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  • Access php multidimensional array key based on a variable string

    - by ggirtsou
    I have stored the XML path to items in a string like this: response->items->item. What I need to do is to access an array called $xml_array like this: $xml_array['response']['items']['item'] When I write it in the code it works. The thing is that I want it to be done on the fly. I use this to convert response->items->item to ['response']['items']['item']: $xml_path = 'response->items->item'; $explode_path = explode('->', $xml_path); $correct_string = false; foreach($explode_path as $path) { $correct_string .= '[\''.$path.'\']'; } the problem is that I can't access $xml_array by doing this: $xml_array[$correct_string] So I end up with this: $xml_tag = 'title'; $xml_path = 'response->items->item'; $correct_string = '$items = $xml2array'; $explode_path = explode('->', $xml_path); foreach($explode_path as $path) { $correct_string .= '[\''.$path.'\']'; } $correct_string .= ';'; eval($correct_string); foreach($items as $item) { echo $item[$xml_tag].'<br />'; } and access the $xml_array array through $items array. Is there any way I can do this and avoid using eval()? Thanks in advance!

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  • Enable/Disable Input based on selection (jQuery)

    - by Nimbuz
    <select name="state" class="select" id="state"> <option value="something">Something</option> <option value="other">Other</option> </select> <input type="text" name="province" class="text" id="province" /> jQuery $('#state').change(function () { if ($('#state Other:selected').text() == "Other"){ $('#province').attr('disabled', false); alert(1); } else { alert(2); } }); Doesn't seem to work. I must be doing something wrong.

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  • Image switch based on if a layer is visible

    - by Zuno
    I have a website that contains multiple pages as layers (not as separate HTML files). I have three images: <img src="image1.png" onclick="showlayer(1);return false;" /> <br /> <img src="image2.png" onclick="showlayer(2);return false;" /> <br /> <img src="image3.png" onclick="showlayer(3);return false;" /> When an image is clicked, it shows the relevant layer and hides the others. I want it to also change the image to image1_active.png / image2_active.png / image3_active.png depending on which layer is visible (not via the onclick event handler). Why not via the onclick event handler?... Layer 1 is set as visible by default in the CSS, so image1 needs to be image1_active.png by default too - since the user has not had to click on anything yet, this is why I need the image switch to detect the layer's visibility/display to change the image. The showlayer script is: function showlayer(n){ for(i=1;i<=3;i++){document.getElementById("layer"+i).style.display="none";document.getElementById("layer"+n).style.display="block"; }} Is it possible to adapt this script for this purpose? thank you

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  • Information about how much time in spent in a function, based on the input of this function

    - by olchauvin
    Is there a (quantitative) tool to measure performance of functions based on its input? So far, the tools I used to measure performance of my code, tells me how much time I spent in functions (like Jetbrain Dottrace for .Net), but I'd like to have more information about the parameters passed to the function in order to know which parameters impact the most the performance. Let's say that I have function like that: int myFunction(int myParam1, int myParam 2) { // Do and return something based on the value of myParam1 and myParam2. // The code is likely to use if, for, while, switch, etc.... } If would like a tool that would allow me to tell me how much time is spent in myFunction based on the value of myParam1 and myParam2. For example, the tool would give me a result looking like this: For "myFunction" : value | value | Number of | Average myParam1 | myParam2 | call | time ---------|----------|-----------|-------- 1 | 5 | 500 | 301 ms 2 | 5 | 250 | 1253 ms 3 | 7 | 1268 | 538 ms ... That would mean that myFunction has been call 500 times with myParam1=1 and myParam2=5, and that with those parameters, it took on average 301ms to return a value. The idea behind that is to do some statistical optimization by organizing my code such that, the blocs of codes that are the most likely to be executed are tested before the one that are less likely to be executed. To put it bluntly, if I know which values are used the most, I can reorganize the if/while/for etc.. structure of the function (and the whole program) to optimize it. I'd like to find such tools for C++, Java or.Net. Note: I am not looking for technical tips to optimize the code (like passing parameters as const, inlining functions, initializing the capacity of vectors and the like).

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  • What .NET objects should I use to create a cookie based session in MVC?

    - by makerofthings7
    I'm writing a custom password reset application that uses a validation technique that doesn't fit cleanly with ASP.NET Membership Provider's challenge questions. Namely I need to invoke a workflow and collect information from the end user (backup phone number, email address) after the user logs in using a custom form. The only way I know to create a cookie-based session (without too much "innovation" on my part) is to use WIF. What other standard objects can I use with ASP.NET MVC to create an authenticated session that works with non-windows user stores? Ideally I can store "role" or claim information in the session object such as "admin", "departmentXadmin", "normalUser", or "restrictedUser" The workflow would look like this: User logs in with username and password If the username and pw are correct a (stateless) cookie based session is created The user gets redirected to a HTML form that allows them to enter their backup phone number (for SMS dual factor), or validate it if already set. The user can then change their password using the form provided The "forgot password" would look like this User requests OTP code to be sent to the phone User logs in using username and OTP If the OTP is valid and not expired then create a cookie based session and redirect to a form that allows password reset Show password reset form, and process results.

