yourself in the foot with that package: You can watch the screen redraw.Outlook Makes it really easy to let everyone know you shot yourself in the foot!Shooting yourself in the foot using delegates.You really need to shoot yourself in the foot but you hate firearms (you don't want any dependency on the specifics of shooting) so you delegate it to somebody else. You don't care how it is done as long is shooting your foot. You can do it asynchronously in case you know you may faint so you are called back/slapped in the face by your shooter/friend (or background worker) when everything is done.C#You prepare the gun and the bullet, carefully modeling all of the physics of a bullet traveling through a foot. Just before you're about to pull the trigger, you stumble on System.Windows.BodyParts.Foot.ShootAt(System.Windows.Firearms.IGun gun) in the extended framework, realize you just wasted the entire afternoon, and shoot yourself in the head.PHP<?phprequire("foot_safety_check.php");?><!DOCTYPE HTML><html><head> <!--Lower!--><title>Shooting me in the foot</title></head> <body> <!--LOWER!!!--><leg> <!--OK, I made this one up...--><footer><?php echo (dungSift($_SERVER['HTTP_USER_AGENT'], "ie"))?("Your foot is safe, but you might want to wear a hard hat!"):("<div class=\"shot\">BANG!</div>"); ?></footer></leg> </body> </html>

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• Primefaces datatable in-cell edit to update other rows in the same datatable with ajax rowEdit event processing

  - by Java Thu

  I have issue to update other rows in the same datatable when one row updated using primeface datatable in-cell edit ajax rowEdit. But failed to update other row with ajax call. The ajax response only return the same row data which was updated. The codes are as following: <h:form id="testForm"> <p:dataTable id="testDT" var="d" rowIndexVar="rowIndex" value="#{testBean.lists}" editable="true"> <p:column> <f:facet name="header">No</f:facet> <h:outputText value="#{rowIndex}" /> </p:column> <p:column headerText="Value"> <p:cellEditor> <f:facet name="output"> <h:outputText value="#{d.value}" /> </f:facet> <f:facet name="input"> <p:inputText value="#{d.value}" size="5" /> </f:facet> </p:cellEditor> </p:column> <p:column headerText="Edit" style="width:50px"> <p:outputPanel rendered="#{d.editable}"> <p:rowEditor> </p:rowEditor> </p:outputPanel> </p:column> <p:ajax event="rowEdit" update=":testForm:testDT" listener="#{testBean.onRowUpdate}" /> </p:dataTable> </h:form> My TestBean: package web.bean.test; import java.util.ArrayList; import java.util.List; import javax.annotation.PostConstruct; import javax.faces.bean.ManagedBean; import javax.faces.bean.ViewScoped; import org.primefaces.event.RowEditEvent; @ManagedBean(name="testBean") @ViewScoped public class TestBean { private List<TestData> lists = new ArrayList<>(); @PostConstruct protected void init() { TestData d = new TestData("Row1Data", 1d, true); lists.add(d); d = new TestData("Row1Data", 11.11d, false); lists.add(d); } public void onRowUpdate(RowEditEvent event) { Object o = event.getObject(); if (o != null) { TestData d = (TestData)o; TestData d1 = lists.get(1); d1.setValue(d1.getValue() + d.getValue()); } } public List<TestData> getLists() { return lists; } public void setLists(List<TestData> lists) { this.lists = lists; } } package web.bean.test; public class TestData { private String name; private double value; private boolean editable; public TestData(String name, double value, boolean editable) { super(); this.name = name; this.value = value; this.editable = editable; } public TestData() { } public String getName() { return name; } public void setName(String name) { this.name = name; } public double getValue() { return value; } public void setValue(double value) { this.value = value; } public boolean isEditable() { return editable; } public void setEditable(boolean editable) { this.editable = editable; } } The ajax response body: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><link type="text/css" rel="stylesheet" href="/Octopus-G/javax.faces.resource/theme.css.xhtml?ln=primefaces-bluesky" /><link type="text/css" rel="stylesheet" href="/Octopus-G/javax.faces.resource/primefaces.css.xhtml?ln=primefaces&amp;v=3.2" /><script type="text/javascript" src="/Octopus-G/javax.faces.resource/jquery/jquery.js.xhtml?ln=primefaces&amp;v=3.2"></script><script type="text/javascript" src="/Octopus-G/javax.faces.resource/primefaces.js.xhtml?ln=primefaces&amp;v=3.2"></script></head><body> <form id="testForm" name="testForm" method="post" action="/Octopus-G/test.xhtml" enctype="application/x-www-form-urlencoded"> <input type="hidden" name="testForm" value="testForm" /> <div id="testForm:testDT" class="ui-datatable ui-widget"><table role="grid"><thead><tr role="row"><th id="testForm:testDT:j_idt5" class="ui-state-default" role="columnheader"><div class="ui-dt-c"><span>No</span></div></th><th id="testForm:testDT:j_idt8" class="ui-state-default" role="columnheader"><div class="ui-dt-c"><span>Value</span></div></th><th id="testForm:testDT:j_idt12" class="ui-state-default" role="columnheader" style="width:50px"><div class="ui-dt-c"><span>Edit</span></div></th></tr></thead><tfoot></tfoot><tbody id="testForm:testDT_data" class="ui-datatable-data ui-widget-content"><tr data-ri="0" class="ui-widget-content ui-datatable-even" role="row"><td role="gridcell"><div class="ui-dt-c">0</div></td><td role="gridcell" class="ui-editable-column"><div class="ui-dt-c"><span id="testForm:testDT:0:j_idt9" class="ui-cell-editor"><span class="ui-cell-editor-output">1.0</span><span class="ui-cell-editor-input"><input id="testForm:testDT:0:j_idt11" name="testForm:testDT:0:j_idt11" type="text" value="1.0" size="5" class="ui-inputfield ui-inputtext ui-widget ui-state-default ui-corner-all" /><script id="testForm:testDT:0:j_idt11_s" type="text/javascript">PrimeFaces.cw('InputText','widget_testForm_testDT_0_j_idt11',{id:'testForm:testDT:0:j_idt11'});</script></span></span></div></td><td role="gridcell" style="width:50px"><div class="ui-dt-c"><span id="testForm:testDT:0:j_idt13"><span id="testForm:testDT:0:j_idt14" class="ui-row-editor"><span class="ui-icon ui-icon-pencil"></span><span class="ui-icon ui-icon-check" style="display:none"></span><span class="ui-icon ui-icon-close" style="display:none"></span></span></span></div></td></tr><tr data-ri="1" class="ui-widget-content ui-datatable-odd" role="row"><td role="gridcell"><div class="ui-dt-c">1</div></td><td role="gridcell" class="ui-editable-column"><div class="ui-dt-c"><span id="testForm:testDT:1:j_idt9" class="ui-cell-editor"><span class="ui-cell-editor-output">11.11</span><span class="ui-cell-editor-input"><input id="testForm:testDT:1:j_idt11" name="testForm:testDT:1:j_idt11" type="text" value="11.11" size="5" class="ui-inputfield ui-inputtext ui-widget ui-state-default ui-corner-all" /><script id="testForm:testDT:1:j_idt11_s" type="text/javascript">PrimeFaces.cw('InputText','widget_testForm_testDT_1_j_idt11',{id:'testForm:testDT:1:j_idt11'});</script></span></span></div></td><td role="gridcell" style="width:50px"><div class="ui-dt-c"></div></td></tr></tbody></table></div><script id="testForm:testDT_s" type="text/javascript">$(function() {PrimeFaces.cw('DataTable','widget_testForm_testDT',{id:'testForm:testDT',editable:true,behaviors:{rowEdit:function(event) {PrimeFaces.ab({source:'testForm:testDT',process:'testForm:testDT',update:'testForm:testDT',event:'rowEdit'}, arguments[1]);}}});});</script><input type="hidden" name="javax.faces.ViewState" id="javax.faces.ViewState" value="-8223787210091934199:-360328890338571623" autocomplete="off" /> </form></body> </html>

