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• Self hosted WCF ServiceHost/WebServiceHost Concurrency/Peformance Design Options (.NET 3.5)

  - by Kyle

  So I'll be providing a few functions via a self hosted (in a WindowsService) WebServiceHost (not sure how to process HTTP GET/POST with ServiceHost), one of which may be called a large amount of the time. This function will also rely on a connection in the appdomain (hosted by the WindowsService so it can stay alive over multiple requests). I have the following concerns and would be oh so thankful for any input/thoughts/comments: Concurrent access - how does the WebServiceHost handle a bunch of concurrent requests. Are they queued and processes sequentially or are new instances of the contracts automagically created? WebServiceHost - WindowsService communication - I need some form of communication from the WebServiceHost to the hosting WindowsService for things like requesting a new session if one does not exist. Perhaps implementing a class which extends the WebServiceHost with events which the WindowsService subscribes to... (unless there is another way I can set off an event in the WindowsService when a request is made...) Multiple WebServiceHosts or Contracts - Would it give any real performance gain to be running multiple WebServiceHost instances in different threads (one per endpoint perhaps?) - A better understanding of the first point would probably help here. WSDL - I'm not sure why (probably just need to do more reading), but I'm not sure how to get the WebServiceHost base endpoint to respond with a WDSL document describing the available contract. Not required as all the operations will be done via GET requests which will not likely change, but it would be nice to have... That's about it for the moment ;) I've been reading a lot on WCF and wish I'd gotten into it long ago, but definitely still learning.

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• CKEditor instance already exists

  - by jackboberg

  I am using jquery dialogs to present forms (fetched via AJAX). On some forms I am using a CKEditor for the textareas. The editor displays fine on the first load. When the user cancels the dialog, I am removing the contents so that they are loaded fresh on a later request. The issue is, once the dialog is reloaded, the CKEditor claims the editor already exists. uncaught exception: [CKEDITOR.editor] The instance "textarea_name" already exists. The API includes a method for destroying existing editors, and I have seen people claiming this is a solution: if (CKEDITOR.instances['textarea_name']) { CKEDITOR.instances['textarea_name'].destroy(); } CKEDITOR.replace('textarea_name'); This is not working for me, as I receive a new error instead: TypeError: Result of expression 'i.contentWindow' [null] is not an object. This error seems to occur on the "destroy()" rather than the "replace()". Has anyone experienced this and found a different solution? Is is possible to 're-render' the existing editor, rather than destroying and replacing it? UPDATED Here is another question dealing with the same problem, but he has provided a downloadable test case.

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• C# Lack of Static Inheritance - What Should I Do?

  - by yellowblood

  Alright, so as you probably know, static inheritance is impossible in C#. I understand that, however I'm stuck with the development of my program. I will try to make it as simple as possible. Lets say our code needs to manage objects that are presenting aircrafts in some airport. The requirements are as follows: There are members and methods that are shared for all aircrafts There are many types of aircrafts, each type may have its own extra methods and members. There can be many instances for each aircraft type. Every aircraft type must have a friendly name for this type, and more details about this type. For example a class named F16 will have a static member FriendlyName with the value of "Lockheed Martin F-16 Fighting Falcon". Other programmers should be able to add more aircrafts, although they must be enforced to create the same static details about the types of the aircrafts. In some GUI, there should be a way to let the user see the list of available types (with the details such as FriendlyName) and add or remove instances of the aircrafts, saved, lets say, to some XML file. So, basically, if I could enforce inherited classes to implement static members and methods, I would enforce the aircraft types to have static members such as FriendlyName. Sadly I cannot do that. So, what would be the best design for this scenario?

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• Using Enterprise Library DAAB in C# Console Project

