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• Installing Ubuntu before or after upgrading from Vista to Win 7?

  - by amh

  I just got a new SSD hard drive for my thinkpad laptop. I just installed Vista with the factory CDs. On my old OS, my main OS was Ubuntu but I do want to keep Windows on a separate partition as a dual booth system. I definitely want to upgrade to Win 7 though and I will get it in a few days. My question is: should I install Ubuntu now and then upgrade to Win 7 in a few days? or is that going to mess up with the grub (or something else)? If that is the case, then I'd rather wait to install Ubuntu until after I upgrade to Vista. P.S. I know that probably any kind of mess done by the Win upgrade could be fixed, but I just want to avoid wasting time.

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• How to separate and maintain customer specific code

  - by WYSIWYG

  I am implementing customer specific code and currently following simple approach like if (cusomterId == 23) do it. I want to separate out all the customer related code in separate place. But I have following problems. In code is in 1. Stored procs 2. Plain old classes. 3. Controllers 4. Views I came up with two solutions. First is to create table CustomerFunctionlity with columns CustomerId, FunctionalityName, method/Proc, inputs/outputs With this table I can simply check if exists, execute given function. Another way is creating a factory which returns customer related object for an interface. I am writting small end to end customer specific functionalities. How can I write maintenable code. Thanks

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• How do I recover my accidentally lost Windows partitions after installing Ubuntu?

  - by Totally newbie

  I have a Toshiba satellite A-200 laptop with a Vista OS on it with 4 NTFS partitions (C:) Vista (D:) Entertainment (E:) Work (F:) Sources and I wanted to start using Ubuntu instead. So I tried it first from the live CD and everything was OK and all the partitions were shown and working and so I decided to install Ubuntu to replace Vista on the (C:) drive. After I did that I can no longer find my folders and files on the (D:), (E:), (F:) partitions and the only file system that is shown is one 198 GB although my HDD is 320 GB. I can't access the lost data on the remaining 120 GB which I hope is still there and not totally lost I am now working from the live CD but I am unable to install testdisk. Can I recover the Vista partitions by the product recovery CD to get my laptop back to the factory settings? Can I recover the NTFS partitions using a recovery program for Windows or will that make the problem worse? I need these data badly as I don't have a backup for them.

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• Deleting a game object

  - by Balls

  I tried doing this but it cause an access violation. void GameObjectFactory::Update() { for( std::list<GameObject*>::iterator it=gameObjectList.begin() ..... (*it)->Update(); } void Bomb::Update() { if( time == 2.0f ) { gameObjectFactory->Remove( this ); } } void GameObjectFactory::Remove( ... ) { gameObjectList.remove( ... ); } My thoughts would be to mark the object to be dead then let the factory handle it the on next frame for deletion. Is it the best and fastest way? What do you think?

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• Legally, can I re reuse code for different customers?

  - by canice

  The company I work for develops custom factory automation applications for multiple customers. Even though each application is custom, they contain common code which is re-used across projects. One of the customers is now looking for the source code to their application, which has caused a major storm in the company. Management have decided that we can't give them the source to the shared components as they are used by other customers. I've been asked to modify the shared components 'enough' so as they aren't common. So my questions are: 1) Legally, should there be any problem with re-using common components for different customer? 2) If I really need to modify the common components, then how much is 'enough' ? (I know this sucks, but I either do this or hand in my notice). Oh yeah, and my company has no license in place with any of these customers.

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• Separating Db from business with Inherited classes using multiple views

  - by catalinux

  I have a software that has a car model that will be used in different views (listing, ads, detail page, carousel, up sell widget,etc). class CarModel extends DbModel{ } I look for a "nice way" (a combination of flexible, easy to maintain,etc) to have this used in views. I'm thinking at two different ways Having object views for each context CarViewBase{ var car;// of type CarModel function constructor(args){ //will instantienta internal variable car based on args } function getThumb(){ } function getTitle(){ } } CarListingView extends CarViewBase{ function getListing(){ } } CarAdsView extends CarViewBase{ //the busines rule changes for ads widget function getThumb(){ } } Extending directly the CarModel The challenges comes when My Car Model might need an abstract factory. Let's say I have a field on my car object that states the type of the car : a truck, or a bike, or van. How would affect that my object view? Let's say that getTitle() rule would be different for each type of it. How would you do it?

