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/**
* Javascript library for working with XmlHttpRequest objects and
* Horde.
*
* $Horde: horde/js/httpclient.js,v 1.2 2004/10/19 19:08:53 chuck Exp $
*
* See the enclosed file COPYING for license information (LGPL). If you did not
* receive this file, see http://www.fsf.org/copyleft/lgpl.html.
*/
// Constructor for generic HTTP client.
function HTTPClient() {};
// Add methods and properties as array.
HTTPClient.prototype = {
url: null,
// Instance of XMLHttpRequest.
request: null,
// Used to make sure multiple calls are not placed with the same
// client object while another in progress.
callInProgress: false,
// The user defined handler - see MyHandler below.
userhandler: null,
init: function(url)
{
this.url = url;
try {
// Mozilla, Safari.
this.request = new XMLHttpRequest();
} catch (e) {
// IE.
var MSXML_XMLHTTP_PROGIDS = new Array(
"MSXML2.XMLHTTP.4.0",
"MSXML2.XMLHTTP.3.0",
"MSXML2.XMLHTTP",
"Microsoft.XMLHTTP"
);
var success = false;
for (var i = 0; i < MSXML_XMLHTTP_PROGIDS.length && !success; i++) {
try {
this.request = new ActiveXObject(MSXML_XMLHTTP_PROGIDS[i]);
success = true;
} catch (e) {}
}
if (!success) {
throw "Unable to create XMLHttpRequest.";
}
}
},
// Handler argument is a user defined object to be called.
asyncGET: function(handler)
{
// Degrade or some such.
if (!this.request) {
return false;
};
// Prevent multiple calls
if (this.callInProgress) {
throw "Call in progress";
};
this.callInProgress = true;
this.userhandler = handler;
// Open an async request - third argument makes it
// asynchronous.
this.request.open('GET', this.url, true);
// Have to assign "this" to a variable.
var self = this;
// Assign a closure to the onreadystatechange callback.
this.request.onreadystatechange = function() {
self.stateChangeCallback(self);
}
this.request.send(null);
},
stateChangeCallback: function(client)
{
switch (client.request.readyState) {
// Request not yet made.
case 1:
try {
client.userhandler.onInit();
} catch (e) { /* Handler method not defined. */ }
break;
// Contact established with server but nothing downloaded
// yet.
case 2:
try {
status = client.request.status;
// Check for HTTP status 200.
if (status != 200) {
client.userhandler.onError(
status,
client.request.statusText
);
// Abort the request.
client.request.abort();
// Call no longer in progress.
client.callInProgress = false;
}
} catch (e) {
/* MSXMLHTTP 3.x+ doesn't populate status until
* readyState 4. */
}
break;
// Called multiple times while download is in progress.
case 3:
// Notify user handler of download progress.
try {
// Get the total content length (useful to work
// out how much has been downloaded).
try {
var contentLength =
client.request.getResponseHeader("Content-Length");
} catch (e) {
var contentLength = NaN;
}
// Call the progress handler with what we've got.
client.userhandler.onProgress(
client.request.responseText,
contentLength
);
} catch (e) { /* Handler method not defined. */ }
break;
// Download complete.
case 4:
try {
client.userhandler.onLoad(client.request.responseText);
} catch (e) {
/* Handler method not defined. */
} finally {
// Call no longer in progress.
client.callInProgress = false;
}
break;
}
}
}
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