  - by Kayes

  How can I prepare the configuration settings (App.config, maybe?) I need to use Enterprise Library Data Access Application Block in a C# console project? Following is what I currently trying with an App.config in the console project. When I call DatabaseFactory.CreateDatabase(), it throws an exception which says: "Configuration system failed to initialize" <configuration> <dataConfiguration> <xmlSerializerSection type="Microsoft.Practices.EnterpriseLibrary.Data. Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"> <enterpriseLibrary.databaseSettings xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" defaultInstance="Northwind" xmlns="http://www.microsoft.com/practices/enterpriselibrary/08-31-2004/data"> <databaseTypes> <databaseType name="Sql Server" type="Microsoft.Practices.EnterpriseLibrary.Data.Sql.SqlDatabase, Microsoft.Practices.EnterpriseLibrary.Data, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" /> </databaseTypes> <instances> <instance name="Northwind" type="Sql Server" connectionString="Northwind" /> </instances> <connectionStrings> <connectionString name="Northwind"> <parameters> <parameter name="Database" value="Northwind" isSensitive="false" /> <parameter name="Integrated Security" value="True" isSensitive="false" /> <parameter name="Server" value="local" isSensitive="false" /> <parameter name="User ID" value="sa" isSensitive="false" /> <parameter name="Password" value="sa1234" isSensitive="true" /> </parameters> </connectionString> </connectionStrings> </enterpriseLibrary.databaseSettings> </xmlSerializerSection> </dataConfiguration> </configuration>

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• Help using mod_jk to forward to backend app server

  - by ravun

  I had mod-jk working a while ago but after switching servers and modifying some files, it no longer works. I am using mod_jk-1.2.28 with JBoss 4.2.3 as the backend. In the JBoss server.xml file I have the AJP 1.3 connector defined on port 8009 and I am binding jboss to the server's new IP address. The app I am trying to forward to is deployed as: [TomcatDeployer] deploy, ctxPath=/ManualAlerts, warUrl=.../tmp/deploy/tmp8097651929280250028ManualAlertsApp.ear-contents/ManualAlerts-exp.war/ On the web server, I have worker.properties with a worker set for the JBoss address and port 8009. The mod-jk.conf has JkMount /ManualAlerts/* worker1. Shouldn't this forward all requests to the web server with the URL http://address/ManualAlerts/ to the backend app named ManualAlerts? The mod-jk.log shows: [Sat Oct 31 14:19:28 2009][30709:3086014224] [error] ajp_send_request::jk_ajp_common.c (1507): (worker1) connecting to backend failed. Tomcat is probably not started or is listening on the wrong port (errno=115) [Sat Oct 31 14:19:28 2009][30709:3086014224] [info] ajp_service::jk_ajp_common.c (2447): (worker1) sending request to tomcat failed (recoverable), because of error during request sending (attempt=2) [Sat Oct 31 14:19:28 2009][30709:3086014224] [error] ajp_service::jk_ajp_common.c (2466): (worker1) connecting to tomcat failed. [Sat Oct 31 14:19:28 2009][30709:3086014224] [info] service::jk_lb_worker.c (1384): service failed, worker worker1 is in error state [Sat Oct 31 14:19:28 2009][30709:3086014224] [info] service::jk_lb_worker.c (1464): All tomcat instances are busy or in error state [Sat Oct 31 14:19:28 2009][30709:3086014224] [error] service::jk_lb_worker.c (1469): All tomcat instances failed, no more workers left Running netstat -an on the app server shows jboss listening on 8009 and the local address is the app server's address. In the mod-jk.log it shows connect to (XXX.XXX.XXX.XXX:8009) failed, and the app-server address is correct here, too. I cannot figure out what's causing the issue.

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• Axis2 webservice (aar archive) properties file

  - by XpiritO

  Hi there, guys. I'm currently developing a set of SOAP webservices over Axis2, deployed over a clustered WebLogic 10.3.2 environment. My webservices use some user settings that I want to be editable without the need for recompiling and regenerating the AAR archive. With this in mind, I chose to put them into a properties file that is loaded and consumed in runtime. Unfortunately, I'm having some questions about this: As far as I know, to achieve what I want, the only option is to put the properties file into the ../axis2/WEB-INF/classes directory of each one of the deployments (on each WebLogic instance) I currently have on my clustered configuration, and then load the file, as follows (or equivalent, this has not been verified for optimization): InputStreamReader fMainProp = new InputStreamReader(this.getClass().getResourceAsStream("myfile.properties")); Properties mainProp = new Properties(); mainProp.load(fMainProp); This is not as practical as I wanted it to be, because each time I want to alter some setting on the properties file, I have to edit each one of the files (deployed over different WebLogic instances) and there is a high probability of modifying one of these files without modifying the others. What I would like to know is if there is any (better) alternative to accomplish what I want, minimizing the potential conflict of configuration that is created by distributing and replicating the properties file through multiple WebLogic instances.

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• Any way for a class to prevent outside code from declaring variables of its type?