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• MVVM/Presentation Model With WinForms

  - by Erik Ashepa

  Hi, I'm currently working on a brownfield application, it's written with winforms, as a preparation to use WPF in a later version, out team plans to at least use the MVVM/Presentation model, and bind it against winforms... I've explored the subject, including the posts in this site (which i love very much), when boiled down, the main advantage of wpf are : binding controls to properties in xaml. binding commands to command objects in the viewmodel. the first feature is easy to implement (in code), or with a generic control binder, which binds all the controls in the form. the second feature is a little harder to implement, but if you inherit from all your controls and add a command property (which is triggered by an internal event such as click), which is binded to a command instance in the ViewModel. The challenges I'm currently aware of are : implementing a commandmanager, (which will trigger the CanInvoke method of the commands as necessery. winforms only supports one level of databinding : datasource, datamember, wpf is much more flexible. am i missing any other major features that winforms lacks in comparison with wpf, when attempting to implement this design pattern? i sure many of you will recommend some sort of MVP pattern, but MVVM/Presentation model is the way to go for me, because I'll want future WPF support. Thanks in advance, Erik.

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• Axis2 embedded in my web app is not working

  - by Shamik

  OKay I lost alsmost the whole day on this. I have a webapp where I would like to add AXIS2 and start working. I added AxisServlets in the web.xml file like - <servlet> <servlet-name>AxisServlet</servlet-name> <display-name>Apache-Axis Servlet</display-name> <servlet-class>org.apache.axis2.transport.http.AxisServlet</servlet-class> <load-on-startup>2</load-on-startup> </servlet> <servlet-mapping> <servlet-name>AxisServlet</servlet-name> <url-pattern>/services/*</url-pattern> </servlet-mapping> I also added Services.xml file like <service name="ReportViewerService"> <description> This is a sample Web Service for illustrating Attachments API of Axis2 </description> <parameter name="ServiceClass">myclass</parameter> <operation name="getReport"> <actionMapping>urn:getReport</actionMapping> <messageReceiver class="org.apache.axis2.rpc.receivers.RPCMessageReceiver"/> </operation> </service> The directory structure is as mentioned here WEB-ING | - conf | |- axis2.xml |-lib | |- all libs |-services |-ReportViewerService | - META-INF |-services.xml |- web.xml The problem is - after all of these, the service endpoint will not come, I can not see the WSDL file http://localhost:8080/BOReportingServer/services/ReportViewerService?wsdl -- this gives an exception like - Throwable occurred: javax.servlet.ServletException: File &quot;/axis2-web/listSingleService.jsp&quot; not found

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• Unknown Entity namespace alias in symfony2

  - by Zoha Ali Khan

  Hey I have two bundles in my symfony2 project. one is Bundle and the other one is PatentBundle. My app/config/route.yml file is MunichInnovationGroupPatentBundle: resource: "@MunichInnovationGroupPatentBundle/Controller/" type: annotation prefix: / defaults: { _controller: "MunichInnovationGroupPatentBundle:Default:index" } MunichInnovationGroupBundle: resource: "@MunichInnovationGroupBundle/Controller/" type: annotation prefix: /v1 defaults: { _controller: "MunichInnovationGroupBundle:Patent:index" } login_check: pattern: /login_check logout: pattern: /logout inside my controller i have <?php namespace MunichInnovationGroup\PatentBundle\Controller; use Symfony\Component\HttpFoundation\Response; use Symfony\Component\HttpFoundation\Request; use JMS\SecurityExtraPatentBundle\Annotation\Secure; use Symfony\Component\Security\Core\Exception\AccessDeniedException; use Symfony\Bundle\FrameworkBundle\Controller\Controller; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Template; use Symfony\Component\Security\Core\SecurityContext; use MunichInnovationGroup\PatentBundle\Entity\Log; use MunichInnovationGroup\PatentBundle\Entity\UserPatent; use MunichInnovationGroup\PatentBundle\Entity\PmPortfolios; use MunichInnovationGroup\PatentBundle\Entity\UmUsers; use MunichInnovationGroup\PatentBundle\Entity\PmPatentgroups; use MunichInnovationGroup\PatentBundle\Form\PortfolioType; use MunichInnovationGroup\PatentBundle\Util\SecurityHelper; use Exception; /** * Portfolio controller. * @Route("/portfolio") */ class PortfolioController extends Controller { /** * Index action. * * @Route("/", name="v2_pm_portfolio") * @Template("MunichInnovationGroupPatentBundle:Portfolio:index.html.twig") */ public function indexAction(Request $request) { $portfolios = $this->getDoctrine() ->getRepository('MunichInnovationGroupPatentBundle:PmPortfolios') ->findBy(array('user' => '$user_id')); // rest of the method } when i try to load localhost/web/app_dev.php/portfolio It says Unknown Entity namespace alias 'MunichInnovationGroupPatentBundle'. I am unable to figure out this error please help me if anyone has any idea I googled it a lot :( Thanks in advance 500 Internal Server Error - ORMException

