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File: transport.js
/**
 * @fileoverview Zapatec Transport library. Used to fetch data from the server,
 * parse and serialize XML and JSON data.
 *
 * <pre>
 * Copyright (c) 2004-2007 by Zapatec, Inc.
 * http://www.zapatec.com
 * 1700 MLK Way, Berkeley, California,
 * 94709, U.S.A.
 * All rights reserved.
 * </pre>
 */

// $Id: transport.js 7699 2007-08-08 11:33:54Z alex $

if (typeof Zapatec == 'undefined') {
	/**
	 * @ignore Namespace definition.
	 */
	Zapatec = function() {};
}

/**
 * @constructor
 */
Zapatec.Transport = function() {};

// Determine most current versions of ActiveX objects available
if (typeof ActiveXObject != 'undefined') {

	/**
	 * String variable with most current version of XMLDOM ActiveX object name
	 * available.
	 * @private
	 */
	Zapatec.Transport.XMLDOM = null;

	/**
	 * String variable with Most current version of XMLHTTP ActiveX object name
	 * available.
	 * @private
	 */
	Zapatec.Transport.XMLHTTP = null;

	/**
	 * @ignore
	 * Returns first available ActiveX object name from the given list.
	 *
	 * @param {object} aVersions List of ActiveX object names to test
	 * @return First available ActiveX object name or null
	 * @type string
	 */
	Zapatec.Transport.pickActiveXVersion = function(aVersions) {
		for (var iVn = 0; iVn < aVersions.length; iVn++) {
			try {
				var oDoc = new ActiveXObject(aVersions[iVn]);
				if (oDoc) {
					// If it gets to this point, the string worked
					return aVersions[iVn];
				}
			} catch (oExpn) {};
		}
		return null;
	};

	/**
	 * Most current version of XMLDOM ActiveX object.
	 * @private
	 */
	Zapatec.Transport.XMLDOM = Zapatec.Transport.pickActiveXVersion([
		'Msxml2.DOMDocument.4.0',
		'Msxml2.DOMDocument.3.0',
		'MSXML2.DOMDocument',
		'MSXML.DOMDocument',
		'Microsoft.XMLDOM'
	]);

	/**
	 * Most current version of XMLHTTP ActiveX object.
	 * @private
	 */
	Zapatec.Transport.XMLHTTP = Zapatec.Transport.pickActiveXVersion([
		'Msxml2.XMLHTTP.4.0',
		'MSXML2.XMLHTTP.3.0',
		'MSXML2.XMLHTTP',
		'Microsoft.XMLHTTP'
	]);

	// We don't need this any more
	Zapatec.Transport.pickActiveXVersion = null;

}

/**
 * Creates cross browser XMLHttpRequest object.
 *
 * @return New XMLHttpRequest object.
 * @type object
 */
Zapatec.Transport.createXmlHttpRequest = function() {
	if (typeof ActiveXObject != 'undefined') {
		try {
			return new ActiveXObject(Zapatec.Transport.XMLHTTP);
		} catch (oExpn) {};
	}
	if (typeof XMLHttpRequest != 'undefined') {
		return new XMLHttpRequest();
	}
	return null;
};

/**
 * Checks if animated GIF is already displayed in the specified div.
 *
 * <pre>
 * Arguments object format:
 * {
 *   busyContainer: [object or string] element where to put animated GIF,
 *   busyImage: [string, optional] standard image name or custom image URL
 * }
 * </pre>
 *
 * @private
 * @param {object} oArg Arguments object
 * @return True if image is displayed
 * @type boolean
 */
Zapatec.Transport.isBusy = function(oArg) {
	// Get container
	var oContr = oArg.busyContainer;
	if (typeof oContr == 'string') {
		oContr = document.getElementById(oContr);
	}
	if (!oContr) {
		return;
	}
	// Get image name
	var sImage = oArg.busyImage;
	if (typeof sImage != 'string') {
		sImage = '';
	}
	sImage = sImage.split('/').pop();
	if (!sImage.length) {
		sImage = 'zpbusy.gif';
	}
	// Check if image is displayed
	var oFC = oContr.firstChild;
	if (oFC) {
		oFC = oFC.firstChild;
		if (oFC) {
			oFC = oFC.firstChild;
			if (oFC && oFC.tagName && oFC.tagName.toLowerCase() == 'img') {
				var sSrc = oFC.getAttribute('src');
				if (typeof sSrc == 'string' && sSrc.length) {
					// Get last token
					sSrc = sSrc.split('/').pop();
					if (sSrc == sImage) {
						return true;
					}
				}
			}
		}
	}
	return false;
};

