/**
===============================================================
HTTP AJAX SERVICES
Copyright (c) 2008,2009 Jason Fries,
Iowa Electronic health Markets,
University of Iowa
Ajax Services Cross browser compliant ajax object
tested: IE6,IE7, Safari 3.0+, Firefox 3.0+
revisions: 2009.7.21 Implemented generic Request object
2009.7.14 first release
===============================================================
**/
function HttpService( url )
{
this.resultFormat = "xml"; //text, xml
this.url = url;
this.method = "POST";
this.request = null;
//IE will create ActiveX object istead of XMLHttpRequest
this.XMLHttpRequest = false;
//parsed response
this.response = null;
//Event Handling
this.eventListeners = new Object();
}
HttpService.RESULT = "result";
HttpService.FAULT = "fault";
/**
* XML Decode (Default)
*
*/
HttpService.prototype.xmlDecode = function(text)
{
var xml;
// code for IE
if(window.ActiveXObject) {
try{
xml = new ActiveXObject("Microsoft.XMLDOM");
xml.async="false";
xml.loadXML(text);
}catch(e) {
alert("ActiveX HttpService xmlDecode ERROR (XML Poorly formed?) " + e);
}
// code for Mozilla, Firefox, Opera, etc.
}else{
try{
var parser = new DOMParser();
xml = parser.parseFromString(text,"text/xml");
}catch(e) {
alert("HttpService xmlDecode ERROR (XML Poorly formed?) " + e);
}
}
return xml;
}
/**
* Add Event Listener
* @description
*/
HttpService.prototype.addEventListener = function( type, callback )
{
this.eventListeners[type] = callback;
}
/**
* Create XMLHttpRequest Object
* @description Native XMLHttpRequest objects are *not*
* supported by
*/
HttpService.createXMLHttpRequest = function()
{
var req;
// branch for native XMLHttpRequest object
if(window.XMLHttpRequest && !window.ActiveXObject ){
try{
req = new XMLHttpRequest();
}catch(e){
alert("ERROR creating XMLHttpRequest Object " + e );
req = false;
}
// branch for IE/Windows ActiveX version
}else if(window.ActiveXObject) {
try{
req = new ActiveXObject("Msxml2.XMLHTTP");
}catch(e){
try{
req = new ActiveXObject("Microsoft.XMLHTTP");
}catch(e) {
req = false;
}
}
}
return req;
}
/**
* Load XML Document
* @description
* @param URL
* @param method 'POST', 'GET'
* @param response parser (xml parser)
* @return
*/
HttpService.prototype.send = function( parameters )
{
this.XMLHttpRequest = HttpService.createXMLHttpRequest();
if(this.XMLHttpRequest) {
//IE6 ActiveX fix
var parent = this;
var req = this.XMLHttpRequest;
// wrapper pass in parent and request object (IE6 ajax/active x fix)
this.XMLHttpRequest.onreadystatechange = function() { handleEvent(parent, req); };
this.XMLHttpRequest.open(this.method, this.url, true);
this.XMLHttpRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
this.XMLHttpRequest.setRequestHeader("Content-length", 0);
this.XMLHttpRequest.setRequestHeader("Connection", "close");
//encode request parameters (if they exist)
if(this.request) this.XMLHttpRequest.send( encodeRequest(this.request) );
else this.XMLHttpRequest.send(parameters);
}
}
HttpService.prototype.toString = function()
{
return "HttpService";
}
/**
* IE6 Ajax Response Wrapper
*
* ActiveX components don't comply fully to javascript; they don't
* allow the dynamic addtion of properties. This is a problem when we must
* use activeX for XMLHttpRequest functionaliy (e.g. IE6). By wrapping the response
* handler we grant them access the sender parent object and can properly handle custom
* xml response parsing, etc.
*
*/
function handleEvent(parent, request)
{
//only if request returns as "loaded"
if(request.readyState == 4) {
// request status is sucessful - "OK"
if(request.status == 200) {
//result type
if(parent.resultFormat == "xml"){
parent.response = parent.xmlDecode( request.responseText );
//dispatch event
if(parent.eventListeners[HttpService.RESULT])
parent.eventListeners[HttpService.RESULT]( parent.response );
}else{
parent.response = request.responseText;
//dispatch event
if(parent.eventListeners[HttpService.RESULT])
parent.eventListeners[HttpService.RESULT]( request.responseText );
}
//FAILURE response
}else{
//dispatch error event
if(parent.eventListeners[HttpService.FAULT])
parent.eventListeners[HttpService.FAULT]( request.statusText );
}
}
}
// XML Utilities
/**
* Encode Request Object
* @description URLEncode Request object into parameter string for XMLHttpRequest
*/
function encodeRequest( object )
{
var params = "";
// i == member variable name and object[i] is the value of that object
for(var i in object )
{
if(params.length == 0)
params += (i + "=" + encodeURI(object[i]));
else
params += ("&" + i + "=" + encodeURI(object[i]));
}
return params;
}
/**
* XML to String
*/
function xmlToString( xmldoc ) {
var xml = "";
try {
// Gecko-based browsers, Safari, Opera.
xml = (new XMLSerializer()).serializeToString(xmldoc);
}catch (e){
try {
// Internet Explorer.
xml = xmldoc.xml;
}catch (e) {
//Strange Browser ??
alert('Xmlserializer not supported');
}
}
return xml;
}