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• MVC: Nested Views, and Controllers (for a website)

  - by incrediman

  I'm doing a PHP website using the MVC pattern. I am not using a framework as the site is fairly simple and I feel that this will give me a good opportunity to learn about the pattern directly. I have a couple questions. Question 1: How should I organize my views? I'm thinking of having a Page view which will have the header and footer, and which will allow for a Content view to be nested between them. Question 2: If I have 5 Content pages, should I make 5 different views that can be used as the content that is nested within the Page view? Or, should I make them all extend an abstract view called AbstractContent? Question 3: What about controllers? I think there should be one main controller at least. But then where does the request go from there? To another controller? Or should I just call the Page view and leave it at that? I thought that controllers were supposed to handle input, possibly modify a model, and select a view. But what if one of the views nested within the view that a controller calls requires additional input to be parsed? Question 4: Are controllers allowed to pass parameters into the view? Or should the controller simply modify the model, which will then affect the view? Or is the model only for DB access and other such things?

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• Code Golf: Code 39 Bar Code

  - by gwell

  The challenge The shortest code by character count to draw an ASCII representation of a Code 39 bar code. Wikipedia article about Code 39: http://en.wikipedia.org/wiki/Code_39 Input The input will be a string of legal characters for Code 39 bar codes. This means 43 characters are valid: 0-9 A-Z (space) and -.$/+%. The * character will not appear in the input as it is used as the start and stop characters. Output Each character encoded in Code 39 bar codes have nine elements, five bars and four spaces. Bars will be represented with # characters, and spaces will be represented with the space character. Three of the nine elements will be wide. The narrow elements will be one character wide, and the wide elements will be three characters wide. A inter-character space of a single space should be added between each character pattern. The pattern should be repeated so that the height of the bar code is eight characters high. The start/stop character * (bWbwBwBwb) would be represented like this: # # ### ### # # # ### ### # # # ### ### # # # ### ### # # # ### ### # # # ### ### # # # ### ### # # # ### ### # ^ ^ ^^ ^ ^ ^ ^^^ | | || | | | ||| narrow bar -+ | || | | | ||| wide space ---+ || | | | ||| narrow bar -----+| | | | ||| narrow space ------+ | | | ||| wide bar --------+ | | ||| narrow space ----------+ | ||| wide bar ------------+ ||| narrow space --------------+|| narrow bar ---------------+| inter-character space ----------------+ The start and stop character * will need to be output at the start and end of the bar code. No quiet space will need to be included before or after the bar code. No check digit will need to be calculated. Full ASCII Code39 encoding is not required, just the standard 43 characters. No text needs to be printed below the ASCII bar code representation to identify the output contents. The character # can be replaced with another character of higher density if wanted. Using the full block character U+2588, would allow the bar code to actually scan when printed. Test cases Input: ABC Output: # # ### ### # ### # # # ### # ### # # ### ### ### # # # # # ### ### # # # ### ### # ### # # # ### # ### # # ### ### ### # # # # # ### ### # # # ### ### # ### # # # ### # ### # # ### ### ### # # # # # ### ### # # # ### ### # ### # # # ### # ### # # ### ### ### # # # # # ### ### # # # ### ### # ### # # # ### # ### # # ### ### ### # # # # # ### ### # # # ### ### # ### # # # ### # ### # # ### ### ### # # # # # ### ### # # # ### ### # ### # # # ### # ### # # ### ### ### # # # # # ### ### # # # ### ### # ### # # # ### # ### # # ### ### ### # # # # # ### ### # Input: 1/3 Output: # # ### ### # ### # # # ### # # # # # ### ### # # # # # ### ### # # # ### ### # ### # # # ### # # # # # ### ### # # # # # ### ### # # # ### ### # ### # # # ### # # # # # ### ### # # # # # ### ### # # # ### ### # ### # # # ### # # # # # ### ### # # # # # ### ### # # # ### ### # ### # # # ### # # # # # ### ### # # # # # ### ### # # # ### ### # ### # # # ### # # # # # ### ### # # # # # ### ### # # # ### ### # ### # # # ### # # # # # ### ### # # # # # ### ### # # # ### ### # ### # # # ### # # # # # ### ### # # # # # ### ### # Input: - $ (minus space dollar) Output: # # ### ### # # # # ### ### # ### # ### # # # # # # # # ### ### # # # ### ### # # # # ### ### # ### # ### # # # # # # # # ### ### # # # ### ### # # # # ### ### # ### # ### # # # # # # # # ### ### # # # ### ### # # # # ### ### # ### # ### # # # # # # # # ### ### # # # ### ### # # # # ### ### # ### # ### # # # # # # # # ### ### # # # ### ### # # # # ### ### # ### # ### # # # # # # # # ### ### # # # ### ### # # # # ### ### # ### # ### # # # # # # # # ### ### # # # ### ### # # # # ### ### # ### # ### # # # # # # # # ### ### # Code count includes input/output (full program).

