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  • Opening a new Windows from ASP.NET code behind

    - by TATWORTH
    At http://weblogs.asp.net/infinitiesloop/archive/2007/09/25/response-redirect-into-a-new-window-with-extension-methods.aspx there is an excellent post on how to open a new windows from code behind. The purists may not like it but it helped solve a problem for a client's client. Here is an update for VS2010 users: using System; using System.Web; using System.Web.UI; /// <summary> /// Response Helper for opening popup windo from code behind. /// </summary> public static class ResponseHelper {   /// <summary>   /// Redirect to popup window   /// </summary>   /// <param name="response">The response.</param>   /// <param name="url">URL to open to</param>   /// <param name="target">Target of window _self or _blank</param>   /// <param name="windowFeatures">Features such as window bar</param>   /// <remarks>   ///     <list type="bullet">   ///         <item>   /// From http://weblogs.asp.net/infinitiesloop/archive/2007/09/25/response-redirect-into-a-new-window-with-extension-methods.aspx   /// </item>   /// <item>   /// Note: If you use it outside the context of a Page request, you can't redirect to a new window. The reason is the need to call the ResolveClientUrl method on Page, which I can't do if there is no Page. I could have just built my own version of that method, but it's more involved than you might think to do it right. So if you need to use this from an HttpHandler other than a Page, you are on your own.   /// </item>   ///         <item>   /// Beware of popup blockers.   /// </item>   /// <item>   /// Note: Obviously when you are redirecting to a new window, the current window will still be hanging around. Normally redirects abort the current request -- no further processing occurs. But for these redirects, processing continues, since we still have to serve the response for the current window (which also happens to contain the script to open the new window, so it is important that it completes).   /// </item>   /// <item>   /// Sample call Response.Redirect("popup.aspx", "_blank", "menubar=0,width=100,height=100");   /// </item>   ///     </list>   /// </remarks>   public static void Redirect(this HttpResponse response, string url, string target, string windowFeatures)   {     if ((String.IsNullOrEmpty(target) || target.Equals("_self", StringComparison.OrdinalIgnoreCase)) && String.IsNullOrEmpty(windowFeatures))     {       response.Redirect(url);     }     else     {       Page page = (Page)HttpContext.Current.Handler;       if (page == null)       {         throw new InvalidOperationException("Cannot redirect to new window outside Page context.");       }       url = page.ResolveClientUrl(url);       string script;       if (!String.IsNullOrEmpty(windowFeatures))       {         script = @"window.open(""{0}"", ""{1}"", ""{2}"");";       }       else       {         script = @"window.open(""{0}"", ""{1}"");";       }       script = String.Format(script, url, target, windowFeatures);       ScriptManager.RegisterStartupScript(page, typeof(Page), "Redirect", script, true);     }   } }

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  • Gartner PCC: A Shovel & Some Ah-Ha's

    - by kellsey.ruppel
    When Gartner Vice President and leading analyst Whit Andrews kicked off the Gartner Portals, Content & Collaboration Summit on Monday, March 12 at the Gaylord Palms in Orlando, FL by bringing a shovel to the stage, eyebrows raised and a few thoughts went through my head. Either this guy plans to go help the construction workers outside construct that new pool at the Gaylord or he took a wrong turn and is at the wrong conference. Oh and how did he get that shovel through airport security? As Whit explained more his objective became more clear…take everything anyone has ever told you about portals and throw it out the window, as portals have evolved and times they are most certainly changing. The future Web is here, available not only on browsers but also via a broad spectrum of access points, including automobiles, consumer electronics and more and more mobile devices. Not merely prevalent, the future Web is also multimedia-driven and operates in real time, driven by mobility, social media, streaming video and other dynamic services. Applications and user experiences are in the midst of an evolution — from the early, simple mobile Web models to today’s Web 2.0 mobile apps and, ultimately, to a world of predominantly Web apps. Additionally, cloud services will forever change how portals and user experience are designed, built, delivered, sourced and managed. So what does this mean for you? Today’s organizations need software that will enable them to not just do their jobs, but to do it in a way that is familiar and easy for them.  What does this mean for IT? Use software and technology as an enabler, not as a roadblock. Overall, we had a great week in Orlando learning about how to improve the user experience, manage content explosion, launch social initiatives, transition to mobile environments and understand cloud and SaaS options.  We had some great conversations throughout the conference and at the Oracle booth. Lots of demonstrations were given of Oracle WebCenter Sites and Oracle Social Network. And as Christie mentioned earlier this week, our Vice President of Product Management and Strategy for WebCenter Loren Weinberg presented on the topic of customer engagement and talked about how organization’s relationships with their customers have fundamentally changed today and the resulting impact that has on their priorities.  Loren also talked about the importance of customer engagement, why that matters now more than ever, and what you can do to help your company or organization succeed in this new world. The question asked in every keynote and session was a simple one: What is your “ah-ha” moment? I personally had quite a few, some of which I’ve captured below. 70% of internal social initiatives eventually fail. By 2014, refusing to communicate with consumers via social media will be as harmful as ignoring emails/phone calls is today. Customer engagement = multi-channel + social & interactive + personal & relevant + optimized. If people choose to talk about your product/company/service, it's because it's remarkable. -- Seth Godin's keynote (one of the highlights of the conference!) The Web will become the primary method used for delivering content and applications to mobile devices. By 2015, 20% of smart phone users worldwide will conduct commerce using context-enriched services on a weekly basis.  86% of customers will pay more for a better customer experience. 6 P's of Quality User Experience. Product. Enabled by: People, Patterns, Process, Profit, Priorities. Did you attend the Gartner Summit? What were your ah-ha moments?

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  • Antenna Aligner Part 7: Connecting the dots

    - by Chris George
    The app is basically ready, so I eagerly started to sort out creating the application entry in iTunes Connect. It's mostly intuitive actually, although I did have to create yet another icon for iTunes sized 512x512 pixels, damn lucky I did the original graphics as vector! It took me longer to write the application description than anything else, I'm so not a tech author! I didn't like the way you have to 'make up' an SKU (Stock Keeping Unit) number. I have to do some googling to find out that it really doesn't matter what it is! It should be more obvious what to do from the actual website itself. That aside, the rest of it was actually fairly straightforward. As well as the details of the application, iPhone and iPad screenshots were also required. This posed somewhat of a problem. The iPhone ones were easy (as I have one!), but I do not (yet) own an iPad . So I thought I'd leave the iPad screenshots out for now. Once the application details were sorted, I moved onto the rights and pricing. At the start of the project I had made the decision that I wouldn't charge any more than the lowest amount £0.59. I believe there is a market for this, but as my first foray into app development I didn't want to take the mick. I did realise, however, that I had built my app with a developer certificate and provisioning profile. This was fairly quickly corrected, and again Nomad made this very easy to switch over to the distribution certificate and provisioning profile. With a sense of excitement I cracked open iTunes connect and clicked the upload button ... ...slight snag... . when the Nomad project was started, Apple allowed uploads of these binaries via iTunes Connect. But this is no longer possible, the only upload path is via the Application Loader available from the Apple Developer program. This itself has one limitation, it only runs on a mac! D'OH!!!  Actually my language was somewhat more colourful when this fact came to light. After picking my laptop up off the floor and putting it back together... ok only joking, but I did nearly throw it out of frustration!... I started to consider the options; I briefly entertained the idea of buying a cheap mac from ebay... no, that defeats the whole object of what I'm doing, plus my wife wouldn't be impressed there are some guys out there in the interweb who will upload your app for a small fee...but I don't really like the idea of giving some faceless email address my apple developer login details, as well as my app binary! find some willing friend with a mac who would kindly let me use it... obviously this is the only sensible option. In the meantime, I informed the Nomad team about this slight 'issue' and they are currently investigating possible solutions...

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  • Ask the Readers: Would You Be Willing to Give Windows Up and Use a Different O.S.?

