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  • Java sockets: multiple client threads on same port on same machine?

    - by espcorrupt
    I am new to Socket programming in Java and was trying to understand if the below code is not a wrong thing to do. My question is: Can I have multiple clients on each thread trying to connect to a server instance in the same program and expect the server to read and write data with isolation between clients" public class Client extends Thread { ... void run() { Socket socket = new Socket("localhost", 1234); doIO(socket); } } public class Server extends Thread { ... void run() { // serverSocket on "localhost", 1234 Socket clientSock = serverSocket.accept(); executor.execute(new ClientWorker(clientSock)); } } Now can I have multiple Client instances on different threads trying to connect on the same port of the current machine? For example, Server s = new Server("localhost", 1234); s.start(); Client[] c = new Client[10]; for (int i = 0; i < c.length; ++i) { c.start(); }

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  • Why there is no scoped locks for multiple mutexes in C++0x or Boost.Thread?

    - by Vicente Botet Escriba
    C++0x thread library or Boost.thread define non-member variadic template function that lock all lock avoiding dead lock. template <class L1, class L2, class... L3> void lock(L1&, L2&, L3&...); While this function avoid help to deadlock, the standard do not includes the associated scoped lock to write exception safe code. { std::lock(l1,l2); // do some thing // unlock li l2 exception safe } That means that we need to use other mechanism as try-catch block to make exception safe code or define our own scoped lock on multiple mutexes ourselves or even do that { std::lock(l1,l2); std::unique_lock lk1(l1, std::adopted); std::unique_lock lk2(l2, std::adopted); // do some thing // unlock li l2 on destruction of lk1 lk2 } Why the standard doesn't includes a scoped lock on multiple mutexes of the same type, as for example { std::array_unique_lock<std::mutex> lk(l1,l2); // do some thing // unlock l1 l2 on destruction of lk } or tuples of mutexes { std::tuple_unique_lock<std::mutex, std::recursive_mutex> lk(l1,l2); // do some thing // unlock l1 l2 on destruction of lk } Is there something wrong on the design?

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  • How to deploy to multiple redundant production servers with "cap deploy"?

    - by Chad Johnson
    Capistrano is working great to deploy to a single server. However, I have multiple production API servers for my web application. When I deploy, my code needs to get deployed to every API server at once. Specifying each server manually is NOT the solution I am looking for (e.g. I don't want to do "cap api1 deploy; cap api2 deploy"). Is there a way, using Capistrano, to deploy to all servers at once, with just a simple "cap deploy"? I'm wondering what changes I would need to make to a typical deploy.rb file, whether I'd need to create a separate file for each server, and whether and how the Capfile would need to be changed. Also, I need to be able to specify a different deploy_to path for each server. And ideally, I wouldn't have to repeat things in different config files for different servers (eg. wouldn't have to specify :repository, :application, etc. multiple times). I have spent hours searching Google on this and looking through tutorials, but I have found nothing helpful. Here is a snippet from my current deploy.rb file: set :application, "testapplication" set :repository, "ssh://domain.com//srv/hg/#{application}" set :scm, :mercurial set :deploy_to, "/srv/www/#{application}" role :web, "domain.com" role :app, "domain.com" role :db, "domain.com", :primary => true, :norelease => true Should I just use the multistage extension and do this? task :deploy_everything do system "cap api1 deploy" system "cap api2 deploy" system "cap api2 deploy" end That could work, but I feel like this isn't what this extension is meant for...

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  • NUnit - Multiple properties of the same name? Linking to requirements

    - by Ryan Ternier
    I'm linking all our our System Tests to test cases and to our Requirements. Every requirement has an ID. Every Test Case / System Tests tests a variety of requirements. Every module of code links to multiple requirements. I'm trying to find the best way to link every system test to its driving requirements. I was hoping to do something like: [NUnit.Framework.Property("Release", "6.0.0")] [NUnit.Framework.Property("Requirement", "FR50082")] [NUnit.Framework.Property("Requirement", "FR50084")] [NUnit.Framework.Property("Requirement", "FR50085")] [TestCase(....)] public void TestSomething(string a, string b...) However, that will break because Property is a Key-Value pair. The system will not allow me to have multiple Properties with the same key. The reason I'm wanting this is to be able to test specific requirements in our system if a module changes that touches these requirements. Rather than run over 1,000 system tests on every build, this would allow us to target what to test based on changes done to our code. Some system tests run upwards of 5 minutes (Enterprise healthcare system), so "Just run all of them" isn't a viable solution. We do that, but only before promoting through our environments. Thoughts?

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  • ant support for dynamic target

    - by Li He
    I previous saw some similar questions on stackoverflow but didn't see any solution. I guess the answer could be impossible and I am trying to see who can provide me this confirmation. AFAIK, an ant project contains several targets and each target may have several tasks. There is an task MacroDef that defines a sequential of `things' (tasks I suppose?). I tried to put target inside this block but ant complains the name of the target is missing (I am using the attribute of the macrodef to generate the name of the target). So it could be a dead end. Then I found that by using a task `script', we have access to the Project and can even call addTarget/AddOrReplaceTarget from there. But it seems that the targets I create there have no impact on the running targets. Does that mean ant doesn't support manipulating dependencies at target runtime? Is there any way to generate these targets before ant start building the dependency graph?

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  • Multiple exports with MEF does some really heinous stuff -- why, and why is it allowed?