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  • Should I build a multi-threaded system that handles events from a game and sorts them, independently, into different threads based on priority?

    - by JonathonG
    Can I build a multi-threaded system that handles events from a game and sorts them, independently, into different threads based on priority, and is it a good idea? Here's more info: I am about to begin work on porting a mid-sized game from Flash/AS3 to Java so that I can continue development with multi-threading capabilities. Here's a small bit of background about the game: The game contains numerous asynchronous activities, such as "world updating" (the game environment is constantly changing based on a set of natural laws and forces), procedural generation of terrain, NPCs, quests, items, etc., and on top of that, the effects of all of the player's interactions with his environment are programmatically calculated in real time, based on a set of constantly changing "stats" and once again, natural laws and forces. All of these things going on at once, in an asynchronous manner, seem to lend themselves to multi-threading very well. My question is: Can I build some kind of central engine that handles the "stacking" of all of these events as they are triggered, and dynamically sorts them out amongst the available threads, and would it be a good idea? As an example: Essentially, every time something happens (IE, a magic missile being generated by a spell, or a bunch of plants need to grow to their next stage), instead of just processing that task right then and adding the new object(s) to a list of managed objects, send a reference to that event to a core "event handler" that throws it into a stack of all other currently queued events, which then sorts them out and orders them according to urgency, splits them between a number of available threads for as-fast-as-possible multithreaded execution.

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  • Intermittent Could not load file or assembly / PolicyExceptions

    - by Mark S. Rasmussen
    Intermittently we'll get errors like these from our .NET 3.5 web applications: Exception: System.Configuration.ConfigurationErrorsException: Could not load file or assembly 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418) (C:\Windows\Microsoft.NET\Framework64\v2.0.50727\Config\web.config line 59) ---> System.IO.FileLoadException: Could not load file or assembly 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418) File name: 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' ---> System.Security.Policy.PolicyException: Execution permission cannot be acquired. at System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission) at System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Int32& securitySpecialFlags, Boolean checkExecutionPermission) at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) at System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) at System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) at System.Reflection.Assembly.Load(String assemblyString) at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) --- End of inner exception stack trace --- at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) at System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() at System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) at System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() at System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) at System.Web.Compilation.WebDirectoryBatchCompiler..ctor(VirtualDirectory vdir) at System.Web.Compilation.BuildManager.BatchCompileWebDirectoryInternal(VirtualDirectory vdir, Boolean ignoreErrors) at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) at System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean noAssert) at System.Web.Compilation.BuildManager.GetCompiledType(String virtualPath) at System.Web.Script.Services.WebServiceData.GetWebServiceData(HttpContext context, String virtualPath, Boolean failIfNoData, Boolean pageMethods, Boolean inlineScript) at System.Web.Script.Services.RestHandler.CreateHandler(HttpContext context) at System.Web.Script.Services.ScriptHandlerFactory.GetHandler(HttpContext context, String requestType, String url, String pathTranslated) at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Inner exception: System.IO.FileLoadException: Could not load file or assembly 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418) File name: 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' ---> System.Security.Policy.PolicyException: Execution permission cannot be acquired. at System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission) at System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Int32& securitySpecialFlags, Boolean checkExecutionPermission) at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) at System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) at System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) at System.Reflection.Assembly.Load(String assemblyString) at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) web.config line 59 being: <add assembly="*"/> When these occur, the sites will YSOD untill we recycle the application pool. The sites may run for days/weeks before this occurs, or it might happen twice within the hour. I have not been able to pinpoint this to any specific request/function in our system. In this case it points to itextsharp, but it randomly points to any assembly referenced by our application, both internal and external. Running caspol verifies that the DLL has full trust permissions: C:\Windows\Microsoft.NET\Framework64\v2.0.50727>caspol -rsg D:\...\bin\itextsharp.dll Microsoft (R) .NET Framework CasPol 2.0.50727.3053 Copyright (c) Microsoft Corporation. All rights reserved. Level = Enterprise Code Groups: 1. All code: FullTrust Level = Machine Code Groups: 1. All code: Nothing 1.1. Zone - MyComputer: FullTrust Level = User Code Groups: 1. All code: FullTrust Success Our application is running on three servers, two of them are on Server 2008 Web x64 while the third is running Server 2008 R2 Web x64, all have .NET 3.5 installed, no .NET 4.0 installations. The problem only occurs on the first two that are running 2008 non R2. Running depends.exe on all three servers gives equal results for the nonR2 servers: My DLL is shown as x86 (compiled as AnyCPU, running in x64 w3wp), all other modules show as x64. Missing IESHIMS.DLL and LINKINFO.DLL - both of these seem to be red herrings according to Google. The third server shows the same, except it does not miss LINKINFO.DLL All servers are running IIS7 (7.5 for the R2 one) under a custom domain account that has been granted the necessary permissions: aspnet_regiis -ga [user] Load user profile is set to false on all three servers. I've tried setting this to true on one of the faulting servers, according to: http://stackoverflow.com/questions/1846816/iis7-failed-to-grant-minimum-permission-requests By running processmonitor I can see that it's now using the C:\Users\TEMP\AppData\Local\Temp directory for various temp files - the other ones are not using any such directory. So far I'll let it run in this way to see if this changes anything. I'm in doubt however given that the third server is not exhibiting the problems, yet still has "Load user profile" set to the same value, false. I've also tried running Fuslogvw on all three servers, logging binding failures to disk. All three servers report the same binding errors for VJSharpCodeProvider and CppCodeProvider, but these seem to be normal as well and can be solved by not defining the DEBUG and TRACE constants during build. We're running about 500 websites on each server (identical, load balanced), of which 50 are under moderate load, the problem has arisen both under heavy load as well as under minimal load however. Right now I'm waiting for the errors to happen again so I can hopefully see a pattern and determine whether "Load user profile" alleviates the issue. Any suggestions in the meantime would be very welcome! Also, I don't understand how the lack of "Load user profile" would cause an issue like this? And even further, how it would seemingly work on R2 but not on plain 2008? Thanks!

