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• NoHostAvailableException With Cassandra & DataStax Java Driver If Large ResultSet

  - by hughj

  The setup: 2-node Cassandra 1.2.6 cluster replicas=2 very large CQL3 table with no secondary index Rowkey is a UUID.randomUUID().toString() read consistency set to ONE Using DataStax java driver 1.0 The request: Attempting to do a table scan by "SELECT some-col from schema.table LIMIT nnn;" The fail: Once I go beyond a certain nnn LIMIT, I start to get NoHostAvailableExceptions from the driver. It reads like this: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.exceptions.NoHostAvailableException.copy(NoHostAvailableException.java:64) at com.datastax.driver.core.ResultSetFuture.extractCauseFromExecutionException(ResultSetFuture.java:214) at com.datastax.driver.core.ResultSetFuture.getUninterruptibly(ResultSetFuture.java:169) at com.jpmc.es.rtm.storage.impl.EventExtract.main(EventExtract.java:36) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.RequestHandler.sendRequest(RequestHandler.java:98) at com.datastax.driver.core.RequestHandler$1.run(RequestHandler.java:165) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) Given: This is probably not the most enlightened thing to do to a large table with millions of rows, but this is how I learn what not to do, so I would really appreciate someone who could volunteer how this kind of error can be debugged. For example, when this happens, there are no indications that the nodes in the cluster ever had an issue with the request (there is nothing in the logs on either node that indicate any timeout or failure). Also, I enabled the trace on the driver, which gives you some nice autotrace (ala Oracle) info as long as the query succeeds. But in this case, the driver blows a NoHostAvailableException and no ExecutionInfo is available, so tracing has not provided any benefit in this case. I also find it interesting that this does not seem to be recorded as a timeout (my JMX consoles tell me no timeouts have occurred). So, I am left not understanding WHERE the failure is actually occurring. I am left with the idea that it is the driver that is having a problem, but I don't know how to debug it (and I would really like to). I have read several posts from folks that state that query'g for resultSets 10000 rows is probably not a good idea, and I am willing to accept this, but I would like to understand what is causing the exception and where the exception is happening. FWIW, I also tried bumping the timeout properties in the cassandra.yaml, but this made no difference whatsoever. I welcome any suggestions, anecdotes, insults, or monetary contributions for my registration in the house of moron-developers. Regards!!

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• Is it worth moving from stored procedures to linq ?

  - by Josef

  I'm looking at standardizing programming in an organisaiton. Half uses stored procedures and the other half Linq. From what i've read there is still some debate going on on this topic. My concern is that MS is trying to slip in it's own proprietry query language 'linq' to make SQL redundant. If a few years back microsoft had tried to win customers from oracle and sybase with their MSSQL database and stated that it didn't use SQL by their own proprietry query langues ie linq. I doubt many would have switched. I believe that is exactly what is happening now by introducting it into the applicaiton business layer. I have used MS for many years but there is one gripe that I have with them and that is that they change their direction a lot. By a lot I mean new releases of .net, silverlight etc are more than 30% different from previous version. So by the time you become productive a new release is on the way. As things stand now a web developer using .net would need to know either vb.net or c#, xml, xaml,javascript,html, sql and now linq. That doesn't make for good productivity in my books. My concern is that once we all start using linq MS will start changing it between releases. and it will become an ever changing landscape. I believe that 'linq to sql' has already been deprecated. At leas with SQL we are dealing with a more stable and standardized language. Are we looking at a programming revolution or a marketing campaign? As far as I know other languages like Cobol have stayed the same for years. A cobol program from 20 years ago could pick up todays code and start working on it. Could a Vb3 person work on a modern .net web app ? Would these large changes need to be made if the underlying original foundation had been sound ? I worry about following MS shaking roadmap with it's deadends and double backs. are there any architects out there who feel the same ? regards Josef

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• WCF .svc Accessible Over HTTP But Accessing WSDL Causes "Connection Was Reset"

  - by Wolfwyrd

  I have a WCF service which is hosted on IIS6 on a Win2003 SP2 machine. The WCF service is hosting correctly and is visible over HTTP giving the usual "To test this service, you will need to create a client and use it to call the service" message. However accessing the .svc?WSDL link causes the connection to be reset. The server itself is returning a 200 in the logs for the WSDL request, an example of which is shown here, the first call gets a connection reset, the second is a successful call for the .svc file. 2010-04-09 11:00:21 W3SVC6 MACHINENAME 10.79.42.115 GET /IntegrationService.svc wsdl 80 - 10.75.33.71 HTTP/1.1 Mozilla/4.0+(compatible;+MSIE+7.0;+Windows+NT+5.1;+.NET+CLR+2.0.50727;+.NET+CLR+1.1.4322;+.NET+CLR+1.0.3705;+InfoPath.1;+.NET+CLR+3.0.04506.30;+MS-RTC+LM+8;+.NET+CLR+3.0.4506.2152;+.NET+CLR+3.5.30729;) - - devsitename.mydevdomain.com 200 0 0 0 696 3827 2010-04-09 11:04:10 W3SVC6 MACHINENAME 10.79.42.115 GET /IntegrationService.svc - 80 - 10.75.33.71 HTTP/1.1 Mozilla/5.0+(Windows;+U;+Windows+NT+5.1;+en-GB;+rv:1.9.1.9)+Gecko/20100315+Firefox/3.5.9+(.NET+CLR+3.5.30729) - - devsitename.mydevdomain.com 200 0 0 3144 457 265 My Web.Config looks like: <system.serviceModel> <serviceHostingEnvironment > <baseAddressPrefixFilters> <add prefix="http://devsitename.mydevdomain.com" /> </baseAddressPrefixFilters> </serviceHostingEnvironment> <behaviors> <serviceBehaviors> <behavior name="My.Service.IntegrationServiceBehavior"> <serviceMetadata httpGetEnabled="true" /> <serviceDebug includeExceptionDetailInFaults="false" /> </behavior> </serviceBehaviors> </behaviors> <services> <service behaviorConfiguration="My.Service.IntegrationServiceBehavior" name="My.Service.IntegrationService"> <endpoint address="" binding="wsHttpBinding" contract="My.Service.Interfaces.IIntegrationService" bindingConfiguration="NoSecurityConfig" /> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services> <bindings> <wsHttpBinding> <binding name="NoSecurityConfig"> <security mode="None" /> </binding> </wsHttpBinding> </bindings> </system.serviceModel> I'm pretty much stumped by this one. It works fine through the local dev server in VS2008 but fails after deployment. For further information, the targeted machine does not have a firewall (it's on the internal network) and the logs show the site thinks it's fine with 200 OK responses. I've also tried updating the endpoint with the full URL to my service however it still makes no difference. I have looked into some of the other options - creating a separate WSDL manually and exposing it through the metadata properties (really don't want to do that due to the maintenance issues). If anyone can offer any thoughts on this or any other workarounds it would be greatly appreciated.

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• Fluent NHibernate - subclasses with shared reference

  - by ollie

  Edit: changed class names. I'm using Fluent NHibernate (v 1.0.0.614) automapping on the following set of classes (where Entity is the base class provided in the S#arp Architecture framework): public class Car : Entity { public virtual int ModelYear { get; set; } public virtual Company Manufacturer { get; set; } } public class Sedan : Car { public virtual bool WonSedanOfYear { get; set; } } public class Company : Entity { public virtual IList<Sedan> Sedans { get; set; } } This results in the following Configuration (as written to hbm.xml): <class name="Company" table="Companies"> <id name="Id" type="System.Int32" unsaved-value="0"> <column name="`ID`" /> <generator class="identity" /> </id> <bag cascade="all" inverse="true" name="Sedans" mutable="true"> <key> <column name="`CompanyID`" /> </key> <one-to-many class="Sedan" /> </bag> </class> <class name="Car" table="Cars"> <id name="Id" type="System.Int32" unsaved-value="0"> <column name="`ID`" /> <generator class="identity" /> </id> <property name="ModelYear" type="System.Int32"> <column name="`ModelYear`" /> </property> <many-to-one cascade="save-update" class="Company" name="Manufacturer"> <column name="`CompanyID`" /> </many-to-one> <joined-subclass name="Sedan"> <key> <column name="`CarID`" /> </key> <property name="WonSedanOfYear" type="System.Boolean"> <column name="`WonSedanOfYear`" /> </property> </joined-subclass> </class> So far so good! But now comes the ugly part. The generated database tables: Table: Companies Columns: ID (PK, int, not null) Table: Cars Columns: ID (PK, int, not null) ModelYear (int, null) CompanyID (FK, int, null) Table: Sedan Columns: CarID (PK, FK, int, not null) WonSedanOfYear (bit, null) CompanyID (FK, int, null) Instead of one FK for Company, I get two! How can I ensure I only get one FK for Company? Override the automapping? Put a convention in place? Or is this a bug? Your thoughts are appreciated.

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• Chaining CSS classes in IE6 - Trying to find a jQuery solution?

