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• C# Serialization Surrogate - Cannot access a disposed object

  - by crushhawk

  I have an image class (VisionImage) that is a black box to me. I'm attempting to serialize the image object to file using Serialization Surrogates as explained on this page. Below is my surrogate code. sealed class VisionImageSerializationSurrogate : ISerializationSurrogate { public void GetObjectData(Object obj, SerializationInfo info, StreamingContext context) { VisionImage image = (VisionImage)obj; byte[,] temp = image.ImageToArray().U8; info.AddValue("width", image.Width); info.AddValue("height", image.Height); info.AddValue("pixelvalues", temp, temp.GetType()); } public Object SetObjectData(Object obj, SerializationInfo info, StreamingContext context, ISurrogateSelector selector) { VisionImage image = (VisionImage)obj; Int32 width = info.GetInt32("width"); Int32 height = info.GetInt32("height"); byte[,] temp = new byte[height, width]; temp = (byte[,])info.GetValue("pixelvalues", temp.GetType()); PixelValue2D tempPixels = new PixelValue2D(temp); image.ArrayToImage(tempPixels); return image; } } I've stepped through it to write to binary. It seems to be working fine (file is getting bigger as the images are captured). I tried to test it read the file back in. The values read back in are correct as far as the "info" object is concerned. When I get to the line image.ArrayToImage(tempPixels); It throws the "Cannot access a disposed object" exception. Upon further inspection, the object and the resulting image are both marked as disposed. My code behind the form spawns an "acquisitionWorker" and runs the following code. void acquisitionWorker_LoadImages(object sender, DoWorkEventArgs e) { // This is the main function of the acquisition background worker thread. // Perform image processing here instead of the UI thread to avoid a // sluggish or unresponsive UI. BackgroundWorker worker = (BackgroundWorker)sender; try { uint bufferNumber = 0; // Loop until we tell the thread to cancel or we get an error. When this // function completes the acquisitionWorker_RunWorkerCompleted method will // be called. while (!worker.CancellationPending) { VisionImage savedImage = (VisionImage) formatter.Deserialize(fs); CommonAlgorithms.Copy(savedImage, imageViewer.Image); // Update the UI by calling ReportProgress on the background worker. // This will call the acquisition_ProgressChanged method in the UI // thread, where it is safe to update UI elements. Do not update UI // elements directly in this thread as doing so could result in a // deadlock. worker.ReportProgress(0, bufferNumber); bufferNumber++; } } catch (ImaqException ex) { // If an error occurs and the background worker thread is not being // cancelled, then pass the exception along in the result so that // it can be handled in the acquisition_RunWorkerCompleted method. if (!worker.CancellationPending) e.Result = ex; } } What am I missing here? Why would the object be immediately disposed?

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• Haskell data serialization of some data implementing a common type class

  - by Evan

  Let's start with the following data A = A String deriving Show data B = B String deriving Show class X a where spooge :: a -> Q [ Some implementations of X for A and B ] Now let's say we have custom implementations of show and read, named show' and read' respectively which utilize Show as a serialization mechanism. I want show' and read' to have types show' :: X a => a -> String read' :: X a => String -> a So I can do things like f :: String -> [Q] f d = map (\x -> spooge $ read' x) d Where data could have been [show' (A "foo"), show' (B "bar")] In summary, I wanna serialize stuff of various types which share a common typeclass so I can call their separate implementations on the deserialized stuff automatically. Now, I realize you could write some template haskell which would generate a wrapper type, like data XWrap = AWrap A | BWrap B deriving (Show) and serialize the wrapped type which would guarantee that the type info would be stored with it, and that we'd be able to get ourselves back at least an XWrap... but is there a better way using haskell ninja-ery? EDIT Okay I need to be more application specific. This is an API. Users will define their As, and Bs and fs as they see fit. I don't ever want them hacking through the rest of the code updating their XWraps, or switches or anything. The most i'm willing to compromise is one list somewhere of all the A, B, etc. in some format. Why? Here's the application. A is "Download a file from an FTP server." B is "convert from flac to mp3". A contains username, password, port, etc. information. B contains file path information. A and B are Xs, and Xs shall be called "Tickets." Q is IO (). Spooge is runTicket. I want to read the tickets off into their relevant data types and then write generic code that will runTicket on the stuff read' from the stuff on disk. At some point I have to jam type information into the serialized data.

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• Unable to host WCF service correctly in IIS7

  - by user206736

  I have a WCF Service library written in .NET 4.0. I have a WCF application (in order to host this service in IIS) within the same solution. It contains the WCF library assembly reference and a service.svc file pointing to the service from the library along with a web.config that is a replica of the WCF service library's app.config. The WCF application is set to host the service in IIS7 (the virtual directory has been set). The same solution contains an ASP.NET Webforms solution to which I have added a service reference pointing to the WCF service I hosted in IIS (as mentioned). When i start an instance of this ASP.NET Web application, I get a message saying that "The WCF service has been hosted" and the ASP.NET application can access the data from it correctly. However, when i try and access this data via a service reference added to an MVC 2 Web Application on the same machine in a different solution (pointing to the service hosted in IIS), I get a "The remote server returned an error: (405) Method Not Allowed." protocol exception . However, the MVC application is able to access the service data if I manually invoke an instance of the WCF Application that I was using to host the WCF Service Library from the other solution. I am using VS2010 Beta 2 as my development IDE. I have been stuck with this issue for a while now. Any help would be appreciated. My service config is as follows:- <system.serviceModel> <services> <service behaviorConfiguration="CruxServices.BasicSearchServiceBehavior" name="CruxServices.BasicSearch.BasicSearch"> <endpoint address="" binding="wsHttpBinding" name="WSBindingEndpoint" bindingConfiguration="WSBindingConfig" contract="CruxServices.BasicSearch.Interfaces.IPropertyListFilter"> <identity> <dns value="localhost" /> </identity> </endpoint> <endpoint address="mex" binding="mexHttpBinding" name="MexEndpoint" contract="IMetadataExchange" /> <host> <baseAddresses> <add baseAddress="http://localhost/CruxServices" /> </baseAddresses> </host> </service> </services> <behaviors> <serviceBehaviors> <behavior name="CruxServices.BasicSearchServiceBehavior"> <serviceMetadata httpGetEnabled="true" /> <serviceDebug includeExceptionDetailInFaults="false" /> </behavior> </serviceBehaviors> </behaviors> <bindings> <wsHttpBinding> <binding name="WSBindingConfig"> <security mode="None"> <transport clientCredentialType="None"/> <message establishSecurityContext="false"/> </security> </binding> </wsHttpBinding> </bindings>

