WCF:System.ServiceModel.ServiceActivationException: The service '/DataService.svc' cannot be activated due to an exception during compilation

      wcf服务 ，在本地测试，远程部署都完全没问题。但是运行一段时间后WCF会出现错误，页面数据不显示了。

      第一次出现的时候，立马想到是不是没有返回数据，抓包查看的时候，有json格式的数据返回。这怎么会不显示呢，对数据进行对比，发现其中部分数据有换行现象，于是将数据一条一条读取，读到有换行的数据是果然读不出来。处理了下一直运行至今毫无问题。

      第二次另外一家客户也反映了这个问题，当时我还抱怨了说数据的时候咋不判断呀，告诉同事说，让他把显示数据过滤一遍，以为跟上回一样可以解决的。但是问题就来了，还是不能解决。我firebug看了下，提示找不到WCF服务。google了一番都是说WCF 配置问题。重新配置了一番，果然可以。正在沾沾自喜的时候，发现了一个问题,只是我打开.svc文件的那个服务好了，没有打开.svc文件的都不行，但是在config里都配置了。这就让我意识到不是配置问题了。

      突然灵机一动看看系统日志会不会有提示。果然有，错误如下：

日志名称:          Application
来源:            System.ServiceModel 4.0.0.0
日期:            2013/9/23 9:57:47
事件 ID:         3
任务类别:          (5)
级别:            错误
关键字:           经典
用户:            NETWORK SERVICE
计算机:           qyyngp
说明:
WebHost failed to process a request.
 Sender Information: System.ServiceModel.ServiceHostingEnvironment+HostingManager/37175364
 Exception: System.ServiceModel.ServiceActivationException: The service '/DataService.svc' cannot be activated due to an exception during compilation.  The exception message is: Could not load file or assembly 'App_Web_ljypiyuh, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. 系统找不到指定的文件。. ---> System.IO.FileNotFoundException: Could not load file or assembly 'App_Web_ljypiyuh, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. 系统找不到指定的文件。
   at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.Load(String assemblyString)
   at System.ServiceModel.Activation.ServiceHostFactory.CreateServiceHost(String constructorString, Uri[] baseAddresses)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.CreateService(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.ActivateService(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath)
   --- End of inner exception stack trace ---
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.EnsureServiceAvailableFast(String relativeVirtualPath)
 Process Name: w3wp
 Process ID: 5620事件 Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="System.ServiceModel 4.0.0.0" />
    <EventID Qualifiers="49154">3</EventID>
    <Level>2</Level>
    <Task>5</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2013-09-23T01:57:47.000Z" />
    <EventRecordID>8471</EventRecordID>
    <Channel>Application</Channel>
    <Computer>qyyngp</Computer>
    <Security UserID="S-1-5-20" />
  </System>
  <EventData>
    <Data>System.ServiceModel.ServiceHostingEnvironment+HostingManager/37175364</Data>
    <Data>System.ServiceModel.ServiceActivationException: The service '/DataService.svc' cannot be activated due to an exception during compilation.  The exception message is: Could not load file or assembly 'App_Web_ljypiyuh, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. 系统找不到指定的文件。. ---&gt; System.IO.FileNotFoundException: Could not load file or assembly 'App_Web_ljypiyuh, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. 系统找不到指定的文件。
   at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark&amp; stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark&amp; stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark&amp; stackMark, Boolean forIntrospection, Boolean suppressSecurityChecks)
   at System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark&amp; stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.Load(String assemblyString)
   at System.ServiceModel.Activation.ServiceHostFactory.CreateServiceHost(String constructorString, Uri[] baseAddresses)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.CreateService(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.ActivateService(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath)
   --- End of inner exception stack trace ---
   at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath)
   at System.ServiceModel.ServiceHostingEnvironment.EnsureServiceAvailableFast(String relativeVirtualPath)</Data>
    <Data>w3wp</Data>
    <Data>5620</Data>
  </EventData>
</Event> 

         跟虚拟目录有关，w3wp是什么，google了一把。        

         w3wp：在IIS（因特网信息服务器）与应用程序池相关联的一个进程，如果你有多个应用程序池，就会有对应的多个w3wp.exe的进程实例运行。

         原来还是iis部署问题。根据相应问题找到解决方案如下：

                 将项目已应用程序的方式部署，而不是已网站形式部署。

        部署之后对比当前网站形势部署。果然在之前的问题依旧，已应用程序部署的OK！！

        这次不知道是彻底解决还是暂时性解决，记录下以备后用。期待该问题下次重现周期。。。。。。