blocks|key|344449|text|我还没有尝试过显式地使用REST，我自己也没有使用ELMAH，但另一个值得研究的选择可能是使用IDispatchMessageInspector而不是IErrorHandler连接到WCF。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|344450|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.idispatchmessageinspector.aspx^0|1B|P|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

I haven't tried doing this explicitly with the REST stuff, and haven't used ELMAH myself, but another option worth looking into might be to hook into WCF using an <a href="http://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.idispatchmessageinspector.aspx" rel="nofollow noreferrer">IDispatchMessageInspector</a> instead of an IErrorHandler.

blocks|key|3324699|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3324700|我基于Will的工作做了这件事，但我想在发布代码之前验证这是正确的方法。|blockquote|3324701|3324702|3324703|我认为这是一个很好的方法(这篇文章对Will赞誉有加！)。我不认为威尔或者你错过了这里的任何东西。实现IErrorHandler是捕获所有可能的服务器端异常的首选方法，否则这些异常可能会导致通信通道出现故障(关闭)，因此这是一个很自然地挂接到一些日志记录的地方。|3324704|Marc|3324705|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|-4|4|5|6|L|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|M|7|@]|8|@]|9|$]]|$1|D|3|-4|4|5|6|N|7|@]|8|@]|9|$]]|$1|E|3|-4|4|5|6|O|7|@]|8|@]|9|$]]|$1|F|3|G|4|5|6|P|7|@]|8|@]|9|$]]|$1|H|3|I|4|5|6|Q|7|@]|8|@]|9|$]]|$1|J|3|-4|4|5|6|R|7|@]|8|@]|9|$]]]|K|$]]

<blockquote>
 I have done this based on Will's work
 but I want to verify that this is the
 correct approach before posting the
 code.
</blockquote>

I think this is a great approach (kudos to Will for this posting!). I don't think Will or you have missed anything here. Implementing IErrorHandler is the preferred way of capturing all possible server-side exceptions that could otherwise cause the communication channel to be faulted (torn down) and thus it's a natural place to hook in some logging like ELMAH.

Marc

blocks|key|3324755|text|我的博客文章中的解决方案(在OP中引用)是基于我们在错误状态期间用来更改HTTP响应代码的现有解决方案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3324756|因此，对于我们来说，将异常传递给ELMAH只需要一行代码。如果有更好的解决方案，我也很想知道。|3324757|对于后代/参考，和潜在的改进-这里是来自当前解决方案的代码。|3324758|HttpErrorHandler和ServiceErrorBehaviourAttribute类|3324759|using+System;
using+System.ServiceModel;
using+System.ServiceModel.Dispatcher;
using+System.ServiceModel.Channels;
using+System.ServiceModel.Description;
using+System.Collections.ObjectModel;
using+System.Net;
using+System.Web;
using+Elmah;
namespace+YourApplication
{
++++///+<summary>
++++///+Your+handler+to+actually+tell+ELMAH+about+the+problem.
++++///+</summary>
++++public+class+HttpErrorHandler+:+IErrorHandler
++++{
++++++++public+bool+HandleError(Exception+error)
++++++++{
++++++++++++return+false;
++++++++}

++++++++public+void+ProvideFault(Exception+error,+MessageVersion+version,+ref+Message+fault)
++++++++{
++++++++++++if+(error+!=+null+)+//+Notify+ELMAH+of+the+exception.
++++++++++++{
++++++++++++++++if+(System.Web.HttpContext.Current+==+null)
++++++++++++++++++++return;
++++++++++++++++Elmah.ErrorSignal.FromCurrentContext().Raise(error);
++++++++++++}
++++++++}
++++}
++++///+<summary>
++++///+So+we+can+decorate+Services+with+the+[ServiceErrorBehaviour(typeof(HttpErrorHandler))]
++++///+...and+errors+reported+to+ELMAH
++++///+</summary>
++++public+class+ServiceErrorBehaviourAttribute+:+Attribute,+IServiceBehavior
++++{
++++++++Type+errorHandlerType;