  - by supercat

  Is it possible for a class of exposing a type for function returns, without allowing users of that class to create variables of that type? A couple usage scenarios: A Fluent interface on a large class; a statement like "foo=bar.WithX(5).WithY(9).WithZ(19);" would be inefficient if it had to create three new instances of the class, but could be much more efficient if the WithX could create one instance, and the other statements could simply use it. A class may wish to support a statement like "foo[19].x = 9;" even when foo itself isn't an array, and does not hold the data in class instances that can be exposed to the public; one way to do that is to have foo[19] return a struct which holds a reference to 'foo' and the value '19', and has a member property 'x' which could call "foo.SetXValue(19, 9);" Such a struct could have a conversion operator to convert itself to the "apparent" type of foo[19]. In both of these scenarios, storing the value returned by a method or property into a variable and then using it more than once would cause strange behavior. It would be desirable if the designer of the class exposing such methods or properties could ensure that callers wouldn't be able to use them more than once. Is there any practical way to accomplish that?

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• ServerIdentity memory leak with IHttpAsyncHandler

  - by Anton

  I have a .NET web application that consists of a single HTTP handler class that implements IHttpAsyncHandler. All requests to this handler are handled asynchronously, though some requests are short-lived and some are long-lived (nothing over a few seconds). The problem is that memory consumption grows over time as requests are handled. All profiling results point to an unbounded growth of String objects held by instances of System.Runtime.Remoting.ServerIdentity. Every String value is different, but they all look similar to: /dd41c00e_1566_4702_b660_c81cdea18a43/vigefresi5pfv8n0ekddg57z_1154.rem There is nothing in my application that uses ServerIdentity directly, and unless I am mistaken, the ServerIdentity instances are proportional to the number of incoming requests. If this is an internal .NET structure, it looks like the CLR is not cleaning up after itself. What could be causing the leak? UPDATE A little less than half of the String objects are being held by System.Runtime.Remoting. The remaining String objects are being held by System.Runtime.Serialization and look similar to: +1sgess5rjcrgbmp3kqr6bmv_3474.rem Also, the problem only seems to occur when lots of simultaneous HTTP web requests arrive.

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• Factories, or Dependency Injection for object instantiation in WCF, when coding against an interface

  - by Saajid Ismail

  Hi I am writing a client/server application, where the client is a Windows Forms app, and the server is a WCF service hosted in a Windows Service. Note that I control both sides of the application. I am trying to implement the practice of coding against an interface: i.e. I have a Shared assembly which is referenced by the client application. This project contains my WCF ServiceContracts and interfaces which will be exposed to clients. I am trying to only expose interfaces to the clients, so that they are only dependant on a contract, not any specific implementation. One of the reasons for doing this is so that I can have my service implementation, and domain change at any time without having to recompile and redeploy the clients. The interfaces/contracts will in this case not change. I only need to recompile and redeploy my WCF service. The design issue I am facing now, is: on the client, how do I create new instances of objects, e.g. ICustomer, if the client doesn't know about the Customer concrete implementation? I need to create a new customer to be saved to the DB. Do I use dependency injection, or a Factory class to instantiate new objects, or should I just allow the client to create new instances of concrete implementations? I am not doing TDD, and I will typically only have one implementation of ICustomer or any other exposed interface.

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• how to create and track multiple pairs "View-ViewModel"?

  - by Gianluca Colucci

  Hi! I am building an application that is based on MVVM-Light. I am in the need of creating multiple instances of the same View, and each one should bind to its own ViewModel. The default ViewModelLocator implements ViewModels as singletons, therefore different instances of the same View will bind to the same ViewModel. I could create the ViewModel in the VMLocator as a non-static object (as simple as returning new VM()...), but that would only partially help me. In fact, I still need to keep track of the opened windows. Nevertheless, each window might open several other windows (of a different kind, though). In this situation I might need to execute some operation on the parent View and all its children. For example before closing the View P, I might want to close all its children (view C1, view C2, etc.). Hence, is there any simple and easy way to achieve this? Or is there any best practice you would advice me to follow? Thanks in advance for your precious help. Cheers, Gianluca.

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• Error displaying a WinForm in Design mode with a custom control on it.

