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  • Reading same file from multiple threads in C#

    - by Gustavo Rubio
    Hi. I was googling for some advise about this and I found some links. The most obvious was this one but in the end what im wondering is how well my code is implemented. I have basically two classes. One is the Converter and the other is ConverterThread I create an instance of this Converter class that has a property ThreadNumber that tells me how many threads should be run at the same time (this is read from user) since this application will be used on multi-cpu systems (physically, like 8 cpu) so it is suppossed that this will speed up the import The Converter instance reads a file that can range from 100mb to 800mb and each line of this file is a tab-delimitted value record that is imported to another destination like a database. The ConverterThread class simply runs inside the thread (new Thread(ConverterThread.StartThread)) and has event notification so when its work is done it can notify the Converter class and then I can sum up the progress for all these threads and notify the user (in the GUI for example) about how many of these records have been imported and how many bytes have been read. It seems, however that I'm having some trouble because I get random errors about the file not being able to be read or that the sum of the progress (percentage) went above 100% which is not possible and I think that happens because threads are not being well managed and probably the information returned by the event is malformed (since it "travels" from one thread to another) Do you have any advise on better practices of implementation of threads so I can accomplish this? Thanks in advance.

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  • To have efficient many-to-many relation in Java

    - by Masi
    How can you make the efficient many-to-many -relation from fileID to Words and from word to fileIDs without database -tools like Postgres in Java? I have the following classes. The relation from fileID to words is cheap, but not the reverse, since I need three for -loops for it. My solution is not apparently efficient. Other options may be to create an extra class that have word as an ID with the ArrayList of fileIDs. Reply to JacobM's answer The relevant part of MyFile's constructors is: /** * Synopsis of data in wordToWordConutInFile.txt: * fileID|wordID|wordCount * * Synopsis of the data in the file wordToWordID.txt: * word|wordID **/ /** * Getting words by getting first wordIDs from wordToWordCountInFile.txt and then words in wordToWordID.txt. */ InputStream in2 = new FileInputStream("/home/dev/wordToWordCountInFile.txt"); BufferedReader fi2 = new BufferedReader(new InputStreamReader(in2)); ArrayList<Integer> wordIDs = new ArrayList<Integer>(); String line = null; while ((line = fi2.readLine()) != null) { if ((new Integer(line.split("|")[0]) == currentFileID)) { wordIDs.add(new Integer(line.split("|")[6])); } } in2.close(); // Getting now the words by wordIDs. InputStream in3 = new FileInputStream("/home/dev/wordToWordID.txt"); BufferedReader fi3 = new BufferedReader(new InputStreamReader(in3)); line = null; while ((line = fi3.readLine()) != null) { for (Integer wordID : wordIDs) { if (wordID == (new Integer(line.split("|")[1]))) { this.words.add(new Word(new String(line.split("|")[0]), fileID)); break; } } } in3.close(); this.words.addAll(words); The constructor of Word is at the paste.

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  • Silverlight Async Design Pattern Issue

    - by Mike Mengell
    I'm in the middle of a Silverlight application and I have a function which needs to call a webservice and using the result complete the rest of the function. My issue is that I would have normally done a synchronous web service call got the result and using that carried on with the function. As Silverlight doesn't support synchronous web service calls without additional custom classes to mimic it, I figure it would be best to go with the flow of async rather than fight it. So my question relates around whats the best design pattern for working with async calls in program flow. In the following example I want to use the myFunction TypeId parameter depending on the return value of the web service call. But I don't want to call the web service until this function is called. How can I alter my code design to allow for the async call? string _myPath; bool myFunction(Guid TypeId) { WS_WebService1.WS_WebService1SoapClient proxy = new WS_WebService1.WS_WebService1SoapClient(); proxy.GetPathByTypeIdCompleted += new System.EventHandler<WS_WebService1.GetPathByTypeIdCompleted>(proxy_GetPathByTypeIdCompleted); proxy.GetPathByTypeIdAsync(TypeId); // Get return value if (myPath == "\\Server1") { //Use the TypeId parameter in here } } void proxy_GetPathByTypeIdCompleted(object sender, WS_WebService1.GetPathByTypeIdCompletedEventArgs e) { string server = e.Result.Server; myPath = '\\' + server; } Thanks in advance, Mike

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  • Best way to get a single value from a DataTable?