  - by Mike Baxter

  Right, perhaps I ask the impossible? I consider myself fairly new to Javscript and jQuery, but that being said, I have written some fairly complex code recently so I am definitely getting there... however I am now possed with a rather interesting issue at my current freelance contract. The previous web coder has taken a Grid-960 approach to the HTML and as a result has used chained classes to style many of the elements. The example below is typical of what can be found in the code: <div class='blocks four-col-1 orange highlight'>Some content</div> And in the css there will be different declarations for: (not actual css... but close enough) .blocks {margin-right:10px;} .orange {background-image:url(someimage.jpg);} .highlight {font-weight:bold;} .four-col-1 {width:300px;} and to make matters worse... this is in the CSS: .blocks.orange.highlight {background-colour:#dd00ff;} Anyone not familiar with this particular bug can read more on it here: http://www.ryanbrill.com/archives/multiple-classes-in-ie/ it is very real and very annoying. Without wanting to go into the merrits of not chaining classes (I told them this, but it is no longer feasible to change their approach... 100 hand coded pages into a 150 page website, no CMS... sigh) and without the luxury of being able to change the way these blocks are styled... can anyone advise me on the complexity and benefits between any of my below proposed approaches or possible other options that would adequately solve this problem. Potential Solution 1 Using conditional comments I am considering loading a jquery script only for IE6 that: Reads the class of all divs in a certain section of the page and pushes to an array creates empty boxes off screen with only one of the classes applied at a time Reads the applied CSS values for each box Re-applies these styles to the individual box, somehow bearing in mind the order in which they are called and overwriting conflicting instructions as required Potential Solution 2 read the class of all divs in a certain section of the page and push to an array Scan the document for links to style sheets Ajax grab the stylesheets and traverse looking for matching names to those in class array Apply styles as needed Potential Solution 3 Create an IE6 only stylesheet containing the exact style to be applied as a unique name (ie: class='blocks orange highlight' becomes class='blocks-orange-highlight') Traverse the document in IE6 and convert all spaces in class declarations to hyphens and reapply classes based on new style name Summary: Solution 1 allows the people at this company to apply any styles in the future and the script will adjust as needed. However it does not allow for the chained style to be added, only the individual style... it is also processor intensive and time consuming, but also the most likely to be converted into a plugin that could be used the world over Solution 2 is a potential nightmare to code. But again will allow for an endless number of updates without breaking Solution 3 will require someone at the companty to hardcode the new styles every time they make a change, and if they don't, IE6 will break. Ironically the site, whilst needing to conform to IE6 in a limited manner, does not need to run wihtout javascript (they've made the call... have JS or go away), so consider all jQuery and JS solutions to be 'game on'. Did I mention how much i hate IE6? Anyway... any thoughts or comments would be appreciated. I will continue to develop my own solution and if I discover one that can be turned into a jQuery plugin I will post it here in the comments. Regards, Mike.

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• Backbone.js Model change events in nested collections not firing as expected

  - by Pallavi Kaushik

  I'm trying to use backbone.js in my first "real" application and I need some help debugging why certain model change events are not firing as I would expect. I have a web service at /employees/{username}/tasks which returns a JSON array of task objects, with each task object nesting a JSON array of subtask objects. For example, [{ "id":45002, "name":"Open Dining Room", "subtasks":[ {"id":1,"status":"YELLOW","name":"Clean all tables"}, {"id":2,"status":"RED","name":"Clean main floor"}, {"id":3,"status":"RED","name":"Stock condiments"}, {"id":4,"status":"YELLOW","name":"Check / replenish trays"} ] },{ "id":47003, "name":"Open Registers", "subtasks":[ {"id":1,"status":"YELLOW","name":"Turn on all terminals"}, {"id":2,"status":"YELLOW","name":"Balance out cash trays"}, {"id":3,"status":"YELLOW","name":"Check in promo codes"}, {"id":4,"status":"YELLOW","name":"Check register promo placards"} ] }] Another web service allows me to change the status of a specific subtask in a specific task, and looks like this: /tasks/45002/subtasks/1/status/red [aside - I intend to change this to a HTTP Post-based service, but the current implementation is easier for debugging] I have the following classes in my JS app: Subtask Model and Subtask Collection var Subtask = Backbone.Model.extend({}); var SubtaskCollection = Backbone.Collection.extend({ model: Subtask }); Task Model with a nested instance of a Subtask Collection var Task = Backbone.Model.extend({ initialize: function() { // each Task has a reference to a collection of Subtasks this.subtasks = new SubtaskCollection(this.get("subtasks")); // status of each Task is based on the status of its Subtasks this.update_status(); }, ... }); var TaskCollection = Backbone.Collection.extend({ model: Task }); Task View to renders the item and listen for change events to the model var TaskView = Backbone.View.extend({ tagName: "li", template: $("#TaskTemplate").template(), initialize: function() { _.bindAll(this, "on_change", "render"); this.model.bind("change", this.on_change); }, ... on_change: function(e) { alert("task model changed!"); } }); When the app launches, I instantiate a TaskCollection (using the data from the first web service listed above), bind a listener for change events to the TaskCollection, and set up a recurring setTimeout to fetch() the TaskCollection instance. ... TASKS = new TaskCollection(); TASKS.url = ".../employees/" + username + "/tasks" TASKS.fetch({ success: function() { APP.renderViews(); } }); TASKS.bind("change", function() { alert("collection changed!"); APP.renderViews(); }); // Poll every 5 seconds to keep the models up-to-date. setInterval(function() { TASKS.fetch(); }, 5000); ... Everything renders as expected the first time. But at this point, I would expect either (or both) a Collection change event or a Model change event to get fired if I change a subtask's status using my second web service, but this does not happen. Funnily, I did get change events to fire if I added one additional level of nesting, with the web service returning a single object that has the Tasks Collection embedded, for example: "employee":"pkaushik", "tasks":[{"id":45002,"subtasks":[{"id":1..... But this seems klugey... and I'm afraid I haven't architected my app right. I'll include more code if it helps, but this question is already rather verbose. Thoughts?

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• iPhone Memory Error - when using Build & Debug, How to debug?

  - by LonH99

  I'm a newbie and need some help with an iPhone App running on the Simulator. The app works fine running with Build & Run or Build & Run - breakpoints off, but blows when running with Build & Debug - Breakpoints on. Any help or thoughts would be greatly appreciated. Lon Specifics: No breakpoints set, never gets to any visible simulator results, seems to blow during initialization phase before it can generate any output. Source of app is the DrinkMixer example, in the "Head First iPhone development" book (example built up to page 280) by Dan & Tracey Pilone. Blows With this Error Message: Attaching to process 970. Pending breakpoint 1 - "*0x01c1b001" resolved Program received signal: “EXC_BAD_ACCESS”. No memory available to program now: unsafe to call malloc Data Formatters temporarily unavailable, will re-try after a 'continue'. (Not safe to call dlopen at this time.) No memory available to program now: unsafe to call malloc --- Leaks: The only object noted as "leaked Object" is: Leaked Object # Address Size Responsible Library Responsible Frame Malloc 128 Bytes <blank> 0x3c11950 128Bytes CoreGraphics open_handle_to_dylib_path ___ Object Allocations shows (Highest at top = CFString): Category --- Overall Bytes -- #Overall -- Live Bytes -- #Living * All Allocations * 497kb #5888 496kb #5878 10 CFString 42kb #1126 42kb Malloc 32.00 KB 32kb #1 32kb Malloc 1.00 KB 29kb #29 29kb Malloc 8.00 KB 24kb #3 24kb Malloc 32 Bytes 20.81kb #666 20.75kb Malloc 1.50 KB 19.5kb #13 19.5kb CFDictionary (key-store) 17.64kb #159 17.64kb (note: Except for "All Allocations, the #Living is the same as #Overall) --- List of Calls from Debugger: #0 0x01c1b010 in CFStringCreateByCombiningStrings #1 0x023a0779 in LoadFontPathCache #2 0x023a096b in Initialize #3 0x023a0f3e in GSFontCreateWithName #4 0x003d4575 in +[UIFont boldSystemFontOfSize:] #5 0x002cddaa in +[UINavigationButton defaultFont] #6 0x002d9e37 in -[UINavigationButton initWithValue:width:style:barStyle:possibleTitles:tintColor:] #7 0x002cdc75 in -[UINavigationButton initWithImage:width:style:] #8 0x00468eeb in -[UIBarButtonItem(Static) createViewForNavigationItem:] #9 0x002d1b56 in -[UINavigationItem customRightView] #10 0x002d20e3 in -[UINavigationItem updateNavigationBarButtonsAnimated:] #11 0x002d1e1a in -[UINavigationItem setRightBarButtonItem:] #12 0x00002e7b in -[RootViewController viewDidLoad] at RootViewController.m:41 #13 0x00313796 in -[UIViewController view] #14 0x00311d92 in -[UIViewController contentScrollView] #15 0x0031c2b4 in -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] #16 0x0031b32e in -[UINavigationController _layoutViewController:] #17 0x0031cd1a in -[UINavigationController _startTransition:fromViewController:toViewController:] #18 0x0031831a in -[UINavigationController _startDeferredTransitionIfNeeded] #19 0x004362e4 in -[UILayoutContainerView layoutSubviews] #20 0x035342b0 in -[CALayer layoutSublayers] #21 0x0353406f in CALayerLayoutIfNeeded #22 0x035338c6 in CA::Context::commit_transaction #23 0x0353353a in CA::Transaction::commit #24 0x00295ef9 in -[UIApplication _reportAppLaunchFinished] #25 0x0029bb88 in -[UIApplication handleEvent:withNewEvent:] #26 0x002976d3 in -[UIApplication sendEvent:] #27 0x0029e0b5 in _UIApplicationHandleEvent #28 0x023a3ed1 in PurpleEventCallback #29 0x01bb6b80 in CFRunLoopRunSpecific #30 0x01bb5c48 in CFRunLoopRunInMode #31 0x00295e69 in -[UIApplication _run] #32 0x0029f003 in UIApplicationMain #33 0x00002ba0 in main at main.m:14 The code, including line #41 (noted below) is as follows. And thanks for the formatting help and comment: import "RootViewController.h" import "DrinkDetailViewController.h"; import "DrinkConstants.h" import "AddDrinkViewController.h" @implementation RootViewController @synthesize drinks, addButtonItem; - (void)viewDidLoad { [super viewDidLoad]; // add PATH for PLIST NSString *path = [[NSBundle mainBundle] pathForResource: @"DrinkDirections" ofType:@"plist"]; NSMutableArray *tmpArray = [[NSMutableArray alloc] initWithContentsOfFile:path]; self.drinks = tmpArray; [tmpArray release]; // Next is Line #41 - I removed earlier empty lines & Comments self.navigationItem.rightBarButtonItem = self.addButtonItem; } - (IBAction) addButtonPressed: (id) sender { NSLog(@"Add button pressed!");