    - by Asian Angel
    When it comes to computers, Windows definitely rules the desktop in comparison to other operating systems. What we would like to know this week is if you would actually be willing to give up using Windows altogether and move to a different operating system on your computers. Note: This week’s Ask the Readers post is posing a hypothetical situation, so please refrain from starting arguments or a flame war in the comments. Good reasoned discussion is always welcome. There is no doubt that Windows is the dominant operating system in use today. Everywhere you go or look it is easy to find computers with Windows installed such as at work, home, the library, government offices, and more. For many people it is the operating system that they know and are comfortable with, which makes changing to a different operating system less appealing. Adding to the preference for Windows (or dependency based on your view) is the custom software that many businesses use on a daily basis. Throw in the high volume of people who depend on and use Microsoft Office as a standard for their business documents and it is little wonder that Windows is so dominant. So what would you use if you did decide to take a break from or permanently move away from Windows? If your choice is Linux then you have a large and wonderful variety of distributions to choose from based on what you want out of your system. Want a distribution that is easy to work with? You could choose Ubuntu, Linux Mint, or others that are engineered to be ready to go “out of the box”. Like a challenge? Perhaps Arch Linux is more your style. One of the most attractive features of all about Linux is the price…it is very hard to beat free! Maybe Mac OS X sounds like the perfect choice. It has a certain mystique and elegance associated with it and many OS X fans refuse to use anything else if given a choice. Then there is the soon to be released Chrome OS with its’ emphasis on cloud computing. This is a system that is definitely focused on being as low-maintenance and hassle-free as possible. Quick on, quick off, minimalist, and made to be portable. All of the system’s updates will occur automatically leaving you free to work and play in the cloud. But it does have its’ limitations…no installing all of those custom apps that you love using on Windows or other systems…it is literally all about the browsing window and web apps. So there you have it. If the opportunity presented itself would you, could you give Windows up and use a different operating system? Would it be easy or hard for you to do? Perhaps it would not really matter so long as you could do what you needed or wanted to do on a computer. And maybe this is the perfect time to try something new and find out…that new favorite operating system could be just an install disc away. Let us know your thoughts in the comments! How-To Geek Polls require Javascript. Please Click Here to View the Poll. Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor The Brothers Mario – Epic Gangland Style Mario Brothers Movie Trailer [Video] Score Awesome Games on the Cheap with the Humble Indie Bundle Add a Colorful Christmas Theme to Your Windows 7 Desktop This Windows Hack Changes the Blue Screen of Death to Red Edit Images Quickly in Firefox with Pixlr Grabber Zoho Writer, Sheet, and Show Now Available in Chrome Web Store

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  • Help needed throwing a ball in AS3

    - by Opoe
    I'm working on a flash game, coding on the time line. What I'm trying to accomplish is the following: With the mouse you swing and throw/release a ball which bounces against the walls and eventualy comes to point where it lays still (like a real ball). I allmost had it working, but now the ball sticks to the mouse, in stead of being released, my question to you is: Can you help me make this work and explain to me what I did wrong? You can simply preview my code by making a movieclip named 'circle' on a 550x400 stage. stage.addEventListener(Event.ENTER_FRAME, circle_update); var previousPostionX:Number; var previousPostionY:Number; var throwSpeedX:Number; var throwSpeedY:Number; var isItDown:Boolean; var xSpeed:Number = 0; var ySpeed:Number = 0; var friction:Number = 0.96; var offsetX:Number = 0; var offsetY:Number = 0; var newY:Number = 0; var oldY:Number = 0; var newX:Number = 0; var oldX:Number = 0; var dragging:Boolean; circle.buttonMode = true; circle.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler); circle.addEventListener(Event.ENTER_FRAME, throwcircle); circle.addEventListener(MouseEvent.MOUSE_DOWN, clicked); circle.addEventListener(MouseEvent.MOUSE_UP, released); function mouseDownHandler(e:MouseEvent):void { dragging = true; stage.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler); offsetX = mouseX - circle.x; offsetY = mouseY - circle.y; } function mouseUpHandler(e:MouseEvent):void { dragging = false; } function throwcircle(e:Event) { circle.x += xSpeed; circle.y += ySpeed; xSpeed *= friction; ySpeed *= friction; } function changeFriction(e:Event):void { friction = e.target.value; trace(e.target.value); } function circle_update(e:Event){ if ( dragging == true ) { circle.x = mouseX - offsetX; circle.y = mouseY - offsetY; } if(circle.x + (circle.width * 0.50) >= 550){ circle.x = 550 - circle.width * 0.50; } if(circle.x - (circle.width * 0.50) <= 0){ circle.x = circle.width * 0.50; } if(circle.y + (circle.width * 0.50) >= 400){ circle.y = 400 - circle.height * 0.50; } if(circle.y - (circle.width * 0.50) <= 0){ circle.y = circle.height * 0.50; } } function clicked(theEvent:Event) { isItDown =true; addEventListener(Event.ENTER_FRAME, updateView); } function released(theEvent:Event) { isItDown =false; } function updateView(theEvent:Event) { if (isItDown==true){ throwSpeedX = mouseX - previousPostionX; throwSpeedY = mouseY - previousPostionY; circle.x = mouseX; circle.y = mouseY; } else{ circle.x += throwSpeedX; circle.y += throwSpeedY; throwSpeedX *=0.9; throwSpeedY *=0.9; } previousPostionX= circle.x; previousPostionY= circle.y; }

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  • Question on the implementation of my Entity System

    - by miguel.martin
    I am currently creating an Entity System, in C++, it is almost completed (I have all the code there, I just have to add a few things and test it). The only thing is, I can't figure out how to implement some features. This Entity System is based off a bit from the Artemis framework, however it is different. I'm not sure if I'll be able to type this out the way my head processing it. I'm going to basically ask whether I should do something over something else. Okay, now I'll give a little detail on my Entity System itself. Here are the basic classes that my Entity System uses to actually work: Entity - An Id (and some methods to add/remove/get/etc Components) Component - An empty abstract class ComponentManager - Manages ALL components for ALL entities within a Scene EntitySystem - Processes entities with specific components Aspect - The class that is used to help determine what Components an Entity must contain so a specific EntitySystem can process it EntitySystemManager - Manages all EntitySystems within a Scene EntityManager - Manages entities (i.e. holds all Entities, used to determine whether an Entity has been changed, enables/disables them, etc.) EntityFactory - Creates (and destroys) entities and assigns an ID to them Scene - Contains an EntityManager, EntityFactory, EntitySystemManager and ComponentManager. Has functions to update and initialise the scene. Now in order for an EntitySystem to efficiently know when to check if an Entity is valid for processing (so I can add it to a specific EntitySystem), it must recieve a message from the EntityManager (after a call of activate(Entity& e)). Similarly the EntityManager must know when an Entity is destroyed from the EntityFactory in the Scene, and also the ComponentManager must know when an Entity is created AND destroyed. I do have a Listener/Observer pattern implemented at the moment, but with this pattern I may remove a Listener (which is this case is dependent on the method being called). I mainly have this implemented for specific things related to a game, i.e. Teams, Tagging of entities, etc. So... I was thinking maybe I should call a private method (using friend classes) to send out when an Entity has been activated, deleted, etc. i.e. taken from my EntityFactory void EntityFactory::killEntity(Entity& e) { // if the entity doesn't exsist in the entity manager within the scene if(!getScene()->getEntityManager().doesExsist(e)) { return; // go back to the caller! (should throw an exception or something..) } // tell the ComponentManager and the EntityManager that we killed an Entity getScene()->getComponentManager().doOnEntityWillDie(e); getScene()->getEntityManager().doOnEntityWillDie(e); // notify the listners for(Mouth::iterator i = getMouth().begin(); i != getMouth().end(); ++i) { (*i)->onEntityWillDie(*this, e); } _idPool.addId(e.getId()); // add the ID to the pool delete &e; // delete the entity } As you can see on the lines where I am telling the ComponentManager and the EntityManager that an Entity will die, I am calling a method to make sure it handles it appropriately. Now I realise I could do this without calling it explicitly, with the help of that for loop notifying all listener objects connected to the EntityFactory's Mouth (an object used to tell listeners that there's an event), however is this a good idea (good design, or what)? I've gone over the PROS and CONS, I just can't decide what I want to do. Calling Explicitly: PROS Faster? Since these functions are explicitly called, they can't be "removed" CONS Not flexible Bad design? (friend functions) Calling through Listener objects (i.e. ComponentManager/EntityManager inherits from a EntityFactoryListener) PROS More Flexible? Better Design? CONS Slower? (virtual functions) Listeners can be removed, i.e. may be removed and not get called again during the program, which could cause in a crash. P.S. If you wish to view my current source code, I am hosting it on BitBucket.

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  • what is the best way to use loops to detect events while the main loop is running?