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• Control XML serialization of generic types

  - by Luca

  I'm investigating about XML serialization, and since I use lot of dictionary, I would like to serialize them as well. I found the following solution for that (I'm quite proud of it! :) ). [XmlInclude(typeof(Foo))] public class XmlDictionary<TKey, TValue> { /// <summary> /// Key/value pair. /// </summary> public struct DictionaryItem { /// <summary> /// Dictionary item key. /// </summary> public TKey Key; /// <summary> /// Dictionary item value. /// </summary> public TValue Value; } /// <summary> /// Dictionary items. /// </summary> public DictionaryItem[] Items { get { List<DictionaryItem> items = new List<DictionaryItem>(ItemsDictionary.Count); foreach (KeyValuePair<TKey, TValue> pair in ItemsDictionary) { DictionaryItem item; item.Key = pair.Key; item.Value = pair.Value; items.Add(item); } return (items.ToArray()); } set { ItemsDictionary = new Dictionary<TKey,TValue>(); foreach (DictionaryItem item in value) ItemsDictionary.Add(item.Key, item.Value); } } /// <summary> /// Indexer base on dictionary key. /// </summary> /// <param name="key"></param> /// <returns></returns> public TValue this[TKey key] { get { return (ItemsDictionary[key]); } set { Debug.Assert(value != null); ItemsDictionary[key] = value; } } /// <summary> /// Delegate for get key from a dictionary value. /// </summary> /// <param name="value"></param> /// <returns></returns> public delegate TKey GetItemKeyDelegate(TValue value); /// <summary> /// Add a range of values automatically determining the associated keys. /// </summary> /// <param name="values"></param> /// <param name="keygen"></param> public void AddRange(IEnumerable<TValue> values, GetItemKeyDelegate keygen) { foreach (TValue v in values) ItemsDictionary.Add(keygen(v), v); } /// <summary> /// Items dictionary. /// </summary> [XmlIgnore] public Dictionary<TKey, TValue> ItemsDictionary = new Dictionary<TKey,TValue>(); } The classes deriving from this class are serialized in the following way: <XmlProcessList xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Items> <DictionaryItemOfInt32Foo> <Key/> <Value/> </DictionaryItemOfInt32XmlProcess> <Items> This give me a good solution, but: How can I control the name of the element DictionaryItemOfInt32Foo What happens if I define a Dictionary<FooInt32, Int32> and I have the classes Foo and FooInt32? Is it possible to optimize the class above? THank you very much!

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• Node Serialization in NetBeans Platform 7.0

  - by Geertjan

  Node serialization makes sense when you're not interested in the data (since that should be serialized to a database), but in the state of the application. For example, when the application restarts, you want the last selected node to automatically be selected again. That's not the kind of information you'll want to store in a database, hence node serialization is not about data serialization but about application state serialization. I've written about this topic in October 2008, here and here, but want to show how to do this again, using NetBeans Platform 7.0. Somewhere I remember reading that this can't be done anymore and that's typically the best motivation for me, i.e., to prove that it can be done after all. Anyway, in a standard POJO/Node/BeanTreeView scenario, do the following: Remove the "@ConvertAsProperties" annotation at the top of the class, which you'll find there if you used the Window Component wizard. We're not going to use property-file based serialization, but plain old java.io.Serializable  instead. In the TopComponent, assuming it is named "UserExplorerTopComponent", typically at the end of the file, add the following: @Override public Object writeReplace() { //We want to work with one selected item only //and thanks to BeanTreeView.setSelectionMode, //only one node can be selected anyway: Handle handle = NodeOp.toHandles(em.getSelectedNodes())[0]; return new ResolvableHelper(handle); } public final static class ResolvableHelper implements Serializable { private static final long serialVersionUID = 1L; public Handle selectedHandle; private ResolvableHelper(Handle selectedHandle) { this.selectedHandle = selectedHandle; } public Object readResolve() { WindowManager.getDefault().invokeWhenUIReady(new Runnable() { @Override public void run() { try { //Get the TopComponent: UserExplorerTopComponent tc = (UserExplorerTopComponent) WindowManager.getDefault().findTopComponent("UserExplorerTopComponent"); //Get the display text to search for: String selectedDisplayName = selectedHandle.getNode().getDisplayName(); //Get the root, which is the parent of the node we want: Node root = tc.getExplorerManager().getRootContext(); //Find the node, by passing in the root with the display text: Node selectedNode = NodeOp.findPath(root, new String[]{selectedDisplayName}); //Set the explorer manager's selected node: tc.getExplorerManager().setSelectedNodes(new Node[]{selectedNode}); } catch (PropertyVetoException ex) { Exceptions.printStackTrace(ex); } catch (IOException ex) { Exceptions.printStackTrace(ex); } } }); return null; } } Assuming you have a node named "UserNode" for a type named "User" containing a property named "type", add the bits in bold below to your "UserNode": public class UserNode extends AbstractNode implements Serializable { static final long serialVersionUID = 1L; public UserNode(User key) { super(Children.LEAF); setName(key.getType()); } @Override public Handle getHandle() { return new CustomHandle(this, getName()); } public class CustomHandle implements Node.Handle { static final long serialVersionUID = 1L; private AbstractNode node = null; private final String searchString; public CustomHandle(AbstractNode node, String searchString) { this.node = node; this.searchString = searchString; } @Override public Node getNode() { node.setName(searchString); return node; } } } Run the application and select one of the user nodes. Close the application. Start it up again. The user node is not automatically selected, in fact, the window does not open, and you will see this in the output: Caused: java.io.InvalidClassException: org.serialization.sample.UserNode; no valid constructor Read this article and then you'll understand the need for this class: public class BaseNode extends AbstractNode { public BaseNode() { super(Children.LEAF); } public BaseNode(Children kids) { super(kids); } public BaseNode(Children kids, Lookup lkp) { super(kids, lkp); } } Now, instead of extending AbstractNode in your UserNode, extend BaseNode. Then the first non-serializable superclass of the UserNode has an explicitly declared no-args constructor, Do the same as the above for each node in the hierarchy that needs to be serialized. If you have multiple nodes needing serialization, you can share the "CustomHandle" inner class above between all the other nodes, while all the other nodes will also need to extend BaseNode (or provide their own non-serializable super class that explicitly declares a no-args constructor). Now, when I run the application, I select a node, then I close the application, restart it, and the previously selected node is automatically selected when the application has restarted.