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• How do I configure CI hudson with PHPunit and how do I run phpunit using hudson?

  - by Vinesh

  Hi, I am getting following error mentioned below. Help is much needed for this... kindly go through the errors. Started by an SCM change Updating https://suppliesguys.unfuddle.com/svn/suppliesguys_frontend2/Frontend-Texity/src U sites\all\modules\print\print_pdf\print_pdf.pages.inc At revision 1134 [workspace] $ sh -xe C:\WINDOWS\TEMP\hudson6292587174545072503.sh The system cannot find the file specified FATAL: command execution failed java.io.IOException: Cannot run program "sh" (in directory "E:\Projects\Hudson.hudson\jobs\TSG\workspace"): CreateProcess error=2, The system cannot find the file specified at java.lang.ProcessBuilder.start(Unknown Source) at hudson.Proc$LocalProc.(Proc.java:149) at hudson.Proc$LocalProc.(Proc.java:121) at hudson.Launcher$LocalLauncher.launch(Launcher.java:636) at hudson.Launcher$ProcStarter.start(Launcher.java:271) at hudson.Launcher$ProcStarter.join(Launcher.java:278) at hudson.tasks.CommandInterpreter.perform(CommandInterpreter.java:83) at hudson.tasks.CommandInterpreter.perform(CommandInterpreter.java:58) at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:19) at hudson.model.AbstractBuild$AbstractRunner.perform(AbstractBuild.java:584) at hudson.model.Build$RunnerImpl.build(Build.java:174) at hudson.model.Build$RunnerImpl.doRun(Build.java:138) at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:416) at hudson.model.Run.run(Run.java:1244) at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46) at hudson.model.ResourceController.execute(ResourceController.java:88) at hudson.model.Executor.run(Executor.java:122) Caused by: java.io.IOException: CreateProcess error=2, The system cannot find the file specified at java.lang.ProcessImpl.create(Native Method) at java.lang.ProcessImpl.(Unknown Source) at java.lang.ProcessImpl.start(Unknown Source) ... 17 more Publishing Javadoc Publishing Clover coverage report... No Clover report will be published due to a Build Failure [xUnit] Starting to record. [xUnit] [PHPUnit] - Use the embedded style sheet. [xUnit] [ERROR] - No test report file(s) were found with the pattern 'build/logs/phpunit.xml' relative to 'E:\Projects\Hudson.hudson\jobs\TSG\workspace' for the testing framework 'PHPUnit'. Did you enter a pattern relative to the correct directory? Did you generate the result report(s) for 'PHPUnit'? [xUnit] Stopping recording. Finished: FAILURE