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• Adobe Coldfusion Railo OpenBD Apache Tomcat Multiple Sites

  - by chris hough

  Here's what I am trying to do, unless I am crazy: I am trying to use Tomcat with the multiple workers, so far I got OpenBD working, but having trouble with Railo, and will be tackling Adobe after. each engine deployed as a war separated by different workers I wanted to keep both the sites and engines inside my sites directory I have to remap the symlink for the WEB-INF when I switch engines = have not found a way around this my thought is to have everything separated into modules and I want to be able to execute both cfm and php code in a single site.  Ideally, it would be amazing if there would be a way to not have to remap the symlink as well. thoughts? can this be done? I am trying to mimic how this would be setup on a live server, not using eclipse for example. here is what I am working with so far: my apache workers.properties worker.list=openbd, openbdadmin, railo, railoadmin  worker.openbd.type=ajp13  worker.openbd.host=local.mydev.openbd  worker.openbd.port=8009 worker.openbdadmin.type=ajp13  worker.openbdadmin.host=local.admin.openbd worker.openbdadmin.port=8009   worker.railo.type=ajp13  worker.railo.host=local.mydev.railo  worker.railo.port=8009 worker.railoadmin.type=ajp13  worker.railoadmin.host=local.admin.railo worker.railoadmin.port=8009   my tomcat servers.xml < Host name="local.admin.openbd" appBase="/Users/[myusername]/Websites/coldfusion.engines"  unpackWARs="false" autoDeploy="true" xmlValidation="true" xmlNamespaceAware="false"        < Context path="" docBase="openbd/" reloadable="true" privileged="true" antiResourceLocking="false" anitJARLocking="false" allowLinking="true" < /Host        < Host name="local.admin.railo"   appBase="/Users/[my username]/Websites/coldfusion.engines" unpackWARs="false" autoDeploy="true" xmlValidation="true" xmlNamespaceAware="false"        < Context path="" docBase="railo/"  reloadable="true" privileged="true" antiResourceLocking="false" anitJARLocking="false" allowLinking="true" < /Host < Host name="local.mydev.openbd"   appBase="/Users/[my username]/Websites/coldfusion.engines" unpackWARs="false" autoDeploy="true" xmlValidation="true" xmlNamespaceAware="false" < Context path="" docBase="/Users/[my username]/Websites/example.mydev/wwwroot/"  reloadable="true" privileged="true" antiResourceLocking="false" anitJARLocking="false" allowLinking="true"< /Context < /Host < Host name="local.mydev.railo"   appBase="/Users/[my username]/Websites/coldfusion.engines"  unpackWARs="false" autoDeploy="true" xmlValidation="true" xmlNamespaceAware="false" < Context path="" docBase="/Users/[my username]/Websites/example.mydev/wwwroot/"  reloadable="true" privileged="true" antiResourceLocking="false" anitJARLocking="false" allowLinking="true" < /Host my apache vhosts ServerName local.admin.openbd DocumentRoot /Users/[my username]/Websites/coldfusion.engines/openBD/ #Mount OpenBD and tell it to only server cfml files JkMount /*.cfm openbdadmin ErrorLog "/Users/[my username]/Websites/apache.logs/local_openbdadmin_error.log" ServerName local.admin.railo DocumentRoot /Users/[my username]/Websites/coldfusion.engines/railo/ #Mount Railo and tell it to only server cfml files JkMount /*.cfm railoadmin ErrorLog "/Users/[my username]/Websites/apache.logs/local_railoadmin_error.log" ServerName local.mydev DocumentRoot /Users/[my username]/Websites/example.mydev/wwwroot ErrorLog "/Users/[my username]/Websites/apache.logs/local_example_mydev_error.log" ServerName local.mydev.openbd DocumentRoot /Users/[my username]/Websites/example.mydev/wwwroot #Mount OpenBD and tell it to only server cfml files JkMount /*.cfm openbd ErrorLog "/Users/[my username]/Websites/apache.logs/local_example_mydev_openbd_error.log" ServerName local.mydev.railo DocumentRoot /Users/[my username]/Websites/example.mydev/wwwroot JkMount /*.cfm railo ErrorLog "/Users/[my username]/Websites/apache.logs/local_example_mydev_railo_error.log" my folder structure I am using websites/apache.logs/ websites/coldfusion.engines/ websites/coldfusion.engines/cfusion/ websites/coldfusion.engines/openBD/ websites/coldfusion.engines/railo/ websites/example.mydev/ websites/example.mydev/wwwroot/ websites/example.mydev/wwwroot/index.cfm   websites/example.mydev/wwwroot/index.htm   websites/example.mydev/wwwroot/index.php   error log output [Thu Aug 27 00:54:50.443 2009] [11279:2686719776] [info] init_jk::mod_jk.c (3183): mod_jk/1.2.28 initialized [Thu Aug 27 00:54:51.346 2009] [11280:2686719776] [info] init_jk::mod_jk.c (3183): mod_jk/1.2.28 initialized [Thu Aug 27 00:55:18.963 2009] [11284:2686719776] [info] jk_open_socket::jk_connect.c (594): connect to 127.0.0.1:8009 failed (errno=61) [Thu Aug 27 00:55:18.963 2009] [11284:2686719776] [info] ajp_connect_to_endpoint::jk_ajp_common.c (922): Failed opening socket to (127.0.0.1:8009) (errno=61) [Thu Aug 27 00:55:18.963 2009] [11284:2686719776] [error] ajp_send_request::jk_ajp_common.c (1507): (openbdadmin) connecting to backend failed. Tomcat is probably not started or is listening on the wrong port (errno=61) [Thu Aug 27 00:55:18.963 2009] [11284:2686719776] [info] ajp_service::jk_ajp_common.c (2447): (openbdadmin) sending request to tomcat failed (recoverable), because of error during request sending (attempt=1) [Thu Aug 27 00:55:19.063 2009] [11284:2686719776] [info] jk_open_socket::jk_connect.c (594): connect to 127.0.0.1:8009 failed (errno=61) [Thu Aug 27 00:55:19.063 2009] [11284:2686719776] [info] ajp_connect_to_endpoint::jk_ajp_common.c (922): Failed opening socket to (127.0.0.1:8009) (errno=61) [Thu Aug 27 00:55:19.063 2009] [11284:2686719776] [error] ajp_send_request::jk_ajp_common.c (1507): (openbdadmin) connecting to backend failed. Tomcat is probably not started or is listening on the wrong port (errno=61) [Thu Aug 27 00:55:19.063 2009] [11284:2686719776] [info] ajp_service::jk_ajp_common.c (2447): (openbdadmin) sending request to tomcat failed (recoverable), because of error during request sending (attempt=2) [Thu Aug 27 00:55:19.063 2009] [11284:2686719776] [error] ajp_service::jk_ajp_common.c (2466): (openbdadmin) connecting to tomcat failed. [Thu Aug 27 00:55:19.063 2009] [11284:2686719776] [info] jk_handler::mod_jk.c (2615): Service error=-3 for worker=openbdadmin [Thu Aug 27 00:55:20.377 2009] [11283:2686719776] [info] jk_open_socket::jk_connect.c (594): connect to 127.0.0.1:8009 failed (errno=61) [Thu Aug 27 00:55:20.377 2009] [11283:2686719776] [info] ajp_connect_to_endpoint::jk_ajp_common.c (922): Failed opening socket to (127.0.0.1:8009) (errno=61) [Thu Aug 27 00:55:20.377 2009] [11283:2686719776] [error] ajp_send_request::jk_ajp_common.c (1507): (railoadmin) connecting to backend failed. Tomcat is probably not started or is listening on the wrong port (errno=61) [Thu Aug 27 00:55:20.377 2009] [11283:2686719776] [info] ajp_service::jk_ajp_common.c (2447): (railoadmin) sending request to tomcat failed (recoverable), because of error during request sending (attempt=1) [Thu Aug 27 00:55:20.477 2009] [11283:2686719776] [info] jk_open_socket::jk_connect.c (594): connect to 127.0.0.1:8009 failed (errno=61) [Thu Aug 27 00:55:20.477 2009] [11283:2686719776] [info] ajp_connect_to_endpoint::jk_ajp_common.c (922): Failed opening socket to (127.0.0.1:8009) (errno=61) [Thu Aug 27 00:55:20.477 2009] [11283:2686719776] [error] ajp_send_request::jk_ajp_common.c (1507): (railoadmin) connecting to backend failed. Tomcat is probably not started or is listening on the wrong port (errno=61) [Thu Aug 27 00:55:20.477 2009] [11283:2686719776] [info] ajp_service::jk_ajp_common.c (2447): (railoadmin) sending request to tomcat failed (recoverable), because of error during request sending (attempt=2) [Thu Aug 27 00:55:20.477 2009] [11283:2686719776] [error] ajp_service::jk_ajp_common.c (2466): (railoadmin) connecting to tomcat failed. [Thu Aug 27 00:55:20.477 2009] [11283:2686719776] [info] jk_handler::mod_jk.c (2615): Service error=-3 for worker=railoadmin