    - by PiersMyers
    I have a number of static classes that contain tables like this: using System; using System.Data; using System.Globalization; public static class TableFoo { private static readonly DataTable ItemTable; static TableFoo() { ItemTable = new DataTable("TableFoo") { Locale = CultureInfo.InvariantCulture }; ItemTable.Columns.Add("Id", typeof(int)); ItemTable.Columns["Id"].Unique = true; ItemTable.Columns.Add("Description", typeof(string)); ItemTable.Columns.Add("Data1", typeof(int)); ItemTable.Columns.Add("Data2", typeof(double)); ItemTable.Rows.Add(0, "Item 1", 1, 1.0); ItemTable.Rows.Add(1, "Item 2", 1, 1.0); ItemTable.Rows.Add(2, "Item 3", 2, 0.75); ItemTable.Rows.Add(3, "Item 4", 4, 0.25); ItemTable.Rows.Add(4, "Item 5", 1, 1.0); } public static DataTable GetItemTable() { return ItemTable; } public static int Data1(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (int)dr[0]["Data1"]; } public static double Data2(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (double)dr[0]["Data2"]; } } Is there a better way of writing the Data1 or Data2 methods that return a single value from a single row that matches the given id?

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  • What is likely cause of Android runtime exception "No suitable Log implementation" related to loggin

    - by M.Bearden
    I am creating an Android app that includes a third party jar. That third party jar utilizes internal logging that is failing to initialize when I run the app, with this error: "org.apache.commons.logging.LogConfigurationException: No suitable Log implementation". The 3rd party jar appears to be using org.apache.commons.logging and to depend on log4j, specifically log4j-1.2.14.jar. I have packaged the log4j jar into the Android app. The third party jar was packaged with a log4j.xml configuration file, which I have tried packaging into the app as an XML resource (and also as a raw resource). The "No suitable Log implementation" error message is not very descriptive, and I have no immediate familiarity with Java logging. So I am looking for likely causes of the problem (what class or configuration resources might I be missing?) or for some debugging technique that will result in a different error message that is more explicit about the problem. I do not have access to source code for the 3rd party jar. Here is the exception stack trace. When I run the app, I get the following exception as soon as one of the third party jar classes attempts to initialize its internal logging. DEBUG/AndroidRuntime(15694): Shutting down VM WARN/dalvikvm(15694): threadid=3: thread exiting with uncaught exception (group=0x4001b180) ERROR/AndroidRuntime(15694): Uncaught handler: thread main exiting due to uncaught exception ERROR/AndroidRuntime(15694): java.lang.ExceptionInInitializerError ERROR/AndroidRuntime(15694): Caused by: org.apache.commons.logging.LogConfigurationException: No suitable Log implementation ERROR/AndroidRuntime(15694): at org.apache.commons.logging.impl.LogFactoryImpl.discoverLogImplementation(LogFactoryImpl.java:842) ERROR/AndroidRuntime(15694): at org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.java:601) ERROR/AndroidRuntime(15694): at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:333) ERROR/AndroidRuntime(15694): at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:307) ERROR/AndroidRuntime(15694): at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:645) ERROR/AndroidRuntime(15694): at org.apache.commons.configuration.ConfigurationFactory.<clinit>(ConfigurationFactory.java:77)

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  • JAAS + authentification from database

    - by AhmedDrira
    i am traying to performe an authentification from data base using JAAS i v configured the login-config.xml like this <application-policy name="e-procurment_domaine"> <authentication> <login-module code="org.jboss.security.auth.spi.DatabaseServerLoginModule" flag="required"> <module-option name = "dsJndiName">BasepfeDS</module-option> <module-option name="securityDomain">java:/jaas/e-procurment_domaine</module-option> <module-option name="principalsQuery">SELECT pass FROM personne WHERE login=?</module-option> <module-option name="rolesQuery">SELECT disc FROM personne WHERE login=?</module-option> </login-module> </authentication> </application-policy> and I've written a test : this one @Test public void testFindALL() { System.out.println("Debut test de la méthode findALL"); // WebAuthentication wa=new WebAuthentication(); // wa.login("zahrat", "zahrat"); securityClient.setSimple("zahrat", "zahrat"); try { securityClient.login(); } catch (LoginException e) { // TODO Auto-generated catch block e.printStackTrace(); } Acheteur acheteur = new Acheteur(); System.out.println("" + acheteurRemote.findAll().size()); // } catch (EJBAccessException ex) { // System.out.println("Erreur attendue de type EJBAccessException: " // + ex.getMessage()); // } catch (Exception ex) { // ex.printStackTrace(); // fail("Exception pendant le test find ALL"); System.out.println("Fin test find ALL");} // } the test is fail i dont know why , but when i change the polycy with the methode of .property file it works .. i am using the annotation on the session BEAN classes @SecurityDomain("e-procurment_domaine") @DeclareRoles({"acheteur","vendeur","physique"}) @RolesAllowed({"acheteur","vendeur","physique"}) and the annotation on the session for the methode @RolesAllowed("physique") @Override public List<Acheteur> findAll() { log.debug("fetching all Acheteur"); return daoGenerique.findWithNamedQuery("Acheteur.findAll"); } i think that the test have an acess to my data base doe's it need mysql DRIVER or a special config on JBOSS?