  - by George

  I have a UserControl that is part of a Class library. I reference this project from my solution. This adds a control from the referenced project to my toolbox. I add tghe control to a form. Everything looks good, I compile all and run. Perfect... But when I close the .frm with the control on it and re-open it, I get this error. The code continues to run. It may have something to do with namespaces. The original namespace was simply "Design" and this was ambiguous and conflicting so i decided to rename it. I think that's when my problems began. To prevent possible data loss before loading the designer, the following errors must be resolved: 2 Errors Ignore and Continue Why am I seeing this page? Could not find type 'Besi.Winforms.HtmlEditor.Editor'. Please make sure that the assembly that contains this type is referenced. If this type is a part of your development project, make sure that the project has been successfully built using settings for your current platform or Any CPU. Instances of this error (1) 1. There is no stack trace or error line information available for this error. Help with this error Could not find an associated help topic for this error. Check Windows Forms Design-Time error list Forum posts about this error Search the MSDN Forums for posts related to this error The variable 'Editor1' is either undeclared or was never assigned. Go to code Instances of this error (1) 1. BesiAdmin frmOrder.Designer.vb Line:775 Column:1 Show Call Stack at System.ComponentModel.Design.Serialization.CodeDomSerializerBase.Error(IDesignerSerializationManager manager, String exceptionText, String helpLink) at System.ComponentModel.Design.Serialization.CodeDomSerializerBase.DeserializeExpression(IDesignerSerializationManager manager, String name, CodeExpression expression) at System.ComponentModel.Design.Serialization.CodeDomSerializerBase.DeserializeExpression(IDesignerSerializationManager manager, String name, CodeExpression expression) at System.ComponentModel.Design.Serialization.CodeDomSerializerBase.DeserializeStatement(IDesignerSerializationManager manager, CodeStatement statement) Help with this error MSDN Help Forum posts about this error Search the MSDN Forums for posts related to this error

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• Unable to call RESTful web services methods

  - by Alessandro

  Hello, I'm trying to dive into the RESTful web services world and have started with the following template: [ServiceContract] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)] public class Test { // TODO: Implement the collection resource that will contain the SampleItem instances [WebGet(UriTemplate = ""), OperationContract] public List<SampleItem> GetCollection() { // TODO: Replace the current implementation to return a collection of SampleItem instances return new List<SampleItem>() {new SampleItem() {Id = 1, StringValue = "Hello"}}; } [WebInvoke(UriTemplate = "", Method = "POST"), OperationContract] public SampleItem Create(SampleItem instance) { // TODO: Add the new instance of SampleItem to the collection throw new NotImplementedException(); } [WebGet(UriTemplate = "{id}"), OperationContract] public SampleItem Get(string id) { // TODO: Return the instance of SampleItem with the given id throw new NotImplementedException(); } [WebInvoke(UriTemplate = "{id}", Method = "PUT"), OperationContract] public SampleItem Update(string id, SampleItem instance) { return new SampleItem { Id = 99, StringValue = "Done" }; } [WebInvoke(UriTemplate = "{id}", Method = "DELETE"), OperationContract] public void Delete(string id) { // TODO: Remove the instance of SampleItem with the given id from the collection throw new NotImplementedException(); } } I am able to perform the GET operation but I am unable to perform PUT, POST or DELETE requests. Can anyone explain me how to perform these operations and how to create the correct URLs? Best regards Alessandro

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• Creative ways to punish (or just curb) laziness in coworkers

  - by FerretallicA

  Like the subject suggests, what are some creative ways to curb laziness in co-workers? By laziness I'm talking about things like using variable names like "inttheemplrcd" instead of "intEmployerCode" or not keeping their projects synced with SVN, not just people who use the last of the sugar in the coffee room and don't refill the jar. So far the two most effective things I've done both involve the core library my company uses. Since most of our programs are in VB.net the lack of case sensitivity is abused a lot. I've got certain features of the library using Reflection to access data in the client apps, which has a negligible performance hit and introduces case sensitivity in a lot places where it is used. In instances where we have an agreed standard which is compromised by blatant laziness I take it a step further, like the DatabaseController class which will blatantly reject any DataTable passed to it which isn't named dtSomething (ie- must begin with dt and third letter must be capitalised). It's frustrating to have to resort to things like this but it has also gradually helped drill more attention to detail into their heads. Another is adding some code to the library's initialisation function to display a big and potentially embarrassing (only if seen by a client) message advising that the program is running in debug mode. We have had many instances where projects are sent to clients built in debug mode which has a lot of implications for us (especially with regard to error recovery) and doing that has made sure they always build to release before distributing. Any other creative (ie- not StyleCop etc) approaches like this?