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• What is "elegant" code?

  - by Breton

  I see a lot of lip service and talk about the most "elegant" way to do this or that. I think if you spend enough time programming you begin to obtain a sort of intuitive feel for what it is we call "elegance". But I'm curious. Even if we can look at a bit of code, and say instinctively "That's elegant", or "That's messy", I wonder if any of us really understands what that means. Is there a precise definition for this "elegance" we keep referring to? If there is, what is it? Now, what I mean by a precise definition, is a series of statements which can be used to derive questions about a peice of code, or a program as a whole, and determine objectively, or as objectively as possible, whether that code is "elegant" or not. May I assert, that perhaps no such definition exists, and it's all just personal preference. In this case, I ask you a slightly different question: Is there a better word for "elegance", or a better set of attributes to use for judging code quality that is perhaps more objective than merely appealing to individual intuition and taste? Perhaps code quality is a matter of taste, and the answer to both of my questions is "no". But I can't help but feel that we could be doing better than just expressing wishy washy feelings about our code quality. For example, user interface design is something that to a broad range of people looks for all the world like a field of study that oughtta be 100% subjective matter of taste. But this is shockingly and brutally not the case, and there are in fact many objective measures that can be applied to a user interface to determine its quality. A series of tests could be written to give a definitive and repeatable score to user interface quality. (See GOMS, for instance). Now, okay. is Elegance simply "code quality" or is it something more? Is it something that can be measured? Or is it a matter of taste? Does our profession have room for taste? Maybe I'm asking the wrong questions altogether. Help me out here. Bonus Round If there is such a thing as elegance in code, and that concept is useful, do you think that justifies classifying the field of programming as an "Art" capital A, or merely a "craft". Or is it just an engineering field populated by a bunch of wishful thinking humans? Consider this question in the light of your thoughts about the elegance question. Please note that there is a distinction between code which is considered "art" in itself, and code that was written merely in the service of creating an artful program. When I ask this question, I ask if the code itself justifies calling programming an art. Bounty Note I liked the answers to this question so much, I think I'd like to make a photographic essay book from it. Released as a free PDF, and published on some kind of on demand printing service of course, such as "zazz" or "tiggle" or "printley" or something . I'd like some more answers, please!

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• How to break a Hibernate session?

  - by Péter Török

  In the Hibernate reference, it is stated several times that All exceptions thrown by Hibernate are fatal. This means you have to roll back the database transaction and close the current Session. You aren’t allowed to continue working with a Session that threw an exception. One of our legacy apps uses a single session to update/insert many records from files into a DB table. Each recourd update/insert is done in a separate transaction, which is then duly committed (or rolled back in case an error occurred). Then for the next record a new transaction is opened etc. But the same session is used throughout the whole process, even if a HibernateException was caught in the middle. We are using Oracle 9i btw with Hibernate 3.24.sp1 on JBoss 4.2. Reading the above in the book, I realized that this design may fail. So I refactored the app to use a separate session for each record update. In a unit test with a mock session factory, I could prove that it is now requesting a new session for each record update. So far, so good. However, we found no way to reproduce the session failure while testing the whole app (would this be a stress test btw, or ...?). We thought of shutting down the listener of the DB but we realized that the app is keeping a bunch of connections open to the DB, and the listener would not affect those connections. (This is a web app, activated once every night by a scheduler, but it can also be activated via the browser.) Then we tried to kill some of those connections in the DB while the app was processing updates - this resulted in some failed updates, but then the app happily continued. Apparently Hibernate is clever enough to reopen broken connections under the hood without breaking the whole session. So this might not be a critical issue, as our app seems to be robust enough even in its original form. However, the issue keeps bugging me. I would like to know: Under what circumstances does the Hibernate session really become unusable after a HibernateException was thrown? How to reproduce this in a test? (What's the proper term for such a test?)

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• Does this code follow the definition of recursion?

  - by dekz

  Hi All, I have a piece of code which I am doubting it as a implementation of recursion by its definition. My understanding is that the code must call itself, the exact same function. I also question whether writing the code this way adds additional overhead which can be seen with the use of recursion. What are your thoughts? class dhObject { public: dhObject** children; int numChildren; GLdouble linkLength; //ai GLdouble theta; //angle of rot about the z axis GLdouble twist; //about the x axis GLdouble displacement; // displacement from the end point of prev along z GLdouble thetaMax; GLdouble thetaMin; GLdouble thetaInc; GLdouble direction; dhObject(ifstream &fin) { fin >> numChildren >> linkLength >> theta >> twist >> displacement >> thetaMax >> thetaMin; //std::cout << numChildren << std::endl; direction = 1; thetaInc = 1.0; if (numChildren > 0) { children = new dhObject*[numChildren]; for(int i = 0; i < numChildren; ++i) { children[i] = new dhObject(fin); } } } void traverse(void) { glPushMatrix(); //draw move initial and draw transform(); draw(); //draw children for(int i = 0; i < numChildren; ++i) { children[i]->traverse(); } glPopMatrix(); } void update(void) { //Update the animation, if it has finished all animation go backwards if (theta <= thetaMin) { thetaInc = 1.0; } else if (theta >= thetaMax) { thetaInc = -1.0; } theta += thetaInc; //std::cout << thetaMin << " " << theta << " " << thetaMax << std::endl; for(int i = 0; i < numChildren; ++i) { children[i]->update(); } } void draw(void) { glPushMatrix(); glColor3f (0.0f,0.0f,1.0f); glutSolidCube(0.1); glPopMatrix(); } void transform(void) { //Move in the correct way, R, T, T, R glRotatef(theta, 0, 0, 1.0); glTranslatef(0,0,displacement); glTranslatef(linkLength, 0,0); glRotatef(twist, 1.0,0.0,0.0); } };

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• WCF via SSL connectivity problems

  - by Brett Widmeier

  Hello, I am hosting a WCF service from inside a Windows service using WAS. When I set the service to listen on 127.0.0.1, I have connectivity from my local machine as well as from my network. However, when I set it to listen on my outbound interface port 443, I can no longer even see the wsdl by connecting with a browser. Strangely, I can connect to the service by using telnet. The cert I am using was generated for my interface by a CA, and I have successfully used this exact cert with this service before. When checking the application log, I see that the service starts without error and is listening on the correct interface. From this information, it seems to me that the config file is in a valid state, but somehow misconfigured for what I want. I have, however, previously deployed this same setup on other sites using this config file. In case it is helpful, below is my config file. Any thoughts? <!--<system.diagnostics> <sources> <source name="System.ServiceModel" switchValue="Warning, ActivityTracing" propagateActivity="true"> <listeners> <add type="System.Diagnostics.DefaultTraceListener" name="Default"> <filter type="" /> </add> <add name="ServiceModelTraceListener"> <filter type="" /> </add> </listeners> </source> </sources> <sharedListeners> <add initializeData="app_tracelog.svclog" type="System.Diagnostics.XmlWriterTraceListener, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" name="ServiceModelTraceListener" traceOutputOptions="Timestamp"> <filter type="" /> </add> </sharedListeners> </system.diagnostics>--> <appSettings/> <connectionStrings/> <system.serviceModel> <!--<diagnostics> <messageLogging logEntireMessage="true" logMalformedMessages="true" logMessagesAtServiceLevel="true" logMessagesAtTransportLevel="true" maxMessagesToLog ="1000" maxSizeOfMessageToLog="524288"/> </diagnostics>--> <bindings> <basicHttpBinding> <binding name="basicHttps"> <security mode="Transport"> <transport clientCredentialType="None"/> <message /> </security> </binding> </basicHttpBinding> </bindings> <services> <service behaviorConfiguration="ServiceBehavior" name="<fully qualified name of service>"> <endpoint address="" binding="basicHttpBinding" name="OrdersSoap" contract="<fully qualified name of contract>" bindingNamespace="http://emr.orders.com/WebServices" bindingConfiguration="basicHttps" /> <endpoint binding="mexHttpsBinding" address="mex" contract="IMetadataExchange" /> <host> <baseAddresses> <add baseAddress="https://<external IP>/<name of service>>/" /> </baseAddresses> </host> </service> </services> <behaviors> <serviceBehaviors> <behavior name="ServiceBehavior"> <serviceMetadata httpsGetEnabled="False"/> <serviceDebug includeExceptionDetailInFaults="True" /> <dataContractSerializer maxItemsInObjectGraph="2147483646"/> </behavior> </serviceBehaviors> </behaviors> </system.serviceModel>