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  • backbone.js Model.get() returns undefined, scope using coffeescript + coffee toaster?

    - by benipsen
    I'm writing an app using coffeescript with coffee toaster (an awesome NPM module for stitching) that builds my app.js file. Lots of my application classes and templates require info about the current user so I have an instance of class User (extends Backbone.Model) stored as a property of my main Application class (extends Backbone.Router). As part of the initialization routine I grab the user from the server (which takes care of authentication, roles, account switching etc.). Here's that coffeescript: @user = new models.User @user.fetch() console.log(@user) console.log(@user.get('email')) The first logging statement outputs the correct Backbone.Model attributes object in the console just as it should: User _changing: false _escapedAttributes: Object _pending: Object _previousAttributes: Object _silent: Object attributes: Object account: Object created_on: "1983-12-13 00:00:00" email: "[email protected]" icon: "0" id: "1" last_login: "2012-06-07 02:31:38" name: "Ben Ipsen" roles: Object __proto__: Object changed: Object cid: "c0" id: "1" __proto__: ctor app.js:228 However, the second returns undefined despite the model attributes clearly being there in the console when logged. And just to make things even more interesting, typing "window.app.user.get('email')" into the console manually returns the expected value of "[email protected]"... ? Just for reference, here's how the initialize method compiles into my app.js file: Application.prototype.initialize = function() { var isMobile; isMobile = navigator.userAgent.match(/(iPhone|iPod|iPad|Android|BlackBerry)/); this.helpers = new views.DOMHelpers().initialize().setup_viewport(isMobile); this.user = new models.User(); this.user.fetch(); console.log(this.user); console.log(this.user.get('email')); return this; }; I initialize the Application controller in my static HTML like so: jQuery(document).ready(function(){ window.app = new controllers.Application(); }); Suggestions please and thank you!

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  • PHP: tips/resources/patterns for learning to implement a basic ORM

    - by BoltClock
    I've seen various MVC frameworks as well as standalone ORM frameworks for PHP, as well as other ORM questions here; however, most of the questions ask for existing frameworks to get started with, which is not what I'm looking for. (I have also read this SO question but I'm not sure what to make of it, and the answers are vague.) Instead, I figured I'd learn best by getting my hands dirty and actually writing my own ORM, even a simple one. Except I don't really know how to get started, especially since the code I see in other ORMs is so complicated. With my PHP 5.2.x (this is important) MVC framework I have a basic custom database abstraction layer, that has: Very simple methods like connect($host, $user, $pass, $base), query($sql, $binds), etc Subclasses for each DBMS that it supports A class (and respective subclasses) to represent SQL result sets But does not have: Active Record functionality, which I assume is an ORM thing (correct me if I'm wrong) I've read up a little about ORM, and from my understanding they provide a means to further abstract data models from the database itself by representing data as nothing more than PHP-based classes/objects; again, correct me if I am wrong or have missed out in any way. Still, I'd like some simple tips from anyone else who's dabbled more or less with ORM frameworks. Is there anything else I need to take note of, simple example code for me to refer to, or resources I can read? Thanks a lot in advance!

