public String logoutRequest(String sessionID, String userName) {
    /*Serialize the logout request as the following format:
    {
        "logoutInfo": {
            "userName" : "username"
        },
        "request" : "/user/logout.json",
        "sessionID" : "sessionID"
    }*/
    Gson gson = new Gson();
    UserFullInfo logoutInfo = new UserFullInfo();
    LogoutRequestProtocol requestData = new LogoutRequestProtocol();

    logoutInfo.setUserName(userName);
    requestData.setRequest("/user/logout.json");
    requestData.setSessionID(sessionID);
    requestData.setLogoutInfo(logoutInfo);

    String requestJson = gson.toJson(requestData);
    return requestJson;
  }
  public String registerRequest(String userName, String userNickname, String password) {
    /*Serialize the register request as the following format:
    {
        "userInfo" : {
            "userName" : "userName",
            "userNickname" : "userNickname",
            "password" : "password"
        },
        "request" : "/user/register.json"
    }*/
    UserFullInfo userInfo = new UserFullInfo();
    userInfo.setUserName(userName);
    userInfo.setUserNickname(userNickname);
    userInfo.setPassword(password);

    RegisterRequestProtocol requestData = new RegisterRequestProtocol();
    requestData.setUserInfo(userInfo);
    requestData.setRequest("/user/register.json");

    Gson gson = new Gson();
    String requestJson = gson.toJson(requestData);
    return requestJson;
  }