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• iPhone Image Processing--matrix convolution

  - by James

  I am implementing a matrix convolution blur on the iPhone. The following code converts the UIImage supplied as an argument of the blur function into a CGImageRef, and then stores the RGBA values in a standard C char array. CGImageRef imageRef = imgRef.CGImage; int width = imgRef.size.width; int height = imgRef.size.height; CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); unsigned char *pixels = malloc((height) * (width) * 4); NSUInteger bytesPerPixel = 4; NSUInteger bytesPerRow = bytesPerPixel * (width); NSUInteger bitsPerComponent = 8; CGContextRef context = CGBitmapContextCreate(pixels, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big); CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef); CGContextRelease(context); Then the pixels values stored in the pixels array are convolved, and stored in another array. unsigned char *results = malloc((height) * (width) * 4); Finally, these augmented pixel values are changed back into a CGImageRef, converted to a UIImage, and the returned at the end of the function with the following code. context = CGBitmapContextCreate(results, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big); CGImageRef finalImage = CGBitmapContextCreateImage(context); UIImage *newImage = [UIImage imageWithCGImage:CGBitmapContextCreateImage(context)]; CGImageRelease(finalImage); NSLog(@"edges found"); free(results); free(pixels); CGColorSpaceRelease(colorSpace); return newImage; This works perfectly, once. Then, once the image is put through the filter again, very odd, unprecedented pixel values representing input pixel values that don't exist, are returned. Is there any reason why this should work the first time, but then not afterward? Beneath is the entirety of the function. -(UIImage*) blur:(UIImage*)imgRef { CGImageRef imageRef = imgRef.CGImage; int width = imgRef.size.width; int height = imgRef.size.height; CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); unsigned char *pixels = malloc((height) * (width) * 4); NSUInteger bytesPerPixel = 4; NSUInteger bytesPerRow = bytesPerPixel * (width); NSUInteger bitsPerComponent = 8; CGContextRef context = CGBitmapContextCreate(pixels, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big); CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef); CGContextRelease(context); height = imgRef.size.height; width = imgRef.size.width; float matrix[] = {0,0,0,0,1,0,0,0,0}; float divisor = 1; float shift = 0; unsigned char *results = malloc((height) * (width) * 4); for(int y = 1; y < height; y++){ for(int x = 1; x < width; x++){ float red = 0; float green = 0; float blue = 0; int multiplier=1; if(y>0 && x>0){ int index = (y-1)*width + x; red = matrix[0]*multiplier*(float)pixels[4*(index-1)] + matrix[1]*multiplier*(float)pixels[4*(index)] + matrix[2]*multiplier*(float)pixels[4*(index+1)]; green = matrix[0]*multiplier*(float)pixels[4*(index-1)+1] + matrix[1]*multiplier*(float)pixels[4*(index)+1] + matrix[2]*multiplier*(float)pixels[4*(index+1)+1]; blue = matrix[0]*multiplier*(float)pixels[4*(index-1)+2] + matrix[1]*multiplier*(float)pixels[4*(index)+2] + matrix[2]*multiplier*(float)pixels[4*(index+1)+2]; index = (y)*width + x; red = red+ matrix[3]*multiplier*(float)pixels[4*(index-1)] + matrix[4]*multiplier*(float)pixels[4*(index)] + matrix[5]*multiplier*(float)pixels[4*(index+1)]; green = green + matrix[3]*multiplier*(float)pixels[4*(index-1)+1] + matrix[4]*multiplier*(float)pixels[4*(index)+1] + matrix[5]*multiplier*(float)pixels[4*(index+1)+1]; blue = blue + matrix[3]*multiplier*(float)pixels[4*(index-1)+2] + matrix[4]*multiplier*(float)pixels[4*(index)+2] + matrix[5]*multiplier*(float)pixels[4*(index+1)+2]; index = (y+1)*width + x; red = red+ matrix[6]*multiplier*(float)pixels[4*(index-1)] + matrix[7]*multiplier*(float)pixels[4*(index)] + matrix[8]*multiplier*(float)pixels[4*(index+1)]; green = green + matrix[6]*multiplier*(float)pixels[4*(index-1)+1] + matrix[7]*multiplier*(float)pixels[4*(index)+1] + matrix[8]*multiplier*(float)pixels[4*(index+1)+1]; blue = blue + matrix[6]*multiplier*(float)pixels[4*(index-1)+2] + matrix[7]*multiplier*(float)pixels[4*(index)+2] + matrix[8]*multiplier*(float)pixels[4*(index+1)+2]; red = red/divisor+shift; green = green/divisor+shift; blue = blue/divisor+shift; if(red<0){ red=0; } if(green<0){ green=0; } if(blue<0){ blue=0; } if(red>255){ red=255; } if(green>255){ green=255; } if(blue>255){ blue=255; } int realPos = 4*(y*imgRef.size.width + x); results[realPos] = red; results[realPos + 1] = green; results[realPos + 2] = blue; results[realPos + 3] = 1; }else { int realPos = 4*((y)*(imgRef.size.width) + (x)); results[realPos] = 0; results[realPos + 1] = 0; results[realPos + 2] = 0; results[realPos + 3] = 1; } } } context = CGBitmapContextCreate(results, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big); CGImageRef finalImage = CGBitmapContextCreateImage(context); UIImage *newImage = [UIImage imageWithCGImage:CGBitmapContextCreateImage(context)]; CGImageRelease(finalImage); free(results); free(pixels); CGColorSpaceRelease(colorSpace); return newImage;} THANKS!!!