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• Haskell Linear Algebra Matrix Library for Arbitrary Element Types

  - by Johannes Weiß

  I'm looking for a Haskell linear algebra library that has the following features: Matrix multiplication Matrix addition Matrix transposition Rank calculation Matrix inversion is a plus and has the following properties: arbitrary element (scalar) types (in particular element types that are not Storable instances). My elements are an instance of Num, additionally the multiplicative inverse can be calculated. The elements mathematically form a finite field (??2256). That should be enough to implement the features mentioned above. arbitrary matrix sizes (I'll probably need something like 100x100, but the matrix sizes will depend on the user's input so it should not be limited by anything else but the memory or the computational power available) as fast as possible, but I'm aware that a library for arbitrary elements will probably not perform like a C/Fortran library that does the work (interfaced via FFI) because of the indirection of arbitrary (non Int, Double or similar) types. At least one pointer gets dereferenced when an element is touched (written in Haskell, this is not a real requirement for me, but since my elements are no Storable instances the library has to be written in Haskell) I already tried very hard and evaluated everything that looked promising (most of the libraries on Hackage directly state that they wont work for me). In particular I wrote test code using: hmatrix, assumes Storable elements Vec, but the documentation states: Low Dimension : Although the dimensionality is limited only by what GHC will handle, the library is meant for 2,3 and 4 dimensions. For general linear algebra, check out the excellent hmatrix library and blas bindings I looked into the code and the documentation of many more libraries but nothing seems to suit my needs :-(. Update Since there seems to be nothing, I started a project on GitHub which aims to develop such a library. The current state is very minimalistic, not optimized for speed at all and only the most basic functions have tests and therefore should work. But should you be interested in using or helping out developing it: Contact me (you'll find my mail address on my web site) or send pull requests.

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• First-chance exception at std::set dectructor

  - by bartek

  Hi, I have a strange exception at my class destructor: First-chance exception reading location 0x00000 class DispLst{ // For fast instance existance test std::set< std::string > instances; [...] DispLst::~DispLst(){ this->clean(); DeleteCriticalSection( &instancesGuard ); } <---- here instances destructor raises exception Call stack: X.exe!std::_Tree,std::allocator ,std::less,std::allocator ,std::allocator,std::allocator ,0 ::begin() Line 556 + 0xc bytes C++ X.exe!std::_Tree,std::allocator ,std::less,std::allocator ,std::allocator,std::allocator ,0 ::_Tidy() Line 1421 + 0x64 bytes C++ X.exe!std::_Tree,std::allocator ,std::less,std::allocator ,std::allocator,std::allocator ,0 ::~_Tree,std::allocator ,std::less,std::allocator ,std::allocator,std::allocator ,0 () Line 541 C++ X.exe!std::set,std::allocator ,std::less,std::allocator ,std::allocator,std::allocator ::~set,std::allocator ,std::less,std::allocator ,std::allocator,std::allocator () + 0x2b bytes C++ X.exe!DispLst::~DispLst() Line 82 + 0xf bytes C++ The exact place of error in xtree: void _Tidy() { // free all storage erase(begin(), end()); <------------------- HERE this->_Alptr.destroy(&_Left(_Myhead)); this->_Alptr.destroy(&_Parent(_Myhead)); this->_Alptr.destroy(&_Right(_Myhead)); this->_Alnod.deallocate(_Myhead, 1); _Myhead = 0, _Mysize = 0; } iterator begin() { // return iterator for beginning of mutable sequence return (_TREE_ITERATOR(_Lmost())); <---------------- HERE } What is going on ? I'm using Visual Studio 2008.

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• RESTfully Nesting Resource Routes with Single Identifiers

  - by Craig Walker

  In my Rails app I have a fairly standard has_many relationship between two entities. A Foo has zero or more Bars; a Bar belongs to exactly one Foo. Both Foo and Bar are identified by a single integer ID value. These values are unique across all of their respective instances. Bar is existence dependent on Foo: it makes no sense to have a Bar without a Foo. There's two ways to RESTfully references instances of these classes. Given a Foo.id of "100" and a Bar.id of "200": Reference each Foo and Bar through their own "top-level" URL routes, like so: /foo/100 /bar/200 Reference Bar as a nested resource through its instance of Foo: /foo/100 /foo/100/bar/200 I like the nested routes in #2 as it more closely represents the actual dependency relationship between the entities. However, it does seem to involve a lot of extra work for very little gain. Assuming that I know about a particular Bar, I don't need to be told about a particular Foo; I can derive that from the Bar itself. In fact, I probably should be validating the routed Foo everywhere I go (so that you couldn't do /foo/150/bar/200, assuming Bar 200 is not assigned to Foo 150). Ultimately, I don't see what this brings me. So, are there any other arguments for or against these two routing schemes?