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  • W2k8, Sybase Driver, Permissions

    - by Clustermagnet
    Trying to get a .net (32bit) app running on a Windows 2008 server. My experience in the Windows world is quite limited. Is this related to the Full/Medium trust settings? Have been Googling for quite some time. Appreciate your feedback! Seeing the following error: Required permissions cannot be acquired. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Security.Policy.PolicyException: Required permissions cannot be acquired. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [PolicyException: Required permissions cannot be acquired.] System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission) +7606467 System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Int32& securitySpecialFlags, Boolean checkExecutionPermission) +57 [FileLoadException: Could not load file or assembly 'Sybase.Data.AseClient, Version=1.155.1000.0, Culture=neutral, PublicKeyToken=26e0f1529304f4a7' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)] System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +0 System.Reflection.Assembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +43 System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +127 System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +142 System.Reflection.Assembly.Load(String assemblyString) +28 System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +46 [ConfigurationErrorsException: Could not load file or assembly 'Sybase.Data.AseClient, Version=1.155.1000.0, Culture=neutral, PublicKeyToken=26e0f1529304f4a7' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)] System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +613 System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +203 System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +105 System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +178 System.Web.Compilation.WebDirectoryBatchCompiler..ctor(VirtualDirectory vdir) +163 System.Web.Compilation.BuildManager.BatchCompileWebDirectoryInternal(VirtualDirectory vdir, Boolean ignoreErrors) +53 System.Web.Compilation.BuildManager.BatchCompileWebDirectory(VirtualDirectory vdir, VirtualPath virtualDir, Boolean ignoreErrors) +175 System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) +86 System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) +261 System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile) +101 System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean noAssert) +126 System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp, Boolean noAssert) +62 System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) +33 System.Web.UI.PageHandlerFactory.GetHandler(HttpContext context, String requestType, String virtualPath, String path) +37 System.Web.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +307 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 Version Information: Microsoft .NET Framework Version:2.0.50727.4959; ASP.NET Version:2.0.50727.4955

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  • Unable to generate temporary class for web service

    - by sac
    I have an application with a proxy class for my webservice - This works fine in all 32-bit machines. However the same app throws an exception in windows server 2008 64-bit machine. It looks like the temporary class could not be generated for the web service. The error in the event viewer is "error CS0008: Unexpected error reading metadata from file '' -- 'Bad Key. ' Here's the call stack... at System.Xml.Serialization.Compiler.Compile(Assembly parent, String ns, XmlSerializerCompilerParameters xmlParameters, Evidence evidence) at System.Xml.Serialization.TempAssembly.GenerateAssembly(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, Evidence evidence, XmlSerializerCompilerParameters parameters, Assembly assembly, Hashtable assemblies) at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, String location, Evidence evidence) at System.Xml.Serialization.XmlSerializer.GetSerializersFromCache(XmlMapping[] mappings, Type type) at System.Xml.Serialization.XmlSerializer.FromMappings(XmlMapping[] mappings, Type type) at System.Web.Services.Protocols.SoapClientType..ctor(Type type) at System.Web.Services.Protocols.SoapHttpClientProtocol..ctor() at Fusion.ServiceCatalogProxy..ctor() I am not able to get any info about this bad key error....