    - by yao jiang
    I am making an "game" that has pathfinding using pygame. I am using Astar algo. I have a main loop which draws the whole map. In the loop I check for events. If user press "enter" or "space", random start and end are selected, then animation starts and it will try to get from start to end. My draw function is stupid as hell right now, it works as expected but I feel that I am doing it wrong. It'll draw everything to the end of the animation. I am also detecting events in there as well. What is a better way of implementing the draw function such that it will draw one "step" at a time while checking for events? animating = False; while loop: check events: if not animating: # space or enter press will choose random start/end coords if enter_pressed or space_pressed: start, end = choose_coords route = find_route(start, end) draw(start, end, grid, route) else: # left click == generate an event to block the path # right click == user can choose a new destination if left_mouse_click: gen_event() reroute() elif right_mouse_click: new_end = new_end() new_start = current_pos() route = find_route(new_start, new_end) draw(new_start, new_end, grid, route) # draw out the grid def draw(start, end, grid, route_coord): # draw the end coords color = red; pick_image(screen, color, width*end[1],height*end[0]); pygame.display.flip(); # then draw the rest of the route for i in range(len(route_coord)): # pausing because we want animation time.sleep(speed); # get the x/y coords x,y = route_coord[i]; event_on = False; if grid[x][y] == 2: color = green; elif grid[x][y] == 3: color = blue; for event in pygame.event.get(): if event.type == pygame.MOUSEBUTTONDOWN: if event.button == 3: print "destination change detected, rerouting"; # get mouse position, px coords pos = pygame.mouse.get_pos(); # get grid coord c = pos[0] // width; r = pos[1] // height; grid[r][c] = 4; end = [r, c]; elif event.button == 1: print "user generated event"; pos = pygame.mouse.get_pos(); # get grid coord c = pos[0] // width; r = pos[1] // height; # mark it as a block for now grid[r][c] = 1; event_on = True; if check_events([x,y]) or event_on: # there is an event # mark it as a block for now grid[y][x] = 1; pick_image(screen, event_x, width*y, height*x); pygame.display.flip(); # then find a new route new_start = route_coord[i-1]; marked_grid, route_coord = find_route(new_start, end, grid); draw(new_start, end, grid, route_coord); return; # just end draw here so it wont throw the "index out of range" error elif grid[x][y] == 4: color = red; pick_image(screen, color, width*y, height*x); pygame.display.flip(); # clear route coord list, otherwise itll just add more unwanted coords route_coord_list[:] = [];

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  • Crime Scene Investigation: SQL Server

    - by Rodney Landrum
    “The packages are running slower in Prod than they are in Dev” My week began with this simple declaration from one of our lead BI developers, quickly followed by an emailed spreadsheet demonstrating that, over 5 executions, an extensive ETL process was running average 630 seconds faster on Dev than on Prod. The situation needed some scientific investigation to determine why the same code, the same data, the same schema would yield consistently slower results on a more powerful server. Prod had yet to be officially christened with a “Go Live” date so I had the time, and having recently been binge watching CSI: New York, I also had the inclination. An inspection of the two systems, Prod and Dev, revealed the first surprise: although Prod was indeed a “bigger” system, with double the amount of RAM of Dev, the latter actually had twice as many processor cores. On neither system did I see much sign of resources being heavily taxed, while the ETL process was running. Without any real supporting evidence, I jumped to a conclusion that my years of performance tuning should have helped me avoid, and that was that the hardware differences explained the better performance on Dev. We spent time setting up a Test system, similarly scoped to Prod except with 4 times the cores, and ported everything across. The results of our careful benchmarks left us truly bemused; the ETL process on the new server was slower than on both other systems. We burned more time tweaking server configurations, monitoring IO and network latency, several times believing we’d uncovered the smoking gun, until the results of subsequent test runs pitched us back into confusion. Finally, I decided, enough was enough. Hadn’t I learned very early in my DBA career that almost all bottlenecks were caused by code and database design, not hardware? It was time to get back to basics. With over 100 SSIS packages and hundreds of queries, each handling specific tasks such as file loads, bulk inserts, transforms, logging, and so on, the task seemed formidable. And yet, after barely an hour spent with Profiler, Extended Events, and wait statistics DMVs, I had a lead in the shape of a query that joined three tables, containing millions of rows, returned 3279 results, but performed 239K logical reads. As soon as I looked at the execution plans for the query in Dev and Test I saw the culprit, an implicit conversion warning on a join predicate field that was numeric in one table and a varchar(50) in another! I turned this information over to the BI developers who quickly resolved the data type mismatches and found and fixed “several” others as well. After the schema changes the same query with the same databases ran in under 1 second on all systems and reduced the logical reads down to fewer than 300. The analysis also revealed that on Dev, the ETL task was pulling data across a LAN, whereas Prod and Test were connected across slower WAN, in large part explaining why the same process ran slower on the latter two systems. Loading the data locally on Prod delivered a further 20% gain in performance. As we progress through our DBA careers we learn valuable lessons. Sometimes, with a project deadline looming and pressure mounting, we choose to forget them. I was close to giving into the temptation to throw more hardware at the problem. I’m pleased at least that I resisted, though I still kick myself for not looking at the code on day one. It can seem a daunting prospect to return to the fundamentals of the code so close to roll out, but with the right tools, and surprisingly little time, you can collect the evidence that reveals the true problem. It is a lesson I trust I will remember for my next 20 years as a DBA, if I’m ever again tempted to bypass the evidence.

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  • Application Module Extension in Oracle Application R12

    - by Manoj Madhusoodanan
    In this blog I will describe how to Extend Application Module.I will explain this based on my previous blog PL/SQL based EO.  I want to extend FndUserAM to add a procedure to raise a custom business event when the FND_USER has created successfully. Here I am using a custom business event "xxcust.oracle.apps.demo_event". Please find the code used in Business Event. TablePackage Following steps needs to perform. 1) Download all files pertaining to "Entity Object Based on PL/SQL" to JDEV_USER_HOME/myprojects and JDEV_USER_HOME/myclasses.If you want to see the content of source java file decompile it and save it in JDEV_USER_HOME/myprojects. 2) Create XXFndUserAM as follows. 3) Add following method to XXFndUserAMImpl.    import oracle.apps.fnd.framework.OAException;   import oracle.apps.fnd.framework.server.OADBTransactionImpl;   import oracle.apps.fnd.wf.bes.BusinessEvent;   import oracle.apps.fnd.wf.bes.BusinessEventException;    import java.sql.Connection;     public void raiseEvent(String userName) {        String eventName = "xxcust.oracle.apps.demo_event";        String eventKey = userName;        Connection conn = ((OADBTransactionImpl)getOADBTransaction()).getJdbcConnection();         BusinessEvent event = null;         try{             event = new BusinessEvent(eventName, eventKey);             /* Setting Parameters */             event.setStringProperty("USER_NAME",userName);             event.setStringProperty("STATUS","User has created sucessfully");             event.raise(conn);             }             catch (BusinessEventException e) {                 throw new OAException("Exception occured when invoking web service - "+e.getMessage());             }             getOADBTransaction().commit();    } 4) Create a controller which extends from xxcust.oracle.apps.fnd.user.webui.CreateFndUserCO.Call raiseEvent method from new controller. 5) Create substitution for FndUserAM. 6) Migrate following files to $JAVA_TOP. xxcustom.oracle.apps.fnd.user.server.FndUserAMImpl.javaxxcustom.oracle.apps.fnd.user.server.XXFndUserAM.xmlxxcustom.oracle.apps.fnd.user.webui.XXCreateFndUserCO.java 8) Migrate the substitution. 9) Restart the server. 10) Personalize the page /xxcust/oracle/apps/fnd/user/webuiCreateFndUserPG and set the new controller. 11) Verify the substitution has properly applied by clicking About the Page. 12) Access the page and create a user. You can the the result of the Business Event.

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  • Scenarios for Throwing Exceptions

    - by Joe Mayo
    I recently came across a situation where someone had an opinion that differed from mine of when an exception should be thrown. This particular case was an issue opened on LINQ to Twitter for an Exception on EndSession.  The premise of the issue was that the poster didn’t feel an exception should be raised, regardless of authentication status.  As first, this sounded like a valid point.  However, I went back to review my code and decided not to make any changes. Here's my rationale: 1. The exception doesn’t occur if the user is authenticated when EndAccountSession is called. 2. The exception does occur if the user is not authenticated when EndAccountSession is called. 3. The exception represents the fact that EndAccountSession is not able to fulfill its intended purpose - to end the session.  If a session never existed, then it would not be possible to perform the requested action.  Therefore, an exception is appropriate. To help illustrate how to handle this situation, I've modified the following code in Program.cs in the LinqToTwitterDemo project to illustrate the situation: static void EndSession(ITwitterAuthorizer auth) { using (var twitterCtx = new TwitterContext(auth, "https://api.twitter.com/1/", "https://search.twitter.com/")) { try { //Log twitterCtx.Log = Console.Out; var status = twitterCtx.EndAccountSession(); Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } catch (TwitterQueryException tqe) { var webEx = tqe.InnerException as WebException; if (webEx != null) { var webResp = webEx.Response as HttpWebResponse; if (webResp != null && webResp.StatusCode == HttpStatusCode.Unauthorized) Console.WriteLine("Twitter didn't recognize you as having been logged in. Therefore, your request to end session is illogical.\n"); } var status = tqe.Response; Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } } } As expected, LINQ to Twitter wraps the exception in a TwitterQueryException as the InnerException.  The TwitterQueryException serves a very useful purpose through it's Response property.  Notice in the example above that the response has Request and Error proprieties.  These properties correspond to the information that Twitter returns as part of it's response payload.  This is often useful while debugging to help you understand why Twitter was unable to perform the  requested action.  Other times, it's cryptic, but that's another story.  At least you have some way of knowing in your code how to anticipate and handle these situations, along with having extra information to debug with. To sum things up, there are two points to make: when and why an exception should be raised and when to wrap and re-throw an exception in a custom exception type. I felt it was necessary to allow the exception to be raised because the called method was unable to perform the task it was designed for.  I also felt that it is inappropriate for a general library to do anything with exceptions because that could potentially hide a problem from the caller.  A related point is that it should be the exclusive decision of the application that uses the library on what to do with an exception.  Another aspect of this situation is that I wrapped the exception in a custom exception and re-threw.  This is a tough call because I don’t want to hide any stack trace information.  However, the need to make the exception more meaningful by including vital information returned from Twitter swayed me in the direction to design an interface that was as helpful as possible to library consumers.  As shown in the code above, you can dig into the exception and pull out a lot of good information, such as the fact that the underlying HTTP response was a 401 Unauthorized.  In all, trade-offs are seldom perfect for all cases, but combining the fact that the method was unable to perform its intended function, this is a library, and the extra information can be more helpful, it seemed to be the better design. @JoeMayo