/**
 * Shows animated GIF in the specified div.
 *
 * <pre>
 * Arguments object format:
 * {
 *   busyContainer: [object or string] element where to put animated GIF,
 *   busyImage: [string, optional] standard image name or custom image URL,
 *   busyImageWidth: [number or string, optional] image width,
 *   busyImageHeight: [number or string, optional] image height
 * }
 * </pre>
 *
 * @param {object} oArg Arguments object
 */
Zapatec.Transport.showBusy = function(oArg) {
	// Make sure image is not displayed yet
	if (Zapatec.Transport.isBusy(oArg)) {
		return;
	}
	// Get container
	var oContr = oArg.busyContainer;
	if (typeof oContr == 'string') {
		oContr = document.getElementById(oContr);
	}
	if (!oContr) {
		return;
	}
	// Get image name and dimensions
	var sImage = oArg.busyImage;
	var sImageWidth = oArg.busyImageWidth;
	var sImageHeight = oArg.busyImageHeight;
	if (typeof sImage != 'string' || !sImage.length) {
		sImage = 'zpbusy.gif';
	} else {
		if (typeof sImageWidth == 'number' ||
		 (typeof sImageWidth == 'string' && /\d$/.test(sImageWidth))) {
			sImageWidth += 'px';
		}
		if (typeof sImageHeight == 'number' ||
		 (typeof sImageHeight == 'string' && /\d$/.test(sImageHeight))) {
			sImageHeight += 'px';
		}
	}
	if (!sImageWidth) {
		sImageWidth = '65px';
	}
	if (!sImageHeight) {
		sImageHeight = '35px';
	}
	// Get path
	var sPath = '';
	// Check if path is specified
	if (sImage.indexOf('/') < 0) {
		// Use default path
		if (Zapatec.zapatecPath) {
			sPath = Zapatec.zapatecPath;
		} else {
			sPath = Zapatec.Transport.getPath('transport.js');
		}
	}
	// Form tag
	var aImg = [];
	aImg.push('<img src="');
	aImg.push(sPath);
	aImg.push(sImage);
	aImg.push('"');
	if (sImageWidth || sImageHeight) {
		aImg.push(' style="');
		if (sImageWidth) {
			aImg.push('width:');
			aImg.push(sImageWidth);
			aImg.push(';');
		}
		if (sImageHeight) {
			aImg.push('height:');
			aImg.push(sImageHeight);
		}
		aImg.push('"');
	}
	aImg.push(' />');
	// Get container dimensions
	var iContainerWidth = oContr.offsetWidth;
	var iContainerHeight = oContr.offsetHeight;
	// Display image
	var oBusyContr = Zapatec.Utils.createElement('div');
	oBusyContr.style.position = 'relative';
	oBusyContr.style.zIndex = 2147483583;
	var oBusy = Zapatec.Utils.createElement('div', oBusyContr);
	oBusy.style.position = 'absolute';
	oBusy.innerHTML = aImg.join('');
	oContr.insertBefore(oBusyContr, oContr.firstChild);
	// Move to the center of container
	var iBusyWidth = oBusy.offsetWidth;
	var iBusyHeight = oBusy.offsetHeight;
	if (iContainerWidth > iBusyWidth) {
		oBusy.style.left = oContr.scrollLeft +
		 (iContainerWidth - iBusyWidth) / 2 + 'px';
	}
	if (iContainerHeight > iBusyHeight) {
		oBusy.style.top = oContr.scrollTop +
		 (iContainerHeight - iBusyHeight) / 2 + 'px';
	}
};

/**
 * Removes animated GIF which was put by {@link Zapatec.Transport#showBusy}
 * from the specified div.
 *
 * <pre>
 * Arguments object format:
 * {
 *   busyContainer: [object or string] element where to put animated GIF,
 *   busyImage: [string, optional] standard image name or custom image URL
 * }
 * </pre>
 *
 * @param {object} oArg Arguments object
 */
Zapatec.Transport.removeBusy = function(oArg) {
	// Get container
	var oContr = oArg.busyContainer;
	if (typeof oContr == 'string') {
		oContr = document.getElementById(oContr);
	}
	if (!oContr) {
		return;
	}
	// Make sure image is displayed
	if (Zapatec.Transport.isBusy(oArg)) {
		// Remove image
		oContr.removeChild(oContr.firstChild);
	}
};