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  • Scaling-out Your Services by Message Bus based WCF Transport Extension &ndash; Part 1 &ndash; Background

    - by Shaun
    Cloud computing gives us more flexibility on the computing resource, we can provision and deploy an application or service with multiple instances over multiple machines. With the increment of the service instances, how to balance the incoming message and workload would become a new challenge. Currently there are two approaches we can use to pass the incoming messages to the service instances, I would like call them dispatcher mode and pulling mode.   Dispatcher Mode The dispatcher mode introduces a role which takes the responsible to find the best service instance to process the request. The image below describes the sharp of this mode. There are four clients communicate with the service through the underlying transportation. For example, if we are using HTTP the clients might be connecting to the same service URL. On the server side there’s a dispatcher listening on this URL and try to retrieve all messages. When a message came in, the dispatcher will find a proper service instance to process it. There are three mechanism to find the instance: Round-robin: Dispatcher will always send the message to the next instance. For example, if the dispatcher sent the message to instance 2, then the next message will be sent to instance 3, regardless if instance 3 is busy or not at that moment. Random: Dispatcher will find a service instance randomly, and same as the round-robin mode it regardless if the instance is busy or not. Sticky: Dispatcher will send all related messages to the same service instance. This approach always being used if the service methods are state-ful or session-ful. But as you can see, all of these approaches are not really load balanced. The clients will send messages at any time, and each message might take different process duration on the server side. This means in some cases, some of the service instances are very busy while others are almost idle. For example, if we were using round-robin mode, it could be happened that most of the simple task messages were passed to instance 1 while the complex ones were sent to instance 3, even though instance 1 should be idle. This brings some problem in our architecture. The first one is that, the response to the clients might be longer than it should be. As it’s shown in the figure above, message 6 and 9 can be processed by instance 1 or instance 2, but in reality they were dispatched to the busy instance 3 since the dispatcher and round-robin mode. Secondly, if there are many requests came from the clients in a very short period, service instances might be filled by tons of pending tasks and some instances might be crashed. Third, if we are using some cloud platform to host our service instances, for example the Windows Azure, the computing resource is billed by service deployment period instead of the actual CPU usage. This means if any service instance is idle it is wasting our money! Last one, the dispatcher would be the bottleneck of our system since all incoming messages must be routed by the dispatcher. If we are using HTTP or TCP as the transport, the dispatcher would be a network load balance. If we wants more capacity, we have to scale-up, or buy a hardware load balance which is very expensive, as well as scaling-out the service instances. Pulling Mode Pulling mode doesn’t need a dispatcher to route the messages. All service instances are listening to the same transport and try to retrieve the next proper message to process if they are idle. Since there is no dispatcher in pulling mode, it requires some features on the transportation. The transportation must support multiple client connection and server listening. HTTP and TCP doesn’t allow multiple clients are listening on the same address and port, so it cannot be used in pulling mode directly. All messages in the transportation must be FIFO, which means the old message must be received before the new one. Message selection would be a plus on the transportation. This means both service and client can specify some selection criteria and just receive some specified kinds of messages. This feature is not mandatory but would be very useful when implementing the request reply and duplex WCF channel modes. Otherwise we must have a memory dictionary to store the reply messages. I will explain more about this in the following articles. Message bus, or the message queue would be best candidate as the transportation when using the pulling mode. First, it allows multiple application to listen on the same queue, and it’s FIFO. Some of the message bus also support the message selection, such as TIBCO EMS, RabbitMQ. Some others provide in memory dictionary which can store the reply messages, for example the Redis. The principle of pulling mode is to let the service instances self-managed. This means each instance will try to retrieve the next pending incoming message if they finished the current task. This gives us more benefit and can solve the problems we met with in the dispatcher mode. The incoming message will be received to the best instance to process, which means this will be very balanced. And it will not happen that some instances are busy while other are idle, since the idle one will retrieve more tasks to make them busy. Since all instances are try their best to be busy we can use less instances than dispatcher mode, which more cost effective. Since there’s no dispatcher in the system, there is no bottleneck. When we introduced more service instances, in dispatcher mode we have to change something to let the dispatcher know the new instances. But in pulling mode since all service instance are self-managed, there no extra change at all. If there are many incoming messages, since the message bus can queue them in the transportation, service instances would not be crashed. All above are the benefits using the pulling mode, but it will introduce some problem as well. The process tracking and debugging become more difficult. Since the service instances are self-managed, we cannot know which instance will process the message. So we need more information to support debug and track. Real-time response may not be supported. All service instances will process the next message after the current one has done, if we have some real-time request this may not be a good solution. Compare with the Pros and Cons above, the pulling mode would a better solution for the distributed system architecture. Because what we need more is the scalability, cost-effect and the self-management.   WCF and WCF Transport Extensibility Windows Communication Foundation (WCF) is a framework for building service-oriented applications. In the .NET world WCF is the best way to implement the service. In this series I’m going to demonstrate how to implement the pulling mode on top of a message bus by extending the WCF. I don’t want to deep into every related field in WCF but will highlight its transport extensibility. When we implemented an RPC foundation there are many aspects we need to deal with, for example the message encoding, encryption, authentication and message sending and receiving. In WCF, each aspect is represented by a channel. A message will be passed through all necessary channels and finally send to the underlying transportation. And on the other side the message will be received from the transport and though the same channels until the business logic. This mode is called “Channel Stack” in WCF, and the last channel in the channel stack must always be a transport channel, which takes the responsible for sending and receiving the messages. As we are going to implement the WCF over message bus and implement the pulling mode scaling-out solution, we need to create our own transport channel so that the client and service can exchange messages over our bus. Before we deep into the transport channel, let’s have a look on the message exchange patterns that WCF defines. Message exchange pattern (MEP) defines how client and service exchange the messages over the transportation. WCF defines 3 basic MEPs which are datagram, Request-Reply and Duplex. Datagram: Also known as one-way, or fire-forgot mode. The message sent from the client to the service, and no need any reply from the service. The client doesn’t care about the message result at all. Request-Reply: Very common used pattern. The client