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• AspNetCompatibility in WCF Services &ndash; easy to trip up

  - by Rick Strahl

  This isn’t the first time I’ve hit this particular wall: I’m creating a WCF REST service for AJAX callbacks and using the WebScriptServiceHostFactory host factory in the service: <%@ ServiceHost Language="C#" Service="WcfAjax.BasicWcfService" CodeBehind="BasicWcfService.cs" Factory="System.ServiceModel.Activation.WebScriptServiceHostFactory" %>   to avoid all configuration. Because of the Factory that creates the ASP.NET Ajax compatible format via the custom factory implementation I can then remove all of the configuration settings that typically get dumped into the web.config file. However, I do want ASP.NET compatibility so I still leave in: <system.serviceModel> <serviceHostingEnvironment aspNetCompatibilityEnabled="true"/> </system.serviceModel> in the web.config file. This option allows you access to the HttpContext.Current object to effectively give you access to most of the standard ASP.NET request and response features. This is not recommended as a primary practice but it can be useful in some scenarios and in backwards compatibility scenerios with ASP.NET AJAX Web Services. Now, here’s where things get funky. Assuming you have the setting in web.config, If you now declare a service like this: [ServiceContract(Namespace = "DevConnections")] #if DEBUG [ServiceBehavior(IncludeExceptionDetailInFaults = true)] #endif public class BasicWcfService (or by using an interface that defines the service contract) you’ll find that the service will not work when an AJAX call is made against it. You’ll get a 500 error and a System.ServiceModel.ServiceActivationException System error. Worse even with the IncludeExceptionDetailInFaults enabled you get absolutely no indication from WCF what the problem is. So what’s the problem?  The issue is that once you specify aspNetCompatibilityEnabled=”true” in the configuration you *have to* specify the AspNetCompatibilityRequirements attribute and one of the modes that enables or at least allows for it. You need either Required or Allow: [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Required)] without it the service will simply fail without further warning. It will also fail if you set the attribute value to NotAllowed. The following also causes the service to fail as above: [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.NotAllowed)] This is not totally unreasonable but it’s a difficult issue to debug especially since the configuration setting is global – if you have more than one service and one requires traditional ASP.NET access and one doesn’t then both must have the attribute specified. This is one reason why you’d want to avoid using this functionality unless absolutely necessary. WCF REST provides some basic access to some of the HTTP features after all, although what’s there is severely limited. I also wish that ServiceActivation errors would provide more error information. Getting an Activation error without further info on what actually is wrong is pretty worthless especially when it is a technicality like a mismatched configuration/attribute setting like this.© Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  WCF  AJAX  

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• How do I properly host a WCF Data Service in IIS? Why am I getting errors?

  - by j0rd4n

  I'm playing around with WCF Data Services (ADO.NET Data Services). I have an entity framework model pointed at the AdventureWorks database. When I debug my svc file from within Visual Studio, it works great. I can say /awservice.svc/Customers and get back the ATOM feed I expect. If I publish the service (hosted in an ASP.NET web application) to IIS7, the same query string returns a 500 fault. The root svc page itself works as expected and successfully returns ATOM. The /Customers path fails. Here is what my grants look like in the svc file: public class AWService : DataService<AWEntities> { public static void InitializeService( DataServiceConfiguration config ) { config.SetEntitySetAccessRule( "*", EntitySetRights.All ); config.SetServiceOperationAccessRule( "*", ServiceOperationRights.All ); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; } } Update: I enabled verbose errors and get the following in the XML message: <innererror> <message>The underlying provider failed on Open.</message> <type>System.Data.EntityException</type> <stacktrace> at System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf( ... ... <internalexception> <message> Login failed for user 'IIS APPPOOL\DefaultAppPool'. </message> <type>System.Data.SqlClient.SqlException</type> <stacktrace> at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, ...

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• RIA Services versus WCF services: what is a difference

  - by Budda

  There are a lot of information how to build Silverlight application using .NET RIA services, but it isn't clear what is unique thing in RIA that is absent in WCF? Here are few topics that are talking around this topic: http://stackoverflow.com/questions/1647225/ria-services-versus-wcf-services http://stackoverflow.com/questions/945123/net-ria-services-wcf-services But they doesn't give an answer to the question. Sorry for the stupid question, but what does "RIA Services" layer bring into your app if you already have "Silverlight <-- WCF Service <-- Business Logic <-- Entity Framework Model <-- Database"? Authentication? Validation? Is it relly asset for you? At the moment the only thing I see: with RIA services usage you don't need to host WCF service manually and don't need to configure any references on the client side (clien side == Silverlight application). Probably I don't know some very useful features of the RIA Services? So could you please point me to the good doc for that? Many thanks.

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• Autofac Wcf Integration Security Problem

  - by ecoffey

  I've created a Wcf Service to back a Ajax page (.Net 3.5). It's hosted in IIS 6.1 Integrated Pipeline. (The rest of Autofac is setup correctly for Web Forms integration). Everything works fine and dandy with the normal Wcf pipeline. However when I plug in the Autofac Wcf Integration (as per the Autofac wiki) I get this delightful exception: [SecurityException: That assembly does not allow partially trusted callers.] Autofac.Integration.Wcf.AutofacHostFactory.CreateServiceHost(String constructorString, Uri[] baseAddresses) in c:\Working\Autofac\src\Source\Autofac.Integration.Wcf\AutofacHostFactory.cs:78 System.ServiceModel.HostingManager.CreateService(String normalizedVirtualPath) +604 System.ServiceModel.HostingManager.ActivateService(String normalizedVirtualPath) +46 System.ServiceModel.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath) +654 My Google-fu has failed me on finding a solution to this problem. Any insights or workarounds would be appreciated.