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  • Problem with Restlet on GAE

    - by Leaf
    I'm trying to implement a calculator web service on GAE using Java Restlets... it works perfectly fine on localhost but when I upload my project to the Google App Engine everytime I try the web service link it says the link is broken. Here's the code I used: public Restlet createInboundRoot() { // Create a router Restlet that routes each call to a // new instance of HelloWorldResource. Router router = new Router(getContext()); Restlet restlet = new Restlet() { public void handle(Request request, Response response) { // Print the requested URI path String parameters = request.getResourceRef().getRemainingPart(); String message; if(parameters.charAt(0)=='?'){ message = "" + Calculator.calculate(parameters.substring(1)); } else { message = ""; } response.setEntity(message, MediaType.TEXT_PLAIN); } }; // Defines only one route router.attachDefault(restlet); return router; } The Application it's on is mapped to the /calcservice but as I said when I upload to GAE it comes back with a broken link error. I'm developing on Eclipse 3.4 and I'm wondering if there are any parameters I have to change to include the Restlet classes.

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  • Is there a tool I can use to generate interfaces and wrappers for object mocking in c#

    - by fostandy
    Given a class like System.Timers.Timer, or ANY managed class (whether user defined, from the .net framework, or some 3rd party library) is there some program I can use to (a) generate an interface based on this class and (b) generate a wrapper for the given class? for example if I have a public class Foo { public object MyProperty { get { ... } set { ... } } public int SomeMethod(object a) { ... } } it will create an interface interface IFoo { object MyProperty { get; set; } int SomeMethod(object a) { ... } } and maybe even a wrapper class FooWrap { // something for relay constructor here ... Foo _me; public object MyProperty { get { return _me.MyProperty; } set { _me.MyProperty = value; } } public int SomeMethod(object a) { return _me.SomeMethod(); } } Obviously there's stuff I haven't thought about like events, generics etc. I want a DWIMNWIS-PSICHTO(-Plus-Stuff-I-Clearly-Haven't-Thought-Of). I'm aware resharper can be used to extract an interface but I've only been able to use this on my own classes. Aside: Wow, it is amazing how simply becoming accustomed to a previously 'unacceptable' idea eventually gives it legitimacy. A year ago the idea of having to create interfaces for all objects I want to mock and adopting an injection framework would have seemed like the height of madness. It turns out that while it's not quite death and taxes, it is sparta. I am aware of and have used typemock. It certainly is the work of elvish wizards. One day when $800 does not seem like quite so much money I intend to buy it.

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  • How to Elegantly convert switch+enum with polymorphism

    - by Kyle
    I'm trying to replace simple enums with type classes.. that is, one class derived from a base for each type. So for example instead of: enum E_BASE { EB_ALPHA, EB_BRAVO }; E_BASE message = someMessage(); switch (message) { case EB_ALPHA: applyAlpha(); case EB_BRAVO: applyBravo(); } I want to do this: Base* message = someMessage(); message->apply(this); // use polymorphism to determine what function to call. I have seen many ways to do this which all seem less elegant even then the basic switch statement. Using dyanimc_pointer_cast, inheriting from a messageHandler class that needs to be updated every time a new message is added, using a container of function pointers, all seem to defeat the purpose of making code easier to maintain by replacing switches with polymorphism. This is as close as I can get: (I use templates to avoid inheriting from an all-knowing handler interface) class Base { public: template<typename T> virtual void apply(T* sandbox) = 0; }; class Alpha : public Base { public: template<typename T> virtual void apply(T* sandbox) { sandbox->applyAlpha(); } }; class Bravo : public Base { public: template<typename T> virtual void apply(T* sandbox) { sandbox->applyBravo(); } }; class Sandbox { public: void run() { Base* alpha = new Alpha; Base* bravo = new Bravo; alpha->apply(this); bravo->apply(this); delete alpha; delete bravo; } void applyAlpha() { // cout << "Applying alpha\n"; } void applyBravo() { // cout << "Applying bravo\n"; } }; Obviously, this doesn't compile but I'm hoping it gets my problem accross.

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  • Strange behavior with complex Q object filter queries in Django