/**
 * Fetches specified URL using new XMLHttpRequest object.
 *
 * <pre>
 * Asynchronous mode is recommended because it is safer and there is no risk of
 * having your script hang in case of network problem. Synchronous mode means
 * that the code will hang until a response comes back.
 *
 * When request is completed, one of provided callback functions is called:
 * onLoad on success or onError on error. In synchronous mode onLoad callback
 * can be omitted. Instead use returned object.
 *
 * onLoad callback function receives XMLHttpRequest object as argument and may
 * use its various properties like responseText, responseXML, etc.
 *
 * onError callback function receives following object:
 * {
 *   errorCode: server status number (404, etc.) [number],
 *   errorDescription: human readable error description [string]
 * }
 *
 * Note: Some browsers implement caching for GET requests. Caching can be
 * prevented by adding 'r=' + Math.random() parameter to URL.
 *
 * If you use POST method, content argument should be something like
 * 'var1=value1&var2=value2' with urlencoded values. If you wish to send other
 * content, set appropriate contentType. E.g. 'multipart/form-data', 'text/xml',
 * etc.
 *
 * If server response contains non-ASCII characters, server must send
 * corresponding content-type header. E.g.
 * "Content-type: text/plain; charset=utf-8" or
 * "Content-type: text/plain; charset=windows-1251".
 *
 * Arguments object format:
 * {
 *   url: [string] relative or absolute URL to fetch,
 *   method: [string, optional] method ('GET', 'POST', 'HEAD', 'PUT'),
 *   async: [boolean, optional] use asynchronous mode (default: true),
 *   contentType: [string, optional] content type when using POST,
 *   content: [string or object, optional] postable string or DOM object data
 *    when using POST,
 *   onLoad: [function, optional] function reference to call on success,
 *   onError: [function, optional] function reference to call on error,
 *   username: [string, optional] username,
 *   password: [string, optional] password,
 *   busyContainer: [object or string, optional] element or id of element where
 *    to put "Busy" animated GIF,
 *   busyImage: [string, optional] standard image name or custom image URL,
 *   busyImageWidth: [number or string, optional] image width,
 *   busyImageHeight: [number or string, optional] image height
 * }
 * </pre>
 *
 * @param {object} oArg Arguments object
 * @return In synchronous mode XMLHttpRequest object or null. In asynchronous
 * mode always null.
 * @type object
 */
Zapatec.Transport.fetch = function(oArg) {
	// Check arguments
	if (oArg == null || typeof oArg != 'object') {
		return null;
	}
	if (!oArg.url) {
		return null;
	}
	if (!oArg.method) {
		oArg.method = 'GET';
	}
	if (typeof oArg.async == 'undefined') {
		oArg.async = true;
	}
	if (!oArg.contentType && oArg.method.toUpperCase() == 'POST') {
		oArg.contentType = 'application/x-www-form-urlencoded';
	}
	if (!oArg.content) {
		oArg.content = null;
	}
	if (!oArg.onLoad) {
		oArg.onLoad = null;
	}
	if (!oArg.onError) {
		oArg.onError = null;
	}
	// Request URL
	var oRequest = Zapatec.Transport.createXmlHttpRequest();
	if (oRequest == null) {
		return null;
	}
	// Show "Busy" animated GIF
	Zapatec.Transport.showBusy(oArg);
	// IE 6 calls onreadystatechange and then raises exception if local file was
	// not found. This flag is used to prevent duplicate onError calls.
	var bErrorDisplayed = false;
	// Onready handler
	var funcOnReady = function () {
		// Remove "Busy" animated GIF
		Zapatec.Transport.removeBusy(oArg);
		// Process response
		try {
			if (oRequest.status == 200 || oRequest.status == 304 ||
			 (location.protocol == 'file:' && !oRequest.status)) {
				// OK or found, but determined unchanged and loaded from cache
				if (typeof oArg.onLoad == 'function') {
					oArg.onLoad(oRequest);
				}
			} else if (!bErrorDisplayed) {
				bErrorDisplayed = true;
				// 404 Not found, etc.
				Zapatec.Transport.displayError(oRequest.status,
				 "Error: Can't fetch " + oArg.url + '.\n' +
				 (oRequest.statusText || ''),
				 oArg.onError);
			}
		} catch (oExpn) {
			// Firefox 1.5 raises exception on attempt to access any property of
			// oRequest if URL was not found
			if (!bErrorDisplayed) {
				bErrorDisplayed = true;
				if (oExpn.name && oExpn.name == 'NS_ERROR_NOT_AVAILABLE') {
					Zapatec.Transport.displayError(0,
					 "Error: Can't fetch " + oArg.url + '.\nFile not found.',
					 oArg.onError);
				} else {
					Zapatec.Transport.displayError(0,
					 "Error: Can't fetch " + oArg.url + '.\n' +
					 (oExpn.message || ''),
					 oArg.onError);
				}
			}
		};
	};
	try {
		// Open request
		if (typeof oArg.username != 'undefined' &&
		 typeof oArg.password != 'undefined') {
			oRequest.open(oArg.method, oArg.url, oArg.async,
			 oArg.username, oArg.password);
		} else {
			oRequest.open(oArg.method, oArg.url, oArg.async);
		}
		// Prevent duplicate funcOnReady call in synchronous mode
		if (oArg.async) {
			// Set onreadystatechange handler
			oRequest.onreadystatechange = function () {
				if (oRequest.readyState == 4) {
					// Request complete
					funcOnReady();
					// Prevent memory leak
					oRequest.onreadystatechange = {};
				}
			};
		}
		// Set content type if needed
		if (oArg.contentType) {
			oRequest.setRequestHeader('Content-Type', oArg.contentType);
		}
		// Send request
		oRequest.send(oArg.content);
		// In synchronous mode the result is ready on the next line
		if (!oArg.async) {
			funcOnReady();
			return oRequest;
		}
	} catch (oExpn) {
		// Remove "Busy" animated GIF
		Zapatec.Transport.removeBusy(oArg);
		// Process error
		if (!bErrorDisplayed) {
			bErrorDisplayed = true;
			if (oExpn.name && oExpn.name == 'NS_ERROR_FILE_NOT_FOUND') {
				Zapatec.Transport.displayError(0,
				 "Error: Can't fetch " + oArg.url + '.\nFile not found.',
				 oArg.onError);
			} else {
				Zapatec.Transport.displayError(0,
				 "Error: Can't fetch " + oArg.url + '.\n' +
				 (oExpn.message || ''),
				 oArg.onError);
			}
		}
	};
	return null;
};