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• Why won't "!important" override ":first-line"?

  - by bazzlevi

  I am trying to do the tutorial in Chapter 6 of the 2nd edition of "CSS: The Missing Manual", and I've run into an issue I'm trying to understand. I have one style that looks like this: #main p:first-line { color: #999999; font-weight: bold; } Later I have another style that looks like this: #main p.byline { color: #00994D !important; font-size: 1.6em; margin: 5px 0 25px 50px; } I am confused because the second one won't override the color choice in the first one despite the fact that the second one has "!important" in it. I put both classes into an online specificity calculator, and the second one comes out being more specific, so I'm doubly confused. By the way, the inclusion of "!important" is the work-around suggested in the errata for the book. Odd that it still doesn't work! Here's the code for the entire page: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>CSS Typography</title> <style type="text/css"> html, body, h1, h2, h3, h4, h5, h6, p, ol, ul, li, pre, code, address, variable, form, fieldset, blockquote { padding: 0; margin: 0; font-size: 100%; font-weight: normal; } table { border-collapse: collapse; border-spacing: 0; } td, th, caption { font-weight: normal; text-align: left; } img, fieldset { border: 0; } ol { padding-left: 1.4em; list-style: decimal; } ul { padding-left: 1.4em; list-style:square; } q:before, q:after { content:''; } body { color: #002D4B; font-family: Arial, Helvetica, sans-serif; font-size: 62.5% } #main h1 { color: #F60; font-family: "Arial Black", Arial, Helvetica, sans-serif; font-size: 4em; } #main h2 { font: bold 3.5em "Hoefler Text", Garamond, Times, serif; border-bottom: 1px solid #002D4B; margin-top: 25px; } #main h3 { color: #F60; font-size: 1.9em; font-weight: bold; text-transform: uppercase; margin-top: 25px; margin-bottom: 10px; } #main p { font-size: 1.5em; line-height: 150%; margin-left: 150px; margin-right: 50px; margin-bottom: 10px; } #main p:first-line { color: #999999; font-weight: bold; } #main ul { margin: 50px 0 25px 50px; width: 150px; float: right; } #main li { color: #207EBF; font-size: 1.5em; margin-bottom: 7px; } #main p.byline { color: #00994D !important; font-size: 1.6em; margin: 5px 0 25px 50px; } #main .byline strong { color: #207EBF; text-transform: uppercase; margin-left: 5px; } </style> </head> <body> <div id="main"> <h1><strong>CSS</strong> The Missing Manual</h1> <h2>Exploring Typographic Possibilities</h2> <p class="byline">november 30 <strong>Rod Dibble</strong></p> <ul> <li>Lorem Ipsum</li> <li>Reprehenderit qui in ea</li> <li>Lorem Ipsum</li> <li>Reprehenderit qui in ea</li> <li>Lorem Ipsum</li> <li>Reprehenderit qui in ea</li> </ul> <h3>Esse quam nulla</h3> <p>Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur? Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?</p> <h3>Quis autem vel eum</h3> <p>Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur? Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui dolorem eum fugiat quo voluptas nulla pariatur?</p> </div> </body> </html> Here is the above code on JSBin: http://jsbin.com/unexe3

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• Why does fprintf start printing out of order or not at all?

