Question

I have a simple WCF web service on my machine which I have developed to serve Android and IOS devices.

The service has a single method as following :

[OperationContract]
    [WebInvoke(RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped, UriTemplate = "/?message={message}")]
    string ServiceMessage(string message);

I have 3 clients , one .NET test client using HttpWebRequest which works fine , one IOS client which works fine and one Android client which I have developed with the HttpPost and HttpClient classes that fails.

Using Fiddler reverse proxy I have debugged the output of the .net client :

POST http://127.0.0.1:8888/Service1.svc/?message=_|JSON MESSAGE BODY|_HTTP/1.1
Content-Type: application/json; charset=utf-8
Host: 127.0.0.1:8888
Content-Length: 338
Expect: 100-continue
Connection: Keep-Alive

_|JSON MESSAGE BODY|_

On the other hand , this is the output of the Android HTTP Post :

POST http://10.0.2.2:8888/Service1.svc/ HTTP/1.1
Content-Type: application/json; charset=utf-8
Content-Length: 139
Host: 10.0.2.2:8888
Connection: Keep-Alive
User-Agent: Apache-HttpClient/UNAVAILABLE (java 1.4)
Expect: 100-Continue

message=_|JSON MESSAGE BODY|_

As you can see , .Net puts the message parameter on the Post at the top and does not
put the message variable name at the bottom while Android does not put the message body at the Post at the top and does put the message variable name at the bottom.

This is my Android post code ,

    HttpPost httpPost = new HttpPost(url);      
    String messageBody = "message=" + jsonMessageParameter;
    StringEntity entity = new StringEntity(messageBody);
    httpPost.setEntity(entity);
    httpPost.setHeader("Content-Type", "application/json; charset=utf-8");
    HttpResponse response = hc.execute(httpPost);
    InputStream content = response.getEntity().getContent();
    String json = ConvertStreamToString(content);

When calling with this code , the server method is called but the message method parameter is null.
I tried playing with the Uri.Builder class to also make the android post put the message at the header , but doesnt quite work.
If can someone help me out here , I am stuck on this for hours over hours.

Thank you in advance ,

James

EDIT :

I changed the Android code to :

    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
    nameValuePairs.add(new BasicNameValuePair("message", jsonMessageParameter));

    HttpPost httpPost = new HttpPost(url);
     UrlEncodedFormEntity urlEncodedFromEntity = new UrlEncodedFormEntity(
     nameValuePairs);
     urlEncodedFromEntity.setContentType(new BasicHeader("Content-Type",
     "application/json; charset=utf-8"));

    httpPost.setEntity(urlEncodedFromEntity);

    InputStream postStream = httpPost.getEntity().getContent();
    String postOutput = ConvertStreamToString(postStream);
    HttpResponse response = hc.execute(httpPost);
    InputStream content = response.getEntity().getContent();
    String json = ConvertStreamToString(content);

But still the Fiddler monitoring is as following :

POST http://10.0.2.2:8888/Service1.svc/ HTTP/1.1
Content-Length: 189
Content-Type: application/json; charset=utf-8
Host: 10.0.2.2:8888
Connection: Keep-Alive
User-Agent: Apache-HttpClient/UNAVAILABLE (java 1.4)
Expect: 100-Continue

message=_|MESSAGE_JSON|_

Answer 1

There a number of points here.

First, you specifically added message= to your Android POST body:

String messageBody = "message=" + jsonMessageParameter;

This can be also problematic since you specified Content-Type: application/json but by adding message= you are not providing a valid JSON object.

Second, why does the .Net implementation replicate the JSON object both as parameter in the URL and in the body? This looks strange and very uncommon for a POST request, and can cause problem if your JSON object makes the URL exceed the maximum URL length.

So I would try removing message= in the body and removing the JSON object as a URL parameter, since servers processing POSTs should read the body and not the URL.