    - by Dave
    I have an interesting situation where I need to do something like this: [Export[typeof(ICandy1)] [Export[typeof(ICandy2)] public class Candy : ICandy2 { ... } where public interface ICandy1 { ... } public interface ICandy2 : ICandy1 { ... } I couldn't find any posts anywhere regarding using multiple [Export] attributes, so I figured, what the hell, might as well try it. At first glance, it actually seemed to work. I have a couple of methods that call into both interfaces of a Candy instance, and it was fine. However, as I started to test the app, I saw that the behavior wasn't right, and when looking at the Output window, I saw that I was getting tons of COMExceptions. I couldn't track down where they were all coming from, but they always occurred when a worker thread was sleeping. I figured that it had to be from the main thread, then, but didn't know how to debug this at all. Nothing should have been going on in the GUI, and I disabled my DispatchTimers just in case -- same thing. Even more strange than the COMExceptions was the really, really erratic behavior when stepping through code. About 30% of the time, when I single stepped, it would pop out of the method, or it would single step over two lines of code! Totally weird stuff that I am not used to seeing. The only thing that changed between working and non-working code was the introduction of MEF through my plugin loading code. So as a test, I changed my plugin assembly to only export one interface, and I hardcoded everything in the app that relied on the other (now not-implemented) interface. And now the COMExceptions are gone, and the weird debugging behavior is gone. Is this something people here have seen before? If MEF is not expected to allow a class to Export multiple interfaces, then shouldn't a CompositionException get raised when composing the parts? Can anyone explain why MEF would cause these weird problems???

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  • What's a good way to do testing a plug-in on multiple Windows and Outlook versions?

    - by Andrei
    Hello, We're building a plug-in for Outlook that should work on multiple Windows versions (XP, Vista, 7) and also with different Outlook versions (2003, 2007, 2010). The testing problem I am facing right now, is that I can't figure out a good/convenient/thorough way to test the application on multiple Windows and Outlook versions. At the moment, I have a VirtualBox which runs many virtual machines, with different Windows versions and Outlook versions. So I would have a virtual machine with Windows 7 testing Outlook 2010, and another one with Windows 7 testing Outlook 2007, Windows Vista with Outlook 2010 and so on, going through some of the possible combinations. It kind of gets the job done, although it is cumbersome and takes a long time to test. Some of the testing included in the application is unit testing, but this is also rather tied in with the machine I test it on (windows 7 with outlook 2010). For example, I was using ManagementObject recently, which worked fine on my system (and thus passed the unit test for that method), however, using that object threw an exception in another person's system, which crashed the application. I work on Visual Studio 2010 Ultimate. The questions: Is there a more elegant way to make the testing process more streamline and more efficient? Any other testing methods you recommend? How would you deal with this problem? Thanks! Looking forward to your replies.

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  • Map a struts2 action result to a controller instead of a jsp

    - by Jim
    Hello, I'm working on on a site built using struts2. The vast majority of our targets generate xml, so mapping the result to a jsp page makes sense. A couple of our targets actually generated binaries. I'm wondering if there is a convenient way to say that the result should come from a servlet/controller instead of a jsp. Obviously this could be done by modifying the web.xml so the struts filter doesn't apply to those targets and mapping those targets as servlets, but this is non-ideal. Currently, the struts filter applies to the entire site, and we would like to keep it that way. Ideas? Thanks!

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  • RESTful web service, PUTting an unnamed resource?

    - by James L
    I have a back-end service that creates unique identifiers for resources. The general idea is that resources are saved and versioned, so you can perform: GET http://service/sales/targets/7818181919/latest or GET http://service/sales/targets/7818181919/4 for version 4, and so on. My question is about the most correct way to upload these resources in the first place. How about: PUT http://service/sales/targets/ returning 303 See other /service/sales/targets/ It seems a little wrong as you should PUT and GET from exactly the same place using a resource-oriented interface, but I can't think of a better option. Any ideas?

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  • How can I attach multiple urls to a single git remote?

    - by deterb
    I'm currently using git on windows through a combination of msysgit and Cygwin. I have a laptop which I move around quite a bit, so it's not on a consistent location. Unfortunately, I don't have a consistent name for it due to the computer name not being resolved on all of the locations I connect to, so I can't just use the computer name as the host for the url (e.g. git://compname/repo), so I have to use the IP address. Is there a way I can add multiple urls to pull from for a particular remote? I've seen git remote set-url --add [--push] <name> <newurl> as a way to add multiple URLs to a remote, and I can see the updates in the .git/config file, but git only tries to use the first one. Is there a way to get git to try to use all of the urls? I've tried both git fetch and git remote update, but neither tries anything after the first url. Note that I haven't tried this on linux yet, and I can't fix the computer name resolution as this is at work. Thanks

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  • Implementing search functionality with multiple optional parameters against database table.

    - by quarkX
    Hello, I would like to check if there is a preferred design pattern for implementing search functionality with multiple optional parameters against database table where the access to the database should be only via stored procedures. The targeted platform is .Net with SQL 2005, 2008 backend, but I think this is pretty generic problem. For example, we have customer table and we want to provide search functionality to the UI for different parameters, like customer Type, customer State, customer Zip, etc., and all of them are optional and can be selected in any combinations. In other words, the user can search by customerType only or by customerType, customerZIp or any other possible combinations. There are several available design approaches, but all of them have some disadvantages and I would like to ask if there is a preferred design among them or if there is another approach. Generate sql where clause sql statement dynamically in the business tier, based on the search request from the UI, and pass it to a stored procedure as parameter. Something like @Where = ‘where CustomerZip = 111111’ Inside the stored procedure generate dynamic sql statement and execute it with sp_executesql. Disadvantage: dynamic sql, sql injection Implement a stored procedure with multiple input parameters, representing the search fields from the UI, and use the following construction for selecting the records only for the requested fields in the where statement. WHERE (CustomerType = @CustomerType OR @CustomerType is null ) AND (CustomerZip = @CustomerZip OR @CustomerZip is null ) AND ………………………………………… Disadvantage: possible performance issue for the sql. 3.Implement separate stored procedure for each search parameter combinations. Disadvantage: The number of stored procedures will increase rapidly with the increase of the search parameters, repeated code.