  - by Steve Melvin

  This code should take an integer, create pipes, spawn two children, wait until they are dead, and start all over again. However, around the third time around the loop I lose my prompt to enter a number and it no longer prints the number I've entered. Any ideas? #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #define WRITE 1 #define READ 0 int main (int argc, const char * argv[]) { //Pipe file-descriptor array unsigned int isChildA = 0; int pipeA[2]; int pipeB[2]; int num = 0; while(1){ fprintf(stderr,"Enter an integer: "); scanf("%i", &num); if(num == 0){ fprintf(stderr,"You entered zero, exiting...\n"); exit(0); } //Open Pipes if(pipe(pipeA) < 0){ fprintf(stderr,"Could not create pipe A.\n"); exit(1); } if(pipe(pipeB) < 0){ fprintf(stderr,"Could not create pipe B.\n"); exit(1); } fprintf(stderr,"Value read: %i \n", num); fprintf(stderr,"Parent PID: %i\n", getpid()); pid_t procID = fork(); switch (procID) { case -1: fprintf(stderr,"Fork error, quitting...\n"); exit(1); break; case 0: isChildA = 1; break; default: procID = fork(); if (procID<0) { fprintf(stderr,"Fork error, quitting...\n"); exit(1); } else if(procID == 0){ isChildA = 0; } else { write(pipeA[WRITE], &num, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); pid_t pid; while (pid = waitpid(-1, NULL, 0)) { if (errno == ECHILD) { break; } } } break; } if (procID == 0) { //We're a child, do kid-stuff. ssize_t bytesRead = 0; int response; while (1) { while (bytesRead == 0) { bytesRead = read((isChildA?pipeA[READ]:pipeB[READ]), &response, sizeof(int)); } if (response < 2) { //Kill other child and self fprintf(stderr, "Terminating PROCID: %i\n", getpid()); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); close(pipeA[WRITE]); close(pipeA[READ]); close(pipeB[WRITE]); close(pipeB[READ]); return 0; } else if(!(response%2)){ //Even response/=2; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } else { //Odd response*=3; response++; fprintf(stderr,"PROCID: %i, VALUE: %i\n", getpid(), response); write((isChildA?pipeB[WRITE]:pipeA[WRITE]), &response, sizeof(int)); bytesRead = 0; } } } } return 0; } This is the output I am getting... bash-3.00$ ./proj2 Enter an integer: 101 Value read: 101 Parent PID: 9379 PROCID: 9380, VALUE: 304 PROCID: 9381, VALUE: 152 PROCID: 9380, VALUE: 76 PROCID: 9381, VALUE: 38 PROCID: 9380, VALUE: 19 PROCID: 9381, VALUE: 58 PROCID: 9380, VALUE: 29 PROCID: 9381, VALUE: 88 PROCID: 9380, VALUE: 44 PROCID: 9381, VALUE: 22 PROCID: 9380, VALUE: 11 PROCID: 9381, VALUE: 34 PROCID: 9380, VALUE: 17 PROCID: 9381, VALUE: 52 PROCID: 9380, VALUE: 26 PROCID: 9381, VALUE: 13 PROCID: 9380, VALUE: 40 PROCID: 9381, VALUE: 20 PROCID: 9380, VALUE: 10 PROCID: 9381, VALUE: 5 PROCID: 9380, VALUE: 16 PROCID: 9381, VALUE: 8 PROCID: 9380, VALUE: 4 PROCID: 9381, VALUE: 2 PROCID: 9380, VALUE: 1 Terminating PROCID: 9381 Terminating PROCID: 9380 Enter an integer: 102 Value read: 102 Parent PID: 9379 PROCID: 9386, VALUE: 51 PROCID: 9387, VALUE: 154 PROCID: 9386, VALUE: 77 PROCID: 9387, VALUE: 232 PROCID: 9386, VALUE: 116 PROCID: 9387, VALUE: 58 PROCID: 9386, VALUE: 29 PROCID: 9387, VALUE: 88 PROCID: 9386, VALUE: 44 PROCID: 9387, VALUE: 22 PROCID: 9386, VALUE: 11 PROCID: 9387, VALUE: 34 PROCID: 9386, VALUE: 17 PROCID: 9387, VALUE: 52 PROCID: 9386, VALUE: 26 PROCID: 9387, VALUE: 13 PROCID: 9386, VALUE: 40 PROCID: 9387, VALUE: 20 PROCID: 9386, VALUE: 10 PROCID: 9387, VALUE: 5 PROCID: 9386, VALUE: 16 PROCID: 9387, VALUE: 8 PROCID: 9386, VALUE: 4 PROCID: 9387, VALUE: 2 PROCID: 9386, VALUE: 1 Terminating PROCID: 9387 Terminating PROCID: 9386 Enter an integer: 104 Value read: 104 Parent PID: 9379 Enter an integer: PROCID: 9388, VALUE: 52 PROCID: 9389, VALUE: 26 PROCID: 9388, VALUE: 13 PROCID: 9389, VALUE: 40 PROCID: 9388, VALUE: 20 PROCID: 9389, VALUE: 10 PROCID: 9388, VALUE: 5 PROCID: 9389, VALUE: 16 PROCID: 9388, VALUE: 8 PROCID: 9389, VALUE: 4 PROCID: 9388, VALUE: 2 PROCID: 9389, VALUE: 1 Terminating PROCID: 9388 Terminating PROCID: 9389 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9395, VALUE: 316 PROCID: 9396, VALUE: 158 PROCID: 9395, VALUE: 79 PROCID: 9396, VALUE: 238 PROCID: 9395, VALUE: 119 PROCID: 9396, VALUE: 358 PROCID: 9395, VALUE: 179 PROCID: 9396, VALUE: 538 PROCID: 9395, VALUE: 269 PROCID: 9396, VALUE: 808 PROCID: 9395, VALUE: 404 PROCID: 9396, VALUE: 202 PROCID: 9395, VALUE: 101 PROCID: 9396, VALUE: 304 PROCID: 9395, VALUE: 152 PROCID: 9396, VALUE: 76 PROCID: 9395, VALUE: 38 PROCID: 9396, VALUE: 19 PROCID: 9395, VALUE: 58 PROCID: 9396, VALUE: 29 PROCID: 9395, VALUE: 88 PROCID: 9396, VALUE: 44 PROCID: 9395, VALUE: 22 PROCID: 9396, VALUE: 11 PROCID: 9395, VALUE: 34 PROCID: 9396, VALUE: 17 PROCID: 9395, VALUE: 52 PROCID: 9396, VALUE: 26 PROCID: 9395, VALUE: 13 PROCID: 9396, VALUE: 40 PROCID: 9395, VALUE: 20 PROCID: 9396, VALUE: 10 PROCID: 9395, VALUE: 5 PROCID: 9396, VALUE: 16 PROCID: 9395, VALUE: 8 PROCID: 9396, VALUE: 4 PROCID: 9395, VALUE: 2 PROCID: 9396, VALUE: 1 Terminating PROCID: 9395 Terminating PROCID: 9396 105 Value read: 105 Parent PID: 9379 Enter an integer: PROCID: 9397, VALUE: 316 PROCID: 9398, VALUE: 158 PROCID: 9397, VALUE: 79 PROCID: 9398, VALUE: 238 PROCID: 9397, VALUE: 119 PROCID: 9398, VALUE: 358 PROCID: 9397, VALUE: 179 PROCID: 9398, VALUE: 538 PROCID: 9397, VALUE: 269 PROCID: 9398, VALUE: 808 PROCID: 9397, VALUE: 404 PROCID: 9398, VALUE: 202 PROCID: 9397, VALUE: 101 PROCID: 9398, VALUE: 304 PROCID: 9397, VALUE: 152 PROCID: 9398, VALUE: 76 PROCID: 9397, VALUE: 38 PROCID: 9398, VALUE: 19 PROCID: 9397, VALUE: 58 PROCID: 9398, VALUE: 29 PROCID: 9397, VALUE: 88 PROCID: 9398, VALUE: 44 PROCID: 9397, VALUE: 22 PROCID: 9398, VALUE: 11 PROCID: 9397, VALUE: 34 PROCID: 9398, VALUE: 17 PROCID: 9397, VALUE: 52 PROCID: 9398, VALUE: 26 PROCID: 9397, VALUE: 13 PROCID: 9398, VALUE: 40 PROCID: 9397, VALUE: 20 PROCID: 9398, VALUE: 10 PROCID: 9397, VALUE: 5 PROCID: 9398, VALUE: 16 PROCID: 9397, VALUE: 8 PROCID: 9398, VALUE: 4 PROCID: 9397, VALUE: 2 PROCID: 9398, VALUE: 1 Terminating PROCID: 9397 Terminating PROCID: 9398 106 Value read: 106 Parent PID: 9379 Enter an integer: PROCID: 9399, VALUE: 53 PROCID: 9400, VALUE: 160 PROCID: 9399, VALUE: 80 PROCID: 9400, VALUE: 40 PROCID: 9399, VALUE: 20 PROCID: 9400, VALUE: 10 PROCID: 9399, VALUE: 5 PROCID: 9400, VALUE: 16 PROCID: 9399, VALUE: 8 PROCID: 9400, VALUE: 4 PROCID: 9399, VALUE: 2 PROCID: 9400, VALUE: 1 Terminating PROCID: 9399 Terminating PROCID: 9400 ^C Another thing that's strange, when ran from within XCode it behaves normally. However, when ran from bash on Solaris or OSX it acts up.