/**
 * Parses HTML fragment into HTMLElement object.
 *
 * @param {string} sHtml HTML fragment
 * @return Div element which contains parsed HTML fragment
 * @type object
 */
Zapatec.Transport.parseHtml = function(sHtml) {
	// Convert to string
	sHtml += '';
	// Remove leading whitespace characters because Firefox and Opera don't parse
	// fragment that starts from whitespace character
	sHtml = sHtml.replace(/^\s+/g, '');
	// Create temporaty container
	var oTmpContr;
	if (document.createElementNS) {
		// use the XHTML namespace
		oTmpContr =
		 document.createElementNS('http://www.w3.org/1999/xhtml', 'div');
	} else {
		oTmpContr = document.createElement('div');
	}
	// Parse HTML fragment
	oTmpContr.innerHTML = sHtml;
	// Return container element
	return oTmpContr;
};

/**
 * Evaluates javascript in global scope.
 *
 * <p><b>
 * Note: Global variables must be declared without "var" keyword. Otherwise
 * they will be ignored by Safari.
 * </b></p>
 *
 * @param {string} sScript Script to evaluate
 */
Zapatec.Transport.evalGlobalScope = function(sScript) {
	if (typeof sScript != 'string' || !sScript.match(/\S/)) {
		return;
	}
	if (window.execScript) {
		// IE
		window.execScript(sScript, 'javascript');
	} else if (window.eval) {
		// Others
		window.eval(sScript);
/*
 This should never be reached
	} else {
		var funcScript = new Function(sScript);
		funcScript.call(window);
*/
	}
};