send the request message to the service and wait until the reply message comes from the service. Duplex: The client sent message to the service, when the service processing the message it can callback to the client. When callback the service would be like a client while the client would be like a service. In WCF, each MEP represent some channels associated. MEP Channels Datagram IInputChannel, IOutputChannel Request-Reply IRequestChannel, IReplyChannel Duplex IDuplexChannel And the channels are created by ChannelListener on the server side, and ChannelFactory on the client side. The ChannelListener and ChannelFactory are created by the TransportBindingElement. The TransportBindingElement is created by the Binding, which can be defined as a new binding or from a custom binding. For more information about the transport channel mode, please refer to the MSDN document. The figure below shows the transport channel objects when using the request-reply MEP. And this is the datagram MEP. And this is the duplex MEP. After investigated the WCF transport architecture, channel mode and MEP, we finally identified what we should do to extend our message bus based transport layer. They are: Binding: (Optional) Defines the channel elements in the channel stack and added our transport binding element at the bottom of the stack. But we can use the build-in CustomBinding as well. TransportBindingElement: Defines which MEP is supported in our transport and create the related ChannelListener and ChannelFactory. This also defines the scheme of the endpoint if using this transport. ChannelListener: Create the server side channel based on the MEP it’s. We can have one ChannelListener to create channels for all supported MEPs, or we can have ChannelListener for each MEP. In this series I will use the second approach. ChannelFactory: Create the client side channel based on the MEP it’s. We can have one ChannelFactory to create channels for all supported MEPs, or we can have ChannelFactory for each MEP. In this series I will use the second approach. Channels: Based on the MEPs we want to support, we need to implement the channels accordingly. For example, if we want our transport support Request-Reply mode we should implement IRequestChannel and IReplyChannel. In this series I will implement all 3 MEPs listed above one by one. Scaffold: In order to make our transport extension works we also need to implement some scaffold stuff. For example we need some classes to send and receive message though out message bus. We also need some codes to read and write the WCF message, etc.. These are not necessary but would be very useful in our example.   Message Bus There is only one thing remained before we can begin to implement our scaling-out support WCF transport, which is the message bus. As I mentioned above, the message bus must have some features to fulfill all the WCF MEPs. In my company we will be using TIBCO EMS, which is an enterprise message bus product. And I have said before we can use any message bus production if it’s satisfied with our requests. Here I would like to introduce an interface to separate the message bus from the WCF. This allows us to implement the bus operations by any kinds bus we are going to use. The interface would be like this. 1: public interface IBus : IDisposable 2: { 3: string SendRequest(string message, bool fromClient, string from, string to = null); 4:  5: void SendReply(string message, bool fromClient, string replyTo); 6:  7: BusMessage Receive(bool fromClient, string replyTo); 8: } There are only three methods for the bus interface. Let me explain one by one. The SendRequest method takes the responsible for sending the request message into the bus. The parameters description are: message: The WCF message content. fromClient: Indicates if this message was came from the client. from: The channel ID that this message was sent from. The channel ID will be generated when any kinds of channel was created, which will be explained in the following articles. to: The channel ID that this message should be received. In Request-Reply and Duplex MEP this is necessary since the reply message must be received by the channel which sent the related request message. The SendReply method takes the responsible for sending the reply message. It’s very similar as the previous one but no “from” parameter. This is because it’s no need to reply a reply message again in any MEPs. The Receive method takes the responsible for waiting for a incoming message, includes the request message and specified reply message. It returned a BusMessage object, which contains some information about the channel information. The code of the BusMessage class is 1: public class BusMessage 2: { 3: public string MessageID { get; private set; } 4: public string From { get; private set; } 5: public string ReplyTo { get; private set; } 6: public string Content { get; private set; } 7:  8: public BusMessage(string messageId, string fromChannelId, string replyToChannelId, string content) 9: { 10: MessageID = messageId; 11: From = fromChannelId; 12: ReplyTo = replyToChannelId; 13: Content = content; 14: } 15: } Now let’s implement a message bus based on the IBus interface. Since I don’t want you to buy and install the TIBCO EMS or any other message bus products, I will implement an in process memory bus. This bus is only for test and sample purpose. It can only be used if the service and client are in the same process. Very straightforward. 1: public class InProcMessageBus : IBus 2: { 3: private readonly ConcurrentDictionary<Guid, InProcMessageEntity> _queue; 4: private readonly object _lock; 5:  6: public InProcMessageBus() 7: { 8: _queue = new ConcurrentDictionary<Guid, InProcMessageEntity>(); 9: _lock = new object(); 10: } 11:  12: public string SendRequest(string message, bool fromClient, string from, string to = null) 13: { 14: var entity = new InProcMessageEntity(message, fromClient, from, to); 15: _queue.TryAdd(entity.ID, entity); 16: return entity.ID.ToString(); 17: } 18:  19: public void SendReply(string message, bool fromClient, string replyTo) 20: { 21: var entity = new InProcMessageEntity(message, fromClient, null, replyTo); 22: _queue.TryAdd(entity.ID, entity); 23: } 24:  25: public BusMessage Receive(bool fromClient, string replyTo) 26: { 27: InProcMessageEntity e = null; 28: while (true) 29: { 30: lock (_lock) 31: { 32: var entity = _queue 33: .Where(kvp => kvp.Value.FromClient == fromClient && (kvp.Value.To == replyTo || string.IsNullOrWhiteSpace(kvp.Value.To))) 34: .FirstOrDefault(); 35: if (entity.Key != Guid.Empty && entity.Value != null) 36: { 37: _queue.TryRemove(entity.Key, out e); 38: } 39: } 40: if (e == null) 41: { 42: Thread.Sleep(100); 43: } 44: else 45: { 46: return new BusMessage(e.ID.ToString(), e.From, e.To, e.Content); 47: } 48: } 49: } 50:  51: public void Dispose() 52: { 53: } 54: } The InProcMessageBus stores the messages in the objects of InProcMessageEntity, which can take some extra information beside the WCF message itself. 1: public class InProcMessageEntity 2: { 3: public Guid ID { get; set; } 4: public string Content { get; set; } 5: public bool FromClient { get; set; } 6: public string From { get; set; } 7: public string To { get; set; } 8:  9: public InProcMessageEntity() 10: : this(string.Empty, false, string.Empty, string.Empty) 11: { 12: } 13:  14: public InProcMessageEntity(string content, bool fromClient, string from, string to) 15: { 16: ID = Guid.NewGuid(); 17: Content = content; 18: FromClient = fromClient; 19: From = from; 20: To = to; 21: } 22: }   Summary OK, now I have all necessary stuff ready. The next step would be implementing our WCF message bus transport extension. In this post I described two scaling-out approaches on the service side especially if we are using the cloud platform: dispatcher mode and pulling mode. And I compared the Pros and Cons of them. Then I introduced the WCF channel stack, channel mode and the transport extension part, and identified what we should do to create our own WCF transport extension, to let our WCF services using pulling mode based on a message bus. And finally I provided some classes that need to be used in the future posts that working against an in process memory message bus, for the demonstration purpose only. In the next post I will begin to implement the transport extension step by step.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • How to store Role Based Access rights in web application?