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• Do servlet containers prevent web applications from causing each other interference and how do they do it?

  - by chrisbunney

  I know that a servlet container, such as Apache Tomcat, runs in a single instance of the JVM, which means all of its servlets will run in the same process. I also know that the architecture of the servlet container means each web application exists in its own context, which suggests it is isolated from other web applications. As depicted here: Accepting that each web application is isolated, I would expect that you could create 2 copies of an identical web application, change the names and context paths of each (as well as any other relevant configuration), and run them in parallel without one affecting the other. The answers to this question appear to support this view. However, a colleague disagrees based on their experience of attempting just that. They took a web application and tried to run 2 separate instances (with different names etc) in the same servlet container and experienced issues with the 2 instances conflicting (I'm unable to elaborate more as I wasn't involved in that work). Based on this, they argue that since the web applications run in the same process space, they can't be isolated and things such as class attributes would end up being inadvertently shared. This answer appears to suggest the same thing The two views don't seem to be compatible, so I ask you: Do servlet containers prevent web applications deployed to the same container from conflicting with each other? If yes, How do they do this? If no, Why does interference occur? and finally, Under what circumstances could separate web applications conflict and cause each other interference?, perhaps scenarios involving resources on the file system, native code, or database connections?

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• Python Locking Implementation (with threading module)

  - by Matty

  This is probably a rudimentary question, but I'm new to threaded programming in Python and am not entirely sure what the correct practice is. Should I be creating a single lock object (either globally or being passed around) and using that everywhere that I need to do locking? Or, should I be creating multiple lock instances in each of the classes where I will be employing them. Take these 2 rudimentary code samples, which direction is best to go? The main difference being that a single lock instance is used in both class A and B in the second, while multiple instances are used in the first. Sample 1 class A(): def __init__(self, theList): self.theList = theList self.lock = threading.Lock() def poll(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.append(something) finally: self.lock.release() class B(threading.Thread): def __init__(self,theList): self.theList = theList self.lock = threading.Lock() self.start() def run(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.remove(something) finally: self.lock.release() if __name__ == "__main__": aList = [] for x in range(10): B(aList) A(aList).poll() Sample 2 class A(): def __init__(self, theList,lock): self.theList = theList self.lock = lock def poll(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.append(something) finally: self.lock.release() class B(threading.Thread): def __init__(self,theList,lock): self.theList = theList self.lock = lock self.start() def run(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.remove(something) finally: self.lock.release() if __name__ == "__main__": lock = threading.Lock() aList = [] for x in range(10): B(aList,lock) A(aList,lock).poll()

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• Is jQuery always the answer?

  - by Kibbee

  I've come across a couple questions, such as this one, and I really have to wonder why "Use jQuery" seems to be the answer when somebody asks how to do something in JavaScript. I understand that jQuery can save you a lot of time, and can help you out a lot, especially when you are doing a lot of fancy JavaScript in your site. However, in instances like this, and in many other instances, it seems like it's just jumping around the problem instead of answering the question. I also feel like this builds too much dependency into libraries. I've seen way too many developers that simply rely too much on libraries, and if they encounter a situation where they didn't have the library, they would be completely unable to function. I feel like there are already enough developers who don't know JavaScript, without just telling everybody to not learn JavaScript, and use jQuery. So, just to reiterate the question. Do you think there's too much of a tendency to use jQuery, for small pieces of JavaScript, when most of the functionality of jQuery isn't being used. Should developers be fluent in the use of bare JavaScript so they don't get too dependent on using libraries? [Additional related conversation topic] Does the existence of jQuery give too much slack to web browser developers who write the JavaScript engines? If we just have workarounds to cover all the inconsistencies in JavaScript, what pressure is there on browser makers to ensure that their JavaScript library works as it should. I feel like this extrapolates the same problem discussed in SO Podcast #36 of "be conservative in what you send, liberal in what you accept". By being so liberal with bad JavaScript engines, and using a common library to work around the flaws, we are promoting their use, and extending the problem.