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• C# Windows Service XML

  - by Goober

  Scenario I have a windows service written in C# that performs some processing based on parsing an XML file and use that data to carry out various tasks. The service also does various bits of logging - which uses settings from an APP.Config file. The Problem When the service is compiled, installed and run, the XML file seems to disappear. I'm getting the impression that it is just ignored or something like that. So far I've tried using TWO App.Config files, one named App.Config that contains settings for the service, and the other called MyService.exe.config that contains all of the data that was used in the XML file (the idea being that I can parse the XML from a config file that actually gets compiled and appears in my installation directory. However When I do this, all that happens is that ONE config file appears (with the name MyService.exe.config), but it contains the contents of the App.Config file and not the XML data that I want to parse. What I need All I want is to have a config file for my settings, and an XML file for my data. Question Is this possible? I know the application works as it was originally built as a console application that ran fine. Other The application has to be designed this way (as in, I need my data stored as XML, and my settings stored in a config file). Thoughts If I could somehow combine the contents of the two files into ONE config file, that would be one way of solving the problem. However, I have tried this and of course I get a "Type Initialisation Exception", as the config file cannot interprate the XML data (probably because the tags are custom and do not form any part of the config schema - or something like that). Ideas Please could someone explain to me if it is possible for me to have an XML file AND a config file that will actually be compiled and stored in my installation directory for the service when it is run? CODE Custom XML/Data Config File <?xml version="1.0" encoding="utf-8" ?> <configuration> <servers> <SV066930> <add name="Name" value = "SV066930" /> <processes> <SimonTest1> <add name="ProcessName" value="notepad.exe" /> <add name="CommandLine" value="C:\\WINDOWS\\system32\\notepad.exe C:\\WINDOWS\\Profiles\\TA2TOF1\\Desktop\\SimonTest1.txt" /> </SimonTest1> </processes> </SV066930> </servers> </configuration> APP.Config Settings File <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name="dataConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=xxxxxxxxxxx" /> </configSections> <connectionStrings> <add name="DB" connectionString="Data Source=etc......" /> </connectionStrings> </configuration> Help greatly appreciated.

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• Why are my USB 2.0 devices hanging Windows XP?

  - by BenAlabaster

  Background on the machine I'm having a problem with: The machine was inherited and appears to be circa 2003 (there's a date stamp on the power supply which leads me to this conclusion). I've got it set up as a Skype terminal for my 2 year old to keep in touch with her grandparents and other members of the family - which everyone loves. It has a DFI CM33-TL/G ATX (identified using SiSoft Sandra) motherboard hosting an Intel Celeron 1.3GHz CPU, 768Mb PC133 SDRAM, a D-LINK WDA-2320 54G Wi-Fi network card and a generic USB 2.0 expansion board based on the NEC uPD720102 chipset containing 3 external and 1 internal USB sockets. It's also hosting a 1.44Mb floppy drive on FDD0, a new 80Gb Western Digital hard drive running as master on IDE0 and a Panasonic DVD+/-RW running as master on IDE1. All this is sitting in a slimline case running off a Macron Power MPT-135 135W Flex power supply. The motherboard is running a version of Award BIOS 05/24/2002-601T-686B-6A6LID4AC-00. Could this be updated? If so, from where? I've raked through the manufacturer's website but can't find any hint of downloads for either drivers or BIOS updates. The hard disk is freshly formatted and built with Windows XP Professional/Service Pack 3 and is up to date with all current patches. In addition to Windows XP, the only other software it's running is Skype 4.1 (4.2 hangs the whole machine as soon as it starts up, requiring a hard boot to recover). It's got a Daytek MV150 15" touch screen hooked up to the on board VGA and COM1 sockets with the most current drivers from the Daytek website and the most current version of ELO-Touchsystems drivers for the touch component. The webcam is a Logitech Webcam C200 with the latest drivers from the Logitech website. The problem: If I hook any devices to the USB 2.0 sockets, it hangs the whole machine and I have to hard boot it to get it back up. If I have any devices attached to the USB 2.0 sockets when I boot up, it hangs before Windows gets to the login prompt and I have to hard boot it to recover. Workarounds found: I can plug the same devices into the on board USB 1.0 sockets and everything works fine, albeit at reduced performance. I've tried 3 different kinds of USB thumb drives, 3 different makes/models of webcams and my iPhone all with the same effect. They're recognized and don't hang the machine when I hook them to the USB 1.0 but if I hook them to the USB 2.0 ports, the machine hangs within a couple of seconds of recognizing the devices were connected. Attempted solutions: I've seen suggestions that this could be a power problem - that the PSU just doesn't have the wattage to drive these ports. While I'm doubtful this is the problem [after all the motherboard has the same standard connector regardless of the PSU wattage], I tried disabling all the on board devices that I'm not using - on board LAN, the second COM port, the AGP connector etc. through the BIOS in what I'm sure is a futile attempt to reduce the power consumption... I also modified the ACPI and power management settings. It didn't have any noticeable affect, although it didn't do any harm either. Could the wattage of the PSU really cause this problem? If it can, is there anything I need to be aware of when replacing it or do I just need to make sure it's got a higher wattage than the current one? My interpretation was that the wattage only affected the number of drives you could hook up to the power connectors, is that right? I've installed the USB card in another machine and it works without issue, so it's not a problem with the USB card itself, and Windows says the card is installed and working correctly... right up until I connect a device to it. The only thing I haven't done which I only just thought of while writing this essay is trying the USB 2.0 card in a different PCI slot, or re-ordering the wi-fi and USB cards in the slots... although I'm not sure if this will make any difference - does anyone have any experience that would suggest this might work? Other thoughts/questions: Perhaps this is an incompatibility between the USB 2.0 card and the BIOS, would re-flashing the BIOS with a newer version help? Do I need to be able to identify the manufacturer of the motherboard in order to be able to find a BIOS edition specific for this motherboard or will any version of Award BIOS function in its place? Question: Does anyone have any ideas that could help me get my USB 2.0 devices hooked up to this machine?

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• Domain Validation in a CQRS architecture