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  • Game Networking Help Jmonkey SpiderMonkey

    - by user185812
    I have decided I think Jmonkey Engine will be best for my project, (an online RTS), but I have one question. If my game were to be successful (Yes I understand how slim the chances are, and how difficult this can be) I don't quite understand an aspect of networking. Do games like this require multiple servers, or only a single server? If multiple servers, I was unable to find anything regarding if Jmonkey's SpirderMonkey Networking supports this. (Something to allow equal distribution of traffic to multiple servers). UPDATE: I plan on using Jmonkey for my project. My Project is an online RTS, but with somewhat of an FPS twist. I am currently trying to figure out if the game has heavy traffic if having multiple servers to host the game is recommended. In addition to this, if using multiple hosting servers is supported in Jmonkey as I can't seem to find any documentation regarding it.

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  • Access violation in DirectX OMSetRenderTargets

    - by IDWMaster
    I receive the following error (Unhandled exception at 0x527DAE81 (d3d11_1sdklayers.dll) in Lesson2.Triangles.exe: 0xC0000005: Access violation reading location 0x00000000) when running the Triangle sample application for DirectX 11 in D3D_FEATURE_LEVEL_9_1. This error occurs at the OMSetRenderTargets function, as shown below, and does not happen if I remove that function from the program (but then, the screen is blue, and does not render the triangle) //// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF //// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO //// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A //// PARTICULAR PURPOSE. //// //// Copyright (c) Microsoft Corporation. All rights reserved #include #include #include "DirectXSample.h" #include "BasicMath.h" #include "BasicReaderWriter.h" using namespace Microsoft::WRL; using namespace Windows::UI::Core; using namespace Windows::Foundation; using namespace Windows::ApplicationModel::Core; using namespace Windows::ApplicationModel::Infrastructure; // This class defines the application as a whole. ref class Direct3DTutorialViewProvider : public IViewProvider { private: CoreWindow^ m_window; ComPtr m_swapChain; ComPtr m_d3dDevice; ComPtr m_d3dDeviceContext; ComPtr m_renderTargetView; public: // This method is called on application launch. void Initialize( _In_ CoreWindow^ window, _In_ CoreApplicationView^ applicationView ) { m_window = window; } // This method is called after Initialize. void Load(_In_ Platform::String^ entryPoint) { } // This method is called after Load. void Run() { // First, create the Direct3D device. // This flag is required in order to enable compatibility with Direct2D. UINT creationFlags = D3D11_CREATE_DEVICE_BGRA_SUPPORT; #if defined(_DEBUG) // If the project is in a debug build, enable debugging via SDK Layers with this flag. creationFlags |= D3D11_CREATE_DEVICE_DEBUG; #endif // This array defines the ordering of feature levels that D3D should attempt to create. D3D_FEATURE_LEVEL featureLevels[] = { D3D_FEATURE_LEVEL_11_1, D3D_FEATURE_LEVEL_11_0, D3D_FEATURE_LEVEL_10_1, D3D_FEATURE_LEVEL_10_0, D3D_FEATURE_LEVEL_9_3, D3D_FEATURE_LEVEL_9_1 }; ComPtr d3dDevice; ComPtr d3dDeviceContext; DX::ThrowIfFailed( D3D11CreateDevice( nullptr, // specify nullptr to use the default adapter D3D_DRIVER_TYPE_HARDWARE, nullptr, // leave as nullptr if hardware is used creationFlags, // optionally set debug and Direct2D compatibility flags featureLevels, ARRAYSIZE(featureLevels), D3D11_SDK_VERSION, // always set this to D3D11_SDK_VERSION &d3dDevice, nullptr, &d3dDeviceContext ) ); // Retrieve the Direct3D 11.1 interfaces. DX::ThrowIfFailed( d3dDevice.As(&m_d3dDevice) ); DX::ThrowIfFailed( d3dDeviceContext.As(&m_d3dDeviceContext) ); // After the D3D device is created, create additional application resources. CreateWindowSizeDependentResources(); // Create a Basic Reader-Writer class to load data from disk. This class is examined // in the Resource Loading sample. BasicReaderWriter^ reader = ref new BasicReaderWriter(); // Load the raw vertex shader bytecode from disk and create a vertex shader with it. auto vertexShaderBytecode = reader-ReadData("SimpleVertexShader.cso"); ComPtr vertexShader; DX::ThrowIfFailed( m_d3dDevice-CreateVertexShader( vertexShaderBytecode-Data, vertexShaderBytecode-Length, nullptr, &vertexShader ) ); // Create an input layout that matches the layout defined in the vertex shader code. // For this lesson, this is simply a float2 vector defining the vertex position. const D3D11_INPUT_ELEMENT_DESC basicVertexLayoutDesc[] = { { "POSITION", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 }, }; ComPtr inputLayout; DX::ThrowIfFailed( m_d3dDevice-CreateInputLayout( basicVertexLayoutDesc, ARRAYSIZE(basicVertexLayoutDesc), vertexShaderBytecode-Data, vertexShaderBytecode-Length, &inputLayout ) ); // Load the raw pixel shader bytecode from disk and create a pixel shader with it. auto pixelShaderBytecode = reader-ReadData("SimplePixelShader.cso"); ComPtr pixelShader; DX::ThrowIfFailed( m_d3dDevice-CreatePixelShader( pixelShaderBytecode-Data, pixelShaderBytecode-Length, nullptr, &pixelShader ) ); // Create vertex and index buffers that define a simple triangle. float3 triangleVertices[] = { float3(-0.5f, -0.5f,13.5f), float3( 0.0f, 0.5f,0), float3( 0.5f, -0.5f,0), }; D3D11_BUFFER_DESC vertexBufferDesc = {0}; vertexBufferDesc.ByteWidth = sizeof(float3) * ARRAYSIZE(triangleVertices); vertexBufferDesc.Usage = D3D11_USAGE_DEFAULT; vertexBufferDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER; vertexBufferDesc.CPUAccessFlags = 0; vertexBufferDesc.MiscFlags = 0; vertexBufferDesc.StructureByteStride = 0; D3D11_SUBRESOURCE_DATA vertexBufferData; vertexBufferData.pSysMem = triangleVertices; vertexBufferData.SysMemPitch = 