Question

I have a self-hosted WCF web service running, and an Android client application. I am able to GET or retrieve data from the web service in json format, however I am unable to POST or send any data to the server.

Below is the code from the WCF service:

 [OperationContract]
 [WebInvoke(Method = "POST",
 UriTemplate = "/SetValue",
 RequestFormat = WebMessageFormat.Json,
 ResponseFormat = WebMessageFormat.Json,
 BodyStyle = WebMessageBodyStyle.Wrapped)]
 public string SetValue(TestClass someValue)
 {
     return someValue.Something.ToString();
 }

[DataContract]
public class TestClass
{
    [DataMember(Name = "something")]
    public int Something
    {
        get;
        set;
    }
}

Below is the code from the Android client:

 HttpClient httpClient = new DefaultHttpClient();
 HttpPost request = new HttpPost("http://xxx.xxx.x.x:8000/SetValue");
 List<NameValuePair> params = new ArrayList<NameValuePair>(1);
 params.add(new BasicNameValuePair("something", "12345"));
 request.setEntity(new UrlEncodedFormEntity(params));
 HttpResponse response = httpClient.execute(request);

The following is how I start the self-hosted service:

 class Program
 {
    static void Main()
    {
        Uri baseAddress = new Uri("http://localhost:8000/");

        using (WebServiceHost host = new WebServiceHost(typeof(ServerSideProfileService), baseAddress))
        {
            host.AddServiceEndpoint(typeof(ServerSideProfileService), new BasicHttpBinding(), "Soap");
            ServiceEndpoint endpoint = host.AddServiceEndpoint(typeof(ServerSideProfileService), new WebHttpBinding(), "Web");
            endpoint.Behaviors.Add(new WebHttpBehavior());

            // Open the service host, service is now listening
            host.Open();
        }
     }
  }

I only have an app.config which just has:

 <?xml version="1.0"?>
 <configuration>
 <startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/></startup></configuration>

The response I’m getting when I run httpClient.execute(request) from the Android client includes:

 HTTP/1.1 400 Bad Request
 Request Error
 The server encountered an error processing the request. See server logs for more details.

And that’s pretty much it. I am very new to WCF and don’t know where this ‘server log’ would be, and am at a loss as to how to troubleshoot or debug this? (I have tried Fiddler2 but it doesn’t seem to detect anything from the Android client.)

[EDIT]

I have also tried

 JSONObject json = new JSONObject(); 
 json.put("something", "12345"); 
 StringEntity entity = new StringEntity(json.toString()); 
 entity.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
 entity.setContentType( new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));  
 request.setEntity(entity); 

which also results in the error.

I also noticed that if I change ‘SetValue’ to return a constant, such as “abcd”, instead of someValue.Something.ToString(), then everything works?

Answer 1

Your client code is sending a html form post formatted payload, but your server is expecting a json payload, you need the client to be something like

HttpClient httpClient = new DefaultHttpClient();
HttpPost request = new HttpPost("http://xxx.xxx.x.x:8000/SetValue");
StringEntity e = new StringEntity("{ \"something\":12345 }", "UTF-8");
request.setEntity(e);
request.setHeader("content-type", "application/json");
HttpResponse response = httpClient.execute(request);