  - by Jupaol

  Basically I want to know if there is a better way to validate my domain entities. This is how I am planning to do it but I would like your opinion The first approach I considered was: class Customer : EntityBase<Customer> { public void ChangeEmail(string email) { if(string.IsNullOrWhitespace(email)) throw new DomainException(“...”); if(!email.IsEmail()) throw new DomainException(); if(email.Contains(“@mailinator.com”)) throw new DomainException(); } } I actually do not like this validation because even when I am encapsulating the validation logic in the correct entity, this is violating the Open/Close principle (Open for extension but Close for modification) and I have found that violating this principle, code maintenance becomes a real pain when the application grows up in complexity. Why? Because domain rules change more often than we would like to admit, and if the rules are hidden and embedded in an entity like this, they are hard to test, hard to read, hard to maintain but the real reason why I do not like this approach is: if the validation rules change, I have to come and edit my domain entity. This has been a really simple example but in RL the validation could be more complex So following the philosophy of Udi Dahan, making roles explicit, and the recommendation from Eric Evans in the blue book, the next try was to implement the specification pattern, something like this class EmailDomainIsAllowedSpecification : IDomainSpecification<Customer> { private INotAllowedEmailDomainsResolver invalidEmailDomainsResolver; public bool IsSatisfiedBy(Customer customer) { return !this.invalidEmailDomainsResolver.GetInvalidEmailDomains().Contains(customer.Email); } } But then I realize that in order to follow this approach I had to mutate my entities first in order to pass the value being valdiated, in this case the email, but mutating them would cause my domain events being fired which I wouldn’t like to happen until the new email is valid So after considering these approaches, I came out with this one, since I am going to implement a CQRS architecture: class EmailDomainIsAllowedValidator : IDomainInvariantValidator<Customer, ChangeEmailCommand> { public void IsValid(Customer entity, ChangeEmailCommand command) { if(!command.Email.HasValidDomain()) throw new DomainException(“...”); } } Well that’s the main idea, the entity is passed to the validator in case we need some value from the entity to perform the validation, the command contains the data coming from the user and since the validators are considered injectable objects they could have external dependencies injected if the validation requires it. Now the dilemma, I am happy with a design like this because my validation is encapsulated in individual objects which brings many advantages: easy unit test, easy to maintain, domain invariants are explicitly expressed using the Ubiquitous Language, easy to extend, validation logic is centralized and validators can be used together to enforce complex domain rules. And even when I know I am placing the validation of my entities outside of them (You could argue a code smell - Anemic Domain) but I think the trade-off is acceptable But there is one thing that I have not figured out how to implement it in a clean way. How should I use this components... Since they will be injected, they won’t fit naturally inside my domain entities, so basically I see two options: Pass the validators to each method of my entity Validate my objects externally (from the command handler) I am not happy with the option 1 so I would explain how I would do it with the option 2 class ChangeEmailCommandHandler : ICommandHandler<ChangeEmailCommand> { public void Execute(ChangeEmailCommand command) { private IEnumerable<IDomainInvariantValidator> validators; // here I would get the validators required for this command injected, and in here I would validate them, something like this using (var t = this.unitOfWork.BeginTransaction()) { var customer = this.unitOfWork.Get<Customer>(command.CustomerId); this.validators.ForEach(x =. x.IsValid(customer, command)); // here I know the command is valid // the call to ChangeEmail will fire domain events as needed customer.ChangeEmail(command.Email); t.Commit(); } } } Well this is it. Can you give me your thoughts about this or share your experiences with Domain entities validation EDIT I think it is not clear from my question, but the real problem is: Hiding the domain rules has serious implications in the future maintainability of the application, and also domain rules change often during the life-cycle of the app. Hence implementing them with this in mind would let us extend them easily. Now imagine in the future a rules engine is implemented, if the rules are encapsulated outside of the domain entities, this change would be easier to implement

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• Is it possible to implement bitwise operators using integer arithmetic?

  - by Statement

  Hello World! I am facing a rather peculiar problem. I am working on a compiler for an architecture that doesn't support bitwise operations. However, it handles signed 16 bit integer arithmetics and I was wondering if it would be possible to implement bitwise operations using only: Addition (c = a + b) Subtraction (c = a - b) Division (c = a / b) Multiplication (c = a * b) Modulus (c = a % b) Minimum (c = min(a, b)) Maximum (c = max(a, b)) Comparisons (c = (a < b), c = (a == b), c = (a <= b), et.c.) Jumps (goto, for, et.c.) The bitwise operations I want to be able to support are: Or (c = a | b) And (c = a & b) Xor (c = a ^ b) Left Shift (c = a << b) Right Shift (c = a b) (All integers are signed so this is a problem) Signed Shift (c = a b) One's Complement (a = ~b) (Already found a solution, see below) Normally the problem is the other way around; how to achieve arithmetic optimizations using bitwise hacks. However not in this case. Writable memory is very scarce on this architecture, hence the need for bitwise operations. The bitwise functions themselves should not use a lot of temporary variables. However, constant read-only data & instruction memory is abundant. A side note here also is that jumps and branches are not expensive and all data is readily cached. Jumps cost half the cycles as arithmetic (including load/store) instructions do. On other words, all of the above supported functions cost twice the cycles of a single jump. Some thoughts that might help: I figured out that you can do one's complement (negate bits) with the following code: // Bitwise one's complement b = ~a; // Arithmetic one's complement b = -1 - a; I also remember the old shift hack when dividing with a power of two so the bitwise shift can be expressed as: // Bitwise left shift b = a << 4; // Arithmetic left shift b = a * 16; // 2^4 = 16 // Signed right shift b = a >>> 4; // Arithmetic right shift b = a / 16; For the rest of the bitwise operations I am slightly clueless. I wish the architects of this architecture would have supplied bit-operations. I would also like to know if there is a fast/easy way of computing the power of two (for shift operations) without using a memory data table. A naive solution would be to jump into a field of multiplications: b = 1; switch (a) { case 15: b = b * 2; case 14: b = b * 2; // ... exploting fallthrough (instruction memory is magnitudes larger) case 2: b = b * 2; case 1: b = b * 2; } Or a Set & Jump approach: switch (a) { case 15: b = 32768; break; case 14: b = 16384; break; // ... exploiting the fact that a jump is faster than one additional mul // at the cost of doubling the instruction memory footprint. case 2: b = 4; break; case 1: b = 2; break; }

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• Build path issues learning Guice

  - by Preston

  I can't figure out why I'm getting this error below I have included all the appropriate jars as far as I can tell(I have included eclipses .classpath file below.) All of the classpath entries resolve just fine. What am I missing? The type javax.servlet.ServletContextListener cannot be resolved. It is indirectly referenced from required .class files on the "extends GuiceServletContextListener" line - import com.google.inject.Guice; import com.google.inject.Injector; import com.google.inject.servlet.GuiceServletContextListener; import com.google.inject.servlet.ServletModule; public class ServletConfig extends GuiceServletContextListener { @Override protected Injector getInjector() { return Guice.createInjector(new ServletModule(){ @Override protected void configureServlets() { // TODO: add necessary code to bind } }); } } .Classpath <?xml version="1.0" encoding="UTF-8"?> <classpath> <classpathentry kind="src" path="src"/> <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/jdk1.7.0_21"> <attributes> <attribute name="owner.project.facets" value="java"/> </attributes> </classpathentry> <classpathentry kind="con" path="oracle.eclipse.tools.glassfish.lib.system"> <attributes> <attribute name="owner.project.facets" value="jst.web"/> </attributes> </classpathentry> <classpathentry kind="con" path="org.eclipse.jst.j2ee.internal.web.container"/> <classpathentry kind="con" path="org.eclipse.jst.j2ee.internal.module.container"/> <classpathentry kind="lib" path="guice-3.0/aopalliance.jar"/> <classpathentry kind="lib" path="guice-3.0/guice-3.0.jar"/> <classpathentry kind="lib" path="guice-3.0/guice-servlet-3.0.jar"/> <classpathentry kind="lib" path="guice-3.0/javax.inject.jar"/> <classpathentry kind="output" path="build/classes"/> </classpath>

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• NHibernate (3.1.0.4000) NullReferenceException using Query<> and NHibernate Facility

  - by TigerShark

  I have a problem with NHibernate, I can't seem to find any solution for. In my project I have a simple entity (Batch), but whenever I try and run the following test, I get an exception. I've triede a couple of different ways to perform a similar query, but almost identical exception for all (it differs in which LINQ method being executed). The first test: [Test] public void QueryLatestBatch() { using (var session = SessionManager.OpenSession()) { var batch = session.Query<Batch>() .FirstOrDefault(); Assert.That(batch, Is.Not.Null); } } The exception: System.NullReferenceException : Object reference not set to an instance of an object. at NHibernate.Linq.NhQueryProvider.PrepareQuery(Expression expression, ref IQuery query, ref NhLinqExpression nhQuery) at NHibernate.Linq.NhQueryProvider.Execute(Expression expression) at System.Linq.Queryable.FirstOrDefault(IQueryable`1 source) The second test: [Test] public void QueryLatestBatch2() { using (var session = SessionManager.OpenSession()) { var batch = session.Query<Batch>() .OrderBy(x => x.Executed) .Take(1) .SingleOrDefault(); Assert.That(batch, Is.Not.Null); } } The exception: System.NullReferenceException : Object reference not set to an instance of an object. at NHibernate.Linq.NhQueryProvider.PrepareQuery(Expression expression, ref IQuery query, ref NhLinqExpression nhQuery) at NHibernate.Linq.NhQueryProvider.Execute(Expression expression) at System.Linq.Queryable.SingleOrDefault(IQueryable`1 source) However, this one is passing (using QueryOver<): [Test] public void QueryOverLatestBatch() { using (var session = SessionManager.OpenSession()) { var batch = session.QueryOver<Batch>() .OrderBy(x => x.Executed).Asc .Take(1) .SingleOrDefault(); Assert.That(batch, Is.Not.Null); Assert.That(batch.Executed, Is.LessThan(DateTime.Now)); } } Using the QueryOver< API is not bad at all, but I'm just kind of baffled that the Query< API isn't working, which is kind of sad, since the First() operation is very concise, and our developers really enjoy LINQ. I really hope there is a solution to this, as it seems strange if these methods are failing such a simple test. EDIT I'm using Oracle 11g, my mappings are done with FluentNHibernate registered through Castle Windsor with the NHibernate Facility. As I wrote, the odd thing is that the query works perfectly with the QueryOver< API, but not through LINQ.

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• What are the benefits of using ORM over XML Serialization/Deserialization?