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• log4j:WARN No appenders could be found for logger in web.xml

  - by cometta

  I already put the log4jConfigLocation in web.xml, but still, i get warning log4j:WARN No appenders could be found for logger (org.springframework.web.context.ContextLoader). log4j:WARN Please initialize the log4j system properly. what did i missed out? <context-param> <param-name>contextConfigLocation</param-name> <param-value> /WEB-INF/applicationContext.xml </param-value> </context-param> <context-param> <param-name>log4jConfigLocation</param-name> <param-value>/WEB-INF/classes/log4j.properties</param-value> </context-param> <listener> <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class> </listener> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <servlet> <servlet-name>suara2</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>suara2</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping>

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• Configuring xUnit test output in Hudson

  - by graham.reeds

  I have a simple PoC project in Hudson. The PoC has unit tests written via UnitTest++ and outputs the results as XML for consumption by xUnit to munge into jUnit format. Here are the salient relevant I have my project configured to use MSBuild to build the 2008 solution. The project contains both the dll it is to build and the unit tests which are run as a post-build step. My workspace in Hudson is set to c:\develop\money (Money is the name of the project) and in the Hudson console I can see the workspace folders, the solution file and output folders (/bin, /doc, etc). The test console app outputs its file 'money_unit_tests.xml' to the folder 'reports' (making c:\develop\money\reports). I've restarted Hudson since installing xUnit and setting the workspace. However when I start Hudson building I am given the following message: [xUnit] Starting to record. [xUnit] [UnitTest] - Use the embedded style sheet. [xUnit] [ERROR] - No test report file(s) were found with the pattern 'reports/money_unit_tests.xml' relative to 'C:\.hudson\jobs\Money\workspace' for the testing framework 'UnitTest'. Did you enter a pattern relative to the correct directory? Did you generate the result report(s) for 'UnitTest'? [xUnit] Stopping recording. Finished: FAILURE Why does Hudson seem to think the workspace is in C:.hudson... and not C:\Develop...? What can I do change it? If I can't change it, what can I do to mitigate these changes? (I don't exactly want to hardcode the output for the xml to C:.hudson...)

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• How to let Tomcat publish WSDL for the WS it provides (CXF 2.2, Spring 3, Tomcat6)

  - by Zwei Steinen

  Hi, I am trying to implement a simple web service provider using Tomcat6, CXF 2.2, Spring 3, and actually the service itself runs fine (I can call web methods using the original WSDL and SoapUI). However, Tomcat returns a blank page on "?wsdl" requests. Also, when I try to manipulate the (would-be) published WSDL by adding a publishedEndpointURL property to the jaxws:endpoint element, Tomcat will issue a XML parse exception (something like property publishedEndpointURL is not allowed in element jaxws:endpoint) <jaxws:endpoint id="service" implementor="org.sample.ServiceImpl" implementorClass="org.sample.ServiceImpl" address="/service" publishedEndpointURL="http://localhost:8080/MyService/service"> I used "contract first" style. EDIT: What I did so far: Setup tomcat6 with Spring3 Generate CXF implementation class by using maven Provide web.xml (only relevant part shown) <listener> <listener-class>org.springframework.web.context.ContextLoaderListener </listener-class> </listener> <servlet> <servlet-name>cxf</servlet-name> <servlet-class> org.apache.cxf.transport.servlet.CXFServlet </servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>cxf</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping> Provide applicationContext.xml (only relevant part is shown) Package generated stuff into war and deploy

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• Is HttpContextWrapper all that....useful?