++++++++public+ServiceErrorBehaviourAttribute(Type+errorHandlerType)
++++++++{
++++++++++++this.errorHandlerType+=+errorHandlerType;
++++++++}

++++++++public+void+Validate(ServiceDescription+description,+ServiceHostBase+serviceHostBase)
++++++++{
++++++++}

++++++++public+void+AddBindingParameters(ServiceDescription+description,+ServiceHostBase+serviceHostBase,+Collection<ServiceEndpoint>+endpoints,+BindingParameterCollection+parameters)
++++++++{
++++++++}

++++++++public+void+ApplyDispatchBehavior(ServiceDescription+description,+ServiceHostBase+serviceHostBase)
++++++++{
++++++++++++IErrorHandler+errorHandler;
++++++++++++errorHandler+=+(IErrorHandler)Activator.CreateInstance(errorHandlerType);
++++++++++++foreach+(ChannelDispatcherBase+channelDispatcherBase+in+serviceHostBase.ChannelDispatchers)
++++++++++++{
++++++++++++++++ChannelDispatcher+channelDispatcher+=+channelDispatcherBase+as+ChannelDispatcher;
++++++++++++++++channelDispatcher.ErrorHandlers.Add(errorHandler);
++++++++++++}
++++++++}
++++}
}|code-block|syntax|javascript|3324760|使用示例|3324761|使用ServiceErrorBehaviour属性装饰您的WCF服务：|3324762|[ServiceContract(Namespace+=+"http://example.com/api/v1.0/")]
[ServiceErrorBehaviour(typeof(HttpErrorHandler))]
public+class+MyServiceService
{
++//+...
}|3324763|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|X|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|Y|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|J|7|11|8|@]|9|@]|A|$K|L]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

The solution from my blog post (referenced in the OP) was based on an existing solution we were/are using to alter HTTP Response Codes during an error state. 

So, for us it was a one-line change to pass the Exception to ELMAH. If there's a better solution, I'd love to know about it too. 

For Posterity/Reference, and potential improvement - here's the code from the current solution. 

<h3>HttpErrorHandler and ServiceErrorBehaviourAttribute Classes</h3>

<pre><code>using System;
using System.ServiceModel;
using System.ServiceModel.Dispatcher;
using System.ServiceModel.Channels;
using System.ServiceModel.Description;
using System.Collections.ObjectModel;
using System.Net;
using System.Web;
using Elmah;
namespace YourApplication
{
 /// &lt;summary&gt;
 /// Your handler to actually tell ELMAH about the problem.
 /// &lt;/summary&gt;
 public class HttpErrorHandler : IErrorHandler
 {
 public bool HandleError(Exception error)
 {
 return false;
 }

 public void ProvideFault(Exception error, MessageVersion version, ref Message fault)
 {
 if (error != null ) // Notify ELMAH of the exception.
 {
 if (System.Web.HttpContext.Current == null)
 return;
 Elmah.ErrorSignal.FromCurrentContext().Raise(error);
 }
 }
 }
 /// &lt;summary&gt;
 /// So we can decorate Services with the [ServiceErrorBehaviour(typeof(HttpErrorHandler))]
 /// ...and errors reported to ELMAH
 /// &lt;/summary&gt;
 public class ServiceErrorBehaviourAttribute : Attribute, IServiceBehavior
 {
 Type errorHandlerType;

 public ServiceErrorBehaviourAttribute(Type errorHandlerType)
 {
 this.errorHandlerType = errorHandlerType;
 }

 public void Validate(ServiceDescription description, ServiceHostBase serviceHostBase)
 {
 }

 public void AddBindingParameters(ServiceDescription description, ServiceHostBase serviceHostBase, Collection&lt;ServiceEndpoint&gt; endpoints, BindingParameterCollection parameters)
 {
 }

 public void ApplyDispatchBehavior(ServiceDescription description, ServiceHostBase serviceHostBase)
 {
 IErrorHandler errorHandler;
 errorHandler = (IErrorHandler)Activator.CreateInstance(errorHandlerType);
 foreach (ChannelDispatcherBase channelDispatcherBase in serviceHostBase.ChannelDispatchers)
 {
 ChannelDispatcher channelDispatcher = channelDispatcherBase as ChannelDispatcher;
 channelDispatcher.ErrorHandlers.Add(errorHandler);
 }
 }
 }
}
</code></pre>

