Send xml message over HTTP POST

I require to send an HL7 message, which is parsed into an XML message to the below end point.

• Host: iol.sandbox.ohie.org


• Port: 5001


• username: admin


• password: admin


• HTTP method: POST


• HTTP Path: /ws/rest/v1/patients/

I am using Apache HttpClient to achieve this. Below is the code which I am using.

public void simpleHttpMessage() throws Exception{
    String url = "iol.sandbox.ohie.org";
    String USER_AGENT = "/ws/rest/v1/patients/";

    HttpClient client = new DefaultHttpClient();
    HttpPost post = new HttpPost(url);

    // add header
    post.setHeader("User-Agent", USER_AGENT);

    List<NameValuePair> urlParameters = new ArrayList<NameValuePair>();
    urlParameters.add(new BasicNameValuePair("username", "admin"));
    urlParameters.add(new BasicNameValuePair("password", "admin"));

    post.setEntity(new UrlEncodedFormEntity(urlParameters));


    HttpResponse response = client.execute(post);
    System.out.println("\nSending 'POST' request to URL : " + url);
    System.out.println("Post parameters : " + post.getEntity());
    System.out.println("Response Code : " + 
                                response.getStatusLine().getStatusCode());

    BufferedReader rd = new BufferedReader(
                    new InputStreamReader(response.getEntity().getContent()));

    StringBuffer result = new StringBuffer();
    String line = "";
    while ((line = rd.readLine()) != null) {
        result.append(line);
    }

    System.out.println(result.toString());
}

I am not sure where I should pass the actual xml message which I want to send. I am basically trying to send a HL7 message which is parsed into XML, over HTTP POST.

I would be grateful if someone who help me with what I am missing from the above code snippet.