  - by bakasan

  I've been going through the process of cleaning up our controller code to make each action as testable. Generally speaking, this hasn't been too difficult--where we have opportunity to use a fixed object, like say FormsAuthentication, we generally introduce some form of wrapper as appropriate and be on our merry way. For reasons not particularly germaine to this conversation, when it came to dealing with usage of HttpContext, we decided to use the newly created HttpContextWrapper class rather than inventing something homegrown. One thing we did introduce was the ability to swap in a HttpContextWrapper (like say, for unit testing). This was wholly inspired by the way Oren Eini handles unit testing with DateTimes (see article, a pattern we also use) public static class FooHttpContext { public static Func<HttpContextWrapper> Current = () => new HttpContextWrapper(HttpContext.Current); public static void Reset() { Current = () => new HttpContextWrapper(HttpContext.Current); } } Nothing particularly fancy. And it works just fine in our controller code. The kicker came when we go to write unit tests. We're using Moq as our mocking framework, but alas var context = new Mock<HttpContextWrapper>() breaks since HttpContextWrapper doesn't have a parameterless ctor. And what does it take as a ctor parameter? A HttpContext object. So I find myself in a catch 22. I'm using the prescribed way to decouple HttpContext--but I can't mock a value in because the original HttpContext object was sealed and therefore difficult to test. I can map HttpContextBase, which both derive from--but that doesn't really get me what I'm after. Am I just missing the point somewhere with regard to HttpContextWrapper? I can find ways to work around the issue, but we are kind of fond of remaining consistent in decoupling using the Function delegate pattern--but it seems like we're not fully grokking intent of the wrapper.

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• Websphere 7 simple realm (like tomcat-users.xml)

  - by Heavy Bytes

  I am trying to port a J2EE app from Tomcat to Websphere and I'm not too familiar with Websphere. The only problem I am having is authorization (I use basic-authentication in my web.xml). In Tomcat I use the tomcat-users.xml file to define my users/passwords and to what roles they belong. How do I do this "simply" in Websphere? When deploying the EAR to Websphere it also asks me to map my role from web.xml to a user or group. Do I have to set up some sort of realm? Custom user registry? Thanks. UPDATE: I configured a Standalone custom registry, however I can't get a log-in prompt for username/password. It works just fine in Tomcat, and it doesn't in Websphere. Code from web.xml <security-constraint> <web-resource-collection> <web-resource-name>basic-auth security</web-resource-name> <url-pattern>/*</url-pattern> </web-resource-collection> <auth-constraint> <role-name>HELLO_USER</role-name> </auth-constraint> <user-data-constraint>NONE</user-data-constraint> </security-constraint> <login-config> <auth-method>BASIC</auth-method> </login-config> <security-role> <role-name>HELLO_USER</role-name> </security-role>

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• jax-ws on glassfish3 init method

  - by Alex

  Hi all, I've created simple jax-ws (anotated Java 6 class to web service) service and deploied it on glassfish v3. The web.xml <?xml version="1.0" encoding="ISO-8859-1"?> <web-app> <servlet> <servlet-name>MyServiceName</servlet-name> <description>Blablabla</description> <servlet-class>com.foo-bar.somepackage.TheService</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>MyServiceName</servlet-name> <url-pattern>/MyServiceName</url-pattern> </servlet-mapping> <session-config> <session-timeout>30</session-timeout> </session-config> </web-app> There is no sun-jaxws.xml in the war. The service works fine but I have 2 issues: I'm using apache common configuration package to read my configuration, so i have init function that calls configuration stuff. 1. How can I configure init method for jaxws service (like i can do for the servlets for example) 2. the load on startup parameter is not affecting the service, I see that for every request init function called again (and c-tor). How can I set scope for my service? Thanks a lot,

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• Atomic UPSERT in SQL Server 2005

  - by rabidpebble

  What is the correct pattern for doing an atomic "UPSERT" (UPDATE where exists, INSERT otherwise) in SQL Server 2005? I see a lot of code on SO (e.g. see http://stackoverflow.com/questions/639854/tsql-check-if-a-row-exists-otherwise-insert) with the following two-part pattern: UPDATE ... FROM ... WHERE <condition> -- race condition risk here IF @@ROWCOUNT = 0 INSERT ... or IF (SELECT COUNT(*) FROM ... WHERE <condition>) = 0 -- race condition risk here INSERT ... ELSE UPDATE ... where will be an evaluation of natural keys. None of the above approaches seem to deal well with concurrency. If I cannot have two rows with the same natural key, it seems like all of the above risk inserting rows with the same natural keys in race condition scenarios. I have been using the following approach but I'm surprised not to see it anywhere in people's responses so I'm wondering what is wrong with it: INSERT INTO <table> SELECT <natural keys>, <other stuff...> FROM <table> WHERE NOT EXISTS -- race condition risk here? ( SELECT 1 FROM <table> WHERE <natural keys> ) UPDATE ... WHERE <natural keys> (Note: I'm assuming that rows will not be deleted from this table. Although it would be nice to discuss how to handle the case where they can be deleted -- are transactions the only option? Which level of isolation?) Is this atomic? I can't locate where this would be documented in SQL Server documentation.