<h3>Usage Example</h3>

Decorate your WCF Services with the ServiceErrorBehaviour Attribute: 

<pre><code>[ServiceContract(Namespace = "http://example.com/api/v1.0/")]
[ServiceErrorBehaviour(typeof(HttpErrorHandler))]
public class MyServiceService
{
 // ...
}
</code></pre>

blocks|key|339619|text|在创建配置时，甚至可以使用BehaviorExtensionElement激活行为：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|339620|public+class+ErrorBehaviorExtensionElement+:+BehaviorExtensionElement
{
++++public+override+Type+BehaviorType
++++{
++++++++get+{+return+typeof(ServiceErrorBehaviourAttribute);+}
++++}

++++protected+override+object+CreateBehavior()
++++{
++++++++return+new+ServiceErrorBehaviourAttribute(typeof(HttpErrorHandler));
++++}
}|code-block|syntax|javascript|339621|配置：|339622|<system.serviceModel>
++++<extensions>
++++++<behaviorExtensions>
++++++++<add+name="elmah"+type="Namespace.ErrorBehaviorExtensionElement,+YourAssembly,+Version=1.0.0.0,+Culture=neutral,+PublicKeyToken=null"/>
++++++</behaviorExtensions>
++++</extensions>
++++<behaviors>
++++++<serviceBehaviors>
++++++++<behavior>
++++++++++<elmah+/>
++++++++</behavior>
++++++</serviceBehaviors>
++++</behaviors>
++</system.serviceModel>|339623|通过这种方式，还可以将ELMAH与RIA服务结合使用！|339624|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

When creating a BehaviorExtensionElement it is even possible to activate the behavior using config:

<pre><code>public class ErrorBehaviorExtensionElement : BehaviorExtensionElement
{
 public override Type BehaviorType
 {
 get { return typeof(ServiceErrorBehaviourAttribute); }
 }

 protected override object CreateBehavior()
 {
 return new ServiceErrorBehaviourAttribute(typeof(HttpErrorHandler));
 }
}
</code></pre>

Config:

<pre><code>&lt;system.serviceModel&gt;
 &lt;extensions&gt;
 &lt;behaviorExtensions&gt;
 &lt;add name="elmah" type="Namespace.ErrorBehaviorExtensionElement, YourAssembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"/&gt;
 &lt;/behaviorExtensions&gt;
 &lt;/extensions&gt;
 &lt;behaviors&gt;
 &lt;serviceBehaviors&gt;
 &lt;behavior&gt;
 &lt;elmah /&gt;
 &lt;/behavior&gt;
 &lt;/serviceBehaviors&gt;
 &lt;/behaviors&gt;
 &lt;/system.serviceModel&gt;
</code></pre>

That way it is also possible to use ELMAH in combination with RIA services!

blocks|key|339640|text|这对一些人来说可能是显而易见的，但我只是花了相当长的时间试图弄清楚为什么我的HttpContext.Current是空的，尽管遵循了威尔·休斯的所有优秀答案。令人尴尬的是，我意识到这是因为我的WCF服务是由MSMQ消息激活的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|339641|我最终重写了ProvideFault()方法：|offset|length|style|CODE|339642|if+(HttpContext.Current+==+null)
{
++++ErrorLog.GetDefault(null).Log(new+Error(error));
}
else
{
++++ErrorSignal.FromCurrentContext().Raise(error);
}|code-block|syntax|javascript|339643|entityMap^0|0|6|E|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@$D|Q|E|R|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|S|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

This may well be obvious to some people but I just spent quite a while trying to figure out why my HttpContext.Current was null despite following all of Will Hughes' excellent answer. Embarassingly, I realised that this was because my WCF service is activated by a MSMQ message.

