According to the JMX API I can use classes like StandardMBean and StandardEmitterMBean to use customization hooks. SO instead of registering the MXBean itself directly I can wrap it in one of these classes.
This is working fine, but as soon as I try to use the JMX Notification framework no Notification will be fired when using this wrapped class instead of the MXBean directly.
Some example code:
The MXBean interface
public interface MyMXBean {
public void hello();
}
The implementation
public class MyMXBeanImpl extends NotificationBroadcasterSupport implements MyMXBean {
#Override
public void hello() {
Notification n = //...creating new Notification
sendNotification(n);
}
}
The Registation:
public class Registration() {
public static void main(String[] args) throws Exception {
MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
ObjectName oname =
new ObjectName("example:type=myexample,name=MyExamleMXBean");
// does not fire any notifications
mbs.registerMBean(
new StandardEmitterMBean(new MyMXBeanImpl(), MyMXBean.class, true), oname);
// would fire the notification
// mbs.register(new MyMXBeanImpl(), oname);
}
}
When I connect JConsole to my bean, subscribe to the Notification mechanism and execute the hello() Method nothing happens. Only when registering the MXBean directly everything works fine.
It's also not working when adding custom NotificationListeners to my MXBean.
I've already tried to somehow catch this Notification event in the wrapping class and forward it somehow but this didn't work either.
Do you have any idea what I am missing here? Or is it just not working when using one of the wrapping classes?
Thanks in advance for your help!
Briefly ( on mobile u see ), you need to extend your class to provide notification-info metadata for your notification types.
Related
We have implemented several custom ORM objects in our webshop implementation that have references (dependencies) to Intershop Product system object.
When a user tries to delete a certain product in back-office, it causes problems because references to that product may still exist in our custom objects. Naturally, deleting a product that is referenced from one of our custom objects generates an exception like this:
java.sql.SQLTransactionRollbackException: ORA-02091: transaction rolled back ORA-02292: integrity constraint (INTERSHOP.A1POSTPAIDPRICE_CO_002) violated - child record found
We have figured that we could solve that by implementing an ORMObjectListener and overriding objectDeleting method to delete all the references before the product actually gets deleted.
Intershop cookbook for ORM layer states:
"Instances must implement the interface ORMObjectListener for a given ORM object type and register at the factory. The listener is called when instances of the given type are created, changed or removed."
(https://support.intershop.com/kb/index.php/Display/2G3270#Cookbook-ORMLayer-Recipe:NotificationofPersistentObjectChanges)
However, we cannot find a cookbook for registering the listener at the factory. What do we need to do to register the listener?
Also, if there is some better way for handling dependencies to system objects on our custom objects during delete event, I'm open to suggestions.
UPDATE:
This is the listener class I have tried with so far:
public class ProductDeleteListener implements ORMObjectListener<ProductPO> {
#Inject
ProductPOFactory productPOFactory;
/** The Constant LOGGER. */
private static final Logger LOGGER = LoggerFactory.getLogger(ProductDeleteListener.class);
public ProductDeleteListener() {
productPOFactory.addObjectListener(this, new AttributeDescription[0]);
}
#Override
public boolean isOldStateNeeded() {
// TODO Auto-generated method stub
return false;
}
#Override
public void objectChanged(ProductPO object, Map<AttributeDescription, Object> previousValues) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("PRODUCT LISTENER TEST - CHANGE");
}
}
#Override
public void objectChanging(ProductPO object, Map<AttributeDescription, Object> previousValues) {
// TODO Auto-generated method stub
}
#Override
public void objectCreated(ProductPO object) {
// TODO Auto-generated method stub
}
#Override
public void objectCreating(ProductPO object) {
// TODO Auto-generated method stub
}
#Override
public void objectDeleted(ORMObjectKey objectKey) {
// TODO Auto-generated method stub
}
#Override
public void objectDeleting(ProductPO object) {
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("PRODUCT LISTENER TEST - PRE DELETE");
}
}
}
But it is not working. Nothing gets logged when object changes or gets deleted.