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  • A more elegant way of embedding a SOAP security header in Silverlight 4

    - by Your DisplayName here!
    The current situation with Silverlight is, that there is no support for the WCF federation binding. This means that all security token related interactions have to be done manually. Requesting the token from an STS is not really the bad part, sending it along with outgoing SOAP messages is what’s a little annoying. So far you had to wrap all calls on the channel in an OperationContextScope wrapping an IContextChannel. This “programming model” was a little disruptive (in addition to all the async stuff that you are forced to do). It seems that starting with SL4 there is more support for traditional WCF extensibility points – especially IEndpointBehavior, IClientMessageInspector. I never read somewhere that these are new features in SL4 – but I am pretty sure they did not exist in SL3. With the above mentioned interfaces at my disposal, I thought I have another go at embedding a security header – and yeah – I managed to make the code much prettier (and much less bizarre). Here’s the code for the behavior/inspector: public class IssuedTokenHeaderInspector : IClientMessageInspector {     RequestSecurityTokenResponse _rstr;       public IssuedTokenHeaderInspector(RequestSecurityTokenResponse rstr)     {         _rstr = rstr;     }       public void AfterReceiveReply(ref Message reply, object correlationState)     { }       public object BeforeSendRequest(ref Message request, IClientChannel channel)     {         request.Headers.Add(new IssuedTokenHeader(_rstr));                  return null;     } }   public class IssuedTokenHeaderBehavior : IEndpointBehavior {     RequestSecurityTokenResponse _rstr;       public IssuedTokenHeaderBehavior(RequestSecurityTokenResponse rstr)     {         if (rstr == null)         {             throw new ArgumentNullException();         }           _rstr = rstr;     }       public void ApplyClientBehavior(       ServiceEndpoint endpoint, ClientRuntime clientRuntime)     {         clientRuntime.MessageInspectors.Add(new IssuedTokenHeaderInspector(_rstr));     }       // rest omitted } This allows to set up a proxy with an issued token header and you don’t have to worry anymore with embedding the header manually with every call: var client = GetWSTrustClient();   var rst = new RequestSecurityToken(WSTrust13Constants.KeyTypes.Symmetric) {     AppliesTo = new EndpointAddress("https://rp/") };   client.IssueCompleted += (s, args) => {     _proxy = new StarterServiceContractClient();     _proxy.Endpoint.Behaviors.Add(new IssuedTokenHeaderBehavior(args.Result));   };   client.IssueAsync(rst); Since SL4 also support the IExtension<T> interface, you can also combine this with Nicholas Allen’s AutoHeaderExtension.

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  • Reducing Deadlocks - not a DBA issue ?

    - by steveh99999
     As a DBA, I'm involved on an almost daily basis troubleshooting 'SQL Server' performance issues. Often, this troubleshooting soon veers away from a 'its a SQL Server issue' to instead become a wider application/database design/coding issue.One common perception with SQL Server is that deadlocking is an application design issue - and is fixed by recoding...  I see this reinforced by MCP-type questions/scenarios where the answer to prevent deadlocking is simply to change the order in code in which tables are accessed....Whilst this is correct, I do think this has led to a situation where many 'operational' or 'production support' DBAs, when faced with a deadlock, are happy to throw the issue over to developers without analysing the issue further....A couple of 'war stories' on deadlocks which I think are interesting :- Case One , I had an issue recently on a third-party application that I support on SQL 2008.  This particular third-party application has an unusual support agreement where the customer is allowed to change the index design on the third-party provided database.  However, we are not allowed to alter application code or modify table structure..This third-party application is also known to encounter occasional deadlocks – indeed, I have documentation from the vendor that up to 50 deadlocks per day is not unusual !So, as a DBA I have to support an application which in my opinion has too many deadlocks - but, I cannot influence the design of the tables or stored procedures for the application. This should be the classic - blame the third-party developers scenario, and hope this issue gets addressed in a future application release - ie we could wait years for this to be resolved and implemented in our production environment...But, as DBAs  can change the index layout, is there anything I could do still to reduce the deadlocks in the application ?I initially used SQL traceflag 1222 to write deadlock detection output to the SQL Errorlog – using this I was able to identify one table heavily involved in the deadlocks.When I examined the table definition, I was surprised to see it was a heap – ie no clustered index existed on the table.Using SQL profiler to see locking behaviour and plan for the query involved in the deadlock, I was able to confirm a table scan was being performed.By creating an appropriate clustered index - it was possible to produce a more efficient plan and locking behaviour.So, less locks, held for less time = less possibility of deadlocks. I'm still unhappy about the overall number of deadlocks on this system - but that's something to be discussed further with the vendor.Case Two,  a system which hadn't changed for months suddenly started seeing deadlocks on a regular basis. I love the 'nothing's changed' scenario, as it gives me the opportunity to appear wise and say 'nothings changed on this system, except the data'.. This particular deadlock occurred on a table which had been growing rapidly. By using DBCC SHOW_STATISTICS - the DBA team were able to see that the deadlocks seemed to be occurring shortly after auto-update stats had regenerated the table statistics using it's default sampling behaviour.As a quick fix, we were able to schedule a nightly UPDATE STATISTICS WITH FULLSCAN on the table involved in the deadlock - thus, greatly reducing the potential for stats to be updated via auto_update_stats, consequently reducing the potential for a bad plan to be generated based on an unrepresentative sample of the data. This reduced the possibility of a deadlock occurring.  Not a perfect solution by any means, but quick, easy to implement, and needed no application code changes. This fix gave us some 'breathing space'  to properly fix the code during the next scheduled application release.   The moral of this post - don't dismiss deadlocks as issues that can only be fixed by developers...

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  • Feynman's inbox

    - by user12607414
    Here is Richard Feynman writing on the ease of criticizing theories, and the difficulty of forming them: The problem is not just to say something might be wrong, but to replace it by something — and that is not so easy. As soon as any really definite idea is substituted it becomes almost immediately apparent that it does not work. The second difficulty is that there is an infinite number of possibilities of these simple types. It is something like this. You are sitting working very hard, you have worked for a long time trying to open a safe. Then some Joe comes along who knows nothing about what you are doing, except that you are trying to open the safe. He says ‘Why don’t you try the combination 10:20:30?’ Because you are busy, you have tried a lot of things, maybe you have already tried 10:20:30. Maybe you know already that the middle number is 32 not 20. Maybe you know as a matter of fact that it is a five digit combination… So please do not send me any letters trying to tell me how the thing is going to work. I read them — I always read them to make sure that I have not already thought of what is suggested — but it takes too long to answer them, because they are usually in the class ‘try 10:20:30’. (“Seeking New Laws”, page 161 in The Character of Physical Law.) As a sometime designer (and longtime critic) of widely used computer systems, I have seen similar difficulties appear when anyone undertakes to publicly design a piece of software that may be used by many thousands of customers. (I have been on both sides of the fence, of course.) The design possibilities are endless, but the deep design problems are usually hidden beneath a mass of superfluous detail. The sheer numbers can be daunting. Even if only one customer out of a thousand feels a need to express a passionately held idea, it can take a long time to read all the mail. And it is a fact of life that many of those strong suggestions are only weakly supported by reason or evidence. Opinions are plentiful, but substantive research is time-consuming, and hence rare. A related phenomenon commonly seen with software is bike-shedding, where interlocutors focus on surface details like naming and syntax… or (come to think of it) like lock combinations. On the other hand, software is easier than quantum physics, and the population of people able to make substantial suggestions about software systems is several orders of magnitude bigger than Feynman’s circle of colleagues. My own work would be poorer without contributions — sometimes unsolicited, sometimes passionately urged on me — from the open source community. If a Nobel prize winner thought it was worthwhile to read his mail on the faint chance of learning a good idea, I am certainly not going to throw mine away. (In case anyone is still reading this, and is wondering what provoked a meditation on the quality of one’s inbox contents, I’ll simply point out that the volume has been very high, for many months, on the Lambda-Dev mailing list, where the next version of the Java language is being discussed. Bravo to those of my colleagues who are surfing that wave.) I started this note thinking there was an odd parallel between the life of the physicist and that of a software designer. On second thought, I’ll bet that is the story for anybody who works in public on something requiring special training. (And that would be pretty much anything worth doing.) In any case, Feynman saw it clearly and said it well.