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• XSL Template outputting massive chunk of text, rather than HTML. But only on one section

  - by Throlkim

  I'm having a slightly odd situation with an XSL template. Most of it outputs fine, but a certain for-each loop is causing me problems. Here's the XML: <area> <feature type="Hall"> <Heading><![CDATA[Hall]]></Heading> <Para><![CDATA[Communal gardens, pathway leading to PVCu double glazed communal front door to]]></Para> </feature> <feature type="Entrance Hall"> <Heading><![CDATA[Communal Entrance Hall]]></Heading> <Para><![CDATA[Plain ceiling, centre light fitting, fire door through to inner hallway, wood and glazed panelled front door to]]></Para> </feature> <feature type="Inner Hall"> <Heading><![CDATA[Inner Hall]]></Heading> <Para><![CDATA[Plain ceiling with pendant light fitting and covings, security telephone, airing cupboard housing gas boiler serving domestic hot water and central heating, telephone point, storage cupboard housing gas and electric meters, wooden panelled doors off to all rooms.]]></Para> </feature> <feature type="Lounge (Reception)" width="3.05" length="4.57" units="metre"> <Heading><![CDATA[Lounge (Reception)]]></Heading> <Para><![CDATA[15' 6" x 10' 7" (4.72m x 3.23m) Window to the side and rear elevation, papered ceiling with pendant light fitting and covings, two double panelled radiators, power points, wall mounted security entry phone, TV aerial point.]]></Para> </feature> <feature type="Kitchen" width="3.05" length="3.66" units="metre"> <Heading><![CDATA[Kitchen]]></Heading> <Para><![CDATA[12' x 10' (3.66m x 3.05m) Double glazed window to the rear elevation, textured ceiling with strip lighting, range of base and wall units in Beech with brushed aluminium handles, co-ordinated working surfaces with inset stainless steel sink with mixer taps over, co-ordinated tiled splashbacks, gas and electric cooker points, large storage cupboard with shelving, power points.]]></Para> </feature> <feature type="Entrance Porch"> <Heading><![CDATA[Balcony]]></Heading> <Para><![CDATA[Views across the communal South facing garden, wrought iron balustrade.]]></Para> </feature> <feature type="Bedroom" width="3.35" length="3.96" units="metre"> <Heading><![CDATA[Bedroom One]]></Heading> <Para><![CDATA[13' 6" x 11' 5" (4.11m x 3.48m) Double glazed windows to the front and side elevations, papered ceiling with pendant light fittings and covings, single panelled radiator, power points, telephone point, security entry phone.]]></Para> </feature> <feature type="Bedroom" width="3.05" length="3.35" units="metre"> <Heading><![CDATA[Bedroom Two]]></Heading> <Para><![CDATA[11' 4" x 10' 1" (3.45m x 3.07m) Double glazed window to the front elevation, plain ceiling with centre light fitting and covings, power points.]]></Para> </feature> <feature type="bathroom"> <Heading><![CDATA[Bathroom]]></Heading> <Para><![CDATA[Obscure double glazed window to the rear elevation, textured ceiling with centre light fitting and extractor fan, suite in white comprising of low level WC, wall mounted wash hand basin and walk in shower housing 'Triton T80' electric shower, co-ordinated tiled splashbacks.]]></Para> </feature> </area> And here's the section of my template that processes it: <xsl:for-each select="area"> <li> <xsl:for-each select="feature"> <li> <h5> <xsl:value-of select="Heading"/> </h5> <xsl:value-of select="Para"/> </li> </xsl:for-each> </li> </xsl:for-each> And here's the output: Hall Communal gardens, pathway leading to PVCu double glazed communal front door to Communal Entrance Hall Plain ceiling, centre light fitting, fire door through to inner hallway, wood and glazed panelled front door to Inner Hall Plain ceiling with pendant light fitting and covings, security telephone, airing cupboard housing gas boiler serving domestic hot water and central heating, telephone point, storage cupboard housing gas and electric meters, wooden panelled doors off to all rooms. Lounge (Reception) 15' 6" x 10' 7" (4.72m x 3.23m) Window to the side and rear elevation, papered ceiling with pendant light fitting and covings, two double panelled radiators, power points, wall mounted security entry phone, TV aerial point. Kitchen 12' x 10' (3.66m x 3.05m) Double glazed window to the rear elevation, textured ceiling with strip lighting, range of base and wall units in Beech with brushed aluminium handles, co-ordinated working surfaces with inset stainless steel sink with mixer taps over, co-ordinated tiled splashbacks, gas and electric cooker points, large storage cupboard with shelving, power points. Balcony Views across the communal South facing garden, wrought iron balustrade. Bedroom One 13' 6" x 11' 5" (4.11m x 3.48m) Double glazed windows to the front and side elevations, papered ceiling with pendant light fittings and covings, single panelled radiator, power points, telephone point, security entry phone. Bedroom Two 11' 4" x 10' 1" (3.45m x 3.07m) Double glazed window to the front elevation, plain ceiling with centre light fitting and covings, power points. Bathroom Obscure double glazed window to the rear elevation, textured ceiling with centre light fitting and extractor fan, suite in white comprising of low level WC, wall mounted wash hand basin and walk in shower housing 'Triton T80' electric shower, co-ordinated tiled splashbacks. For reference, here's the entire XSLT: http://pastie.org/private/eq4gjvqoc1amg9ynyf6wzg The rest of it all outputs fine - what am I missing from the above section?