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• publish XML using WCF

  - by khalil

  Hi, I want to publish some data as XML from a SQL Server database using a WCF service to a location on our content delivery network. (www.somelocation-on-cdn/myxml.xml) This data which is published as XML will have to be updated at an interval of time. I was thinking of writing a WCF service to return the data required, create a RSS reader to update / write the XML file to a location on the content delivery network. Is this approach correct? Can I use WCF REST instead of WCF SOAP As a further enhancement I want to be to use this WCF Service to make cross domain calls using JSONP from our website Thanks

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• WCF via Windows Service - Authenticating Clients

  - by Sean

  I am a WCF / Security Newb. I have created a WCF service which is hosted via a windows service. The WCF service grabs data from a 3rd party data source that is secured via windows authentication. I need to either: Pass the client's privileges through the windows service, through the WCF service and into the 3rd party data source, or... Limit who can call the windows service / WCF service to members of a particular AD group. Any suggestions on how I can do either of these tasks?

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• WCF via Windows Service - Authinticating Clients

  - by Sean

  I am a WCF / Security Newb. I have created a WCF service which is hosted via a windows service. The WCF service grabs data from a 3rd party data source that is secured via windows authentication. I need to either: Pass the client's priveleges through the windows service, through the WCF service and into the 3rd party data source, or... Limit who can call the windows service / wcf service to members of a particular AD group. Any suggestions on how I can do either of these tasks?

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• I need to create a small HMI/SCADA WPF application that uses WCF

  - by HomeMade

  Hello I have to create a simple app, that will suit as an example of using WPF and WCF for creating HMI screens. I'm not sure what WCF is supposed to do in such application, I guess there must be an OPC server that my application connects to. Does app connect to OPC server using WCF service and does the WCF service reside inside the application or outside? Is WCF service meant to be used only as a connection to OPC server? I'm not yet quite sure which process to simulate, I need something simple. Please, any ideas are welcomed. Thank you

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• Using WCF authentication service for web application

  - by user200295

  I am using a WCF authentication service I set up with a web application. I have successfully set up and tested the AuthenticationService and RolesService. The web application can successfully call methods like ValidateUser and GetRolesForCurrentUser through the WCF services. I want to integrate the WCF authentication service with my web.config and site.map. Do I need to write a custom provider, or is there some way I can modify the web.config of the web application to use the WCF authentication service as its membership provider? This way I can set what roles have access to what directories based off the WCF authentication service.

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• WCF help, how can I expose a service over http, that calls another service over net.tcp?

  - by Hcabnettek

  Hi All, I have a WCF .svc file hosted in IIS. I want to use basicHTTP binding. This services job is to actually call another service over net.tcp. Everything works fine locally, but when I deployed, I'm getting this error. The provided URI scheme 'http' is invalid; expected 'net.tcp'. Parameter name: via Here is the server config <client> <endpoint address="net.tcp://localhost:9300/InternalInterfaceService" binding="netTcpBinding" bindingConfiguration="NetTcpBinding_IInternalInterfaceService" contract="IInternalInterfaceService" name="NetTcpBinding_IInternalInterfaceService"> <identity> <servicePrincipalName value="localhost" /> </identity> </endpoint> </client> <services> <service name="MyExternalService"> <endpoint address="" binding="basicHttpBinding" contract="IMyExternalService" /> </service> </services> And here is the config that svcutil generates <system.serviceModel> <bindings> <basicHttpBinding> <binding name="BasicHttpBinding_IMyExternalService" closeTimeout="00:01:00" openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00" allowCookies="false" bypassProxyOnLocal="false" hostNameComparisonMode="StrongWildcard" maxBufferSize="65536" maxBufferPoolSize="524288" maxReceivedMessageSize="65536" messageEncoding="Text" textEncoding="utf-8" transferMode="Buffered" useDefaultWebProxy="true"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384" maxBytesPerRead="4096" maxNameTableCharCount="16384" /> <security mode="None"> <transport clientCredentialType="None" proxyCredentialType="None" realm="" /> <message clientCredentialType="UserName" algorithmSuite="Default" /> </security> </binding> </basicHttpBinding> </bindings> <client> <endpoint address="http://myserver.somesdomain.com/Services/MyExternalService.svc" binding="basicHttpBinding" bindingConfiguration="BasicHttpBinding_IMyExternalService" contract="IMyInternalService" name="BasicHttpBinding_IMyExternalService" /> </client> </system.serviceModel> What do I need to do to wire this up correctly. I do not want to expose InternalInterfaceService over http. What am I doing incorrectly here? Any tips or suggestions are certainly appreciated. Thanks, ~ck

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• Invoking WCF functions using Reflection

  - by Jankhana

  I am pretty new to WCF applications. I have a WCF application that is using NetTcpBinding. I wanted to invoke the functions in WCF service using the System.Reflection's Methodbase Invoke method. I mean I wanted to Dynamically call the Function by passing the String as the Function name. Reflection works great for Web Service or a Windows application or any dll or class. So their is certain way to do this for WCF also but I am not able to find that. I am getting the Assembly Name than it's type everything fine but as we cannot create an instance of the Interface class I tried to open the WCF connection using the binding and tried to pass that object but it's throwing the exception as : "Object does not match target type." I have opened the connection and passed the object and type is of interface only. I don't know whether I'm trying wrong thing or in wrong way. Any idea how shall I accomplish this??? The NetTCPBinding all are properly given while opening the connection. And one more thing I am using WCF as a Windows Service using NETTCPBinding.

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• WCF push to client through firewall?

