Ajax GET Request
X in XML
2. In an XML HTTP request, we usually expect the
server to respond with some XML
3. What is XML?A specification for creating languages to store data; used to share data between systems a basic syntax of tags & attributes languages written in XML specify tag names, attribute names, and rules of use Example: XHTML is a "flavor" of XML
4. Short answer: like HTML but You can make up your own tag namesAll tags have to be closed (and there is a shorthand)
Uses of XML
XML file
the new tags (we just made them up)
An XML version number
One tag contains everything (and becomes the root of the document tree)
<?xml version="1. 0" encoding="ISO-8859-1"?>
<note>
<to>saplogic</to>
<from>help4code</from>
<heading>Reminder</heading>
<body>Largest collection of programs</body>
</note>
XML Responding
- We can look at the XML text within a response using the responseText property.
- Even better, we can use the responseXML property to access the XML.
- Best, responseXML. documentElement contains the document tree for the XML.
- This is a document tree in the DOM model that we've seen before (just like document).
function sendRequest() {
var xmlHttp = GetXmlHttpObject();
if (! xmlHttp) {
return false;
}x
mlHttp. onreadystatechange = function() {
if (xmlHttp. readyState == 4) {
var xmlDoc =
xmlHttp. responseXML. documentElement;
}
}v
ar requestURI = xmlURI;
xmlHttp. open("GET", requestURI, true);
xmlHttp. send(null);
}
Prototype Ajax methods and properties
That can be passed to the Ajax.Request constructor:
method : how to fetch the request from the server (default "post" )parameters : query parameters to pass to the server, if any asynchronous (default true), contentType, encoding, requestHeaders events in the Ajax.Request object that you can handle:
onSuccess : request completed successfully
onFailure : request was unsuccessful
onCreate, onComplete, onException, on### (handler for HTTP error code ###)