In addition to what Willem Evertse wrote you need to place your registration code in a class that gets instantiated via Intershop Component Framework.
implementation.component:
<components xmlns="http://www.intershop.de/component/2010" scope="global">
<implementation name="ProductDeleteListenerRegistrar"
class="your.fullqualifed.ProductDeleteRegistrar" start="start" stop="stop"></implementation>
instances.component:
<components xmlns="http://www.intershop.de/component/2010"> <instance name="ORMValidator" with="ORMValidator" scope="global"/></components>
You need to write a class, e.g. ProductDeleteRegistrar and provide start method in which you can add registration calls like Willem described. As for stop method you need to safely unregister your object listener. Make sure both methods are declared to be synchronized.
I think registering a listen would be the right approach. Maybe just look out for performance problems.
You are right that there are no examples of this, but here is an example.
Get the factory that you want to receive messages from. In your case, it is ProductPOFactory
ProductPOFactory productFactory = (ProductPOFactory) NamingMgr.getInstance().lookupFactory(ProductPO.class);
productFactory.addObjectListener(new MyProductChangeListener());
MyProductChangeListener needs to extend AbstractORMObjectListener<ProductPO>
and implement the method public void objectDeleting(T object)
Every time a product gets deleted your listener should be called and then you can clean up your custom orm objects. You can have a look at ImageSetDefinitionPOListener as an example
Consider the following handler:
public class CreateProjectHandler extends AbstractHandler {
#Override
public Object execute(ExecutionEvent event) throws ExecutionException {
// it does not matter what kind of exception this is:
throw new IllegalArgumentException("This is a test!");
}
}
From a customer and developer perspective it's pretty clear what should happen when this handler is executed: an error message of some kind should pop up.
What happens is: Nothing.
More accurate: the exception is logged into the error log (and console, if started from Eclipse). But the user sees nothing, in fact he doesn't even know there was an error.
I could fix this by catching Exception for each and every handler, but besides being ugly and cumbersome it contradicts each style guide ever.
Is there a better way to handle the exceptions swallowed by handlers?
For Eclipse 4 (e4 or 3.x compatbility mode) add a class implementing IEventLoopAdvisor to the application context. The eventLoopException method will be called for the unhandled exceptions.
A suitable place to set this up for e4 is the #PostContextCreate of the RCP life cycle class:
#PostContextCreate
public void postContextCreate(IEclipseContext context)
{
// Event loop advisor for error handling
context.set(IEventLoopAdvisor.class, new EventLoopAdvisor());
You must also implement eventLoopIdle, it is very important that this calls display.sleep(). A standard method would be:
#Override
public void eventLoopIdle(final Display display)
{
display.sleep();
}
For 3.x compatibility mode there is a default event loop advisor installed after the post context create which delegates to the workbench WorkbenchAdvisor. If you are using your own advisor in the RCP you can override the eventLoopException method of the advisor.
I found another way that works for my E3 compatibility application: overridding WorkbenchAdvisor#eventLoopException(Throwable):
public class ApplicationWorkbenchAdvisor extends WorkbenchAdvisor {
#Override
public void eventLoopException(Throwable exception) {
// do magic here
}
// [snipped other methods]
}
I appreciate the pros/cons of singletons in Android and the various arguments for them and for creating singleton instance of an object or the application itself, but it fulfills my need to have a single instance of my Database Manager facade available to the application.
After searching various places for the best approach I found the following code. But findbugs doesn't really like my assignment of 'this' to the static instance.
This class doesn't fully follow the standard singleton approach but supposedly was a better way based on the knowledge that there is only ever one Application created and the order of method calls are known. Can anyone tell me if this code is wrong or let me know how to get around the findbug issue, if it is actually an issue. I've highlighted the bug line.
My source for the code was:
http://androidcookbook.com/Recipe.seam;jsessionid=9A77FA007453433B9F15F792396B744F?recipeId=1218&recipeFrom=ViewTOC
public class DatabaseApplication extends Application {
private static DatabaseApplication instance; //the single instance of this app
private DataManager dataManager; //the database facade, again a single instance
public static DatabaseApplication getInstance() {
return instance;
}
/**
* onCreate will always be called before this.