  - by Sire

  See also How does a WCF server inform a WCF client about changes? (Better solution then simple polling, e.g. Coment or long polling) I need to use push-technology with WCF through client firewalls. This must be a common problem, and I know for a fact it works in theory (see links below), but I have failed to get it working, and I haven't been able to find a code sample that demonstrates it. Requirements: WCF Clients connects to server through tcp port 80 (netTcpBinding). Server pushes back information at irregular intervals (1 min to several hours). Users should not have to configure their firewalls, server pushes must pass through firewalls that have all inbound ports closed. TCP duplex on the same connection is needed for this, a dual binding does not work since a port has to be opened on the client firewall. Clients sends heartbeats to server at regular intervals (perhaps every 15 mins) so server knows client is still alive. Server is IIS7 with WAS. The solution seems to be duplex netTcpBinding. Based on this information: WCF through firewalls and NATs Keeping connections open in IIS But I have yet to find a code sample that works.. I've tried combining the "Duplex" and "TcpActivation" samples from Microsoft's WCF Samples without any luck. Please can someone point me to example code that works, or build a small sample app. Thanks a lot!

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• WCF Custom Delegation/Authentication without Kerberos

  - by MichaelGG

  I'm building a simple WCF service, probably exposed via HTTPS, using NTLM security. Since not all users are going to be capable of using the service directly, we're writing a simple web front-end for the service. Users will auth with HTML to the web front-end. What we want is a way to delegate the user of the web site all the way to the WCF service. I understand Kerberos delegation can do this, but that's not available to us. What I want to do is make the web front-end account a specially trusted account, so that if a request hits the WCF service authenticated as "DOMAIN\WebApp", we read a WCF message header containing the real identity, then switch the principal to that and continue as normal. Is there any "simple" way of achieving this? Should I give up entirely on this idea, and instead make users "sign-in" to the WCF app and then do complete custom auth? The WCF extensibility and security options seem so vast, I'd like to get a heads up on which path to start heading down.

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• WCF Service instead of ASMX Web Service?

  - by wchrisjohnson

  I'm writing a SOAP Server that will act as an endpoint for an external client. The external client expects SOAP 1.1. I'll be taking embedded business objects in the SOAP messages and passing them to an internal application, getting responses back and responding with SOAP messages to the eternal client. I did the traditional ASMX based web services several years ago. Now, I've been exploring WCF Services and wondering the best approach to take. 1) Should WCF be considered a superset of ASMX web services? 2) Is there any reason to still write new web services using ASMX instead of WCF? 3) Does WCF provide better facilities for working with SOAP messages, as opposed to SOAP Extensions? 4) Can I restrict communication to SOAP 1.1 using WCF, the way I can with a web.config change in ASMX? 5) Does WCF have an easy way to log or review the requests that hit the service without resorting to something like SOAP extensions? Sorry my questions are not very specific; still trying to get handle on what I need to know... Using VS2008, Windows Server 2008. Chris

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• Is there anything like ISerializable that works for XMLSerializer?

  - by Billy ONeal

  I've got a class which implements it's own (de)serialization via XLINQ, and I'd like to have clients of my class which attempt to XMLSerialze my class to have my XLINQ method called instead. Is that possible?

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• Prevent <xsi:nil="true"> on Nullable Value Types when Serializing to XML.

  - by Nat Ryall

  I have added some nullable value types to my serializable class. I perform a serialization using XmlSerializer but when the value is set to null, I get an empty node with xsi:nil="true". This is the correct behaviour as I have found here: http://msdn.microsoft.com/en-us/library/ybce7f69%28VS.80%29.aspx Is there a way to switch off this option so that nothing is output when the value type is null?

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• EF4 POCO WCF Serialization problems (no lazy loading, proxy/no proxy, circular references, etc)

  - by kdawg

  OK, I want to make sure I cover my situation and everything I've tried thoroughly. I'm pretty sure what I need/want can be done, but I haven't quite found the perfect combination for success. I'm utilizing Entity Framework 4 RTM and its POCO support. I'm looking to query for an entity (Config) that contains a many-to-many relationship with another entity (App). I turn off lazy loading and disable proxy creation for the context and explicitly load the navigation property (either through .Include() or .LoadProperty()). However, when the navigation property is loaded (that is, Apps is loaded for a given Config), the App objects that were loaded already contain references to the Configs that have been brought to memory. This creates a circular reference. Now I know the DataContractSerializer that WCF uses can handle circular references, by setting the preserveObjectReferences parameter to true. I've tried this with a couple of different attribute implementations I've found online. It is needed to prevent the "the object graph contains circular references and cannot be serialized" error. However, it doesn't prevent the serialization of the entire graph, back and forth between Config and App. If I invoke it via WcfTestClient.exe, I get a stackoverflow (ha!) exception from the client and I'm hosed. I get different results from different invocation environments (C# unit test with a local reference to the web service appears to work ok though I still can drill back and forth between Configs and Apps endlessly, but calling it from a coldfusion environment only returns the first Config in the list and errors out on the others.) My main goal is to have a serialized representation of the graph I explicitly load from EF (ie: list of Configs, each with their Apps, but no App back to Config navigation.) NOTE: I've also tried using the ProxyDataContractResolver technique and keeping the proxy creation enabled from my context. This blows up complaining about unknown types encountered. I read that the ProxyDataContractResolver didn't fully work in Beta2, but should work in RTM. For some reference, here is roughly how I'm querying the data in the service: var repo = BootStrapper.AppCtx["AppMeta.ConfigRepository"] as IRepository<Config>; repo.DisableLazyLoading(); repo.DisableProxyCreation(); //var temp2 = repo.Include(cfg => cfg.Apps).Where(cfg => cfg.Environment.Equals(environment)).ToArray(); var temp2 = repo.FindAll(cfg => cfg.Environment.Equals(environment)).ToArray(); foreach (var cfg in temp2) { repo.LoadProperty(cfg, c => c.Apps); } return temp2; I think the crux of my problem is when loading up navigation properties for POCO objects from Entity Framework 4, it prepopulates navigation properties for objects already in memory. This in turn hoses up the WCF serialization, despite every effort made to properly handle circular references. I know it's a lot of information, but it's really standing in my way of going forward with EF4/POCO in our system. I've found several articles and blogs touching upon these subjects, but for the life of me, I cannot resolve this issue. Feel free to simply ask questions and help me brainstorm this situation. PS: For the sake of being thorough, I am injecting the WCF services using the HEAD build of Spring.NET for the fix to Spring.ServiceModel.Activation.ServiceHostFactory. However I don't think this is the source of the problem.