  - by Tequila Jinx

  I've been reading about NHibernate and Microsoft's Entity Framework to perform Object Relational Mapping against my data access layer. I'm interested in the benefits of having an established framework to perform ORM, but I'm curious as to the performance costs of using it against standard XML Serialization and Deserialization. Right now, I develop stored procedures in Oracle and SQL Server that use XML Types for either input or output parameters and return or shred XML depending on need. I use a custom database command object that uses generics to deserialize the XML results into a specified serializable class. By using a combination of generics, xml (de)serialization and Microsoft's DAAB, I've got a process that's fairly simple to develop against regardless of the data source. Moreover, since I exclusively use Stored Procedures to perform database operations, I'm mostly protected from changes in the data structure. Here's an over-simplified example of what I've been doing. static void main() { testXmlClass test = new test(1); test.Name = "Foo"; test.Save(); } // Example Serializable Class ------------------------------------------------ [XmlRootAttribute("test")] class testXmlClass() { [XmlElement(Name="id")] public int ID {set; get;} [XmlElement(Name="name")] public string Name {set; get;} //create an instance of the class loaded with data. public testXmlClass(int id) { GenericDBProvider db = new GenericDBProvider(); this = db.ExecuteSerializable("myGetByIDProcedure"); } //save the class to the database... public Save() { GenericDBProvider db = new GenericDBProvider(); db.AddInParameter("myInputParameter", DbType.XML, this); db.ExecuteSerializableNonQuery("mySaveProcedure"); } } // Database Handler ---------------------------------------------------------- class GenericDBProvider { public T ExecuteSerializable<T>(string commandText) where T : class { XmlSerializer xml = new XmlSerializer(typeof(T)); // connection and command code is assumed for the purposes of this example. // the final results basically just come down to... return xml.Deserialize(commandResults) as T; } public void ExecuteSerializableNonQuery(string commandText) { // once again, connection and command code is assumed... // basically, just execute the command along with the specified // parameters which have been serialized. } public void AddInParameter(string name, DbType type, object value) { StringWriter w = new StringWriter(); XmlSerializer x = new XmlSerializer(value.GetType()); //handle serialization for serializable classes. if (type == DbType.Xml && (value.GetType() != typeof(System.String))) { x.Serialize(w, value); w.Close(); // store serialized object in a DbParameterCollection accessible // to my other methods. } else { //handle all other parameter types } } } I'm starting a new project which will rely heavily on database operations. I'm very curious to know whether my current practices will be sustainable in a high-traffic situation and whether or not I should consider switching to NHibernate or Microsoft's Entity Framework to perform what essentially seems to boil down to the same thing I'm currently doing. I appreciate any advice you may have.

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• Best Practices / Patterns for Enterprise Protection/Remediation of SSNs (Social Security Numbers)

  - by Erik Neu

  I am interested in hearing about enterprise solutions for SSN handling. (I looked pretty hard for any pre-existing post on SO, including reviewing the terriffic SO automated "Related Questions" list, and did not find anything, so hopefully this is not a repeat.) First, I think it is important to enumerate the reasons systems/databases use SSNs: (note—these are reasons for de facto current state—I understand that many of them are not good reasons) Required for Interaction with External Entities. This is the most valid case—where external entities your system interfaces with require an SSN. This would typically be government, tax and financial. SSN is used to ensure system-wide uniqueness. SSN has become the default foreign key used internally within the enterprise, to perform cross-system joins. SSN is used for user authentication (e.g., log-on) The enterprise solution that seems optimum to me is to create a single SSN repository that is accessed by all applications needing to look up SSN info. This repository substitutes a globally unique, random 9-digit number (ASN) for the true SSN. I see many benefits to this approach. First of all, it is obviously highly backwards-compatible—all your systems "just" have to go through a major, synchronized, one-time data-cleansing exercise, where they replace the real SSN with the alternate ASN. Also, it is centralized, so it minimizes the scope for inspection and compliance. (Obviously, as a negative, it also creates a single point of failure.) This approach would solve issues 2 and 3, without ever requiring lookups to get the real SSN. For issue #1, authorized systems could provide an ASN, and be returned the real SSN. This would of course be done over secure connections, and the requesting systems would never persist the full SSN. Also, if the requesting system only needs the last 4 digits of the SSN, then that is all that would ever be passed. Issue #4 could be handled the same way as issue #1, though obviously the best thing would be to move away from having users supply an SSN for log-on. There are a couple of papers on this: UC Berkely: http://bit.ly/bdZPjQ Oracle Vault: bit.ly/cikbi1

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• Complex relationship between tables in NHibernate

  - by Ilya Kogan

  Hi all, I'm writing a Fluent NHibernate mapping for a legacy Oracle database. The challenge is that the tables have composite primary keys. If I were at total freedom, I would redesign the relationships and auto-generate primary keys, but other applications must write to the same database and read from it, so I cannot do it. These are the two tables I'll focus on: Example data Trips table: 1, 10:00, 11:00 ... 1, 12:00, 15:00 ... 1, 16:00, 19:00 ... 2, 12:00, 13:00 ... 3, 9:00, 18:00 ... Faults table: 1, 13:00 ... 1, 23:00 ... 2, 12:30 ... In this case, vehicle 1 made three trips and has two faults. The first fault happened during the second trip, and the second fault happened while the vehicle was resting. Vehicle 2 had one trip, during which a fault happened. Constraints Trips of the same vehicle never overlap. So the tables have an optional one-to-many relationship, because every fault either happens during a trip or it doesn't. If I wanted to join them in SQL, I would write: select ... from Faults left outer join Trips on Faults.VehicleId = Trips.VehicleId and Faults.FaultTime between Trips.TripStartTime and Trips.TripEndTime and then I'd get a dataset where every fault appears exactly once (one-to-many as I said). Note that there is no Vehicles table, and I don't need one. But I did create a view that contains all VehicleIds from both tables, so I can use it as a junction table. What am I actually looking for? The tables are huge because they cover years of data, and every time I only need to fetch a range of a few hours. So I need a mapping and a criteria that will run something like the following SQL underneath: select ... from Faults left outer join Trips on Faults.VehicleId = Trips.VehicleId and Faults.FaultTime between Trips.TripStartTime and Trips.TripEndTime where Faults.FaultTime between :p0 and :p1 Do you have any ideas how to achieve it? Note 1: Currently the application shouldn't write to the database, so persistence is not a must, although if the mapping supports persistence, it may help at some point in the future. Note 2: I know it's a tough one, so if you give me a great answer, you will be properly rewarded :) Thank you for reading this long question, and now I only hope for the best :)

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• Evidence-Based-Scheduling - are estimations only as accurate as the work-plan they're based on?

  - by Assaf Lavie

  I've been using FogBugz's Evidence Based Scheduling (for the uninitiated, Joel explains) for a while now and there's an inherent problem I can't seem to work around. The system is good at telling me the probability that a given project will be delivered at some date, given the detailed list of tasks that comprise the project. However, it does not take into account the fact that during development additional tasks always pop up. Now, there's the garbage-can approach of creating a generic task/scheduled-item for "last minute hacks" or "integration tasks", or what have you, but that clearly goes against the idea of aggregating the estimates of many small cases. It's often the case that during the development stage of a project you realize that there's a whole area your planning didn't cover, because, well, that's the nature of developing stuff that hasn't been developed before. So now your ~3 month project may very well turn into a 6 month project, but not because your estimations were off (you could be the best estimator in the world, for those task the comprised your initial work plan); rather because you ended up adding a whole bunch of new tasks that weren't there to begin with. EBS doesn't help you with that. It could, theoretically (I guess). It could, perhaps, measure the amount of work you add to a project over time and take that into consideration when estimating the time remaining on a given project. Just a thought. In other words, EBS works on a task basis, but not on a project/release basis - but the latter is what's important. It's what your boss typically cares about - delivery date, not the time it takes to finish each task along the way, and not the time it would have taken, if your planning was perfect. So the question is (yes, there's a question here, don't close it): What's your methodology when it comes to using EBS in FogBugz and how do you solve the problem above, which seems to be a main cause of schedule delays and mispredictions? Edit Some more thoughts after reading a few answers: If it comes down to having to choose which delivery date you're comfortable presenting to your higher-ups by squinting at the delivery-probability graph and choosing 80%, or 95%, or 60% (based on what, exactly?) then we've resorted to plain old buffering/factoring of our estimates. In which case, couldn't we have skipped the meticulous case by case hour-sized estimation effort step? By forcing ourselves to break down tasks that take more than a day into smaller chunks of work haven't we just deluded ourselves into thinking our planning is as tight and thorough as it could be? People may be consistently bad estimators that do not even learn from their past mistakes. In that respect, having an EBS system is certainly better than not having one. But what can we do about the fact that we're not that good in planning as well? I'm not sure it's a problem that can be solved by a similar system. Our estimates are wrong because of tendencies to be overly optimistic/pessimistic about certain tasks, and because of neglect to account for systematic delays (e.g. sick days, major bug crisis) - and usually not because we lack knowledge about the work that needs to be done. Our planning, on the other hand, is often incomplete because we simply don't have enough knowledge in this early stage; and I don't see how an EBS-like system could fill that gap. So we're back to methodology. We need to find a way to accommodate bad or incomplete work plans that's better than voodoo-multiplication.