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• Improving long-polling Ajax performance

  - by Bears will eat you

  I'm writing a webapp (Firefox-compatible only) which uses long polling (via jQuery's ajax abilities) to send more-or-less constant updates from the server to the client. I'm concerned about the effects of leaving this running for long periods of time, say, all day or overnight. The basic code skeleton is this: function processResults(xml) { // do stuff with the xml from the server } function fetch() { setTimeout(function () { $.ajax({ type: 'GET', url: 'foo/bar/baz', dataType: 'xml', success: function (xml) { processResults(xml); fetch(); }, error: function (xhr, type, exception) { if (xhr.status === 0) { console.log('XMLHttpRequest cancelled'); } else { console.debug(xhr); fetch(); } } }); }, 500); } (The half-second "sleep" is so that the client doesn't hammer the server if the updates are coming back to the client quickly - which they usually are.) After leaving this running overnight, it tends to make Firefox crawl. I'd been thinking that this could be partially caused by a large stack depth since I've basically written an infinitely recursive function. However, if I use Firebug and throw a breakpoint into fetch, it looks like this is not the case. The stack that Firebug shows me is only about 4 or 5 frames deep, even after an hour. One of the solutions I'm considering is changing my recursive function to an iterative one, but I can't figure out how I would insert the delay in between Ajax requests without spinning. I've looked at the JS 1.7 "yield" keyword but I can't quite wrap my head around it, to figure out if it's what I need here. Is the best solution just to do a hard refresh on the page periodically, say, once every hour? Is there a better/leaner long-polling design pattern that won't put a hurt on the browser even after running for 8 or 12 hours? Or should I just skip the long polling altogether and use a different "constant update" pattern since I usually know how frequently the server will have a response for me?

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• Design Patterns Recommendation for Filtering Option

  - by Tarik

  Hi people, I am thinking to create a filter object which filters and delete everything like html tags from a context. But I want it to be independent which means the design pattern I can apply will help me to add more filters in the future without effecting the current codes. I thought Abstract Factory but it seems it ain't gonna work out the way I want. So maybe builder but it looks same. I don't know I am kinda confused, some one please recommend me a design pattern which can solve my problem but before that let me elaborate the problem a little bit. Lets say I have a class which has Description field or property what ever. And I need filters which remove the things I want from this Description property. So whenever I apply the filter I can add more filter in underlying tier. So instead of re-touching the Description field, I can easily add more filters and all the filters will run for Description field and delete whatever they are supposed to delete from the Description context. I hope I could describe my problem. I think some of you ran into the same situation before. Thanks in advance...

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• Sync Vs. Async Sockets Performance in C#

  - by Michael Covelli

  Everything that I read about sockets in .NET says that the asynchronous pattern gives better performance (especially with the new SocketAsyncEventArgs which saves on the allocation). I think this makes sense if we're talking about a server with many client connections where its not possible to allocate one thread per connection. Then I can see the advantage of using the ThreadPool threads and getting async callbacks on them. But in my app, I'm the client and I just need to listen to one server sending market tick data over one tcp connection. Right now, I create a single thread, set the priority to Highest, and call Socket.Receive() with it. My thread blocks on this call and wakes up once new data arrives. If I were to switch this to an async pattern so that I get a callback when there's new data, I see two issues The threadpool threads will have default priority so it seems they will be strictly worse than my own thread which has Highest priority. I'll still have to send everything through a single thread at some point. Say that I get N callbacks at almost the same time on N different threadpool threads notifying me that there's new data. The N byte arrays that they deliver can't be processed on the threadpool threads because there's no guarantee that they represent N unique market data messages because TCP is stream based. I'll have to lock and put the bytes into an array anyway and signal some other thread that can process what's in the array. So I'm not sure what having N threadpool threads is buying me. Am I thinking about this wrong? Is there a reason to use the Async patter in my specific case of one client connected to one server?