0; vertexBufferData.SysMemSlicePitch = 0; ComPtr vertexBuffer; DX::ThrowIfFailed( m_d3dDevice-CreateBuffer( &vertexBufferDesc, &vertexBufferData, &vertexBuffer ) ); // Once all D3D resources are created, configure the application window. // Allow the application to respond when the window size changes. m_window-SizeChanged += ref new TypedEventHandler( this, &Direct3DTutorialViewProvider::OnWindowSizeChanged ); // Specify the cursor type as the standard arrow cursor. m_window-PointerCursor = ref new CoreCursor(CoreCursorType::Arrow, 0); // Activate the application window, making it visible and enabling it to receive events. m_window-Activate(); // Enter the render loop. Note that tailored applications should never exit. while (true) { // Process events incoming to the window. m_window-Dispatcher-ProcessEvents(CoreProcessEventsOption::ProcessAllIfPresent); // Specify the render target we created as the output target. ID3D11RenderTargetView* targets[1] = {m_renderTargetView.Get()}; m_d3dDeviceContext-OMSetRenderTargets( 1, targets, NULL // use no depth stencil ); // Clear the render target to a solid color. const float clearColor[4] = { 0.071f, 0.04f, 0.561f, 1.0f }; //Code fails here m_d3dDeviceContext-ClearRenderTargetView( m_renderTargetView.Get(), clearColor ); m_d3dDeviceContext-IASetInputLayout(inputLayout.Get()); // Set the vertex and index buffers, and specify the way they define geometry. UINT stride = sizeof(float3); UINT offset = 0; m_d3dDeviceContext-IASetVertexBuffers( 0, 1, vertexBuffer.GetAddressOf(), &stride, &offset ); m_d3dDeviceContext-IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST); // Set the vertex and pixel shader stage state. m_d3dDeviceContext-VSSetShader( vertexShader.Get(), nullptr, 0 ); m_d3dDeviceContext-PSSetShader( pixelShader.Get(), nullptr, 0 ); // Draw the cube. m_d3dDeviceContext-Draw(3,0); // Present the rendered image to the window. Because the maximum frame latency is set to 1, // the render loop will generally be throttled to the screen refresh rate, typically around // 60Hz, by sleeping the application on Present until the screen is refreshed. DX::ThrowIfFailed( m_swapChain-Present(1, 0) ); } } // This method is called before the application exits. void Uninitialize() { } private: // This method is called whenever the application window size changes. void OnWindowSizeChanged( _In_ CoreWindow^ sender, _In_ WindowSizeChangedEventArgs^ args ) { m_renderTargetView = nullptr; CreateWindowSizeDependentResources(); } // This method creates all application resources that depend on // the application window size. It is called at app initialization, // and whenever the application window size changes. void CreateWindowSizeDependentResources() { if (m_swapChain != nullptr) { // If the swap chain already exists, resize it. DX::ThrowIfFailed( m_swapChain-ResizeBuffers( 2, 0, 0, DXGI_FORMAT_R8G8B8A8_UNORM, 0 ) ); } else { // If the swap chain does not exist, create it. DXGI_SWAP_CHAIN_DESC1 swapChainDesc = {0}; swapChainDesc.Stereo = false; swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT; swapChainDesc.Scaling = DXGI_SCALING_NONE; swapChainDesc.Flags = 0; // Use automatic sizing. swapChainDesc.Width = 0; swapChainDesc.Height = 0; // This is the most common swap chain format. swapChainDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM; // Don't use multi-sampling. swapChainDesc.SampleDesc.Count = 1; swapChainDesc.SampleDesc.Quality = 0; // Use two buffers to enable flip effect. swapChainDesc.BufferCount = 2; // We recommend using this swap effect for all applications. swapChainDesc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL; // Once the swap chain description is configured, it must be // created on the same adapter as the existing D3D Device. // First, retrieve the underlying DXGI Device from the D3D Device. ComPtr dxgiDevice; DX::ThrowIfFailed( m_d3dDevice.As(&dxgiDevice) ); // Ensure that DXGI does not queue more than one frame at a time. This both reduces // latency and ensures that the application will only render after each VSync, minimizing // power consumption. DX::ThrowIfFailed( dxgiDevice-SetMaximumFrameLatency(1) ); // Next, get the parent factory from the DXGI Device. ComPtr dxgiAdapter; DX::ThrowIfFailed( dxgiDevice-GetAdapter(&dxgiAdapter) ); ComPtr dxgiFactory; DX::ThrowIfFailed( dxgiAdapter-GetParent( __uuidof(IDXGIFactory2), &dxgiFactory ) ); // Finally, create the swap chain. DX::ThrowIfFailed( dxgiFactory-CreateSwapChainForImmersiveWindow( m_d3dDevice.Get(), DX::GetIUnknown(m_window), &swapChainDesc, nullptr, // allow on all displays &m_swapChain ) ); } // Once the swap chain is created, create a render target view. This will // allow Direct3D to render graphics to the window. ComPtr backBuffer; DX::ThrowIfFailed( m_swapChain-GetBuffer( 0, __uuidof(ID3D11Texture2D), &backBuffer ) ); DX::ThrowIfFailed( m_d3dDevice-CreateRenderTargetView( backBuffer.Get(), nullptr, &m_renderTargetView ) ); // After the render target view is created, specify that the viewport, // which describes what portion of the window to draw to, should cover // the entire window. D3D11_TEXTURE2D_DESC backBufferDesc = {0}; backBuffer-GetDesc(&backBufferDesc); D3D11_VIEWPORT viewport; viewport.TopLeftX = 0.0f; viewport.TopLeftY = 0.0f; viewport.Width = static_cast(backBufferDesc.Width); viewport.Height = static_cast(backBufferDesc.Height); viewport.MinDepth = D3D11_MIN_DEPTH; viewport.MaxDepth = D3D11_MAX_DEPTH; m_d3dDeviceContext-RSSetViewports(1, &viewport); } }; // This class defines how to create the custom View Provider defined above. ref class Direct3DTutorialViewProviderFactory : IViewProviderFactory { public: IViewProvider^ CreateViewProvider() { return ref new Direct3DTutorialViewProvider(); } }; [Platform::MTAThread] int main(array^) { auto viewProviderFactory = ref new Direct3DTutorialViewProviderFactory(); Windows::ApplicationModel::Core::CoreApplication::Run(viewProviderFactory); return 0; }