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  • Is there a theory for "transactional" sequences of failing and no-fail actions?

    - by Ross Bencina
    My question is about writing transaction-like functions that execute sequences of actions, some of which may fail. It is related to the general C++ principle "destructors can't throw," no-fail property, and maybe also with multi-phase transactions or exception safety. However, I'm thinking about it in language-neutral terms. My concern is with correctly designing error handling in C++ functions that must be reliable. I would like to know what the concepts below are called so that I can learn more about them. I'm sorry that I can't ask the question more directly. Since I don't know this area I have provided an example to explain my question. The question is at the end. Here goes: Consider a sequence of steps or actions executed sequentially, where actions belong to one of two classes: those that always succeed, and those that may fail. In the examples below: S stands for an action that always succeeds (called "no-fail" in some settings). F stands for an action that may fail (for example, it might fail to allocate memory or do I/O that could fail). Consider a sequences of actions (executed sequentially from left to right): S->S->S->S Since each action in the sequence above succeeds, the whole sequence succeeds. On the other hand, the following sequence may fail because the last action may fail: S->S->S->F So, claim: a sequence has the no-fail (S) property if and only if all of its actions are no-fail. Now, I'm interested in action sequences that form "atomic transactions", with "failure atomicity," i.e. where either the whole sequence completes successfully, or there is no effect. I.e. if some action fails, the earlier ones must be rolled back. This requires that any successfully executed actions prior to a failing action must always be able to be rolled back. Consider the sequence: S->S->S->F S<-S<-S In the example above, the first row is the forward path of the transaction, and the second row are inverse actions (executed from right to left) that can be used to roll back if the final top row actions fails. It seems to me that for a transaction to support failure atomicity, the following invariant must hold: Claim: To support failure atomicity (either completion or complete roll-back on failure) all actions preceding the latest failable (F) action on the forward path (marked * in the example below) must have no-fail (S) inverses. The following is an example of a sequence that supports failure atomicity: * S->F->F->F S<-S<-S Further, if we want the transaction to be able to attempt cancellation mid-way through, but still guarantee either full completion or full rollback then we need the following property: Claim: To support failure atomicity and cancellation mid-way through execution, in the face of errors in the inverse (cancellation) path, all actions following the earliest failable (F) inverse on the reverse path (marked *) must be no-fail (S). F->F->F->S->S S<-S<-F<-F * I believe that these two conditions guarantee that an abortable/cancelable transaction will never get "stuck". My questions are: What is the study and theory of these properties called? are my claims correct? and what else is there to know? UPDATE 1: Updated terminology: what I previously called "robustness" is called atomicity in the database literature. UPDATE 2: Added explicit reference to failure atomicity, which seems to be a thing.

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  • Fresh Ubuntu Install - Grub not loading

    - by Ryan Sharp
    System Ubuntu 12.04 64-bit Windows 7 SP1 Samsung 64GB SSD - OS' Samsung 1TB HDD - Games, /Home, Swap WD 300'ishGB HDD - Backup Okay, so I'm very frustrated, so please excuse me if I miss anything out as my head is clouded by anger and impatience, etc. I'll try me best, though. First of all, I'll explain how I got to my predicament. I finally got my new SSD. I firstly installed Windows, which completed without a hitch. Afterwards, I tried to install Ubuntu, which failed several times due to problems irrelevant to this question, but I mention this to explain my frustrations, sorry. Anyway, I finally installed Ubuntu. However, I chose the 'bootloader' to be installed on the same partition as where I was installing the Ubuntu Root partition, as that was what I believed to be the best choice. It was of my thinking that it was supposed to go on the same partition and on the SSD, which is my OS drive, though with my problem, it apparently was wrong. So I tried to fix it by checking guides and following their directions, but seemed to have messed it up even more. Here is what I receive after I use the fdisk -l command: (I also added explanations for which I used each partition for) Disk /dev/sda: 64.0 GB, 64023257088 bytes 255 heads, 63 sectors/track, 7783 cylinders, total 125045424 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x324971d1 Device Boot Start End Blocks Id System /dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT /dev/sda2 208896 48957439 24374272 7 HPFS/NTFS/exFAT /dev/sda3 48959486 125044735 38042625 5 Extended /dev/sda5 48959488 125044735 38042624 83 Linux sda1 --/ Windows Recovery sda2 --/ Windows 7 sda3/5 --/ Ubuntu root [ / ] Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xc0ee6a69 Device Boot Start End Blocks Id System /dev/sdb1 1024208894 1953523711 464657409 5 Extended /dev/sdb3 * 2048 1024206847 512102400 7 HPFS/NTFS/exFAT /dev/sdb5 1024208896 1939851263 457821184 83 Linux /dev/sdb6 1939853312 1953523711 6835200 82 Linux swap / Solaris sdb3 --/ Partition for Steam games, etc. sdb5 --/ Ubuntu Home [ /home ] sdb6 --/ Ubuntu Swap Partition table entries are not in disk order Disk /dev/sdc: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x292eee23 Device Boot Start End Blocks Id System /dev/sdc1 2048 625141759 312569856 7 HPFS/NTFS/exFAT sdc1 --/ Generic backup I also used a Boot Script that other users suggested, so that I can give more details on my partitions and also where Grub is located... ============================= Boot Info Summary: =============================== => Grub2 (v1.99) is installed in the MBR of /dev/sda and looks at sector 1 of the same hard drive for core.img. core.img is at this location and looks for (,msdos5)/boot/grub on this drive. => Grub2 (v1.99) is installed in the MBR of /dev/sdb and looks at sector 1 of the same hard drive for core.img. core.img is at this location and looks for (,msdos5)/boot/grub on this drive. => Windows is installed in the MBR of /dev/sdc. Now that is weird... Why would Grub2 be installed on both my SSD and HDD? Even weirder is why is Windows on the MBR of my backup hard drive? Nothing I did should have done that... Anyway, here is the entire Output from that script... PASTEBIN So, to summarize what I need: How can I fix my setup so grub loads on startup? How can I clean my partitions to remove unnecessary grubs? What did I do wrong so that I don't do something so daft again? Thank you so much for reading, and I hope you can help me. I've been trying to have a successful setup since Friday, and I'm almost at the point that I'm really tempted to throw my computer out the window due to my frustration.

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  • Tetris Movement - Implementation