    - by JonH
    Currently working on a web based CRM type system that deals with various Modules such as Companies, Contacts, Projects, Sub Projects, etc. A typical CRM type system (asp.net web form, C#, SQL Server backend). We plan to implement role based security so that basically a user can have one or more roles. Roles would be broken down by first the module type such as: -Company -Contact And then by the actions for that module for instance each module would end up with a table such as this: Role1 Example: Module Create Edit Delete View Company Yes Owner Only No Yes Contact Yes Yes Yes Yes In the above case Role1 has two module types (Company, and Contact). For company, the person assigned to this role can create companies, can view companies, can only edit records he/she created and cannot delete. For this same role for the module contact this user can create contacts, edit contacts, delete contacts, and view contacts (full rights basically). I am wondering is it best upon coming into the system to session the user's role with something like a: List<Role> roles; Where the Role class would have some sort of List<Module> modules; (can contain Company, Contact, etc.).? Something to the effect of: class Role{ string name; string desc; List<Module> modules; } And the module action class would have a set of actions (Create, Edit, Delete, etc.) for each module: class ModuleActions{ List<Action> actions; } And the action has a value of whether the user can perform the right: class Action{ string right; } Just a rough idea, I know the action could be an enum and the ModuleAction can probably be eliminated with a List<x, y>. My main question is what would be the best way to store this information in this type of application: Should I store it in the User Session state (I have a session class where I manage things related to the user). I generally load this during the initial loading of the application (global.asax). I can simply tack onto this session. Or should this be loaded at the page load event of each module (page load of company etc..). I eventually need to be able to hide / unhide various buttons / divs based on the user's role and that is what got me thinking to load this via session. Any examples or points would be great.