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• How to let short content pages reach the bottom of the browser window and then a footer should appea

  - by UXdesigner

  In this case, I've developed a CSS code for this web application ..and sometimes the resulting data is too small and the footer of the site appears in the middle of the page and looks odd. I'd like to push that whitespace of the background to the browser's bottom and then followed by a footer. AND if the page is long, that text won't get overlapped by the footer. Can someone help me out with this code right here? I've been trying to use some of the codes I found on this page:http://matthewjamestaylor.com/blog/keeping-footers-at-the-bottom-of-the-page which talks about pretty much the same issue, but I can't get it completely done: What am I doing wrong ? @charset "utf-8"; body { margin: 0; padding: 0; text-align: center; height:100%; position: relative; height:100%; /* needed for container min-height */ } .spacer { clear: both; height: 0; margin: 0; padding: 0; font-size: 0.1em; } .spacer_left { clear: left; margin: 0 0 10px 0; padding: 0; font-size: 0.1em; } hr { height: 1px; margin: 20px 0 20px 0; border: 0; color: #ccc; background: #ccc; } #container { position:relative; /* needed for footer positioning*/ height:auto !important; /* real browsers */ height:100%; /* IE6: treaded as min-height*/ min-height:100%; /* real browsers */ width: 1160px; /* width of the site ! */ margin: 0 auto; padding: 0; border: 1px solid #333; text-align: left; } /* Context Bar */ h1#contexto { background:url('../images/menubarbg2.png'); width:1160px; height:30px; position:relative; margin-top:10px; visibility: inherit; font-family:Arial, Helvetica, sans-serif; font-size:12px; } #header { margin: 0; padding: 5px; height:70px; } h1#titulo { margin: 0; padding: 0 0 0; } #content { margin: -15px 20px 0 20px; /*padding: -6px 5px 20px 5px;*/ padding:1em 1em 5em; /* bottom padding for footer */ } div#content.columns { margin-left: 100px; } #content abbr, #content acronym { cursor: help; border-bottom: 1px dotted; } #content ul { list-style-type: square; } #content ul li, #content ol li { margin: 0 0 0.4em 0; padding: 0; } #content blockquote { width: 75%; margin: 0 auto; padding: 20px; } #footer { margin: 0; height: -30px; padding: 5px; clear: both; bottom:0; position:relative; } UPDATE: THE SOLUTION @charset "utf-8"; body, html { margin: 0; padding: 0; text-align: center; position: relative; height:100%; /* needed for footer positioning*/ } .spacer { clear: both; height: 0; margin: 0; padding: 0; font-size: 0.1em; } .spacer_left { clear: left; margin: 0 0 10px 0; padding: 0; font-size: 0.1em; } hr { height: 1px; margin: 20px 0 20px 0; border: 0; color: #ccc; background: #ccc; } #container { position:relative; /* needed for footer positioning*/ min-height: 100%;/* needed for footer positioning*/ height: auto !important;/* needed for footer positioning*/ height: 100%;/* needed for footer positioning*/ margin: 0 auto -30px;/* needed for footer positioning*/ width: 1160px; padding: 0; border: 1px solid #333; text-align: left; } #header { margin: 0; padding: 5px; height:70px; } h1#titulo { margin: 0; padding: 0 0 0; } h1#contexto { background:url('../images/menubarbg2.png'); width:1160px; height:30px; position:relative; margin-top:10px; visibility: inherit; font-family:Arial, Helvetica, sans-serif; font-size:12px; } #content { margin: -15px 20px 30px 20px; /* needed for footer positioning*/ } div#content.columns { margin-left: 100px; } #content abbr, #content acronym { cursor: help; border-bottom: 1px dotted; } #content ul { list-style-type: square; } #content ul li, #content ol li { margin: 0 0 0.4em 0; padding: 0; } #content blockquote { width: 75%; margin: 0 auto; padding: 20px; } #footer, .push /* needed for footer positioning*/ { padding: 5px; clear: both; position:absolute;/* needed for footer positioning*/ bottom:0;/* needed for footer positioning*/ height: -30px;/* needed for footer positioning*/ width:1150px; }

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• Help with Java Program for Prime numbers