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  • Independence Day for Software Components &ndash; Loosening Coupling by Reducing Connascence

    - by Brian Schroer
    Today is Independence Day in the USA, which got me thinking about loosely-coupled “independent” software components. I was reminded of a video I bookmarked quite a while ago of Jim Weirich’s “Grand Unified Theory of Software Design” talk at MountainWest RubyConf 2009. I finally watched that video this morning. I highly recommend it. In the video, Jim talks about software connascence. The dictionary definition of connascence (con-NAY-sense) is: 1. The common birth of two or more at the same time 2. That which is born or produced with another. 3. The act of growing together. The brief Wikipedia page about Connascent Software Components says that: Two software components are connascent if a change in one would require the other to be modified in order to maintain the overall correctness of the system. Connascence is a way to characterize and reason about certain types of complexity in software systems. The term was introduced to the software world in Meilir Page-Jones’ 1996 book “What Every Programmer Should Know About Object-Oriented Design”. The middle third of that book is the author’s proposed graphical notation for describing OO designs. UML became the standard about a year later, so a revised version of the book was published in 1999 as “Fundamentals of Object-Oriented Design in UML”. Weirich says that the third part of the book, in which Page-Jones introduces the concept of connascence “is worth the price of the entire book”. (The price of the entire book, by the way, is not much – I just bought a used copy on Amazon for $1.36, so that was a pretty low-risk investment. I’m looking forward to getting the book and learning about connascence from the original source.) Meanwhile, here’s my summary of Weirich’s summary of Page-Jones writings about connascence: The stronger the form of connascence, the more difficult and costly it is to change the elements in the relationship. Some of the connascence types, ordered from weak to strong are: Connascence of Name Connascence of name is when multiple components must agree on the name of an entity. If you change the name of a method or property, then you need to change all references to that method or property. Duh. Connascence of name is unavoidable, assuming your objects are actually used. My main takeaway about connascence of name is that it emphasizes the importance of giving things good names so you don’t need to go changing them later. Connascence of Type Connascence of type is when multiple components must agree on the type of an entity. I assume this is more of a problem for languages without compilers (especially when used in apps without tests). I know it’s an issue with evil JavaScript type coercion. Connascence of Meaning Connascence of meaning is when multiple components must agree on the meaning of particular values, e.g that “1” means normal customer and “2” means preferred customer. The solution to this is to use constants or enums instead of “magic” strings or numbers, which reduces the coupling by changing the connascence form from “meaning” to “name”. Connascence of Position Connascence of positions is when multiple components must agree on the order of values. This refers to methods with multiple parameters, e.g.: eMailer.Send("[email protected]", "[email protected]", "Your order is complete", "Order completion notification"); The more parameters there are, the stronger the connascence of position is between the component and its callers. In the example above, it’s not immediately clear when reading the code which email addresses are sender and receiver, and which of the final two strings are subject vs. body. Connascence of position could be improved to connascence of type by replacing the parameter list with a struct or class. This “introduce parameter object” refactoring might be overkill for a method with 2 parameters, but would definitely be an improvement for a method with 10 parameters. This points out two “rules” of connascence:  The Rule of Degree: The acceptability of connascence is related to the degree of its occurrence. The Rule of Locality: Stronger forms of connascence are more acceptable if the elements involved are closely related. For example, positional arguments in private methods are less problematic than in public methods. Connascence of Algorithm Connascence of algorithm is when multiple components must agree on a particular algorithm. Be DRY – Don’t Repeat Yourself. If you have “cloned” code in multiple locations, refactor it into a common function.   Those are the “static” forms of connascence. There are also “dynamic” forms, including… Connascence of Execution Connascence of execution is when the order of execution of multiple components is important. Consumers of your class shouldn’t have to know that they have to call an .Initialize method before it’s safe to call a .DoSomething method. Connascence of Timing Connascence of timing is when the timing of the execution of multiple components is important. I’ll have to read up on this one when I get the book, but assume it’s largely about threading. Connascence of Identity Connascence of identity is when multiple components must reference the entity. The example Weirich gives is when you have two instances of the “Bob” Employee class and you call the .RaiseSalary method on one and then the .Pay method on the other does the payment use the updated salary?   Again, this is my summary of a summary, so please be forgiving if I misunderstood anything. Once I get/read the book, I’ll make corrections if necessary and share any other useful information I might learn.   See Also: Gregory Brown: Ruby Best Practices Issue #24: Connascence as a Software Design Metric (That link is failing at the time I write this, so I had to go to the Google cache of the page.)

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  • VirtualBox - multiple guests, each with a single bridged adapter?