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• Hibernate triggering constraint violations using orphanRemoval

  - by ptomli

  I'm having trouble with a JPA/Hibernate (3.5.3) setup, where I have an entity, an "Account" class, which has a list of child entities, "Contact" instances. I'm trying to be able to add/remove instances of Contact into a List<Contact> property of Account. Adding a new instance into the set and calling saveOrUpdate(account) persists everything lovely. If I then choose to remove the contact from the list and again call saveOrUpdate, the SQL Hibernate seems to produce involves setting the account_id column to null, which violates a database constraint. What am I doing wrong? The code below is clearly a simplified abstract but I think it covers the problem as I'm seeing the same results in different code, which really is about this simple. SQL: CREATE TABLE account ( INT account_id ); CREATE TABLE contact ( INT contact_id, INT account_id REFERENCES account (account_id) ); Java: @Entity class Account { @Id @Column public Long id; @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true) @JoinColumn(name = "account_id") public List<Contact> contacts; } @Entity class Contact { @Id @Column public Long id; @ManyToOne(optional = false) @JoinColumn(name = "account_id", nullable = false) public Account account; } Account account = new Account(); Contact contact = new Contact(); account.contacts.add(contact); saveOrUpdate(account); // some time later, like another servlet request.... account.contacts.remove(contact); saveOrUpdate(account); Result: UPDATE contact SET account_id = null WHERE contact_id = ? Edit #1: It might be that this is actually a bug http://opensource.atlassian.com/projects/hibernate/browse/HHH-5091

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• Nested Object Forms not working as expected

  - by Craig Walker

  I'm trying to get a nested model forms view working. As far as I can tell I'm doing everything right, but it still does not work. I'm on Rails 3 beta 3. My models are as expected: class Recipe < ActiveRecord::Base has_many :ingredients, :dependent => :destroy accepts_nested_attributes_for :ingredients attr_accessible :name end class Ingredient < ActiveRecord::Base attr_accessible :name, :sort_order, :amount belongs_to :recipe end I can use Recipe.ingredients_attributes= as expected: recipe = Recipe.new recipe.ingredients_attributes = [ {:name=>"flour", :amount=>"1 cup"}, {:name=>"sugar", :amount=>"2 cups"}] recipe.ingredients.size # -> 2; ingredients contains expected instances However, I cannot create new object graphs using a hash of parameters as shown in the documentation: params = { :name => "test", :ingredients_attributes => [ {:name=>"flour", :amount=>"1 cup"}, {:name=>"sugar", :amount=>"2 cups"}] } recipe = Recipe.new(params) recipe.name # -> "test" recipe.ingredients # -> []; no ingredient instances in the collection Is there something I'm doing wrong here? Or is there a problem in the Rails 3 beta?

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• ASP.NET Event delegation between user controls

  - by Ishan

  Give the following control hierarchy on a ASP.NET page: Page HeaderControl       (User Control) TitleControl       (Server Control) TabsControl       (User Control) other controls I'm trying to raise an event (or some notification) in the TitleControl that bubbles to the Page level. Then, I'd like to (optionally) register an event handler at the Page codebehind that will take the EventArgs and modify the TabsControl in the example above. The important thing to note is that this design will allow me to drop these controls into any Page and make the entire system work seamlessly if the event handler is wired up. The solution should not involve a call to FindControl() since that becomes a strong association. If no handler is defined in the containing Page, the event is still raised by TitleControl but is not handled. My basic goal is to use event-based programming so that I can decouple the user controls from each other. The event from TitleControl is only raised in some instances, and this seemed to be (in my head) the preferred approach. However, I can't seem to find a way to cleanly achieve this. Here are my (poor) attempts: Using HttpContext.Current.Items Add the EventArgs to the Items collection on TitleControl and pick it up on the TabsControl. This works but it's fundamentally hard to decipher since the connection between the two controls is not obvious. Using Reflection Instead of passing events, look for a function on the container Page directly within TitleControl as in: Page.GetType().GetMethod("TabControlHandler").Invoke(Page, EventArgs); This will work, but the method name will have to be a constant that all Page instances will have to defined verbatim. I'm sure that I'm over-thinking this and there must be a prettier solution using delegation, but I can't seem to think of it. Any thoughts?