    - by HWM-Rocker
    Hi I am trying to write a tagging system for Django, but today I encountered a strange behavior in filter or the Q object (django.db.models.Q). I wrote a function, that converts a search string into a Q object. The next step would be to filter the TaggedObject with these query. But unfortunately I get a strange behavior. when I search (id=20) = Q: (AND: ('tags__tag__id', 20)) and it returns 2 Taged Objects with the ID 1127 and 132 when I search (id=4) = Q: (AND: ('tags__tag__id', 4)) and it returns also 2 Objects, but this time 1180 and 1127 until here is everything fine, but when i make a little bit more complex query like (id=4) or (id=20) = Q: (OR: ('tags__tag__id', 4), ('tags__tag__id', 20)) then it returns 4(!) Objects 1180, 1127, 1127, 132 But the object with the ID 1127 is returned twice, but thats not the behaviour I want. Do I have to live with it, and uniqify that list or can I do something different. The representation of the Q object looks fine for me. But the worst is now, when I search for (id=20) and (id=4) = Q: (AND: ('tags__tag__id', 20), ('tags__tag__id', 4)) then it returns no object at all. But why? The representation should be ok and the object with the id 1127 is tagged by both. What am I missing? Here are also the relevant parts of the classes, that are involved: class TaggedObject(models.Model): """ class that represent a tagged object """ tags = generic.GenericRelation('ObjectTagBridge', blank=True, null=True) class ObjectTagBridge(models.Model): """ Help to connect a generic object to a Tag. """ # pylint: disable-msg=W0232,R0903 content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') tag = models.ForeignKey('Tag') class Tag(models.Model): ... Thanks for your help

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  • Should a new language compiler target the JVM?

    - by Pindatjuh
    I'm developing a new language. My initial target was to compile to native x86 for the Windows platform, but now I am in doubt. I've seen some new languages target the JVM (most notable Scala and Clojure). Ofcourse it's not possible to port every language easily to the JVM; to do so, it may lead to small changes to the language and it's design. So that's the reason behind this doubt, and thus this question: Is targetting the JVM a good idea, when creating a compiler for a new language? Or should I stick with x86? I have experience in generating JVM bytecode. Are there any workarounds to JVM's GC? The language has deterministic implicit memory management. How to produce JIT-compatible bytecode, such that it will get the highest speedup? Is it similar to compiling for IA-32, such as the 4-1-1 muops pattern on Pentium? I can imagine some advantages (please correct me if I'm wrong): JVM bytecode is easier than x86. Like x86 communicates with Windows, JVM communicates with the Java Foundation Classes. To provide I/O, Threading, GUI, etc. Implementing "lightweight"-threads.I've seen a very clever implementation of this at http://www.malhar.net/sriram/kilim/. Most advantages of the Java Runtime (portability, etc.) The disadvantages, as I imagined, are: Less freedom? On x86 it'll be more easy to create low-level constructs, while JVM has a higher level (more abstract) processor. Most disadvantages of the Java Runtime (no native dynamic typing, etc.)

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  • .Net assembly references being lost as soon as project is compiled

    - by Truegilly
    I have a windows service project, one of many C# projects in a solution file. I add a reference to my "Data_objects" class library for my windows service. this is added to the references no problem. all the classes become available and I can begin to code. As soon a I compile the windows service it says "The type or namespace name 'Data_Objects' could not be found (are you missing a using directive or an assembly reference?)" yet in the solution explorer the reference is fine, no yellow exclamation mark. I have to remove and add it again for it to pick it up, but then as soon as I compile it loses it. This reference works fine in my two other web application projects. what the hell is going on !! Truegilly Update there are no naming conflicts the only bit of code I have is a using statement - eg using Data_Objects.DataContext; also this only happens with a windows service project, i just created a new web app project and it works fine.

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  • shielding #include within namespace { } block?

    - by Jeff
    Edit: I know that method 1 is essentially invalid and will probably use method 2, but I'm looking for the best hack or a better solution to mitigate rampant, mutable namespace proliferation. I have multiple class or method definitions in one namespace that have different dependencies, and would like to use the fewest namespace blocks or explicit scopings possible but while grouping #include directives with the definitions that require them as best as possible. I've never seen any indication that any preprocessor could be told to exclude namespace {} scoping from #include contents, but I'm here to ask if something similar to this is possible: (see bottom for explanation of why I want something dead simple) // NOTE: apple.h, etc., contents are *NOT* intended to be in namespace Foo! // would prefer something most this: namespace Foo { #include "apple.h" B *A::blah(B const *x) { /* ... */ } #include "banana.h" int B::whatever(C const &var) { /* ... */ } #include "blueberry.h" void B::something() { /* ... */ } } // namespace Foo ... // over this: #include "apple.h" #include "banana.h" #include "blueberry.h" namespace Foo { B *A::blah(B const *x) { /* ... */ } int B::whatever(C const &var) { /* ... */ } void B::something() { /* ... */ } } // namespace Foo ... // or over this: #include "apple.h" namespace Foo { B *A::blah(B const *x) { /* ... */ } } // namespace Foo #include "banana.h" namespace Foo { int B::whatever(C const &var) { /* ... */ } } // namespace Foo #include "blueberry.h" namespace Foo { void B::something() { /* ... */ } } // namespace Foo My real problem is that I have projects where a module may need to be branched but have coexisting components from the branches in the same program. I have classes like FooA, etc., that I've called Foo::A in the hopes being able to branch less painfully as Foo::v1_2::A, where some program may need both a Foo::A and a Foo::v1_2::A. I'd like "Foo" or "Foo::v1_2" to show up only really once per file, as a single namespace block, if possible. Moreover, I tend to prefer to locate blocks of #include directives immediately above the first definition in the file that requires them. What's my best choice, or alternatively, what should I be doing instead of hijacking the namespaces?