    - by Martin
    I am running a dedicated server (located at Hetzner, Germany) that runs VirtualBox in order to virtualize several services accross multiple virtual guests. Those guests are supposed to communicate with each other (for instance, a virtual web server has to access a virtual database server); to be reachable from the dedicated server (for instance, SSH access); and to access the Internet via the dedicated server (for instance, to download security updates) Currently, this is achieved by having host-only adapter vboxnet0 on the dedicated server and two virtual interfaces on each guest. There, virtual adapter eth0 is attached to vboxnet0 (to achieve (1) and (2)), virtual adapter eth1 is attached to VirtualBox' NAT (to achieve (3)). Via eth0, the guests have access to a DHCP and a DNS server, both running on the dedicated server (there, bound to vboxnet0). This allows me to assign custom IP addresses and names. Via eth1, VirtualBox pushes a proper route that enables each guest to access the Internet (via eth0 on the dedicated server). This setup with two virtual adapters frequently leads to problems and at leasts complicates many things. For instance, on the dedicated server there is OpenVPN which allows to access the virtual machines via the Internet; futhermore, there is Shorwall that controls the incoming and outgoing network traffic between the Internet, the dedicated server, and the individual virtual machines. Not to mention automatic installation of servers via PXE... Therefore, I would prefer to have only one single virtual adapter on each guest which would be used for both incoming and outgoing connections. As far as I understand, one would basically use a bridged interface for that very purpose. Now the question arises: Which interface on the dedicated server would the bridge use? eth0 on the host server is not an option, as this is prohibited by the provider. A virtual interface eth0:0 would not make any sense, as a bridge always uses a physical interface (eth0 in this case). Would it be possible to create a bridged interface in each virtual machine that would "dangle in the air"? Thus, without a complement on the dedicated server? How would I have to set up the routing on the host server? Please note that the host / dedicated server has only one network adapter (eth0) which is connected to the provider's network. Regards, Martin

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  • Can I use one virtualbox disk for multiple machines?

    - by mxp
    I'm not sure what search term to use and skimming through the VirtualBox manual didn't help me either, so I ask my two questions here... My setup is this: PC with dual boot into Windows 7 and a Debian operating system (both 64bit). I've created a virtual machine (Kubuntu, 64bit) under Windows and put it's VDI file on a SMB share of my NAS. Then I created a VM under linux using the same settings for memory etc and assigned the existing VDI file to it. My idea was that I could use that virtual machine from Windows and Linux as well. (1) Is this generally something that should work without problems? I noticed that snapshots get me into trouble because they appear to be not visible from the other operating system: The snapshots I took after installing the guest system are not visible under Linux. That's why I shut down the VM after usage and not save its state while it's running. My current problem is this: I have used the VM under Windows first, then under Linux. Now it will only start on Linux. When trying this on Windows the guest OS detects some kind of hard disk error and fails to boot because it cannot mount its drive. Obviously the virtual hard disk won't fail so it must have something to do with me using it under Linux. (2) How can I fix that? Update: It also looks like any changes I made in the VM under Linux have been reset by trying to boot it under Windows. Looks like it's back to the latest snapshot. I'm confused... Update The answer to my first question can be found below. In short: It works, as long as you don't use snapshots. The answer to my second question is this: Under Windows set the VM back to the latest snapshot and then discard the snapshot so it gets merged. There should be no snapshots left at the end. If you have multiple snapshots, discard the earliest ones first (Snapshot 1, then 2, 3, ...). I'm not sure what happens if you start at the end (.., 3, 2, 1). This of course leads to some data loss since you revert all changes since the last snapshot. But at least the VM is usable again.

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  • Blocking 'good' bots in nginx with multiple conditions for certain off-limits URL's where humans can go

    - by Glenn Plas
    After 2 days of searching/trying/failing I decided to post this here, I haven't found any example of someone doing the same nor what I tried seems to be working OK. I'm trying to send a 403 to bots not respecting the robots.txt file (even after downloading it several times). Specifically Googlebot. It will support the following robots.txt definition. User-agent: * Disallow: /*/*/page/ The intent is to allow Google to browse whatever they can find on the site but return a 403 for the following type of request. Googlebot seems to keep on nesting these links eternally adding paging block after block: my_domain.com:80 - 66.x.67.x - - [25/Apr/2012:11:13:54 +0200] "GET /2011/06/ page/3/?/page/2//page/3//page/2//page/3//page/2//page/2//page/4//page/4//pag e/1/&wpmp_switcher=desktop HTTP/1.1" 403 135 "-" "Mozilla/5.0 (compatible; G ooglebot/2.1; +http://www.google.com/bot.html)" It's a wordpress site btw. I don't want those pages to show up, even though after the robots.txt info got through, they stopped for a while only to begin crawling again later. It just never stops .... I do want real people to see this. As you can see, google get a 403 but when I try this myself in a browser I get a 404 back. I want browsers to pass. root@my_domain:# nginx -V nginx version: nginx/1.2.0 I tried different approaches, using a map and plain old nono if's and they both act the same: (under http section) map $http_user_agent $is_bot { default 0; ~crawl|Googlebot|Slurp|spider|bingbot|tracker|click|parser|spider 1; } (under the server section) location ~ /(\d+)/(\d+)/page/ { if ($is_bot) { return 403; # Please respect the robots.txt file ! } } I recently had to polish up my Apache skills for a client where I did about the same thing like this : # Block real Engines , not respecting robots.txt but allowing correct calls to pass # Google RewriteCond %{HTTP_USER_AGENT} ^Mozilla/5\.0\ \(compatible;\ Googlebot/2\.[01];\ \+http://www\.google\.com/bot\.html\)$ [NC,OR] # Bing RewriteCond %{HTTP_USER_AGENT} ^Mozilla/5\.0\ \(compatible;\ bingbot/2\.[01];\ \+http://www\.bing\.com/bingbot\.htm\)$ [NC,OR] # msnbot RewriteCond %{HTTP_USER_AGENT} ^msnbot-media/1\.[01]\ \(\+http://search\.msn\.com/msnbot\.htm\)$ [NC,OR] # Slurp RewriteCond %{HTTP_USER_AGENT} ^Mozilla/5\.0\ \(compatible;\ Yahoo!\ Slurp;\ http://help\.yahoo\.com/help/us/ysearch/slurp\)$ [NC] # block all page searches, the rest may pass RewriteCond %{REQUEST_URI} ^(/[0-9]{4}/[0-9]{2}/page/) [OR] # or with the wpmp_switcher=mobile parameter set RewriteCond %{QUERY_STRING} wpmp_switcher=mobile # ISSUE 403 / SERVE ERRORDOCUMENT RewriteRule .* - [F,L] # End if match This does a bit more than I asked nginx to do but it's about the same principle, I'm having a hard time figuring this out for nginx. So my question would be, why would nginx serve my browser a 404 ? Why isn't it passing, The regex isn't matching for my UA: "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.30 Safari/536.5" There are tons of example to block based on UA alone, and that's easy. It also looks like the matchin location is final, e.g. it's not 'falling' through for regular user, I'm pretty certain that this has some correlation with the 404 I get in the browser. As a cherry on top of things, I also want google to disregard the parameter wpmp_switcher=mobile , wpmp_switcher=desktop is fine but I just don't want the same content being crawled multiple times. Even though I ended up adding wpmp_switcher=mobile via the google webmaster tools pages (requiring me to sign up ....). that also stopped for a while but today they are back spidering the mobile sections. So in short, I need to find a way for nginx to enforce the robots.txt definitions. Can someone shell out a few minutes of their lives and push me in the right direction please ? I really appreciate ANY response that makes me think harder ;-)