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• Silverlight 4 Tools for VS 2010 and WCF RIA Services Released

  - by ScottGu

  The final release of the Silverlight 4 Tools for Visual Studio 2010 and WCF RIA Services is now available for download.  Download and Install If you already have Visual Studio 2010 installed (or the free Visual Web Developer 2010 Express), then you can install both the Silverlight 4 Tooling Support as well as WCF RIA Services support by downloading and running this setup package (note: please make sure to uninstall the preview release of the Silverlight 4 Tools for VS 2010 if you have previously installed that).  The Silverlight 4 Tools for VS 2010 package extends the Silverlight support built into Visual Studio 2010 and enables support for Silverlight 4 applications as well.  It also installs WCF RIA Services application templates and libraries: Today’s release includes the English edition of the Silverlight 4 Tooling – localized versions will be available next month for other Visual Studio languages as well. Silverlight Tooling Support Visual Studio 2010 includes rich tooling support for building Silverlight and WPF applications. It includes a WYSIWYG designer surface that enables you to easily use controls to construct UI – including the ability to take advantage of layout containers, and apply styles and resources: The VS 2010 designer enables you to leverage the rich data binding support within Silverlight and WPF, and easily wire-up bindings on controls.  The Data Sources window within Silverlight projects can be used to reference POCO objects (plain old CLR objects), WCF Services, WCF RIA Services client proxies or SharePoint Lists.  For example, let’s assume we add a “Person” class like below to our project: We could then add it to the Data Source window which will cause it to show up like below in the IDE: We can optionally customize the default UI control types that are associated for each property on the object.  For example, below we’ll default the BirthDate property to be represented by a “DatePicker” control: And then when we drag/drop the Person type from the Data Sources onto the design-surface it will automatically create UI controls that are bound to the properties of our Person class: VS 2010 allows you to optionally customize each UI binding further by selecting a control, and then right-click on any of its properties within the property-grid and pull up the “Apply Bindings” dialog: This will bring up a floating data-binding dialog that enables you to easily configure things like the binding path on the data source object, specify a format convertor, specify string-format settings, specify how validation errors should be handled, etc: In addition to providing WYSIWYG designer support for WPF and Silverlight applications, VS 2010 also provides rich XAML intellisense and code editing support – enabling a rich source editing environment. Silverlight 4 Tool Enhancements Today’s Silverlight 4 Tooling Release for VS 2010 includes a bunch of nice new features.  These include: Support for Silverlight Out of Browser Applications and Elevated Trust Applications You can open up a Silverlight application’s project properties window and click the “Enable Running Application Out of Browser” checkbox to enable you to install an offline, out of browser, version of your Silverlight 4 application.  You can then customize a number of “out of browser” settings of your application within Visual Studio: Notice above how you can now indicate that you want to run with elevated trust, with hardware graphics acceleration, as well as customize things like the Window style of the application (allowing you to build a nice polished window style for consumer applications). Support for Implicit Styles and “Go to Value Definition” Support: Silverlight 4 now allows you to define “implicit styles” for your applications.  This allows you to style controls by type (for example: have a default look for all buttons) and avoid you having to explicitly reference styles from each control.  In addition to honoring implicit styles on the designer-surface, VS 2010 also now allows you to right click on any control (or on one of it properties) and choose the “Go to Value Definition…” context menu to jump to the XAML where the style is defined, and from there you can easily navigate onward to any referenced resources.  This makes it much easier to figure out questions like “why is my button red?”: Style Intellisense VS 2010 enables you to easily modify styles you already have in XAML, and now you get intellisense for properties and their values within a style based on the TargetType of the specified control.  For example, below we have a style being set for controls of type “Button” (this is indicated by the “TargetType” property).  Notice how intellisense now automatically shows us properties for the Button control (even within the <Setter> element): Great Video - Watch the Silverlight Designer Features in Action You can see all of the above Silverlight 4 Tools for Visual Studio 2010 features (and some more cool ones I haven’t mentioned) demonstrated in action within this 20 minute Silverlight.TV video on Channel 9: WCF RIA Services Today we also shipped the V1 release of WCF RIA Services.  It is included and automatically installed as part of the Silverlight 4 Tools for Visual Studio 2010 setup. WCF RIA Services makes it much easier to build business applications with Silverlight.  It simplifies the traditional n-tier application pattern by bringing together the ASP.NET and Silverlight platforms using the power of WCF for communication.  WCF RIA Services provides a pattern to write application logic that runs on the mid-tier and controls access to data for queries, changes and custom operations. It also provides end-to-end support for common tasks such as data validation, authentication and authorization based on roles by integrating with Silverlight components on the client and ASP.NET on the mid-tier. Put simply – it makes it much easier to query data stored on a server from a client machine, optionally manipulate/modify the data on the client, and then save it back to the server.  It supports a validation architecture that helps ensure that your data is kept secure and business rules are applied consistently on both the client and middle-tiers. WCF RIA Services uses WCF for communication between the client and the server  It supports both an optimized .NET to .NET binary serialization format, as well as a set of open extensions to the ATOM format known as ODATA and an optional JavaScript Object Notation (JSON) format that can be used by any client. You can hear Nikhil and Dinesh talk a little about WCF RIA Services in this 13 minutes Channel 9 video. Putting it all Together – the Silverlight 4 Training Kit Check out the Silverlight 4 Training Kit to learn more about how to build business applications with Silverlight 4, Visual Studio 2010 and WCF RIA Services. The training kit includes 8 modules, 25 videos, and several hands-on labs that explain Silverlight 4 and WCF RIA Services concepts and walks you through building an end-to-end application with them.    The training kit is available for free and is a great way to get started. Summary I’m really excited about today’s release – as they really complete the Silverlight development story and deliver a great end to end runtime + tooling story for building applications.  All of the above features are available for use both in VS 2010 as well as the free Visual Web Developer 2010 Express Edition – making it really easy to get started building great solutions. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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• Why is my WCF Rest Service on IIS7 Authenticating TWICE!?!?

