Question

I’m using an ajax enabled wcf service with a jquery POST method which gets data for my sidebar menus.
It works great just after the page loads but if i wait a few minutes and then try to get the data i get no response. Firebug shows the request is sent from the browser however i’m not seeing a hit while in debug mode, the server doesn’t even realize a request was sent.
any suggestions?

EDIT
here is some relevant code
clientSide:

$.ajaxSetup({
    type: "POST",
    contentType: "application/json",
    timeout: 10000,
    cache:false,
    dataType: "json"

});

function getSubcategories(categoryId, onSuccess, onError) {
    var request = new Object();
    request.categoryId = categoryId;
    var jsonData = JSON.stringify(request);
    $.ajax({
        url: "/SiteService.svc/GetSubcategories",
        data: jsonData,
        success: onSuccess,
        error: onError
    });

ServerSide:

[ServiceContract(Namespace = "myService")]

    public interface ISiteService
    {

        [OperationContract()]
        SiteServCategory[] GetSubcategories(int categoryId);
    }

web.confing

 <system.serviceModel>

    <services>

      <service name="App_Code.Services.Website.Site.SiteService" behaviorConfiguration="DebugEnabled">
        <endpoint behaviorConfiguration="SiteServiceAspNetAjaxBehavior" binding="webHttpBinding" contract="App_Code.Services.Website.Site.ISiteService"/>
      </service>
    </services>
    <behaviors>
      <endpointBehaviors>
       <behavior name="SiteServiceAspNetAjaxBehavior">
          <enableWebScript/>
        </behavior>
      </endpointBehaviors>
      <serviceBehaviors>
            <behavior name="DebugEnabled">

          <serviceMetadata httpGetEnabled="true"/>
          <serviceDebug includeExceptionDetailInFaults="true"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true"/>
  </system.serviceModel>

Answer 1

I believe your OperationContract needs to be decorated with either the WebInvoke or WebGet for it to be exposed as JSON.

[WebInvoke(BodyStyle=WebMessageBodyStyle.Bare, ResponseFormat=WebMessageFormat.Json)]