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  • Is there a modern (eg NoSQL) web analytics solution based on log files?

    - by Martin
    I have been using Awstats for many years to process my log files. But I am missing many possibilities (like cross-domain reports) and I hate being stuck with extra fields I created years ago. Anyway, I am not going to continue to use this script. Is there a modern apache logs analytics solution based on modern storage technologies like NoSQL or at least somehow ready to cope with large datasets efficiently? I am primarily looking for something that generates nice sortable and searchable outputs with the focus on web analytics, before having to write my own frontends. (so graylog2 is not an option) This question is purely about log file based solutions.

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  • Are there any Java based libraries that provide game mapping features?

    - by James.Elsey
    Hi All, I'm working on a Java web based game in my spare time (springMVC / JSPs etc), and I'm wondering what are my options for dealing with the "game world" or mapping element. My game will be 2d / text based, so I have no need for any OpenGL / Flash etc. My initial idea was to use Google maps and provide a custom overlay, but I want to know if there are any alternatives? For example, if I create a 2d map with all my zones, are there any libraries that will help me plot players, work out distances and so forth? Regards

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  • How can I use WebGL to create a tile-based multi-layer scrolling platform game?

    - by Nicholas Hill
    I've found WebGL (based on OpenGL) to be a fiendish and unforgiving framework for those learning to write HTML5-based games. Despite the presence of many examples on how to get started, I'm really struggling to understand how I could simply load a bunch of images and render them to a canvas quickly using WebGL. My specific scenario involves trying to render a map using a bespoke but simple multi-layered tile engine, where each value in a three dimensional array points to the image to use for that location in the rendered image. Think "Sonic the Hedgehog" via tilesets, tiles, maps, layers, sprites etc. Can anyone enlighten me: 1) How can I load an image that I can use as a texture in WebGL? 2) How can I dynamically select an image at run time and draw it at any co-ordinate, that I also select at run time?

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  • Can WebGL be used to create a tile-based multi-layer scrolling platform game?

    - by Nicholas Hill
    I've found WebGL (based on OpenGL) to be a fiendish and unforgiving framework for those learning to write HTML5-based games. Despite the presence of many examples on how to get started, I'm really struggling to understand how I could simply load a bunch of images and render them to a canvas quickly using WebGL. My specific scenario involves trying to render a map using a bespoke but simple multi-layered tile engine, where each value in a three dimensional array points to the image to use for that location in the rendered image. Think "Sonic the Hedgehog" via tilesets, tiles, maps, layers, sprites etc. Can anyone enlighten me: 1) How can I load an image that I can use as a texture in WebGL? 2) How can I dynamically select an image at run time and draw it at any co-ordinate, that I also select at run time?

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  • How are design-by-contract and property-based testing (QuickCheck) related?

    - by Todd Owen
    Is their only similarity the fact that they are not xUnit (or more precisely, not based on enumerating specific test cases), or is it deeper than that? Property-based testing (using QuickCheck, ScalaCheck, etc) seem well-suited to a functional programming style where side-effects are avoided. On the other hand, Design by Contract (as implemented in Eiffel) is more suited to OOP languages: you can express post-conditions about the effects of methods, not just their return values. But both of them involve testing assertions that are true in general (rather than assertions that should be true for a specific test case). And both can be tested using randomly generated inputs (with QuickCheck this is the only way, whereas with Eiffel I believe it is an optional feature of the AutoTest tool). Is there an umbrella term to encompass both approaches? Or am I imagining a relationship that doesn't really exist.

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  • Are VM-based languages becoming viable for Graphics since the move to GPU computing?