  - by TheAggie

  Ok, if someone could shed some light on this for me, I would greatly appreciate it. So here we go. I had a rest service running fine the other day but after I accidentally overwrote the web.config all hell broke loose. I've spent the past day and a half trying to sort things out but I can't seem to figure out what is missing or misplaced. So, I've designed this service around WCF Rest Contrib (http://wcfrestcontrib.codeplex.com)'s authentication process. Now, I can get this working fine on my localhost w/ the current web.config (minus the endpoint entry) but once I upload it to discountasp and select "basic authorization" in the ISS7 Manager, it appears that I'm getting authenticated twice! Once using my discount asp.net user/pass and then the next time using the application user/pass. Unfortunately I only provide one set of credentials and don't want to hard code my discountasp account info into the app. Like I said before, this worked fine a few days ago. Anyway. here is my web.config as it is now: <?xml version="1.0"?> <configuration> <connectionStrings> <add name="SQL2008_ConnectionString" connectionString="Data Source=sql2k8xx.discountasp.net;Initial Catalog=SQL2008_xx;Persist Security Info=True;User ID=SQL2008_xx_user;Password=myPass" providerName="System.Data.SqlClient" /> </connectionStrings> <system.web> <httpRuntime maxRequestLength="204800" executionTimeout="3600"/> <compilation debug="true"> <assemblies> <add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/> <add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </assemblies> </compilation> <httpModules> <add name="ServiceAnonymityModule" type="WcfRestContrib.Web.ServiceAnonymityModule, WcfRestContrib"/> </httpModules> </system.web> <system.codedom> <compilers> <compiler language="c#;cs;csharp" extension=".cs" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <providerOption name="CompilerVersion" value="v3.5"/> <providerOption name="WarnAsError" value="false"/> </compiler> </compilers> </system.codedom> <system.webServer> <validation validateIntegratedModeConfiguration="false"/> <modules> <remove name="ServiceAnonymityModule"/> <add name="ServiceAnonymityModule" type="WcfRestContrib.Web.ServiceAnonymityModule, WcfRestContrib"/> </modules> <handlers> <remove name="WebServiceHandlerFactory-Integrated"/> </handlers> </system.webServer> <system.diagnostics> <trace autoflush="true" /> </system.diagnostics> <system.serviceModel> <serviceHostingEnvironment aspNetCompatibilityEnabled="false"> <baseAddressPrefixFilters> <add prefix="http://www.mydomain.com/myServiceBaseAddress"/> </baseAddressPrefixFilters> </serviceHostingEnvironment> <extensions> <behaviorExtensions> <add name="webAuthentication" type="WcfRestContrib.ServiceModel.Configuration.WebAuthentication.ConfigurationBehaviorElement, WcfRestContrib, Version=1.0.5.0, Culture=neutral, PublicKeyToken=89183999a8dc93b5"/> <add name="errorHandler" type="WcfRestContrib.ServiceModel.Configuration.ErrorHandler.BehaviorElement, WcfRestContrib, Version=1.0.5.0, Culture=neutral, PublicKeyToken=89183999a8dc93b5"/> <add name="webFormatter" type="WcfRestContrib.ServiceModel.Configuration.WebDispatchFormatter.ConfigurationBehaviorElement, WcfRestContrib, Version=1.0.5.0, Culture=neutral, PublicKeyToken=89183999a8dc93b5"/> <add name="webErrorHandler" type="WcfRestContrib.ServiceModel.Configuration.WebErrorHandler.ConfigurationBehaviorElement, WcfRestContrib, Version=1.0.5.0, Culture=neutral, PublicKeyToken=89183999a8dc93b5"/> </behaviorExtensions> </extensions> <bindings> <customBinding> <binding name="HttpStreamedRest"> <httpTransport maxReceivedMessageSize="209715200" manualAddressing="true" /> </binding> <binding name="HttpsStreamedRest"> <httpsTransport maxReceivedMessageSize="209715200" manualAddressing="true" /> </binding> </customBinding> </bindings> <behaviors> <serviceBehaviors> <behavior name="Rest"> <webAuthentication requireSecureTransport="false" authenticationHandlerType="WcfRestContrib.ServiceModel.Dispatcher.WebBasicAuthenticationHandler, WcfRestContrib" usernamePasswordValidatorType="MyLibrary.Runtime.SecurityValidator, MyLibrary" source="MyRESTServiceRealm"/> <webFormatter> <formatters defaultMimeType="application/xml"> <formatter mimeTypes="application/xml,text/xml" type="WcfRestContrib.ServiceModel.Dispatcher.Formatters.PoxDataContract, WcfRestContrib"/> <formatter mimeTypes="application/json" type="WcfRestContrib.ServiceModel.Dispatcher.Formatters.DataContractJson, WcfRestContrib"/> <formatter mimeTypes="application/x-www-form-urlencoded" type="WcfRestContrib.ServiceModel.Dispatcher.Formatters.FormUrlEncoded, WcfRestContrib"/> </formatters> </webFormatter> <errorHandler errorHandlerType="WcfRestContrib.ServiceModel.Web.WebErrorHandler, WcfRestContrib"/> <webErrorHandler returnRawException="true" logHandlerType="MyLibrary.Runtime.LogHandler, MyLibrary" unhandledErrorMessage="An error has occured processing your request. Please contact technical support for further assistance."/> </behavior> </serviceBehaviors> </behaviors> </system.serviceModel> </configuration> So, whenever I upload this and change the ISS setting to Basic Authentication, it looks like it is trying to use the default handler for authentication as if I try to enter my web app user/pass, I get an error screen which has the following detailed information about the moduel/handler Detailed Error Information Module: IIS Web Core Notification: AuthenticateRequest Handler: svc-ISAPI-2.0 Error Code: 0x80070005 Requested URL: http://www.mydomain.com:80/MyService.../MyService.svc Physical Path: E:\web\xxxxxx\htdocs\MyServiceBaseAddress\MyService.svc Logon Method: Not yet determined Logon User: Not yet determined Now for the fun stuff... i tried providing my discountasp.net account username/password for kicks and sure enough it responded properly for any [OperationContract] which doesn't have [OperationAuthentication] defined (which is only one or two of the operations I have). I thought this was strange, so I looked at fiddler and saw something interesting. Whenever I try request a procedure with [OperationAuthentication] defined and provide my discountasp.net username/pass I get two different "WWW-Authenticate" headers back in Fiddler: WWW-Authenticate: Basic realm="MyRESTServiceRealm" WWW-Authenticate: Basic realm="www.mydomain.com" On the other hand, if I try to access the same procedures with only my application's user/pass, I only get the site's header: WWW-Authenticate: Basic realm="www.mydomain.com" My hypothesis is that for some reason I'm having to pass through the default "Basic Authorization" layer set by IIS before I can get to the application's "Custom Basic Authorization" layer. After verifying this by created an identical user/pass for my service that I use for my discountasp.net account, I was able to successfully pass both layers of authentication without any issues... so I think I can conclude that this is indeed the issue. Now how do I disable the default one? Do I need to do this in the IIS Manager, or in the web.config? Anyway, I have absolutely no idea how this is possible or what I need to do to resolve the issue, but I know that something is seriously out of whack. Any suggestions would be greatly appreciated! Thanks.