*
* #return data manager, effectively a singleton too
*/
public DataManager getDataManager() {
return dataManager;
}
/*
* onCreate only called when app is created by the system
*
* #see android.app.Application#onCreate()
*/
#Override
public void onCreate() {
super.onCreate();
//Bug: Write to static field
//DatabaseApplication.instance from instance method
//DatabaseApplication.onCreate()
instance = this;
instance.initializeInstance();
}
/**
* Create the one and only dataManager
*/
protected void initializeInstance() {
dataManager = new DataManager(this, false);
}
}
On my service layer I have injected an UnitOfWork and 2 repositories in the constructor. The Unit of Work and repository have an instance of a DbContext I want to share between the two of them. How can I do that with Ninject ? Which scope should be considered ?
I am not in a web application so I can't use InRequestScope.
I try to do something similar... and I am using DI however, I need my UoW to be Disposed and created like this.
using (IUnitOfWork uow = new UnitOfWorkFactory.Create())
{
_testARepository.Insert(a);
_testBRepository.Insert(b);
uow.SaveChanges();
}
EDIT: I just want to be sure i understand… after look at https://github.com/ninject/ninject.extensions.namedscope/wiki/InNamedScope i though about my current console application architecture which actually use Ninject.
Lets say :
Class A is a Service layer class
Class B is an unit of work which take into parameter an interface (IContextFactory)
Class C is a repository which take into parameter an interface (IContextFactory)
The idea here is to be able to do context operations on 2 or more repository and using the unit of work to apply the changes.
Class D is a context factory (Entity Framework) which provide an instance (keep in a container) of the context which is shared between Class B et C (.. and would be for other repositories aswell).
The context factory keep the instance in his container so i don’t want to reuse this instance all the name since the context need to be disposed at the end of the service operaiton.. it is the main purpose of the InNamedScope actually ?
The solution would be but i am not sure at all i am doing it right, the services instance gonna be transcient which mean they actually never disposed ? :
Bind<IScsContextFactory>()
.To<ScsContextFactory>()
.InNamedScope("ServiceScope")
.WithConstructorArgument(
"connectionString",
ConfigurationUtility.GetConnectionString());
Bind<IUnitOfWork>().To<ScsUnitOfWork>();
Bind<IAccountRepository>().To<AccountRepository>();
Bind<IBlockedIpRepository>().To<BlockedIpRepository>();
Bind<IAccountService>().To<AccountService>().DefinesNamedScope("ServiceScope");
Bind<IBlockedIpService>().To<BlockedIpService>().DefinesNamedScope("ServiceScope");
UPDATE: This approach works against NuGet current, but relies in an anomaly in the InCallscope implementation which has been fixed in the current Unstable NuGet packages. I'll be tweaking this answer in a few days to reflect the best approach after some mulling over. NB the high level way of structuring stuff will stay pretty much identical, just the exact details of the Bind<DbContext>() scoping will work. (Hint: CreateNamedScope in unstable would work or one could set up the Command Handler as DefinesNamedScope. Reason I dont just do that is that I want to have something that composes/plays well with InRequestScope)
I highly recommend reading the Ninject.Extensions.NamedScope integration tests (seriously, find them and read and re-read them)
The DbContext is a Unit Of Work so no further wrapping is necessary.
As you want to be able to have multiple 'requests' in flight and want to have a single Unit of Work shared between them, you need to:
Bind<DbContext>()
.ToMethod( ctx =>
new DbContext(
connectionStringName: ConfigurationUtility.GetConnectionString() ))
.InCallScope();
The InCallScope() means that:
for a given object graph composed for a single kernel.Get() Call (hence In Call Scope), everyone that requires an DbContext will get the same instance.
the IDisposable.Dispose() will be called when a Kernel.Release() happens for the root object (or a Kernel.Components.Get<ICache>().Clear() happens for the root if it is not .InCallScope())
There should be no reason to use InNamedScope() and DefinesNamedScope(); You don't have long-lived objects you're trying to exclude from the default pooling / parenting / grouping.