I ended up rewriting the <code>ProvideFault()</code> method:

<pre><code>if (HttpContext.Current == null)
{
 ErrorLog.GetDefault(null).Log(new Error(error));
}
else
{
 ErrorSignal.FromCurrentContext().Raise(error);
}
</code></pre>

blocks|key|340969|text|使用WCF数据服务时，我无法获得建议的答案。我连接了行为属性等，但仍然没有记录任何错误。相反，我最终在服务实现中添加了以下内容：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|340970|protected+override+void+HandleException(HandleExceptionArgs+args)
{
++++Elmah.ErrorSignal.FromCurrentContext().Raise(args.Exception);
++++base.HandleException(args);
}|code-block|syntax|javascript|340971|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I was unable to get the proposed answer working with a WCF Data Service. I wired up the behavior attribute, etc, but still did not get any errors logged. Instead, I ended up adding the following to the service implementation:

<pre><code>protected override void HandleException(HandleExceptionArgs args)
{
 Elmah.ErrorSignal.FromCurrentContext().Raise(args.Exception);
 base.HandleException(args);
}
</code></pre>

We are using the excellent <a href="http://code.google.com/p/elmah" rel="noreferrer">ELMAH</a> to deal with unhandled exceptions in an ASP.NET 3.5 web application. This works extremely well for all of the site apart from WCF services which are being consumed using the REST features. When an exception occurs within the operation methods that is not handled by the application code, WCF handles it in various ways depending on the service contracts and configuration settings. This means that the exception does not end up firing the ASP.NET HttpApplication.Error event that <a href="http://code.google.com/p/elmah" rel="noreferrer">ELMAH</a> uses. The two solutions I am aware of to deal with this are:

<ul>
<li>Wrap all method calls in a try { } catch(Exception ex) { Elmah.ErrorSignal.FromCurrentContext().Raise(ex); throw; } to explicitly call Elmah within the catch block.</li>
<li>Use <a href="http://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.ierrorhandler.aspx" rel="noreferrer">IErrorHandler</a> as described in <a href="http://will.hughesfamily.net.au/about/" rel="noreferrer">Will Hughes'</a> blog post <a href="http://will.hughesfamily.net.au/20090505/making-wcf-and-elmah-play-nice-together/" rel="noreferrer">Making WCF and ELMAH play nice together</a> to factor out the call to ELMAH to a separate ErrorHandler.</li>
</ul>

The first option is extremely simple but is not exactly <a href="http://en.wikipedia.org/wiki/Don&#39;t_repeat_yourself" rel="noreferrer">DRY</a>. The second option only requires you to decorate each service with the custom attribute after implementing the attribute and the ErrorHandler. I have done this based on <a href="http://will.hughesfamily.net.au/about/" rel="noreferrer">Will's</a> work but I want to verify that this is the correct approach before posting the code.

Is there a better way that I have missed?

The MSDN documenation for <a href="http://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.ierrorhandler.aspx" rel="noreferrer">IErrorHandler</a> says that the HandleError method is the place to do the logging but <a href="http://code.google.com/p/elmah" rel="noreferrer">ELMAH</a> accesses the HttpContext.Current.ApplicationInstance, which is null within this method even though HttpContext.Current is available. Making the call to Elmah within the ProvideFault method is a workaround as ApplicationInstance is set but this does not match the intent described in the API documentation. Am I missing something here? The documentation does state that you should not rely on the HandleError method being called on the operation thread which may be why ApplicationInstance is null in this scope.

Exception Logging for WCF Services using ELMAH

服务器

我们正在使用优秀的来处理ASP.NET 3.5Web应用程序中未处理的异常。除了使用REST功能使用的WCF服务之外，这对所有站点都非常有效。当操作方法中发生应用程序代码未处理的异常时，WCF将根据服务契约和配置设置以各种方式处理它。这意味着异常不会触发使用的ASP.NET HttpApplication.Error事...

问使用ELMAH的WCF服务的异常日志记录
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