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  • How to name multiple versioned ServiceContracts in the same WCF service?

    - by Tor Hovland
    When you have to introduce a breaking change in a ServiceContract, a best practice is to keep the old one and create a new one, and use some version identifier in the namespace. If I understand this correctly, I should be able to do the following: [ServiceContract(Namespace = "http://foo.com/2010/01/14")] public interface IVersionedService { [OperationContract] string WriteGreeting(Person person); } [ServiceContract(Name = "IVersionedService", Namespace = "http://foo.com/2010/02/21")] public interface IVersionedService2 { [OperationContract(Name = "WriteGreeting")] Greeting WriteGreeting2(Person2 person); } With this I can create a service that supports both versions. This actually works, and it looks fine when testing from soapUI. However, when I create a client in Visual Studio using "Add Service Reference", VS disregards the namespaces and simply sees two interfaces with the same name. In order to differentiate them, VS adds "1" to the name of one of them. I end up with proxies called ServiceReference.VersionedServiceClient and ServiceReference.VersionedService1Client Now it's not easy for anybody to see which is the newer version. Should I give the interfaces different names? E.g IVersionedService1 IVersionedService2 or IVersionedService/2010/01/14 IVersionedService/2010/02/21 Doesn't this defeat the purpose of the namespace? Should I put them in different service classes and get a unique URL for each version?

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  • Virgin STI Help

    - by Mutuelinvestor
    I am working on a horse racing application and I'm trying to utilize STI to model a horse's connections. A horse's connections is comprised of his owner, trainer and jockey. Over time, connections can change for a variety of reasons: The horse is sold to another owner The owner switches trainers or jockey The horse is claimed by a new owner As it stands now, I have model this with the following tables: horses connections (join table) stakeholders (stakeholder has three sub classes: jockey, trainer & owner) Here are my clases and associations: class Horse < ActiveRecord::Base has_one :connection has_one :owner_stakeholder, :through => :connection has_one :jockey_stakeholder, :through => :connection has_one :trainer_stakeholder, :through => :connection end class Connection < ActiveRecord::Base belongs_to :horse belongs_to :owner_stakeholder belongs_to :jockey_stakeholder belongs_to :trainer_stakeholder end class Stakeholder < ActiveRecord::Base has_many :connections has_many :horses, :through => :connections end class Owner < Stakeholder # Owner specific code goes here. end class Jockey < Stakeholder # Jockey specific code goes here. end class Trainer < Stakeholder # Trainer specific code goes here. end One the database end, I have inserted a Type column in the connections table. Have I modeled this correctly. Is there a better/more elegant approach. Thanks in advance for you feedback. Jim

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  • VB.NET switching from ADO.NET to LINQ

    - by Cj Anderson
    I'm VERY new to Linq. I have an application I wrote that is in VB.NET 2.0. Works great, but I'd like to switch this application to Linq. I use ADO.NET to load XML into a datatable. The XML file has about 90,000 records in it. I then use the Datatable.Select to perform searches against that Datatable. The search control is a free form textbox. So if the user types in terms it searches instantly. Any further terms that are typed in continue to restrict the results. So you can type in Bob, or type in Bob Barker. Or type in Bob Barker Price is Right. The more criteria typed in the more narrowed your result. I bind the results to a gridview. Moving forward what all do I need to do? From a high level, I assume I need to: 1) Go to Project Properties -- Advanced Compiler Settings and change the Target framework to 3.5 from 2.0. 2) Add the reference to System.XML.Linq, Add the Imports statement to the classes. So I'm not sure what the best approach is going forward after that. I assume I use XDocument.Load, then my search subroutine runs against the XDocument. Do I just do the standard Linq query for this sort of repeated search? Like so: var people = from phonebook in doc.Root.Elements("phonebook") where phonebook.Element("userid") = "whatever" select phonebook; Any tips on how to best implement?