If you do the above, you should be able to:
var command = kernel.Get<ICommand>();
try {
command.Execute();
} finally {
kernel.Components.Get<ICache>().Clear( command ); // Dispose of DbContext happens here
}
The Command implementation looks like:
class Command : ICommand {
readonly IAccountRepository _ar;
readonly IBlockedIpRepository _br;
readonly DbContext _ctx;
public Command(IAccountRepository ar, IBlockedIpRepository br, DbContext ctx){
_ar = ar;
_br = br;
_ctx = ctx;
}
void ICommand.Execute(){
_ar.Insert(a);
_br.Insert(b);
_ctx.saveChanges();
}
}
Note that in general, I avoid having an implicit Unit of Work in this way, and instead surface it's creation and Disposal. This makes a Command look like this:
class Command : ICommand {
readonly IAccountService _as;
readonly IBlockedIpService _bs;
readonly Func<DbContext> _createContext;
public Command(IAccountService #as, IBlockedIpServices bs, Func<DbContext> createContext){
_as = #as;
_bs = bs;
_createContext = createContext;
}
void ICommand.Execute(){
using(var ctx = _createContext()) {
_ar.InsertA(ctx);
_br.InsertB(ctx);
ctx.saveChanges();
}
}
This involves no usage of .InCallScope() on the Bind<DbContext>() (but does require the presence of Ninject.Extensions.Factory's FactoryModule to synthesize the Func<DbContext> from a straightforward Bind<DbContext>().
As discussed in the other answer, InCallScope is not a good approach to solving this problem.
For now I'm dumping some code that works against the latest NuGet Unstable / Include PreRelease / Instal-Package -Pre editions of Ninject.Web.Common without a clear explanation. I will translate this to an article in the Ninject.Extensions.NamedScope wiki at some stagehave started to write a walkthrough of this technique in the Ninject.Extensions.NamedScope wiki's CreateNamedScope/GetScope article.
Possibly some bits will become Pull Request(s) at some stage too (Hat tip to #Remo Gloor who supplied me the outline code). The associated tests and learning tests are in this gist for now), pending packaging in a proper released format TBD.
The exec summary is you Load the Module below into your Kernel and use .InRequestScope() on everything you want created / Disposed per handler invocation and then feed requests through via IHandlerComposer.ComposeCallDispose.
If you use the following Module:
public class Module : NinjectModule
{
public override void Load()
{
Bind<IHandlerComposer>().To<NinjectRequestScopedHandlerComposer>();
// Wire it up so InRequestScope will work for Handler scopes
Bind<INinjectRequestHandlerScopeFactory>().To<NinjectRequestHandlerScopeFactory>();
NinjectRequestHandlerScopeFactory.NinjectHttpApplicationPlugin.RegisterIn( Kernel );
}
}
Which wires in a Factory[1] and NinjectHttpApplicationPlugin that exposes:
public interface INinjectRequestHandlerScopeFactory
{
NamedScope CreateRequestHandlerScope();
}
Then you can use this Composer to Run a Request InRequestScope():
public interface IHandlerComposer
{
void ComposeCallDispose( Type type, Action<object> callback );
}
Implemented as:
class NinjectRequestScopedHandlerComposer : IHandlerComposer
{
readonly INinjectRequestHandlerScopeFactory _requestHandlerScopeFactory;
public NinjectRequestScopedHandlerComposer( INinjectRequestHandlerScopeFactory requestHandlerScopeFactory )
{
_requestHandlerScopeFactory = requestHandlerScopeFactory;
}
void IHandlerComposer.ComposeCallDispose( Type handlerType, Action<object> callback )
{
using ( var resolutionRoot = _requestHandlerScopeFactory.CreateRequestHandlerScope() )
foreach ( object handler in resolutionRoot.GetAll( handlerType ) )
callback( handler );
}
}
The Ninject Infrastructure stuff:
class NinjectRequestHandlerScopeFactory : INinjectRequestHandlerScopeFactory
{
internal const string ScopeName = "Handler";
readonly IKernel _kernel;
public NinjectRequestHandlerScopeFactory( IKernel kernel )
{
_kernel = kernel;
}
NamedScope INinjectRequestHandlerScopeFactory.CreateRequestHandlerScope()
{
return _kernel.CreateNamedScope( ScopeName );
}
/// <summary>
/// When plugged in as a Ninject Kernel Component via <c>RegisterIn(IKernel)</c>, makes the Named Scope generated during IHandlerFactory.RunAndDispose available for use via the Ninject.Web.Common's <c>.InRequestScope()</c> Binding extension.