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• Threads in WCF service

  - by dragonfly

  Hi, there is a piece of code: class WCFConsoleHostApp : IBank { private static int _instanceCounter; public WCFConsoleHostApp () { Interlocked.Increment(ref _instanceCounter); Console.WriteLine(string.Format("{0:T} Instance nr " + _instanceCounter + " created", DateTime.Now)); } private static int amount; static void Main(string[] args) { ServiceHost host = new ServiceHost(typeof(WCFConsoleHostApp)); host.Open(); Console.WriteLine("Host is running..."); Console.ReadLine(); } #region IBank Members BankOperationResult IBank.Put(int amount) { Console.WriteLine(string.Format("{0:00} {1}", Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread) + " Putting..."); WCFConsoleHostApp.amount += amount; Thread.Sleep(20000); Console.WriteLine(string.Format("{0:00} {1}", Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread) + " Putting done"); return new BankOperationResult { CurrentAmount = WCFConsoleHostApp.amount, Success = true }; } BankOperationResult IBank.Withdraw(int amount) { Console.WriteLine(string.Format("{0:00} {1}", Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread) + " Withdrawing..."); WCFConsoleHostApp.amount -= amount; Thread.Sleep(20000); Console.WriteLine(string.Format("{0:00} {1}", Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread) + " Withdrawing done"); return new BankOperationResult { CurrentAmount = WCFConsoleHostApp.amount, Success = true }; } #endregion } My test client application calls that service in 50 threads (service is PerCall). What I found very disturbing is when I added Thread.Sleep(20000) WCF creates one service instance per second using different thread from pool. When I remove Thread.Sleep(20000) 50 instances are instanciated straight away, and about 2-4 threads are used to do it - which in fact I consider normal. Could somebody explain why when Thread.Sleep causes those funny delays in creating instances?

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• Using generics to make an algorithm work on lists of "something" instead of only String's

  - by Binary255

  Hi, I have a small algorithm which replaces the position of characters in a String: class Program { static void Main(string[] args) { String pairSwitchedStr = pairSwitch("some short sentence"); Console.WriteLine(pairSwitchedStr); Console.ReadKey(); } private static String pairSwitch(String str) { StringBuilder pairSwitchedStringBuilder = new StringBuilder(); for (int position = 0; position + 1 < str.Length; position += 2) { pairSwitchedStringBuilder.Append((char)str[position + 1]); pairSwitchedStringBuilder.Append((char)str[position]); } return pairSwitchedStringBuilder.ToString(); } } I would like to make it as generic as possible, possibly using Generics. What I'd like to have is something which works with: Anything that is built up using a list of instances. Including strings, arrays, linked lists I suspect that the solution must use generics as the algorithm is working on a list of instances of T (there T is ... something). Version of C# isn't of interest, I guess the solution will be nicer if features from C# version 2.0 is used.

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• proper way to dynamically assign backbone.js view el

  - by kikuchiyo

  I would like to create two ( or more ) view instances, each with different el attributes, and have events bound to them via backbone.js view's events hash ( not through jQuery ). Getting events to trigger when all instantiations have the same el is easy: someView = Backbone.View.extend({ el: '#someDiv', events: { 'click': 'someFunction' }, someFunction: function(){ //Do something here } }); So far, if I assign el in the initialize function, and set events normally as follows, events do not trigger: someView = Backbone.View.extend({ events: { 'click': 'someFunction' }, initialize: function( options ){ this.el = options.el }, someFunction: function(){ //Do something here } }); My first instinct was to have el be a function that returns the string representation of the dom element of interest: someView = Backbone.View.extend({ el: function(){ return '#someDiv-' + this.someNumber }, events: { 'click': 'someFunction' }, initialize: function( options ){ this.someNumber = options.someNumber }, someFunction: function(){ //Do something here } }); However, this triggers someFunction x times if I have x instantiations of someView. Next I tried setting both the el and events attributes in initialize: someView = Backbone.View.extend({ initialize: function( options ){ this.el = options.el this.events = { 'click': 'someFunction' } }, someFunction: function(){ //Do something here } }); but this does not trigger events. At this point I'm pretty much fishing. Does anyone know how instantiate a backbone.js view with an el specific to that instance that has events that only trigger for that instance, and not other instances of the View?

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