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  • How to store some of the entity's values in another table using hibernate?

    - by nimcap
    Hi guys, is there a simple way to persist some of the fields in another class and table using hibernate. For example, I have a Person class with name, surname, email, address1, address2, city, country fields. I want my classes to be: public class Person { private String name; private String surname; private String email; private Address address; // .. } public class Address { private Person person; // to whom this belongs private String address1; private String address2; private String city; private Address country; // .. } and I want to store Address in another table. What is the best way to achieve this? Edit: I am using annotations. It does not have to be the way I described, I am looking for best practices. PS. If there is a way to make Address immutable (to use as a value object) that is even better, or maybe not because I thought everything from wrong perspective :)

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  • WPF View/ViewModels using Generics- how?

    - by Investor5555
    New to WPF, so please bear with me... Suppose I have 2 tables in SQL Thing OtherThing Both have the exact same fields: ID (int) Name (string) Description (string) IsActive (bit/bool) DateModified (DateTime) So, I want to create one Model (not two) and do something like this: BaseModel<T>() { public int ID {get;set;} ... } etc. (of course, using the INotifyPropertyChanged, just trying to keep the code simple). I want to be able to create a BaseView and BaseViewModel that would work with whatever model conforms to the Thing/OtherThing. I am really at a loss as to what to do here to make this generic, so I don't have to have a ThingView/ThingViewModel and a OtherThingView/OtherThingViewModel... It seems that this should be simple, but I cannot seem to figure it out. Does anyone have a code example where they could interchange various items from a dropdown list using one view, one ViewModel, and one base datamodel (and switching out the type from a dropdown)? For example, a combobox has 3 identical table structures for Thing OtherThing SomeThing and on selection changed, I want to pull the data from whatever table was selected, to be able to do standard CRUD operations on any of these 3 tables, without having to create concrete classes for each view/viewmodel.

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  • Can not find Driver when using generic database bundle

    - by Marc
    I have a project that is build up from several OSGi bundles. One of them is a generic Database bundle that defines a DataSource that can be used throughout the project. The spring bean definition of this service is: <osgi:service interface="javax.sql.DataSource"> <bean class="org.postgresql.ds.PGPoolingDataSource"> <property name="databaseName" value="xxx" /> <property name="serverName" value="xxx" /> <property name="user" value="xxx" /> <property name="password" value="xxx" /> </bean> </osgi:service> Now, when using this DataSource is a different bundle, we get an error: No suitable driver found for jdbc:postgresql://localhost/xxx I have tried the following to add the org.postgresql.Driver to the DriverManager: Instantiated an empty bean for that Driver in the spring context, like this: <bean class="org.postgresql.Driver" /> Instantiated the Driver statically in one of the classes, like this: Class.forName("org.postgresql.Driver"); Added a file META-INF\services\java.sql.Driver with the content org.postgresql.Driver None of these solutions seems to help.

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  • Why are Managed Beans not loaded in Tomcat?

    - by c0d3x
    Hi, I created a JSF 2 web application with facelets. The libs for JSF where stored at tomcat/lib, to share it between several applications. I thought maybe it would be better to store the libs inside the WEB-INF/lib folder of the application, to get the application more independent from server configurations. Now when I start tomcat via eclipse, the managed beans are loaded and working. But when I start tomcat directly / standalone the managed beans are not loaded automatically. I used @ManagedBean @SessionScoped / @RequestScoped annotations to declare classes as managed beans. Why is this? What can I do to fix it? I don't use any faces-config.xml file yet. Thanks in advance. edited: Maybe this helps to see whats going on: javax.el.PropertyNotFoundException: /Artikel.xhtml @12,108 value="#{artikelBackingBean.nameFilterPattern}": Target Unreachable, identifier 'artikelBackingBean' resolved to null at com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:93) at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getConvertedValue(HtmlBasicInputRenderer.java:95) at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1008) at javax.faces.component.UIInput.validate(UIInput.java:934) at javax.faces.component.UIInput.executeValidate(UIInput.java:1189) at javax.faces.component.UIInput.processValidators(UIInput.java:691) at javax.faces.component.UIForm.processValidators(UIForm.java:243) at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1080) at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1180) at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76) at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) at javax.faces.webapp.FacesServlet.service(FacesServlet.java:312) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454) at java.lang.Thread.run(Thread.java:619)

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  • How to identify the type of socket data?