/// </summary>
public class NinjectHttpApplicationPlugin : NinjectComponent, INinjectHttpApplicationPlugin
{
readonly IKernel kernel;
public static void RegisterIn( IKernel kernel )
{
kernel.Components.Add<INinjectHttpApplicationPlugin, NinjectHttpApplicationPlugin>();
}
public NinjectHttpApplicationPlugin( IKernel kernel )
{
this.kernel = kernel;
}
object INinjectHttpApplicationPlugin.GetRequestScope( IContext context )
{
// TODO PR for TrgGetScope
try
{
return NamedScopeExtensionMethods.GetScope( context, ScopeName );
}
catch ( UnknownScopeException )
{
return null;
}
}
void INinjectHttpApplicationPlugin.Start()
{
}
void INinjectHttpApplicationPlugin.Stop()
{
}
}
}
I am researching Prism v2 by going thru the quickstarts. And I have created a WCF service with the following signature:
namespace HelloWorld.Silverlight.Web
{
[ServiceContract(Namespace = "http://helloworld.org/messaging")]
[AspNetCompatibilityRequirements(RequirementsMode =
AspNetCompatibilityRequirementsMode.Allowed)]
public class HelloWorldMessageService
{
private string message = "Hello from WCF";
[OperationContract]
public void UpdateMessage(string message)
{
this.message = message;
}
[OperationContract]
public string GetMessage()
{
return message;
}
}
}
When I add a service reference to this service in my silverlight project it generates an interface and a class:
[System.ServiceModel.ServiceContractAttribute
(Namespace="http://helloworld.org/messaging",
ConfigurationName="Web.Services.HelloWorldMessageService")]
public interface HelloWorldMessageService {
[System.ServiceModel.OperationContractAttribute
(AsyncPattern=true,
Action="http://helloworld.org/messaging/HelloWorldMessageService/UpdateMessage",
ReplyAction="http://helloworld.org/messaging/HelloWorldMessageService/UpdateMessageResponse")]
System.IAsyncResult BeginUpdateMessage(string message, System.AsyncCallback callback, object asyncState);
void EndUpdateMessage(System.IAsyncResult result);
[System.ServiceModel.OperationContractAttribute(AsyncPattern=true, Action="http://helloworld.org/messaging/HelloWorldMessageService/GetMessage", ReplyAction="http://helloworld.org/messaging/HelloWorldMessageService/GetMessageResponse")]
System.IAsyncResult BeginGetMessage(System.AsyncCallback callback, object asyncState);
string EndGetMessage(System.IAsyncResult result);
}
public partial class HelloWorldMessageServiceClient : System.ServiceModel.ClientBase<HelloWorld.Core.Web.Services.HelloWorldMessageService>, HelloWorld.Core.Web.Services.HelloWorldMessageService {
{
// implementation
}
I'm trying to decouple my application by passing around the interface instead of the concrete class. But I'm having difficulty finding examples of how to do this. When I try and call EndGetMessage and then update my UI I get an exception about updating the UI on the wrong thread. How can I update the UI from a background thread?
