Sonntag, Juni 22, 2008

How to setup a new AjaxEngine web project

I was asked how to setup a web project that uses the AjaxEngine so here is step by step tutorial for a minimal Ajax web project that calls a server side web service:

1. Create a new web project (I prefer using c#) or use your existing web project.

I started with a new project and named it "mini". There is nothing special that you have to set up. It even works without a web.config.

2. Copy the ajaxcore folder to your project.

You can find this folder and the files on sourceforge
in the subversion repository by using the path
or in one of the source code downloads like

For this project you only need the following core files
ajax.js: the client side AjaxEngine

GetJavaScriptProxy.aspx: the JavaScript proxy generator
wsdl.xslt: the WSDL to JavaScript transformation


That’s all you have to do to prepare the web project to use the core part of the AjaxEngine. I suggest you use the ajaxcore folder

3. Create a folder named "/calc"

This folder will contain the minimal web application by using a web form and a web service.

I guess you don't implement pages in the root folder of your web application so I follow this best practice here too.

4. Implement a service /calc/WebService1.asmx

There is only one method we need so here is some c# code:

using System.ComponentModel;
using System.Web;
using System.Web.Services;
using System.Web.Services.Protocols;

namespace mini.calc {
  /// Summary description for WebService1
  [WebService(Namespace = "")]
  [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
  // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 
  // [System.Web.Script.Services.ScriptService]
  public class WebService1 : System.Web.Services.WebService {

    public double Add(double sum1, double sum2) {
      return (sum1 + sum2);

5. Create a new page named WebForm1.aspx in the calc folder

I just use the new item wizard from visual Studio to do this so the typical elements are there already.
There is not much code that must be put into this file.

6. include the ajax.js:

<script src="../ajaxcore/ajax.js" type="text/javascript"></script>

The ajax.js file reference should be included in the <head> element.

7. include the proxy for the webservice:

<script src="../ajaxcore/GetJavaScriptProxy.aspx?service=/calc/WebService1.asmx" type="text/javascript"></script>

This script include should also be included in the <head> element and will make the just implemented webservice and webmethod available through the JavaScript object proxies.WebService1.Add.

8. Implement the User interface

A minimalist UI means just 3 fields and some text.
You also have to remove the <form> element because the fields are not used to post data to the server. 

<input id="sum1" type="text" /> + <input id="sum2" type="text" /> = <input id="result" type="text" />

9. Implement the JavaScript code

This is the trickiest part of it, but it's simple too:
A timer is used to call a function every 200 milliseconds that checks for some changed input values.
The web service is called if any value has changed.

<script type="text/javascript">
  var sum1_obj = document.getElementById("sum1");
  var sum2_obj = document.getElementById("sum2");
  var result_obj = document.getElementById("result");
  var sum1_val = "";
  var sum2_val = "";

  window.setInterval(window.checkValues, 200);
  function checkValues() {
    if ((sum1_obj.value != sum1_val) || (sum2_obj.value != sum2_val)) {
      sum1_val = sum1_obj.value;
      sum2_val = sum2_obj.value;
      result_obj.value = proxies.WebService1.Add(sum1_val, sum2_val);
    } // if
  } // checkValues

10. And that's all

Start the Web Form and see how it works.


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Karthika Shree hat gesagt…
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