The XMLHttpRequest is an API used in modern web browsers. It contains methods that allow communication between the web browser and a web server through JavaScript. Although the name is XML, it can also support JSON.
Let’s go through an example of how to use it.
First, we will use a previous example where we have a WCF web service set up. This service is then uploaded to Azure so it can be accessed.
Next, create an HTML page with the following JavaScript:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<script type="text/javascript" >
var request = null;
if (window.XMLHttpRequest)
{
request = new XMLHttpRequest();
}
else if (window.ActiveXObject)
{
request = new ActiveXObject("Microsoft.XMLHTTP");
}
request.open ('POST', 'http://webserviceurl/Service1.svc', true);
request.setRequestHeader('SOAPAction', 'http://tempuri.org/IService1/DoWork');
request.setRequestHeader('Content-Type', 'text/xml');
var data = '<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">';
data += ' <soap:Body>';
data += ' <DoWork xmlns="http://tempuri.org/" />';
data += ' </soap:Body>';
data += '</soap:Envelope>';
request.onreadystatechange = function ( )
{
if(request.readyState == 4)
{
var response = request.responseXML;
var DoWorkResult= response.getElementsByTagName("DoWorkResult")[0];
alert(DoWorkResult.textContent);
}
};
request.send(data);
</script>
</head>
<body>
</body>
</html>When the code runs, it will instantiate an object of XmlHttpRequest. The object will then post to the web service a SOAP envelope to the DoWork method. DoWorkRequest is returned from the web service. When we run the code, an alert box will display Hello World:
Note the tool http://webservicestudio.codeplex.com/releases/view/13915 is useful for determining the format of the SOAP requests.
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