I tried but I get UnauthorizedAccessException : Invalid cross-thread access.
string messageresult = _service.EndGetMessage(result);
Application.Current.RootVisual.Dispatcher.BeginInvoke(() => this.Message = messageresult );
The exception is thrown by Application.Current.RootVisual.
Here is something I like doing... The service proxy is generated with an interface
HelloWorldClient : IHelloWorld
But the problem is that IHelloWorld does not include the Async versions of the method. So, I create an async interface:
public interface IHelloWorldAsync : IHelloWorld
{
void HelloWorldAsync(...);
event System.EventHandler<HelloWorldEventRgs> HelloWorldCompleted;
}
Then, you can tell the service proxy to implement the interface via partial:
public partial class HelloWorldClient : IHelloWorldAsync {}
Because the HelloWorldClient does, indeed, implement those async methods, this works.
Then, I can just use IHelloWorldAsync everywhere and tell the UnityContainer to use HelloWorldClient for IHelloWorldAsync interfaces.
Ok, I have been messing with this all day and the solution is really much more simple than that. I originally wanted to call the methods on the interface instead of the concreate class. The interface generated by proxy class generator only includes the BeginXXX and EndXXX methods and I was getting an exception when I called EndXXX.
Well, I just finished reading up on System.Threading.Dispatcher and I finally understand how to use it. Dispatcher is a member of any class that inherits from DispatcherObject, which the UI elements do. The Dispatcher operates on the UI thread, which for most WPF applications there is only 1 UI thread. There are exceptions, but I believe you have to do this explicitly so you'll know if you're doing it. Otherwise, you've only got a single UI thread. So it is safe to store a reference to a Dispatcher for use in non-UI classes.
In my case I'm using Prism and my Presenter needs to update the UI (not directly, but it is firing IPropertyChanged.PropertyChanged events). So what I have done is in my Bootstrapper when I set the shell to Application.Current.RootVisual I also store a reference to the Dispatcher like this:
public class Bootstrapper : UnityBootstrapper
{
protected override IModuleCatalog GetModuleCatalog()
{
// setup module catalog
}
protected override DependencyObject CreateShell()
{
// calling Resolve instead of directly initing allows use of dependency injection
Shell shell = Container.Resolve<Shell>();
Application.Current.RootVisual = shell;
Container.RegisterInstance<Dispatcher>(shell.Dispatcher);
return shell;
}
}
Then my presenter has a ctor which accepts IUnityContainer as an argument (using DI) then I can do the following:
_service.BeginGetMessage(new AsyncCallback(GetMessageAsyncComplete), null);
private void GetMessageAsyncComplete(IAsyncResult result)
{
string output = _service.EndGetMessage(result);
Dispatcher dispatcher = _container.Resolve<Dispatcher>();
dispatcher.BeginInvoke(() => this.Message = output);
}
This is sooooo much simpler. I just didn't understand it before.
Ok, so my real problem was how to decouple my dependency upon the proxy class created by my service reference. I was trying to do that by using the interface generated along with the proxy class. Which could have worked fine, but then I would have also had to reference the project which owned the service reference and so it wouldn't be truly decoupled. So here's what I ended up doing. It's a bit of a hack, but it seems to be working, so far.