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• Issue with XSL Criteria

  - by Rachel

  I am using the below piece of XSL to select the id of the text nodes whose content has a given index. This index value in input will be relative to a spcified node whose id value is known. The criteria to select the text node is, The text node content should contain a index say 'i' relative to node say 'n' whose id value i know. 'i' and 'id of n' is got as index and nodeName from the input param as seen in the xsl. Node 'd1e5' has the text content whose index ranges from 1 to 33. When i give an index value greater than 33 i want the below criteria to fail but it does not, [sum((preceding::text(), .)[normalize-space()][. >> //*[@id=$nodeName]]/string-length(.)) ge $index] Input xml: <?xml version="1.0" encoding="UTF-8"?> <html xmlns="http://www.w3.org/1999/xhtml" id="d1e1"> <head id="d1e3"> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title id="d1e5">Every document must have a title</title> </head> <body id="d1e9"> <h1 id="d1e11" align="center">Very Important Heading</h1> <p id="d1e13">Since this is just a sample, I won't put much text here.</p> </body> </html> XSL code used: <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xsd="http://www.w3.org/2001/XMLSchema" exclude-result-prefixes="xsd" version="2.0"> <xsl:param name="insert-file" as="node()+"> <insert-data><data index="1" nodeName="d1e5"></data><data index="34" nodeName="d1e5"></data></insert-data> </xsl:param> <xsl:param name="nodeName" as="xsd:string" /> <xsl:variable name="main-root" as="document-node()" select="/"/> <xsl:variable name="insert-data" as="element(data)*"> <xsl:for-each select="$insert-file/insert-data/data"> <xsl:sort select="xsd:integer(@index)"/> <xsl:variable name="index" select="xsd:integer(@index)" /> <xsl:variable name="nodeName" select="@nodeName" /> <data text-id="{generate-id($main-root/descendant::text()[sum((preceding::text(), .)[normalize-space()][. >> //*[@id=$nodeName]]/string-length(.)) ge $index][1])}"> </data> </xsl:for-each> </xsl:variable> <xsl:template match="/"> <Output> <xsl:copy-of select="$insert-data" /> </Output> </xsl:template> </xsl:stylesheet> Actual output: <?xml version="1.0" encoding="UTF-8"?> <Output> <data text-id="d1t8"/> <data text-id="d1t14"/> </Output> Expected output: <?xml version="1.0" encoding="UTF-8"?> <Output> <data text-id="d1t8"/> </Output> This solution works fine if index lies between 1 and 33. Any index value greater that 33 causes incorrect text nodes to get selected. I could not understand why the text node 'd1t14' is getting selected. Please share your thoughts.

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• Javascript Closures - What are the negatives?

  - by vol7ron

  Question: There seem to be many benefits to Closures, but what are the negatives (memory leakage? obfuscation problems? bandwidth increasage?)? Additionally, is my understanding of Closures correct? Finally, once closures are created, can they be destroyed? I've been reading a little bit about Javascript Closures. I hope someone a little more knowledgeable will guide my assertions, correcting me where wrong. Benefits of Closures: Encapsulate the variables to a local scope, by using an internal function. The anonymity of the function is insignificant. What I've found helpful is to do some basic testing, regarding local/global scope: <script type="text/javascript"> var global_text = ""; var global_count = 0; var global_num1 = 10; var global_num2 = 20; var global_num3 = 30; function outerFunc() { var local_count = local_count || 0; alert("global_num1: " + global_num1); // global_num1: undefined var global_num1 = global_num1 || 0; alert("global_num1: " + global_num1); // global_num1: 0 alert("global_num2: " + global_num2); // global_num2: 20 global_num2 = global_num2 || 0; // (notice) no definition with 'var' alert("global_num2: " + global_num2); // global_num2: 20 global_num2 = 0; alert("local_count: " + local_count); // local_count: 0 function output() { global_num3++; alert("local_count: " + local_count + "\n" + "global_count: " + global_count + "\n" + "global_text: " + global_text ); local_count++; } local_count++; global_count++; return output; } var myFunc = outerFunc(); myFunc(); /* Outputs: ********************** * local_count: 1 * global_count: 1 * global_text: **********************/ global_text = "global"; myFunc(); /* Outputs: ********************** * local_count: 2 * global_count: 1 * global_text: global **********************/ var local_count = 100; myFunc(); /* Outputs: ********************** * local_count: 3 * global_count: 1 * global_text: global **********************/ alert("global_num1: " + global_num1); // global_num1: 10 alert("global_num2: " + global_num2); // global_num2: 0 alert("global_num3: " + global_num3); // global_num3: 33 </script> Interesting things I took out of it: The alerts in outerFunc are only called once, which is when the outerFunc call is assigned to myFunc (myFunc = outerFunc()). This assignment seems to keep the outerFunc open, in what I would like to call a persistent state. Everytime myFunc is called, the return is executed. In this case, the return is the internal function. Something really interesting is the localization that occurs when defining local variables. Notice the difference in the first alert between global_num1 and global_num2, even before the variable is trying to be created, global_num1 is considered undefined because the 'var' was used to signify a local variable to that function. -- This has been talked about before, in the order of operation for the Javascript engine, it's just nice to see this put to work. Globals can still be used, but local variables will override them. Notice before the third myFunc call, a global variable called local_count is created, but it as no effect on the internal function, which has a variable that goes by the same name. Conversely, each function call has the ability to modify global variables, as noticed by global_var3. Post Thoughts: Even though the code is straightforward, it is cluttered by alerts for you guys, so you can plug and play. I know there are other examples of closures, many of which use anonymous functions in combination with looping structures, but I think this is good for a 101-starter course to see the effects. The one thing I'm concerned with is the negative impact closures will have on memory. Because it keeps the function environment open, it is also keeping those variables stored in memory, which may/may not have performance implications, especially regarding DOM traversals and garbage collection. I'm also not sure what kind of role this will play in terms of memory leakage and I'm not sure if the closure can be removed from memory by a simple "delete myFunc;." Hope this helps someone, vol7ron

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• PostgreSQL - fetch the row which has the Max value for a column

  - by Joshua Berry

  I'm dealing with a Postgres table (called "lives") that contains records with columns for time_stamp, usr_id, transaction_id, and lives_remaining. I need a query that will give me the most recent lives_remaining total for each usr_id There are multiple users (distinct usr_id's) time_stamp is not a unique identifier: sometimes user events (one by row in the table) will occur with the same time_stamp. trans_id is unique only for very small time ranges: over time it repeats remaining_lives (for a given user) can both increase and decrease over time example: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 07:00 | 1 | 1 | 1 09:00 | 4 | 2 | 2 10:00 | 2 | 3 | 3 10:00 | 1 | 2 | 4 11:00 | 4 | 1 | 5 11:00 | 3 | 1 | 6 13:00 | 3 | 3 | 1 As I will need to access other columns of the row with the latest data for each given usr_id, I need a query that gives a result like this: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 11:00 | 3 | 1 | 6 10:00 | 1 | 2 | 4 13:00 | 3 | 3 | 1 As mentioned, each usr_id can gain or lose lives, and sometimes these timestamped events occur so close together that they have the same timestamp! Therefore this query won't work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp) AS max_timestamp FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp = b.time_stamp Instead, I need to use both time_stamp (first) and trans_id (second) to identify the correct row. I also then need to pass that information from the subquery to the main query that will provide the data for the other columns of the appropriate rows. This is the hacked up query that I've gotten to work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp || '*' || trans_id) AS max_timestamp_transid FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp_transid = b.time_stamp || '*' || b.trans_id ORDER BY b.usr_id Okay, so this works, but I don't like it. It requires a query within a query, a self join, and it seems to me that it could be much simpler by grabbing the row that MAX found to have the largest timestamp and trans_id. The table "lives" has tens of millions of rows to parse, so I'd like this query to be as fast and efficient as possible. I'm new to RDBM and Postgres in particular, so I know that I need to make effective use of the proper indexes. I'm a bit lost on how to optimize. I found a similar discussion here. Can I perform some type of Postgres equivalent to an Oracle analytic function? Any advice on accessing related column information used by an aggregate function (like MAX), creating indexes, and creating better queries would be much appreciated! P.S. You can use the following to create my example case: create TABLE lives (time_stamp timestamp, lives_remaining integer, usr_id integer, trans_id integer); insert into lives values ('2000-01-01 07:00', 1, 1, 1); insert into lives values ('2000-01-01 09:00', 4, 2, 2); insert into lives values ('2000-01-01 10:00', 2, 3, 3); insert into lives values ('2000-01-01 10:00', 1, 2, 4); insert into lives values ('2000-01-01 11:00', 4, 1, 5); insert into lives values ('2000-01-01 11:00', 3, 1, 6); insert into lives values ('2000-01-01 13:00', 3, 3, 1);

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