  - by Ben

  Hello everyone, I was wondering if you can help me with this program. I have been struggling with it for hours and have just trashed my code because the TA doesn't like how I executed it. I am completely hopeless and if anyone can help me out step by step, I would greatly appreciate it. In this project you will write a Java program that reads a positive integer n from standard input, then prints out the first n prime numbers. We say that an integer m is divisible by a non-zero integer d if there exists an integer k such that m = k d , i.e. if d divides evenly into m. Equivalently, m is divisible by d if the remainder of m upon (integer) division by d is zero. We would also express this by saying that d is a divisor of m. A positive integer p is called prime if its only positive divisors are 1 and p. The one exception to this rule is the number 1 itself, which is considered to be non-prime. A positive integer that is not prime is called composite. Euclid showed that there are infinitely many prime numbers. The prime and composite sequences begin as follows: Primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, … Composites: 1, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, … There are many ways to test a number for primality, but perhaps the simplest is to simply do trial divisions. Begin by dividing m by 2, and if it divides evenly, then m is not prime. Otherwise, divide by 3, then 4, then 5, etc. If at any point m is found to be divisible by a number d in the range 2 d m-1, then halt, and conclude that m is composite. Otherwise, conclude that m is prime. A moment’s thought shows that one need not do any trial divisions by numbers d which are themselves composite. For instance, if a trial division by 2 fails (i.e. has non-zero remainder, so m is odd), then a trial division by 4, 6, or 8, or any even number, must also fail. Thus to test a number m for primality, one need only do trial divisions by prime numbers less than m. Furthermore, it is not necessary to go all the way up to m-1. One need only do trial divisions of m by primes p in the range 2 p m . To see this, suppose m 1 is composite. Then there exist positive integers a and b such that 1 < a < m, 1 < b < m, and m = ab . But if both a m and b m , then ab m, contradicting that m = ab . Hence one of a or b must be less than or equal to m . To implement this process in java you will write a function called isPrime() with the following signature: static boolean isPrime(int m, int[] P) This function will return true or false according to whether m is prime or composite. The array argument P will contain a sufficient number of primes to do the testing. Specifically, at the time isPrime() is called, array P must contain (at least) all primes p in the range 2 p m . For instance, to test m = 53 for primality, one must do successive trial divisions by 2, 3, 5, and 7. We go no further since 11 53 . Thus a precondition for the function call isPrime(53, P) is that P[0] = 2 , P[1] = 3 , P[2] = 5, and P[3] = 7 . The return value in this case would be true since all these divisions fail. Similarly to test m =143 , one must do trial divisions by 2, 3, 5, 7, and 11 (since 13 143 ). The precondition for the function call isPrime(143, P) is therefore P[0] = 2 , P[1] = 3 , P[2] = 5, P[3] = 7 , and P[4] =11. The return value in this case would be false since 11 divides 143. Function isPrime() should contain a loop that steps through array P, doing trial divisions. This loop should terminate when 2 either a trial division succeeds, in which case false is returned, or until the next prime in P is greater than m , in which case true is returned. Function main() in this project will read the command line argument n, allocate an int array of length n, fill the array with primes, then print the contents of the array to stdout according to the format described below. In the context of function main(), we will refer to this array as Primes[]. Thus array Primes[] plays a dual role in this project. On the one hand, it is used to collect, store, and print the output data. On the other hand, it is passed to function isPrime() to test new integers for primality. Whenever isPrime() returns true, the newly discovered prime will be placed at the appropriate position in array Primes[]. This process works since, as explained above, the primes needed to test an integer m range only up to m , and all of these primes (and more) will already be stored in array Primes[] when m is tested. Of course it will be necessary to initialize Primes[0] = 2 manually, then proceed to test 3, 4, … for primality using function isPrime(). The following is an outline of the steps to be performed in function main(). • Check that the user supplied exactly one command line argument which can be interpreted as a positive integer n. If the command line argument is not a single positive integer, your program will print a usage message as specified in the examples below, then exit. • Allocate array Primes[] of length n and initialize Primes[0] = 2 . • Enter a loop which will discover subsequent primes and store them as Primes[1] , Primes[2], Primes[3] , ……, Primes[n -1] . This loop should contain an inner loop which walks through successive integers and tests them for primality by calling function isPrime() with appropriate arguments. • Print the contents of array Primes[] to stdout, 10 to a line separated by single spaces. In other words Primes[0] through Primes[9] will go on line 1, Primes[10] though Primes[19] will go on line 2, and so on. Note that if n is not a multiple of 10, then the last line of output will contain fewer than 10 primes. Your program, which will be called Prime.java, will produce output identical to that of the sample runs below. (As usual % signifies the unix prompt.) % java Prime Usage: java Prime [PositiveInteger] % java Prime xyz Usage: java Prime [PositiveInteger] % java Prime 10 20 Usage: java Prime [PositiveInteger] % java Prime 75 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239 241 251 257 263 269 271 277 281 283 293 307 311 313 317 331 337 347 349 353 359 367 373 379 % 3 As you can see, inappropriate command line argument(s) generate a usage message which is similar to that of many unix commands. (Try doing the more command with no arguments to see such a message.) Your program will include a function called Usage() having signature static void Usage() that prints this message to stderr, then exits. Thus your program will contain three functions in all: main(), isPrime(), and Usage(). Each should be preceded by a comment block giving it’s name, a short description of it’s operation, and any necessary preconditions (such as those for isPrime().) See examples on the webpage.

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• WCF timeout exception detailed investigation

