ARTICLE

Consuming JSON service in Windows 8 HTML5 Metro App

Posted by Dhananjay Kumar Articles | Windows 8 December 24, 2011
In this post I will discuss a way of consuming a JSON service in a Windows 8 metro style application.
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Consuming JSON in Windows 8 Metro style Application using WinJS

In this post

  • Metro app is created using HTML 5 and a Service is being consumed using WinJS

  • Service is created service using WCF and REST is on service using webHttpBinding

Since creating a simple REST Service returning JSON is not the main focus of this post, I will show creation WCF REST Service returning JSON in a later part of this post.

Consuming JSON using WinJS

We need to consume the service in a HTML 5 Metro application. Very first let us design a HTML page

default.html

<!DOCTYPE html>
<
html>
<
head>
    <meta charset="utf-8" />
    <title>HelloWorldJavaScript</title>

    <!-- WinJS references -->
    <link rel="stylesheet" href="/winjs/css/ui-dark.css" />
    <script src="/winjs/js/base.js"></script>
    <script src="/winjs/js/wwaapp.js"></script>

    <!-- HelloWorldJavaScript references -->
    <link rel="stylesheet" href="/css/default.css" />
    <script src="/js/default.js"></script> 
</head>
<
body>
    <label >First Number</label>
   
<input id="TextboxFirstNumber" type="text" />
    <br/>
     <label >Second Number</label>
    
<input id="TextboxSecondNumber" type="text" />
    <br />
     <button id="ButtonAdd">+</button>    
   
<br />
    <span id="SpanResult" />
</
body>
</html>

I have put a button and two text boxes. User will input number to be added in textboxes and on click event of the button service would get called.

In the JS file to make call to REST Service returning JSON, we need to make call using WinJS.xhr

metrostylapp.gif
In the above snippet

1. The url is URL of REST Service

2. Using JSON.parse we are parsing returned text

3. ResultSpan is span in which result is being displayed

defaul.js

(function ()
{
'use strict';
WinJS.Application.onmainwindowactivated = function (e) {
if (e.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) {
      
Calculator();
        
function Calculator()
        {
            var Number1 = document.getElementById('TextboxFirstNumber');
            var Number2 = document.getElementById('TextboxSecondNumber');
            var ResultSpan = document.getElementById('SpanResult);
            var ButtonToAdd = document.getElementById('ButtonAdd');
            ButtonToAdd.addEventListener('click', function () {
            var baseURl = "http://test2dj8.cloudapp.net/Service1.svc/rest/add/";                   
            var url = baseURl+Number1.value+"/"+Number2.value; 
            WinJS.xhr({ url: url }).then(function (r) {
                        var result = JSON.parse(r.responseText);
                        ResultSpan.innerHTML = result;
                   
});
       }); 
       
}
    }
    WinJS.Application.start();
})();

Creating simple Add Service

To start with let us create a WCF REST Service returning JSON as below. There is one operation contact named Add in the service and that is taking two strings as input parameters and returning integer.

[ServiceContract]
public
interface
IService2
 {
  [OperationContract]
  [WebGet(UriTemplate="/Add/{Number1}/{Number2}",RequestFormat=WebMessageFormat.Json,
 ResponseFormat = WebMessageFormat.Json
                                                  )]
        int Add(string  Number1, string Number2);
 }

Service is implemented as below

using System;
namespace MultipleBindingWCF
{
    public class Service1 :
IService2
    {
        public int Add(string Number1, string Number2)
        {
            int num1 = Convert.ToInt32(Number1);
            int num2 = Convert.ToInt32(Number2);
            return num1 + num2;
   }     
 }
}

Next in this section we need to configure service. We need to configure service webHttpBinding  to eanble it as REST Service.  So in Web.Config  we need to do the below changes.

<?xml version="1.0"?>
<configuration>
<
system.web>
 <
compilation debug="true" targetFramework="4.0" />
 </system.web>
  <
system.serviceModel>
    <
behaviors>
      <
serviceBehaviors>
        <
behavior name ="servicebehavior">        
          <serviceMetadata httpGetEnabled="true"/>        
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </
serviceBehaviors>
      <
endpointBehaviors>
     <
behavior name="restbehavior">
   <webHttp/>
  </
behavior>
  </
endpointBehaviors>
  </
behaviors>
<
services>
                   <endpoint name ="RESTEndPoint"
                  contract ="MultipleBindingWCF.IService2"
                  binding ="webHttpBinding"
                  address ="rest"
   
 behaviorConfiguration ="restbehavior"/>
   </service>
     </
services>   
    </
system.serviceModel>
    <
system.webServer>
    <
modules runAllManagedModulesForAllRequests="true"/>
    </system.webServer
    </
configuration>

After configuring, Service is ready for hosting. After hosting consume service in Windows 8 Metro application.

I hope this post is useful. Thanks for reading. 

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