    - by skiwi
    Perhaps the title is not the most clear, so let me elaborate it more: I am talking about VM-based languages, by that I mean languages that run on the JVM (java) and for example C#. Also I am talking about 3D graphics, just to be clear. Lately the trend has been that most computing is being done on the GPU and not on the CPU, and since times the issue with programming games on a VM-based language is that garbage collecting may happen randomly. So let's take a look which is responsible for what: Showing the graphics: GPU Uploading graphics to the GPU: CPU? Needs to be done every frame? Calculating physics constraints: GPU Doing the real game logic (Determining when to move objects (independent of physics calculations), processing AI): CPU Is my list actually correct? And if it is, is for example Java becoming more viable? Or is uploading the graphics (vertices) still the most expensive operation? Would like to get more insight into this.

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  • Which Git-based MIS to track workflow like Trac/Redmine but on console minimastically?

    - by hhh
    Definitions MIS = management information system Some list about console based solutions here and some GUI-hacks here. Been fed up to install all those dependencies and no make -files with GUI -things so which console-based MIS would you suggest for a game-development team with graphical -repo, animation -repo, code -repo, stories -repo, etc ? P.s. I do use Git -submodules and the reason for repo -fragmentation is due to roles and size, certain repos such as graphic -repos tend to be quite large so better to keep them separate. Perhaps useful to readers interested about this http://stackoverflow.com/questions/5881578/trac-vs-redmine https://github.com/jchris/sofa

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  • Why does the use of interface-based programming appear to be limited to behaviour?

    - by Carnotaurus
    I have been doing a little thinking about inheritance vs. realization vs. composition. I am not about to post the whole detail here. So I was wondering, when are not talking about supporting unit testing: Why does interface-based programming seem to focus upon the grouping of common behaviour, e.g., IPettable (for an animal), IEditable (for a user control), ISubmitable (for a form), etc. Why does the use of interface-based programming appear to be limited to behaviour when we could pragmatically group not so much on behaviour but on commonsense physical similarities which could have nothing to do with behaviour? It is not that there is some limiting feature within OOP; so how come?

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  • How to resolve IPs in DNS based on the subnet of the requesting client?

    - by Nohsib
    Is it possible to configure Bind9 or other DNS to resolve the domain name of a machine into different IPs based on the subnet of the requesting client? e.g. Say the same service is running on 2 different application servers at different geographical points and based on the incoming request to resolve the domain name, the name server provides the IP of the application server based on the requesting client's IP, so the service could be offered by servers that are geographically closer to the client. In short, something like a CDN but just the IP resolution part based on the client's subnet. Is this configurable in any DNS?

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  • How do I configure VMware View location-based printing to use Active Directory Groups?

    - by Jason Pearce
    I am attempting to configure VMware View 4.5's Location-Based Printing, which leverages an included OEM version of ThinPrint, to assign printers to active directory groups. The location-based printing feature maps printers that are physically near client systems to VMware View desktops. I am using the Active Directory group policy setting AutoConnect Location-based Printing for VMware View, which is located in the Microsoft Group Policy Object Editor in the Software Settings folder under Computer Configuration. The AutoConnect Location-based Printing for VMware View appearst to be just a name translation table. It permits me to assign a specific printer or printers to an IP Range, Client Name, Mac Address, User, or User Group. I'm attempting to assign printers to active directory user groups. I have created a new active directory group for each printer that I intend to use in VMware View desktop pools. I will then assign active directory users to the active directory groups that represent each network printer. Example: doej is a member of the PTR-FLOOR2-NORTH-ROOM255 active directory group. Using AutoConnect, I assigned the group to receive a network printer by adding PTR-FLOOR2-NORTH-ROOM255 in the User/Group column. Problem: When doej logs in to his VDI session, the printer is not present. However, if I use a wildcard "*" in the User/Group column instead of the specific PTR-FLOOR2-NORTH-ROOM255 active directory group, the printer is present and functions as designed. Alternatives: I have tried assigning printers to active directory groups within AutoConnect in the following ways, all unsuccesfull: PTR-FLOOR2-NORTH-ROOM255 domainexample\PTR-FLOOR2-NORTH-ROOM255 domainexample.local\PTR-FLOOR2-NORTH-ROOM255 Confirmation: The information used to map the printer to the VMware View desktop is stored in a registry entry on the View desktop in HKEY_LOCAL_MACHINE\SOFTWARE\Policies\thinprint\tpautoconnect. For each of these examples, I have reviewed the registry entry and can confirm that the desktop is receiving the information from the AutoConnect translation table. Summary: Can anyone provide an example of how to configure VMware View 4.5's Location-Based Printing so that I may assign network printers to active directory groups via the included AutoConnect tool? I would welcome a clear example of a working configuration. Thank you.

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  • Does Zend application server provide any sort of pushed-based messaging architecture support?

    - by Alex
    Does Zend application server provide any sort of pushed-based messaging architecture support?I mean some different message-oriented middlewares that can be used for the push-based architecture or email support?There is a need in provision of the non web-based interface for certain users of the website who would get regular messages notifying them of different special offers in their field of interest(it should be push-based)

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