    - by James Brauman
    Hi gamedev, I'm developing a Tetris clone and working on the input at the moment. When I was prototyping, movement was triggered by releasing a directional key. However, in most Tetris games I've played the movement is a bit more complex. When a directional key is pressed, the shape moves one space in that direction. After a short interval, if the key is still held down, the shape starts moving in the direction continuously until the key is released. In the case of the down key being pressed, there is no pause between the initial movement and the subsequent continuous movement. I've come up with a solution, and it works well, but it's totally over-engineered. Hey, at least I can recognize when things are getting silly, right? :) public class TetrisMover { List registeredKeys; Dictionary continuousPressedTime; Dictionary totalPressedTime; Dictionary initialIntervals; Dictionary continousIntervals; Dictionary keyActions; Dictionary initialActionDone; KeyboardState currentKeyboardState; public TetrisMover() { *snip* } public void Update(GameTime gameTime) { currentKeyboardState = Keyboard.GetState(); foreach (Keys currentKey in registeredKeys) { if (currentKeyboardState.IsKeyUp(currentKey)) { continuousPressedTime[currentKey] = TimeSpan.Zero; totalPressedTime[currentKey] = TimeSpan.Zero; initialActionDone[currentKey] = false; } else { if (initialActionDone[currentKey] == false) { keyActions[currentKey](); initialActionDone[currentKey] = true; } totalPressedTime[currentKey] += gameTime.ElapsedGameTime; if (totalPressedTime[currentKey] = initialIntervals[currentKey]) { continuousPressedTime[currentKey] += gameTime.ElapsedGameTime; if (continuousPressedTime[currentKey] = continousIntervals[currentKey]) { keyActions[currentKey](); continuousPressedTime[currentKey] = TimeSpan.Zero; } } } } } public void RegisterKey(Keys key, TimeSpan initialInterval, TimeSpan continuousInterval, Action keyAction) { if (registeredKeys.Contains(key)) throw new InvalidOperationException( string.Format("The key %s is already registered.", key)); registeredKeys.Add(key); continuousPressedTime.Add(key, TimeSpan.Zero); totalPressedTime.Add(key, TimeSpan.Zero); initialIntervals.Add(key, initialInterval); continousIntervals.Add(key, continuousInterval); keyActions.Add(key, keyAction); initialActionDone.Add(key, false); } public void UnregisterKey(Keys key) { *snip* } } I'm updating it every frame, and this is how I'm registering keys for movement: tetrisMover.RegisterKey( Keys.Left, keyHoldStartSpecialInterval, keyHoldMovementInterval, () = { Move(Direction.Left); }); tetrisMover.RegisterKey( Keys.Right, keyHoldStartSpecialInterval, keyHoldMovementInterval, () = { Move(Direction.Right); }); tetrisMover.RegisterKey( Keys.Down, TimeSpan.Zero, keyHoldMovementInterval, () = { PerformGravity(); }); Issues that this doesn't address: If both left and right are held down, the shape moves back and forth really quick. If a directional key is held down and the turn finishes and the shape is replaced by a new one, the new one will move quickly in that direction instead of the little pause it is supposed to have. I could fix the issues, but I think it will make the solution even worse. How would you implement this?

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  • A Reusable Builder Class for .NET testing

    - by Liam McLennan
    When writing tests, other than end-to-end integration tests, we often need to construct test data objects. Of course this can be done using the class’s constructor and manually configuring the object, but to get many objects into a valid state soon becomes a large percentage of the testing effort. After many years of painstakingly creating builders for each of my domain objects I have finally become lazy enough to bother to write a generic, reusable builder class for .NET. To use it you instantiate a instance of the builder and configuring it with a builder method for each class you wish it to be able to build. The builder method should require no parameters and should return a new instance of the type in a default, valid state. In other words the builder method should be a Func<TypeToBeBuilt>. The best way to make this clear is with an example. In my application I have the following domain classes that I want to be able to use in my tests: public class Person { public string Name { get; set; } public int Age { get; set; } public bool IsAndroid { get; set; } } public class Building { public string Street { get; set; } public Person Manager { get; set; } } The builder for this domain is created like so: build = new Builder(); build.Configure(new Dictionary<Type, Func<object>> { {typeof(Building), () => new Building {Street = "Queen St", Manager = build.A<Person>()}}, {typeof(Person), () => new Person {Name = "Eugene", Age = 21}} }); Note how Building depends on Person, even though the person builder method is not defined yet. Now in a test I can retrieve a valid object from the builder: var person = build.A<Person>(); If I need a class in a customised state I can supply an Action<TypeToBeBuilt> to mutate the object post construction: var person = build.A<Person>(p => p.Age = 99); The power and efficiency of this approach becomes apparent when your tests require larger and more complex objects than Person and Building. When I get some time I intend to implement the same functionality in Javascript and Ruby. Here is the full source of the Builder class: public class Builder { private Dictionary<Type, Func<object>> defaults; public void Configure(Dictionary<Type, Func<object>> defaults) { this.defaults = defaults; } public T A<T>() { if (!defaults.ContainsKey(typeof(T))) throw new ArgumentException("No object of type " + typeof(T).Name + " has been configured with the builder."); T o = (T)defaults[typeof(T)](); return o; } public T A<T>(Action<T> customisation) { T o = A<T>(); customisation(o); return o; } }

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  • Type of computer for a developer on the road

    - by nabucosound
    Hi developers: I am planning to be traveling through eurasia and asia (russia, china, korea, japan, south east asia...) for a while and, although there are plenty of marvelous things to see and to do, I must keep on working :(. I am a python developer, dedicated mainly to web projects. I use django, sqlite3, browsers, and ocassionaly (only if I have no choice) I install postgres, mysql, apache or any other servers commonly used in the internets. I do my coding on vim, use ssh to connect, lftp to transfer files, IRC, grep/ack... So I spend most of my time in the terminal shells. But I also use IM or Skype to communicate with my clients and peers, as well as some other software (that after all is not mandatory for my day-to-day work). I currently work with a Macbook Pro (3 years old now) and so far I am very happy with the performance. But I don't want to carry it if I am going to be "on transit" for long time, it is simply huge and heavy for what I am planning to load in my rather small backpack (while traveling, less is more, you know). So here I am reading all kind of opinions about netbooks, because at first sight this is the kind of computer I thought I had to choose. I am going to use Linux for it, Microsoft is not my cup of tea and Mac is not available for them, unless I were to buy a Macbook air, something that I won't do because if I am robbed or rain/dust/truck loaders break it I would burst in tears. I am concerned about wifi performance and connectivity, I am going to use one of those linux distros/tools to hack/test on "open" networks (if you know what I mean) in case I am not in a place with real free wifi access and I find myself in an emergency. CPU speed should be acceptable, but since I don't plan to run Photoshop or expensive IDEs, I guess most of the time I won't be overloading the machine. Apart from this, maybe (surely) I am missing other features to consider. With that said (sorry about the length) here it comes my question, raised from a deep ignorance regarding the wars betweeb betbooks vs notebooks (I assume tablet PCs are not for programming yet): If I buy a netbook will I have to throw it away after 1 month on the road and buy a notebook? Or will I be OK? Thanks! Hector Update I have received great feedback so far! I would like to insist on the fact that I will be traveling through many different countries and scenarios. I am sure that while in Japan I will be more than fine with anything related to technology, connectivity, etc. But consider that I will be, for example, on a train through Russia (transsiberian) and will cross Mongolia as well. I will stay in friends' places sometimes, but most of the time I will have to work from hostel rooms, trains, buses, beaches (hey this last one doesn't sound too bad hehe!). I think some of your answers guys seem to focus on the geek part but loose the point of this "on the road" fact. I am very aware and agree that netbooks suck compared to notebooks, but what I am trying to do here is to find a balance and discover your experiences with netbooks to see first hand if a netbook will be a fail in the mid-long term of the trip for my purposes. So I have resumed the main concepts expressed here on this small list, in no particular order: keyboard/touchpad feel: I use vim so no need of moving mouse pointers that much, unless I am browsing the web, but intensive use of keyboard screen real state: again, terminal work for most of the time battery life: I think something very important weight/size: also very important looks not worth stealing it, don't give a shit if it is lost/stolen/broken: this may depend on kind of person, your economy, etc. Also to prevent losing work, I will upload EVERYTHING to the cloud whenever I'll have a chance. wifi: don't want to discover my wifi is one of those that cannot deal with half the routers on this planet or has poor connectivity. Thanks again for your answers and comments!

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  • Antenna Aligner Part 7: Connecting the dots

    - by Chris George
    The app is basically ready, so I eagerly started to sort out creating the application entry in iTunes Connect. It's mostly intuitive actually, although I did have to create yet another icon for iTunes sized 512x512 pixels, damn lucky I did the original graphics as vector! It took me longer to write the application description than anything else, I'm so not a tech author! I didn't like the way you have to 'make up' an SKU (Stock Keeping Unit) number. I have to do some googling to find out that it really doesn't matter what it is! It should be more obvious what to do from the actual website itself. That aside, the rest of it was actually fairly straightforward. As well as the details of the application, iPhone and iPad screenshots were also required. This posed somewhat of a problem. The iPhone ones were easy (as I have one!), but I do not (yet) own an iPad . So I thought I'd leave the iPad screenshots out for now. Once the application details were sorted, I moved onto the rights and pricing. At the start of the project I had made the decision that I wouldn't charge any more than the lowest amount £0.59. I believe there is a market for this, but as my first foray into app development I didn't want to take the mick. I did realise, however, that I had built my app with a developer certificate and provisioning profile. This was fairly quickly corrected, and again Nomad made this very easy to switch over to the distribution certificate and provisioning profile. With a sense of excitement I cracked open iTunes connect and clicked the upload button ... ...slight snag... . when the Nomad project was started, Apple allowed uploads of these binaries via iTunes Connect. But this is no longer possible, the only upload path is via the Application Loader available from the Apple Developer program. This itself has one limitation, it only runs on a mac! D'OH!!!  Actually my language was somewhat more colourful when this fact came to light. After picking my laptop up off the floor and putting it back together... ok only joking, but I did nearly throw it out of frustration!... I started to consider the options; I briefly entertained the idea of buying a cheap mac from ebay... no, that defeats the whole object of what I'm doing, plus my wife wouldn't be impressed there are some guys out there in the interweb who will upload your app for a small fee...but I don't really like the idea of giving some faceless email address my apple developer login details, as well as my app binary! find some willing friend with a mac who would kindly let me use it... obviously this is the only sensible option. In the meantime, I informed the Nomad team about this slight 'issue' and they are currently investigating possible solutions...