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  • Ingame menu is not working correctly

    - by Johnny
    The ingame menu opens when the player presses Escape during the main game. If the player presses Y in the ingame menu, the game switches to the main menu. Up to here, everything works. But: On the other hand, if the player presses N in the ingame menu, the game should switch back to the main game(should resume the main game). But that doesn't work. The game just rests in the ingame menu if the player presses N. I set a breakpoint in this line of the Ingamemenu class: KeyboardState kbState = Keyboard.GetState(); CurrentSate/currentGameState and LastState/lastGameState have the same state: IngamemenuState. But LastState/lastGameState should not have the same state than CurrentSate/currentGameState. What is wrong? Why is the ingame menu not working correctly? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; IState lastState, currentState; public enum GameStates { IntroState = 0, MenuState = 1, MaingameState = 2, IngamemenuState = 3 } public void ChangeGameState(GameStates newState) { lastGameState = currentGameState; lastState = currentState; switch (newState) { case GameStates.IntroState: currentState = new Intro(this); currentGameState = GameStates.IntroState; break; case GameStates.MenuState: currentState = new Menu(this); currentGameState = GameStates.MenuState; break; case GameStates.MaingameState: currentState = new Maingame(this); currentGameState = GameStates.MaingameState; break; case GameStates.IngamemenuState: currentState = new Ingamemenu(this); currentGameState = GameStates.IngamemenuState; break; } currentState.Load(Content); } public void ChangeCurrentToLastGameState() { currentGameState = lastGameState; currentState = lastState; } public GameStates CurrentState { get { return currentGameState; } set { currentGameState = value; } } public GameStates LastState { get { return lastGameState; } set { lastGameState = value; } } private GameStates currentGameState = GameStates.IntroState; private GameStates lastGameState; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } protected override void Initialize() { ChangeGameState(GameStates.IntroState); base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); currentState.Load(Content); } protected override void Update(GameTime gameTime) { currentState.Update(gameTime); if ((lastGameState == GameStates.MaingameState) && (currentGameState == GameStates.IngamemenuState)) { lastState.Update(gameTime); } base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); if ((lastGameState == GameStates.MaingameState) && (currentGameState == GameStates.IngamemenuState)) { lastState.Render(spriteBatch); } currentState.Render(spriteBatch); spriteBatch.End(); base.Draw(gameTime); } } public interface IState { void Load(ContentManager content); void Update(GameTime gametime); void Render(SpriteBatch batch); } public class Intro : IState { Texture2D Titelbildschirm; private Game1 game1; public Intro(Game1 game) { game1 = game; } public void Load(ContentManager content) { Titelbildschirm = content.Load<Texture2D>("gruft"); } public void Update(GameTime gametime) { KeyboardState kbState = Keyboard.GetState(); if (kbState.IsKeyDown(Keys.Space)) game1.ChangeGameState(Game1.GameStates.MenuState); } public void Render(SpriteBatch batch) { batch.Draw(Titelbildschirm, new Rectangle(0, 0, 1280, 720), Color.White); } } public class Menu:IState { Texture2D Choosescreen; private Game1 game1; public Menu(Game1 game) { game1 = game; } public void Load(ContentManager content) { Choosescreen = content.Load<Texture2D>("menubild"); } public void Update(GameTime gametime) { KeyboardState kbState = Keyboard.GetState(); if (kbState.IsKeyDown(Keys.Enter)) game1.ChangeGameState(Game1.GameStates.MaingameState); if (kbState.IsKeyDown(Keys.Escape)) game1.Exit(); } public void Render(SpriteBatch batch) { batch.Draw(Choosescreen, new Rectangle(0, 0, 1280, 720), Color.White); } } public class Maingame : IState { Texture2D Spielbildschirm, axe; Vector2 position = new Vector2(100,100); private Game1 game1; public Maingame(Game1 game) { game1 = game; } public void Load(ContentManager content) { Spielbildschirm = content.Load<Texture2D>("hauszombie"); axe = content.Load<Texture2D>("axxx"); } public void Update(GameTime gametime) { KeyboardState keyboardState = Keyboard.GetState(); float delta = (float)gametime.ElapsedGameTime.TotalSeconds; position.X += 5 * delta; position.Y += 3 * delta; if (keyboardState.IsKeyDown(Keys.Escape)) game1.ChangeGameState(Game1.GameStates.IngamemenuState); } public void Render(SpriteBatch batch) { batch.Draw(Spielbildschirm, new Rectangle(0, 0, 1280, 720), Color.White); batch.Draw(axe, position, Color.White); } } public class Ingamemenu : IState { Texture2D Quitscreen; private Game1 game1; public Ingamemenu(Game1 game) { game1 = game; } public void Load(ContentManager content) { Quitscreen = content.Load<Texture2D>("quit"); } public void Update(GameTime gametime) { KeyboardState kbState = Keyboard.GetState(); if (kbState.IsKeyDown(Keys.Y)) game1.ChangeGameState(Game1.GameStates.MenuState); if (kbState.IsKeyDown(Keys.N)) game1.ChangeCurrentToLastGameState(); } public void Render(SpriteBatch batch) { batch.Draw(Quitscreen, new Rectangle(200, 200, 200, 200), Color.White); } }

