调用REST服务时如何解决404错误？

Question

I created a WCF service and exposed two endpoints; one for SOAP and one for REST. The SOAP endpoint works and is reachable from web clients, console apps, etc. The REST endpoint was created this morning and doesn't work. I confirmed the SOAP service is still reachable so this problem is specific to the REST portion or configuration changes made this morning.

In the browser, I try to navigate to http://ABC:99/json/categories . I get a 404 - File or directory not found.

I added the following attribute to a method in the class which implements the service interface:

[WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json, UriTemplate = "categories")]

and this to another method:

[WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json, UriTemplate = "reports/{categoryId}")]

The relevant portions of the config file are here:

<system.serviceModel>
  <bindings>
    <basicHttpBinding>
      <binding name="NewBinding0" maxBufferSize="524288" maxReceivedMessageSize="524288" transferMode="StreamedResponse"
      closeTimeout="00:10:00" openTimeout="00:10:00" sendTimeout="00:10:00" receiveTimeout="00:10:00" />
    </basicHttpBinding>
  </bindings>

  <services>
    <service name="XXX.ReportGenerator">
      <endpoint address="" binding="basicHttpBinding" bindingConfiguration="NewBinding0"
      contract="XXX.YYY.IReportGenerator">
        <identity>
          <dns value="localhost" />
        </identity>
      </endpoint>
      <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
    </service>

    <service name="ReportingSvc.JSON">
      <endpoint address="json" binding="webHttpBinding"
      contract="XXX.YYY.ReportingSvc.IReportGenerator" behaviorConfiguration="jsonEndpoint" />
      <host>
        <baseAddresses>
          <add baseAddress="http://ABC:99/" />
        </baseAddresses>
      </host>
    </service>

  </services>

  <behaviors>

    <endpointBehaviors>
      <behavior name="jsonEndpoint">
        <webHttp />
      </behavior>
    </endpointBehaviors>

    <serviceBehaviors>
      <behavior>


        <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->
        <serviceMetadata httpGetEnabled="true"/>
        <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
        <serviceDebug includeExceptionDetailInFaults="true"/>
      </behavior>
    </serviceBehaviors>
  </behaviors>

  <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />
</system.serviceModel>

Any suggestions are greatly appreciated! Thanks!

Answer 1

I can't give you specific help with REST services in WCF as I've no experience there, but WCF Tracing has been a lifesaver for me in multiple instances in the past. Simply follow instructions to add the following to your WCF service's web.config:

<configuration>
   <system.diagnostics>
      <sources>
            <source name="System.ServiceModel" 
                    switchValue="Information, ActivityTracing"
                    propagateActivity="true">
            <listeners>
               <add name="traceListener" 
                   type="System.Diagnostics.XmlWriterTraceListener" 
                   initializeData= "c:\log\Traces.svclog" />
            </listeners>
         </source>
      </sources>
   </system.diagnostics>
</configuration>

Obviously you'd change the path for your log as necessary and make sure the correct permissions were set on the folder you set, but that's essentially it. Once the trace starts being logged, you can use the Service Trace Viewer , which I believe is installed by default, to view the trace and see if you can't pinpoint the source of your problem.

EDIT

Please note though, that service tracing is super resource-intensive, so only turn it on when you need it to debug problems and then turn it off when you don't need it anymore.

Answer 2

If your method is intended to just perform a GET operation its better to use the WebGet attribute rather than using WebInvoke and specifying your method to be GET.

Also the URL for your service for the first method would be as below:

http://ABC:99/categories/json

URL for 2nd method would be

http://ABC:99/reports/5/json

This is because you are defining the address as "json" as your endpoint address which gets appended to the base URL + Resource URL + endpoint address.