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  • Doubts about several best practices for rest api + service layer

    - by TheBeefMightBeTough
    I'm going to be starting a project soon that exposes a restful api for business intelligence. It may not be limited to a restful api, so I plan to delegate requests to a service layer that then coordinates multiple domain objects (each of which have business logic local to the object). The api will likely have many calls as it is a long-term project. While thinking about the design, I recalled a few best practices. 1) Use command objects at the controller layer (I'm using Spring MVC). 2) Use DTOs at the service layer. 3) Validate in both the controller and service layer, though for different reasons. I have my doubts about these recommendations. 1) Using command objects adds a lot of extra single-purpose classes (potentially one per request). What exactly is the benefit? Annotation based validation can be done using this approach, sure. What if I have two requests that take the same parameters, but have different validation requirements? I would have to have two different classes with exactly the same members but different annotations? Bleh. 2) I have heard that using DTOs is preferable to parameters because it makes for more maintainable code down the road (say, e.g., requirements change and the service parameters need to be altered). I don't quite understand this. Shouldn't an api be more-or-less set in stone? I would understand that in the early phases of a project (or, especially, an entire company) the domain itself will not be well understood, and thus core domain objects may change along with the apis that manipulate these objects. At this point however the number of api methods should be small and their dependents few, so changes to the methods could easily be tolerated from a maintainability standpoint. In a large api with many methods and a substantial domain model, I would think having a DTO for potentially each domain object would become unwieldy. Am I misunderstanding something here? 3) I see validation in the controller and service layer as redundant in most cases. Why would I validate that parameters are not null and are in general well formed in the controller if the service is going to do exactly the same (and more). Couldn't I just do all the validation in the service and throw a runtime exception with a list of bad parameters then catch that in the controller to make the error messages more presentable? Better yet, couldn't I just make the error messages user-friendly in the service and let the exception trickle up to a global handler (ControllerAdvice in spring, for example)? Is there something wrong with either of these approaches? (I do see a use case for controller validation if the input does not map one-to-one with the service input, but since the controllers are for a rest api and not forms, the api parameters will probably map directly to service parameters.) I do also have a question about unchecked vs checked exceptions. Namely, I'm not really sure why I'd ever want to use a checked exception. Every time I have seen them used they just get wrapped into general exceptions (DomainException, SystemException, ApplicationException, w/e) to reduce the signature length of methods, or devs catch Exception rather than dealing with the App1Exception, App2Exception, Sys1Exception, Sys2Exception. I don't see how either of these practices is very useful. Why not just use unchecked exceptions always and catch the ones you actually do care about? You could just document what unchecked exceptions the method throws.

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  • Learn Many Languages

    - by Jeff Foster
    My previous blog, Deliberate Practice, discussed the need for developers to “sharpen their pencil” continually, by setting aside time to learn how to tackle problems in different ways. However, the Sapir-Whorf hypothesis, a contested and somewhat-controversial concept from language theory, seems to hold reasonably true when applied to programming languages. It states that: “The structure of a language affects the ways in which its speakers conceptualize their world.” If you’re constrained by a single programming language, the one that dominates your day job, then you only have the tools of that language at your disposal to think about and solve a problem. For example, if you’ve only ever worked with Java, you would never think of passing a function to a method. A good developer needs to learn many languages. You may never deploy them in production, you may never ship code with them, but by learning a new language, you’ll have new ideas that will transfer to your current “day-job” language. With the abundant choices in programming languages, how does one choose which to learn? Alan Perlis sums it up best. “A language that doesn‘t affect the way you think about programming is not worth knowing“ With that in mind, here’s a selection of languages that I think are worth learning and that have certainly changed the way I think about tackling programming problems. Clojure Clojure is a Lisp-based language running on the Java Virtual Machine. The unique property of Lisp is homoiconicity, which means that a Lisp program is a Lisp data structure, and vice-versa. Since we can treat Lisp programs as Lisp data structures, we can write our code generation in the same style as our code. This gives Lisp a uniquely powerful macro system, and makes it ideal for implementing domain specific languages. Clojure also makes software transactional memory a first-class citizen, giving us a new approach to concurrency and dealing with the problems of shared state. Haskell Haskell is a strongly typed, functional programming language. Haskell’s type system is far richer than C# or Java, and allows us to push more of our application logic to compile-time safety. If it compiles, it usually works! Haskell is also a lazy language – we can work with infinite data structures. For example, in a board game we can generate the complete game tree, even if there are billions of possibilities, because the values are computed only as they are needed. Erlang Erlang is a functional language with a strong emphasis on reliability. Erlang’s approach to concurrency uses message passing instead of shared variables, with strong support from both the language itself and the virtual machine. Processes are extremely lightweight, and garbage collection doesn’t require all processes to be paused at the same time, making it feasible for a single program to use millions of processes at once, all without the mental overhead of managing shared state. The Benefits of Multilingualism By studying new languages, even if you won’t ever get the chance to use them in production, you will find yourself open to new ideas and ways of coding in your main language. For example, studying Haskell has taught me that you can do so much more with types and has changed my programming style in C#. A type represents some state a program should have, and a type should not be able to represent an invalid state. I often find myself refactoring methods like this… void SomeMethod(bool doThis, bool doThat) { if (!(doThis ^ doThat)) throw new ArgumentException(“At least one arg should be true”); if (doThis) DoThis(); if (doThat) DoThat(); } …into a type-based solution, like this: enum Action { DoThis, DoThat, Both }; void SomeMethod(Action action) { if (action == Action.DoThis || action == Action.Both) DoThis(); if (action == Action.DoThat || action == Action.Both) DoThat(); } At this point, I’ve removed the runtime exception in favor of a compile-time check. This is a trivial example, but is just one of many ideas that I’ve taken from one language and implemented in another.

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  • Omni-directional light shadow mapping with cubemaps in WebGL

    - by Winged
    First of all I must say, that I have read a lot of posts describing an usage of cubemaps, but I'm still confused about how to use them. My goal is to achieve a simple omni-directional (point) light type shading in my WebGL application. I know that there is a lot more techniques (like using Two-Hemispheres or Camera Space Shadow Mapping) which are way more efficient, but for an educational purpose cubemaps are my primary goal. Till now, I have adapted a simple shadow mapping which works with spotlights (with one exception: I don't know how to cut off the glitchy part beyond the reach of a single shadow map texture): glitchy shadow mapping<<< So for now, this is how I understand the usage of cubemaps in shadow mapping: Setup a framebuffer (in case of cubemaps - 6 framebuffers; 6 instead of 1 because every usage of framebufferTexture2D slows down an execution which is nicely described here <<<) and a texture cubemap. Also in WebGL depth components are not well supported, so I need to render it to RGBA first. this.texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_CUBE_MAP, this.texture); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR); for (var face = 0; face < 6; face++) gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, gl.RGBA, this.size, this.size, 0, gl.RGBA, gl.UNSIGNED_BYTE, null); gl.bindTexture(gl.TEXTURE_CUBE_MAP, null); this.framebuffer = []; for (face = 0; face < 6; face++) { this.framebuffer[face] = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer[face]); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, this.texture, 0); gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthbuffer); var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER); // Check for errors if (e !== gl.FRAMEBUFFER_COMPLETE) throw "Cubemap framebuffer object is incomplete: " + e.toString(); } Setup the light and the camera (I'm not sure if should I store all of 6 view matrices and send them to shaders later, or is there a way to do it with just one view matrix). Render the scene 6 times from the light's position, each time in another direction (X, -X, Y, -Y, Z, -Z) for (var face = 0; face < 6; face++) { gl.bindFramebuffer(gl.FRAMEBUFFER, shadow.buffer.framebuffer[face]); gl.viewport(0, 0, shadow.buffer.size, shadow.buffer.size); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); camera.lookAt( light.position.add( cubeMapDirections[face] ) ); scene.draw(shadow.program); } In a second pass, calculate the projection a a current vertex using light's projection and view matrix. Now I don't know If should I calculate 6 of them, because of 6 faces of a cubemap. ScaleMatrix pushes the projected vertex into the 0.0 - 1.0 region. vDepthPosition = ScaleMatrix * uPMatrixFromLight * uVMatrixFromLight * vWorldVertex; In a fragment shader calculate the distance between the current vertex and the light position and check if it's deeper then the depth information read from earlier rendered shadow map. I know how to do it with a 2D Texture, but I have no idea how should I use cubemap texture here. I have read that texture lookups into cubemaps are performed by a normal vector instead of a UV coordinate. What vector should I use? Just a normalized vector pointing to the current vertex? For now, my code for this part looks like this (not working yet): float shadow = 1.0; vec3 depth = vDepthPosition.xyz / vDepthPosition.w; depth.z = length(vWorldVertex.xyz - uLightPosition) * linearDepthConstant; float shadowDepth = unpack(textureCube(uDepthMapSampler, vWorldVertex.xyz)); if (depth.z > shadowDepth) shadow = 0.5; Could you give me some hints or examples (preferably in WebGL code) how I should build it?