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• Async.Parallel or Array.Parallel.Map ?

  - by gurteen2

  Hello- I'm trying to implement a pattern I read from Don Syme's blog (http://blogs.msdn.com/dsyme/archive/2010/01/09/async-and-parallel-design-patterns-in-f-parallelizing-cpu-and-i-o-computations.aspx) which suggests that there are opportunities for massive performance improvements from leveraging asynchronous I/O. I am currently trying to take a piece of code that "works" one way, using Array.Parallel.Map, and see if I can somehow achieve the same result using Async.Parallel, but I really don't understand Async.Parallel, and cannot get anything to work. I have a piece of code (simplified below to illustrate the point) that successfully retrieves an array of data for one cusip. (A price series, for example) let getStockData cusip = let D = DataProvider() let arr = D.GetPriceSeries(cusip) return arr let data = Array.Parallel.map (fun x -> getStockData x) stockCusips So this approach contructs an array of arrays, by making a connection over the internet to my data vendor for each stock (which could be as many as 3000) and returns me an array of arrays (1 per stock, with a price series for each one). I admittedly don't understand what goes on underneath Array.Parallel.map, but am wondering if this is a scenario where there are resources wasted under the hood, and it actually could be faster using asynchronous I/O? So to test this out, I have attempted to make this function using asyncs, and I think that the function below follows the pattern in Don Syme's article using the URLs, but it won't compile with "let!". let getStockDataAsync cusip = async { let D = DataProvider() let! arr = D.GetData(cusip) return arr } The error I get is: This expression was expected to have type Async<'a but here has type obj It compiles fine with "let" instead of "let!", but I had thought the whole point was that you need the exclamation point in order for the command to run without blocking a thread. So the first question really is, what's wrong with my syntax above, in getStockDataAsync, and then at a higher level, can anyone offer some additional insight about asychronous I/O and whether the scenario I have presented would benefit from it, making it potentially much, much faster than Array.Parallel.map? Thanks so much.

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• How to roll the log file on startup in logback

  - by Mike Q

  Hi all, I would like to configure logback to do the following. Log to a file Roll the file when it reaches 50MB Only keep 7 days worth of logs On startup always generate a new file (do a roll) I have it all working except for the last item, startup roll. Does anyone know how to achieve that? Here's the config... <appender name="File" class="ch.qos.logback.core.rolling.RollingFileAppender"> <layout class="ch.qos.logback.classic.PatternLayout"> <Pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg \(%file:%line\)%n</Pattern> </layout> <File>server.log</File> <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"> <FileNamePattern>server.%d{yyyy-MM-dd}.log</FileNamePattern> <!-- keep 7 days' worth of history --> <MaxHistory>7</MaxHistory> <TimeBasedFileNamingAndTriggeringPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP"> <MaxFileSize>50MB</MaxFileSize> </TimeBasedFileNamingAndTriggeringPolicy> </rollingPolicy> </appender>

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• Help needed implementing a web based file management system with a file hierarchy system, help neede

  - by molleman

  Hello i am trying to create a web application that will allow users to upload files online, i am using gwt while using hibernate for database communication, i am able to upload file to a server , and store them on the server. but what i want is to associate the files with a user. i want the user to be able to create folders and store a file in sub folders. my logic was to use the composite pattern to store folders and fileLocations with a user but i am am finding it difficult to implement this so i can show the files and folders within a gwt tree. what would be the best way to implement a hierarchy of folders and information of the location of a file so it could be displayed in a gwt tree? what i did have was a User would hold a reference to a root folder and then each sub folder could hold folders or fileLocations. i used the composite pattern to implement the file hierarchy, but when i want to display a the contents of a folder i need a for loop for each list. so i could a folder within a folder within a folder that would need 3 for loops to show the contents of my folders. What is the best way to implement this file management system. so what do you guys think?

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