    - by Nitesh Panchal
    Hello, May be i am not able to express my doubt properly in this question but still i will try. Basically i created a simple socket based chat program and everything works fine. But i think i have made many patches in it from the design point of view. I have used ObjectInputStream and ObjectOutputStreams in my program. The question i want to ask is how do i identify the different type of data that i send across the network? say if it is simple String type object i directly add to List<String> chatMessages. Now if want to ban certain users i created an another class :- public class User{ private String name; private String id; //getters and setters } This User class means no importance to me till now but i only created it to properly identify the action. Thus if i receive an instanceOf User i can be sure that some user is to be banned. That way i dont have to hardcode strings. I mean first i thought of sending something like "Banned User :" + userName and then i used to check if string startsWith "Banned User :" then i take some action :p. I've created a User class but it means no importance to me in my program. I want to know whether directly sending strings is good way or create a class for every action that is good. If i am not clear please let me know. If i have hundreds of action do i have to create hundreds of classes so i can check via instanceOf? Say now if i plan to create a BUZZ like facility that is available in yahoo messenger. Should i again create an another class named BUZZ? so it can be identified easily?

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  • Weird bug with C++ lambda expressions in VS2010

    - by Andrei Tita
    In a couple of my projects, the following code: class SmallClass { public: int x1, y1; void TestFunc() { auto BadLambda = [&]() { int g = x1 + 1; //ok int h = y1 + 1; //c2296 int l = static_cast<int>(y1); //c2440 }; int y1_copy = y1; //it works if you create a local copy auto GoodLambda = [&]() { int h = y1_copy + 1; //ok int l = this->y1 + 1; //ok }; } }; generates error C2296: '+' : illegal, left operand has type 'double (__cdecl *)(double)' or alternatively error C2440: 'static_cast' : cannot convert from 'double (__cdecl *)(double)' to 'int' You get the picture. It also happens if catching by value. The error seems to be tied to the member name "y1". It happened in different classes, different projects and with (seemingly) any type for y1; for example, this code: [...] MyClass y1; void TestFunc() { auto BadLambda = [&]()->void { int l = static_cast<int>(y1); //c2440 }; } generates both these errors: error C2440: 'static_cast' : cannot convert from 'MyClass' to 'int' No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called error C2440: 'static_cast' : cannot convert from 'double (__cdecl *)(double)' to 'int' There is no context in which this conversion is possible It didn't, however, happen in a completely new project. I thought maybe it was related to Lua (the projects where I managed to reproduce this bug both used Lua), but I did not manage to reproduce it in a new project linking Lua. It doesn't seem to be a known bug, and I'm at a loss. Any ideas as to why this happens? (I don't need a workaround; there are a few in the code already). Using Visual Studio 2010 Express version 10.0.40219.1 Sp1Rel.

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  • Too many open files in one of my java routine.

    - by Irfan Zulfiqar
    I have a multithreaded code that has to generated a set of objects and write them to a file. When I run it I sometime get "Too many open files" message in Exception. I have checked the code to make sure that all the file streams are being closed properly. Here is the stack trace. When I do ulimit -a, open files allowed is set to 1024. We think increasing this number is not a viable option / solution. [java] java.io.FileNotFoundException: /export/event_1_0.dtd (Too many open files) [java] at java.io.FileInputStream.open(Native Method) [java] at java.io.FileInputStream.<init>(FileInputStream.java:106) [java] at java.io.FileInputStream.<init>(FileInputStream.java:66) [java] at sun.net.www.protocol.file.FileURLConnection.connect(FileURLConnection.java:70) [java] at sun.net.www.protocol.file.FileURLConnection.getInputStream(FileURLConnection.java:161) [java] at java.net.URL.openStream(URL.java:1010) Now what we have identified so far by looking closely at the list of open files is that the VM is opening same class file multiple times. /export/BaseEvent.class 236 /export/EventType1BaseEvent.class 60 /export/EventType2BaseEvent.class 48 /export/EventType2.class 30 /export/EventType1.class 14 Where BaseEvent is partent of all the classes and EventType1 ant EventType2 inherits EventType1BaseEvent and EventType2BaseEvent respectively. Why would a class loader load the same class file 200+ times. It seems it is opening up the base class as many time it create any child instance. Is this normal? Can it be handler any other way apart from increasing the number of open files?

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