First here's my interface definition and an adapter class for the custom event handler args generated with my proxy:
using System.ComponentModel;
namespace HelloWorld.Interfaces.Services
{
public class GetMessageCompletedEventArgsAdapter : System.ComponentModel.AsyncCompletedEventArgs
{
private object[] results;
public GetMessageCompletedEventArgsAdapter(object[] results, System.Exception exception, bool cancelled, object userState) :
base(exception, cancelled, userState)
{
this.results = results;
}
public string Result
{
get
{
base.RaiseExceptionIfNecessary();
return ((string)(this.results[0]));
}
}
}
/// <summary>
/// Create a partial class file for the service reference (reference.cs) that assigns
/// this interface to the class - then you can use this reference instead of the
/// one that isn't working
/// </summary>
public interface IMessageServiceClient
{
event System.EventHandler<GetMessageCompletedEventArgsAdapter> GetMessageCompleted;
event System.EventHandler<AsyncCompletedEventArgs> UpdateMessageCompleted;
void GetMessageAsync();
void GetMessageAsync(object userState);
void UpdateMessageAsync(string message);
void UpdateMessageAsync(string message, object userState);
}
}
Then I just needed to create a partial class which extends the proxy class generated by the service reference:
using System;
using HelloWorld.Interfaces.Services;
using System.Collections.Generic;
namespace HelloWorld.Core.Web.Services
{
public partial class HelloWorldMessageServiceClient : IMessageServiceClient
{
#region IMessageServiceClient Members
private event EventHandler<GetMessageCompletedEventArgsAdapter> handler;
private Dictionary<EventHandler<GetMessageCompletedEventArgsAdapter>, EventHandler<GetMessageCompletedEventArgs>> handlerDictionary
= new Dictionary<EventHandler<GetMessageCompletedEventArgsAdapter>, EventHandler<GetMessageCompletedEventArgs>>();
/// <remarks>
/// This is an adapter event which allows us to apply the IMessageServiceClient
/// interface to our MessageServiceClient. This way we can decouple our modules
/// from the implementation
/// </remarks>
event EventHandler<GetMessageCompletedEventArgsAdapter> IMessageServiceClient.GetMessageCompleted
{
add
{
handler += value;
EventHandler<GetMessageCompletedEventArgs> linkedhandler = new EventHandler<GetMessageCompletedEventArgs>(HelloWorldMessageServiceClient_GetMessageCompleted);
this.GetMessageCompleted += linkedhandler;
handlerDictionary.Add(value, linkedhandler);
}
remove
{
handler -= value;
EventHandler<GetMessageCompletedEventArgs> linkedhandler = handlerDictionary[value];
this.GetMessageCompleted -= linkedhandler;
handlerDictionary.Remove(value);
}
}
void HelloWorldMessageServiceClient_GetMessageCompleted(object sender, GetMessageCompletedEventArgs e)
{
if (this.handler == null)
return;
this.handler(sender, new GetMessageCompletedEventArgsAdapter(new object[] { e.Result }, e.Error, e.Cancelled, e.UserState));
}
#endregion
}
}
This is an explicit implementation of the event handler so I can chain together the events. When user registers for my adapter event, I register for the actual event fired. When the event fires I fire my adapter event. So far this "Works On My Machine".
Passing around the interface (once you have instantiated the client) should be as simply as using HelloWorldMessageService instead of the HelloWorldMessageServiceClient class.
In order to update the UI you need to use the Dispatcher object. This lets you provide a delegate that is invoked in the context of the UI thread. See this blog post for some details.
You can make this much simpler still.
The reason the proxy works and your copy of the contract does not is because WCF generates the proxy with code that "Posts" the callback back on the calling thread rather than making the callback on the thread that is executing when the service call returns.
A much simplified, untested, partial implementation to give you the idea of how WCF proxies work looks something like:
{
var state = new
{
CallingThread = SynchronizationContext.Current,
Callback = yourCallback
EndYourMethod = // assign delegate
};
yourService.BeginYourMethod(yourParams, WcfCallback, state);
}
private void WcfCallback(IAsyncResult asyncResult)
{
// Read the result object data to get state
// Call EndYourMethod and block until the finished
state.Context.Post(state.YourCallback, endYourMethodResultValue);
}
The key is the storing of the syncronizationContext and calling the Post method. This will get the callback to occur on the same thread as Begin was called on. It will always work without involving the Dispatcher object provided you call Begin from your UI thread. If you don't then you are back to square one with using the Dispatcher, but the same problem will occur with a WCF proxy.
This link does a good job of explaining how to do this manually:
http://msdn.microsoft.com/en-us/library/dd744834(VS.95).aspx
Just revisiting old posts left unanswered where I finally found an answer. Here's a post I recently wrote that goes into detail about how I finally handled all this:
http://www.developmentalmadness.com/archive/2009/11/04/mvvm-with-prism-101-ndash-part-6-commands.aspx