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  • ConcurrentDictionary<TKey,TValue> used with Lazy<T>

    - by Reed
    In a recent thread on the MSDN forum for the TPL, Stephen Toub suggested mixing ConcurrentDictionary<T,U> with Lazy<T>.  This provides a fantastic model for creating a thread safe dictionary of values where the construction of the value type is expensive.  This is an incredibly useful pattern for many operations, such as value caches. The ConcurrentDictionary<TKey, TValue> class was added in .NET 4, and provides a thread-safe, lock free collection of key value pairs.  While this is a fantastic replacement for Dictionary<TKey, TValue>, it has a potential flaw when used with values where construction of the value class is expensive. The typical way this is used is to call a method such as GetOrAdd to fetch or add a value to the dictionary.  It handles all of the thread safety for you, but as a result, if two threads call this simultaneously, two instances of TValue can easily be constructed. If TValue is very expensive to construct, or worse, has side effects if constructed too often, this is less than desirable.  While you can easily work around this with locking, Stephen Toub provided a very clever alternative – using Lazy<TValue> as the value in the dictionary instead. This looks like the following.  Instead of calling: MyValue value = dictionary.GetOrAdd( key, () => new MyValue(key)); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would instead use a ConcurrentDictionary<TKey, Lazy<TValue>>, and write: MyValue value = dictionary.GetOrAdd( key, () => new Lazy<MyValue>( () => new MyValue(key))) .Value; This simple change dramatically changes how the operation works.  Now, if two threads call this simultaneously, instead of constructing two MyValue instances, we construct two Lazy<MyValue> instances. However, the Lazy<T> class is very cheap to construct.  Unlike “MyValue”, we can safely afford to construct this twice and “throw away” one of the instances. We then call Lazy<T>.Value at the end to fetch our “MyValue” instance.  At this point, GetOrAdd will always return the same instance of Lazy<MyValue>.  Since Lazy<T> doesn’t construct the MyValue instance until requested, the actual MyClass instance returned is only constructed once.

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  • Make the Time

    - by WonderOfItAll
    Took the little one to the pool tonight for swim lessons. Okay, Okay. They're not really lessons so much as they are "Hey, here's a few bucks, let me rent out a small section of your pool to swim around with my little one" Saw a dad at the pool. Bluetooth on, iPad in hand, and two year old somewhere around there. Saw a mom at the pool. Arguing with her five year old to NOT take a shower after swimming. Bluetooth on, iPad in hand, work laptop open on stadium seats. Her reasoning for not wanting the child to shower "Look, I have to get this stuff to the office by 6:30, we don't have time for you to shower. Let's go" Wait, isn't the whole point of this little experience called Mommy and Me (or, as in my case, Daddy and Me). Wherein Mommy/Daddy is supposed to spend time with little one. Not with the Bluetooth. Not with the work laptop. Dad (yeah, the same dad from earlier), in the pool. Bluetooth off (it's not waterproof or I'm sure he would've had it on), two year old in hand and iPad somewhere put away. Getting frustrated with kid because he won't 'perform' on command. Here's a little exchange Kid: "I don't wanna get in the water" Dad: "Well, we're here for 30 minutes, get in the water" Kid: "No, don't wanna" Dad: "Fine, I'm getting in" and, true to his word, in he goes, off to swim. Kid: Crying Dad: "Well, c'mon" Kid: Walking to stands Dad: Ignoring kid Kid: At stands Dad: Out of pool, drying off. Frustrated. Grabs bag, grabs kid, leaves How sad. It really seems like I am living in a generation of parents who view their children as one big scheduled distraction to another. It's almost like the dad was saying "Look, little 2 year old boy, I have a busy scheduled. Right now my Outlook Calendar tells me that I have 30 mins to spend with you, so, let's go kid: PERFORM because I have the time" Really? Can someone please tell me when the hell this happened? When did spending time with your kid, spending time with your family, spending time with your spouse, etc... become a distraction? I've seen people at work all day Tweeting throughout the day, checked in with Four Square, IM up and running constantly so they can 'stay in touch' only to see these same folks come home and be irritated because their kids or their spouse wants to connect with the. I've seen these very same people leave the house, go to the corner bar/store/you-name-the-place to be 'alone' only to find them there, plugged in, tweeting away, etc, etc, etc I LOVE technology. I love working with technology. But I also know that I am a human being. A person who, by very definition, is a social being. I needed social interactions and contact--and, no, I'm not talking about the Social Graph kind of connections, I'm talking about those interactions which, *GASP* involve eye to eye contact and human contact. A recent study found that the number one complaint of kids is that they feel they have to compete with technology for their parents time and attention. The number one wish from high school kids? That there parents would turn off the computer/tv/cell phone at dinner. This, coming from high school kids. Shouldn't that tell you a whole helluva lot? So, do yourself a favor tomorrow. Plug into technology all day. Throw yourself into it. Be passionate about what you do. When you walk through the door to your family, turn it all off for 30 mins and be there with your loved ones. If you can manage to play Angry Birds, I'm sure you can handle being disconnected for 30 minutes. Make the time

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  • XNA 2D Board game - trouble with the cursor

    - by Adorjan
    I just have started making a simple 2D board game using XNA, but I got stuck at the movement of the cursor. This is my problem: I have a 10x10 table on with I should use a cursor to navigate. I simply made that table with the spriteBatch.Draw() function because I couldn't do it on another way. So here is what I did with the cursor: public override void LoadContent() { ... mutato.Position = new Vector2(X, Y); //X=103, Y=107; mutato.Sebesseg = 45; ... mutato.Initialize(content.Load<Texture2D>("cursor"),mutato.Position,mutato.Sebesseg); ... } public override void HandleInput(InputState input) { if (input == null) throw new ArgumentNullException("input"); // Look up inputs for the active player profile. int playerIndex = (int)ControllingPlayer.Value; KeyboardState keyboardState = input.CurrentKeyboardStates[playerIndex]; if (input.IsPauseGame(ControllingPlayer) || gamePadDisconnected) { ScreenManager.AddScreen(new PauseMenuScreen(), ControllingPlayer); } else { // Otherwise move the player position. if (keyboardState.IsKeyDown(Keys.Down)) { Y = (int)mutato.Position.Y + mutato.Move; } if (keyboardState.IsKeyDown(Keys.Up)) { Y = (int)mutato.Position.Y - mutato.Move; } if (keyboardState.IsKeyDown(Keys.Left)) { X = (int)mutato.Position.X - mutato.Move; } if (keyboardState.IsKeyDown(Keys.Right)) { X = (int)mutato.Position.X + mutato.Move; } } } public override void Draw(GameTime gameTime) { mutato.Draw(spriteBatch); } Here's the cursor's (mutato) class: using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; namespace Battleship.Components { class Cursor { public Texture2D Cursortexture; public Vector2 Position; public int Move; public void Initialize(Texture2D texture, Vector2 position,int move) { Cursortexture = texture; Position = position; Move = move; } public void Update() { } public void Draw(SpriteBatch spriteBatch) { spriteBatch.Draw(Cursortexture, Position, Color.White); } } } And here is a part of the InputState class where I think I should change something: public bool IsNewKeyPress(Keys key, PlayerIndex? controllingPlayer, out PlayerIndex playerIndex) { if (controllingPlayer.HasValue) { // Read input from the specified player. playerIndex = controllingPlayer.Value; int i = (int)playerIndex; return (CurrentKeyboardStates[i].IsKeyDown(key) && LastKeyboardStates[i].IsKeyUp(key)); } } If I leave the movement operation like this it doesn't have any sense: X = (int)mutato.Position.X - mutato.Move; However if I modify it to this: X = (int)mutato.Position.X--; it moves smoothly. Instead of this I need to move the cursor by fields (45 pixels), but I don't have any idea how to manage it.

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