  - by Jason Kealey

  We have an application that has a WCF service (*.svc) running on IIS7 and various clients querying the service. The server is running Win 2008 Server. The clients are running either Windows 2008 Server or Windows 2003 server. I am getting the following exception, which I have seen can in fact be related to a large number of potential WCF issues. System.TimeoutException: The request channel timed out while waiting for a reply after 00:00:59.9320000. Increase the timeout value passed to the call to Request or increase the SendTimeout value on the Binding. The time allotted to this operation may have been a portion of a longer timeout. ---> System.TimeoutException: The HTTP request to 'http://www.domain.com/WebServices/myservice.svc/gzip' has exceeded the allotted timeout of 00:01:00. The time allotted to this operation may have been a portion of a longer timeout. I have increased the timeout to 30min and the error still occurred. This tells me that something else is at play, because the quantity of data could never take 30min to upload or download. The error comes and goes. At the moment, it is more frequent. It does not seem to matter if I have 3 clients running simultaneously or 100, it still occurs once in a while. Most of the time, there are no timeouts but I still get a few per hour. The error comes from any of the methods that are invoked. One of these methods does not have parameters and returns a bit of data. Another takes in lots of data as a parameter but executes asynchronously. The errors always originate from the client and never reference any code on the server in the stack trace. It always ends with: at System.Net.HttpWebRequest.GetResponse() at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout) On the server: I've tried (and currently have) the following binding settings: maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" maxBufferPoolSize="2147483647" It does not seem to have an impact. I've tried (and currently have) the following throttling settings: <serviceThrottling maxConcurrentCalls="1500" maxConcurrentInstances="1500" maxConcurrentSessions="1500"/> It does not seem to have an impact. I currently have the following settings for the WCF service. [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Single)] I ran with ConcurrencyMode.Multiple for a while, and the error still occurred. I've tried restarting IIS, restarting my underlying SQL Server, restarting the machine. All of these don't seem to have an impact. I've tried disabling the Windows firewall. It does not seem to have an impact. On the client, I have these settings: maxReceivedMessageSize="2147483647" <system.net> <connectionManagement> <add address="*" maxconnection="16"/> </connectionManagement> </system.net> My client closes its connections: var client = new MyClient(); try { return client.GetConfigurationOptions(); } finally { client.Close(); } I have changed the registry settings to allow more outgoing connections: MaxConnectionsPerServer=24, MaxConnectionsPer1_0Server=32. I have now just recently tried SvcTraceViewer.exe. I managed to catch one exception on the client end. I see that its duration is 1 minute. Looking at the server side trace, I can see that the server is not aware of this exception. The maximum duration I can see is 10 seconds. I have looked at active database connections using exec sp_who on the server. I only have a few (2-3). I have looked at TCP connections from one client using TCPview. It usually is around 2-3 and I have seen up to 5 or 6. Simply put, I am stumped. I have tried everything I could find, and must be missing something very simple that a WCF expert would be able to see. It is my gut feeling that something is blocking my clients at the low-level (TCP), before the server actually receives the message and/or that something is queuing the messages at the server level and never letting them process. If you have any performance counters I should look at, please let me know. (please indicate what values are bad, as some of these counters are hard to decypher). Also, how could I log the WCF message size? Finally, are there any tools our there that would allow me to test how many connections I can establish between my client and server (independently from my application) Thanks for your time! Extra information added June 20th: My WCF application does something similar to the following. while (true) { Step1GetConfigurationSettingsFromServerViaWCF(); // can change between calls Step2GetWorkUnitFromServerViaWCF(); DoWorkLocally(); // takes 5-15minutes. Step3SendBackResultsToServerViaWCF(); } Using WireShark, I did see that when the error occurs, I have a five TCP retransmissions followed by a TCP reset later on. My guess is the RST is coming from WCF killing the connection. The exception report I get is from Step3 timing out. I discovered this by looking at the tcp stream "tcp.stream eq 192". I then expanded my filter to "tcp.stream eq 192 and http and http.request.method eq POST" and saw 6 POSTs during this stream. This seemed odd, so I checked with another stream such as tcp.stream eq 100. I had three POSTs, which seems a bit more normal because I am doing three calls. However, I do close my connection after every WCF call, so I would have expected one call per stream (but I don't know much about TCP). Investigating a bit more, I dumped the http packet load to disk to look at what these six calls where. 1) Step3 2) Step1 3) Step2 4) Step3 - corrupted 5) Step1 6) Step2 My guess is two concurrent clients are using the same connection, that is why I saw duplicates. However, I still have a few more issues that I can't comprehend: a) Why is the packet corrupted? Random network fluke - maybe? The load is gzipped using this sample code: http://msdn.microsoft.com/en-us/library/ms751458.aspx - Could the code be buggy once in a while when used concurrently? I should test without the gzip library. b) Why would I see step 1 & step 2 running AFTER the corrupted operation timed out? It seems to me as if these operations should not have occurred. Maybe I am not looking at the right stream because my understanding of TCP is flawed. I have other streams that occur at the same time. I should investigate other streams - a quick glance at streams 190-194 show that the Step3 POST have proper payload data (not corrupted). Pushing me to look at the gzip library again.

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• CSS layout problem on Firefox with filling space between end of left column and footer

  - by Jean

  Basically, the left column is supposed to extend to the footer with the continuous red color. However, in Firefox on pages with lots of text, the column does not extend to the footer and leaves a large white gap--see site: http://library.luhs.org/JHSII/about.html I've tried readjusting the heights, creating the sticky footer, and other things I've read about on this site. So I admit that I'm stumped, and what's really odd is that the layout seems to work in IE as there is no white space! I didn't create the site, but I recently inherited it and trying to work through the mess Any help is much appreciated, here's the CSS #html,body{ margin:0; padding:0; border:0; height:100%; } #body{ background:#ffffff; min-width:965px; text-align:center; width: 600px; font: Geneva, Arial, Helvetica, sans-serif; } #.style7{ clear:both; height:1px; overflow:hidden; line-height:1%; font-size:0px; margin-bottom:-1px; } #fullheightcontainer{ margin-left:auto; margin-right:auto; text-align:left; position:relative; width:965px; height:100%; } #wrapper{ min-height:100%; height:100%; background:#660000; background-color: #660000; background-repeat: repeat; } #wrapp\65 r{ height:auto; } # html wrapper{ height:100%; } #outer{ z-index:1; position:relative; margin-left:150px; width:815px; background:#FFFFFF; height:100%; background-color: #FFFFFF; } #left{ width:151px; float:left; display:inline; position:relative; margin-left:-150px; } padding: 20px; border: 0; margin: 0 0 0 240px *>html #left{width:150px;} #container-left{ width:150px; color: #CCCCCC; } * html #left{margin-right:-3px;} #center{ width:800px; float:right; display:inline; margin-left:-1px; } #clearheadercenter{ height:125px; overflow:hidden; } #clearfootercenter{ height:50px; overflow:hidden; } #footer{ z-index:1; position:relative; clear: both; width:965px; height:50px; overflow:hidden; margin-top:-50px; background-color: #660000; } #subfooter1{ background:#FFFFCC; text-align:left; margin-left:150px; height:50px; } #header{ z-index:1; position:absolute; top:0px; width:815px; margin-left:150px; height:100px; overflow:hidden; background-color: #660000; } #subheader1{ background:#FFFFCC; text-align:center; height:70px; } #gfx_bg_middle{ top:0px; position:absolute; height:100%; overflow:hidden; width:815px; margin-left:150px; background:#FFFFFF; } # html #gfx_bg_middle{ display:none; } #floatingnav { margin: 5px 10px 5px 5px; padding: 0px 5px 5px; float: right; font: .75em/1.35em Geneva, Arial, Helvetica, sans-serif; height: 600px; width: 300px; } #floatingnav a { color: #630; } #floatingnav ul { margin-top: -5; } #.floatright { float: right; margin: 0 0 10px 10px; border: 1px solid #666; padding: 2px; } #outer{ word-wrap:break-word; } #table.s1 { border-width: medium; border-spacing: 2px; border-style: none; border-color: rgb(85, 0, 0); border-collapse: collapse; background-color: white; } #table.s1 th { border-width: medium; padding: 2px; border-style: groove; border-color: red; background-color: white; -moz-border-radius: 0px 0px 0px 0px; } #table.s1 td { border-width: medium; padding: 2px; border-style: groove; border-color: #660000; background-color: #FFFFFF; -moz-border-radius: 0px 0px 0px 0px; } #a:link { color: #000066; } #a:visited { color: #000066; } #p.sample { font-family: serif; font-style: normal; font-variant: normal; font-weight: normal; font-size: medium; line-height: 100%; word-spacing: normal; letter-spacing: normal; text-decoration: none; text-transform: none; text-align: left; text-indent: 0ex; }

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