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  • JSF f:event preRenderView is triggered by f:ajax calls and partial renders, something else?

    - by Andrew
    So we have an f:event: <f:metadata> <f:event type="preRenderView" listener="#{dashboardBacking.loadProjectListFromDB}"/> </f:metadata> Which is triggered as desired on initial page load (render). However this preRenderView event is also triggered by an ajax partial page render, which re-renders an h:panelgroup with the id projectListing, as below. <h:commandButton action="#{mrBean.addProject}" value="Create Project" title="Start a new project"> <f:ajax render="projectListing" /> </h:commandButton> I only want the dashboardBacking.loadProjectListFromDB to be called for the initial page render, but not when there is an ajax partial render. Is there a more appropriate event or method I could be using?

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  • How to target multiple versions of .NET Framework from MSBuild?

    - by McKAMEY
    I am improving the builds for an open source project which currently supports .NET Framework v2.0, v3.5, and now v4.0. Up until now, I've restricted myself to v2.0 to ensure compatibility, but with VS2010 I am interested in having real targeted builds. I'm looking for some guidance on how to edit the MSBuild csproj/sln to be able to cleanly produce builds for each target. I'm willing to have complexity in the csproj and in a batch file to control the build. My goal is to be able to have a command line script that could produce the builds without needing Visual Studio installed, but only the necessary .NET Framework(s). Ideally, I'd like to minimize dependencies on additional software. I notice that a lot of people use NAnt (e.g. Ninject builds many targets with NAnt) but I'm unsure if this is necessary or if they are just more familiar with it. I'm pretty sure this can be done but am having trouble finding a definitive guide on setting it up and best practices. Bonus: my next step after getting this set up will be to better support Mono Framework. Any help on doing this same thing for Mono would be much appreciated.

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  • How to merge two FBOs?

    - by DevDevDev
    OK so I have 4 buffers, 3 FBOs and a render buffer. Let me explain. I have a view FBO, which will store the scene before I render it to the render buffer. I have a background buffer, which contains the background of the scene. I have a user buffer, which the user manipulates. When the user makes some action I draw to the user buffer, using some blending. Then to redraw the whole scene what I want to do is clear the view buffer, draw the background buffer to the view buffer, change the blending, then draw the user buffer to the view buffer. Finally render the view buffer to the render buffer. However I can't figure out how to draw a FBO to another FBO. What I want to do is essentially merge and blend two FBOs, but I can't figure out how! I'm very new to OpenGL ES, so thanks for all the help.

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  • url template tag in django template

    - by user192048
    guys: I was trying to use the url template tag in django, but no lucky, I defined my urls.py like this urlpatterns = patterns('', url(r'^analyse/$', views.home, name="home"), url(r'^analyse/index.html', views.index, name="index"), url(r'^analyse/setup.html', views.setup, name="setup"), url(r'^analyse/show.html', views.show, name="show"), url(r'^analyse/generate.html', views.generate, name="generate"), I defined the url pattern in my view like this {% url 'show'%} then I got this error message Caught an exception while rendering: Reverse for ''show'' with arguments '()' and keyword arguments '{}' not found. Original Traceback (most recent call last): File "/Library/Python/2.5/site-packages/django/template/debug.py", line 71, in render_node result = node.render(context) File "/Library/Python/2.5/site-packages/django/template/defaulttags.py", line 155, in render nodelist.append(node.render(context)) File "/Library/Python/2.5/site-packages/django/template/defaulttags.py", line 382, in render raise e NoReverseMatch: Reverse for ''show'' with arguments '()' and keyword arguments '{}' not found. I am wondering why django failed to render? what is the right way to define it in the tempalte?

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  • Decorator for determining HTTP response from a view

    - by polera
    I want to create a decorator that will allow me to return a raw or "string" representation of a view if a GET parameter "raw" equals "1". The concept works, but I'm stuck on how to pass context to my renderer. Here's what I have so far: from django.shortcuts import render_to_response from django.http import HttpResponse from django.template.loader import render_to_string def raw_response(template): def wrap(view): def response(request,*args,**kwargs): if request.method == "GET": try: if request.GET['raw'] == "1": render = HttpResponse(render_to_string(template,{}),content_type="text/plain") return render except Exception: render = render_to_response(template,{}) return render return response return wrap Currently, the {} is there just as a place holder. Ultimately, I'd like to be able to pass a dict like this: @raw_response('my_template_name.html') def view_name(request): render({"x":42}) Any assistance is appreciated.

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