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• Using Node.js as an accelerator for WCF REST services

  - by Elton Stoneman

  Node.js is a server-side JavaScript platform "for easily building fast, scalable network applications". It's built on Google's V8 JavaScript engine and uses an (almost) entirely async event-driven processing model, running in a single thread. If you're new to Node and your reaction is "why would I want to run JavaScript on the server side?", this is the headline answer: in 150 lines of JavaScript you can build a Node.js app which works as an accelerator for WCF REST services*. It can double your messages-per-second throughput, halve your CPU workload and use one-fifth of the memory footprint, compared to the WCF services direct.   Well, it can if: 1) your WCF services are first-class HTTP citizens, honouring client cache ETag headers in request and response; 2) your services do a reasonable amount of work to build a response; 3) your data is read more often than it's written. In one of my projects I have a set of REST services in WCF which deal with data that only gets updated weekly, but which can be read hundreds of times an hour. The services issue ETags and will return a 304 if the client sends a request with the current ETag, which means in the most common scenario the client uses its local cached copy. But when the weekly update happens, then all the client caches are invalidated and they all need the same new data. Then the service will get hundreds of requests with old ETags, and they go through the full service stack to build the same response for each, taking up threads and processing time. Part of that processing means going off to a database on a separate cloud, which introduces more latency and downtime potential.   We can use ASP.NET output caching with WCF to solve the repeated processing problem, but the server will still be thread-bound on incoming requests, and to get the current ETags reliably needs a database call per request. The accelerator solves that by running as a proxy - all client calls come into the proxy, and the proxy routes calls to the underlying REST service. We could use Node as a straight passthrough proxy and expect some benefit, as the server would be less thread-bound, but we would still have one WCF and one database call per proxy call. But add some smart caching logic to the proxy, and share ETags between Node and WCF (so the proxy doesn't even need to call the servcie to get the current ETag), and the underlying service will only be invoked when data has changed, and then only once - all subsequent client requests will be served from the proxy cache.   I've built this as a sample up on GitHub: NodeWcfAccelerator on sixeyed.codegallery. Here's how the architecture looks:     The code is very simple. The Node proxy runs on port 8010 and all client requests target the proxy. If the client request has an ETag header then the proxy looks up the ETag in the tag cache to see if it is current - the sample uses memcached to share ETags between .NET and Node. If the ETag from the client matches the current server tag, the proxy sends a 304 response with an empty body to the client, telling it to use its own cached version of the data. If the ETag from the client is stale, the proxy looks for a local cached version of the response, checking for a file named after the current ETag. If that file exists, its contents are returned to the client as the body in a 200 response, which includes the current ETag in the header. If the proxy does not have a local cached file for the service response, it calls the service, and writes the WCF response to the local cache file, and to the body of a 200 response for the client. So the WCF service is only troubled if both client and proxy have stale (or no) caches.   The only (vaguely) clever bit in the sample is using the ETag cache, so the proxy can serve cached requests without any communication with the underlying service, which it does completely generically, so the proxy has no notion of what it is serving or what the services it proxies are doing. The relative path from the URL is used as the lookup key, so there's no shared key-generation logic between .NET and Node, and when WCF stores a tag it also stores the "read" URL against the ETag so it can be used for a reverse lookup, e.g:   Key Value /WcfSampleService/PersonService.svc/rest/fetch/3 "28cd4796-76b8-451b-adfd-75cb50a50fa6" "28cd4796-76b8-451b-adfd-75cb50a50fa6" /WcfSampleService/PersonService.svc/rest/fetch/3    In Node we read the cache using the incoming URL path as the key and we know that "28cd4796-76b8-451b-adfd-75cb50a50fa6" is the current ETag; we look for a local cached response in /caches/28cd4796-76b8-451b-adfd-75cb50a50fa6.body (and the corresponding .header file which contains the original service response headers, so the proxy response is exactly the same as the underlying service). When the data is updated, we need to invalidate the ETag cache – which is why we need the reverse lookup in the cache. In the WCF update service, we don't need to know the URL of the related read service - we fetch the entity from the database, do a reverse lookup on the tag cache using the old ETag to get the read URL, update the new ETag against the URL, store the new reverse lookup and delete the old one.   Running Apache Bench against the two endpoints gives the headline performance comparison. Making 1000 requests with concurrency of 100, and not sending any ETag headers in the requests, with the Node proxy I get 102 requests handled per second, average response time of 975 milliseconds with 90% of responses served within 850 milliseconds; going direct to WCF with the same parameters, I get 53 requests handled per second, mean response time of 1853 milliseconds, with 90% of response served within 3260 milliseconds. Informally monitoring server usage during the tests, Node maxed at 20% CPU and 20Mb memory; IIS maxed at 60% CPU and 100Mb memory.   Note that the sample WCF service does a database read and sleeps for 250 milliseconds to simulate a moderate processing load, so this is *not* a baseline Node-vs-WCF comparison, but for similar scenarios where the  service call is expensive but applicable to numerous clients for a long timespan, the performance boost from the accelerator is considerable.     * - actually, the accelerator will work nicely for any HTTP request, where the URL (path + querystring) uniquely identifies a resource. In the sample, there is an assumption that the ETag is a GUID wrapped in double-quotes (e.g. "28cd4796-76b8-451b-adfd-75cb50a50fa6") – which is the default for WCF services. I use that assumption to name the cache files uniquely, but it is a trivial change to adapt to other ETag formats.

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