/**
 * Assigns passed HTML fragment to the specified element's innerHTML property
 * and evaluates in global scope javascripts found in the fragment.
 *
 * <pre>
 * Arguments object format:
 * {
 *   html: [string] HTML fragment,
 *   container: [object or string, optional] element or id of element to put
 *    HTML fragment into
 * }
 * </pre>
 *
 * <p><b>
 * Note: Scripts are executed after HTML fragment is assigned to innerHTML.
 * If external scripts are used, they are loaded asynchronously and execution
 * sequence is not preserved.
 * </b></p>
 *
 * <p><b>
 * Note: Global variables must be declared without "var" keyword. Otherwise
 * they will be ignored by Safari.
 * </b></p>
 *
 * @param {object} oArg Arguments object
 */
Zapatec.Transport.setInnerHtml = function(oArg) {
	// Check arguments
	if (!oArg || typeof oArg.html != 'string') {
		return;
	}
	var sHtml = oArg.html;
	// Get container
	var oContr = null;
	if (typeof oArg.container == 'string') {
		oContr = document.getElementById(oArg.container);
	} else if (typeof oArg.container == 'object') {
		oContr = oArg.container;
	}
	// Extract javascripts
	var aScripts = [];
	if (sHtml.match(/<\s*\/\s*script\s*>/i)) {
		// Split whole string by </script>
		var aTokens = sHtml.split(/<\s*\/\s*script\s*>/i);
		var aHtml = [];
		for (var iToken = aTokens.length - 1; iToken >= 0; iToken--) {
			var sToken = aTokens[iToken];
			if (sToken.match(/\S/)) {
				// Search <script ... > in the middle of each token
				var aMatch = sToken.match(/<\s*script([^>]*)>/i);
				if (aMatch) {
					// Separate HTML from javascript
					var aCouple = sToken.split(/<\s*script[^>]*>/i);
					// IE doesn't put empty tokens into the array
					while (aCouple.length < 2) {
						if (sToken.match(/^<\s*script[^>]*>/i)) {
							// HTML part is absent
							aCouple.unshift('');
						} else {
							// javascript part is absent
							aCouple.push('');
						}
					}
					// Save HTML fragment
					aHtml.unshift(aCouple[0]);
					// Get script attributes
					var sAttrs = aMatch[1];
					// Get script text
					var srtScript = aCouple[1];
					// Ignore script text if "src" attribute is present
					if (sAttrs.match(/\s+src\s*=/i)) {
						srtScript = '';
					} else {
						// Fix functions: function aaa() -> aaa = function()
						srtScript = srtScript.replace(/function\s+([^(]+)/g, '$1=function');
					}
					aScripts.push([sAttrs, srtScript]);
				} else if (iToken < aTokens.length - 1) {
					// On error assume this token is a part of previous token
					aTokens[iToken - 1] += '</script>' + sToken;
				} else {
					// If this is last token, assume it is HTML fragment
					aHtml.unshift(sToken);
				}
			} else {
				// Empty token
				aHtml.unshift(sToken);
			}
		}
		// Get HTML part
		sHtml = aHtml.join('');
	}
	// Set inner HTML
	if (oContr) {
		// Opera hack
		if (window.opera) {
			// Without this line Opera will not form correct DOM structure if HTML
			// fragment contains forms
			oContr.innerHTML = '<form></form>';
		}
		oContr.innerHTML = sHtml;
	}
	// Evaluate javascripts
	for (var iScript = 0; iScript < aScripts.length; iScript++) {
		if (aScripts[iScript][1].length) {
			// Evaluate in global scope
			Zapatec.Transport.evalGlobalScope(aScripts[iScript][1]);
		}
		// Load external script
		var sAttrs = aScripts[iScript][0];
		sAttrs = sAttrs.replace(/\s+/g, ' ').replace(/^\s/, '')
		 .replace(/\s$/, '').replace(/ = /g, '=');
		if (sAttrs.indexOf('src=') >= 0) {
			// Get container
			var oContr = document.body;
			if (!oContr) {
				oContr = document.getElementsByTagName('head')[0];
				if (!oContr) {
					oContr = document;
				}
			}
			// Get attributes
			var aAttrs = sAttrs.split(' ');
			// Load script
			var oScript = Zapatec.Utils.createElement('script');
			for (var iAttr = 0; iAttr < aAttrs.length; iAttr++) {
				var aAttr = aAttrs[iAttr].split('=');
				if (aAttr.length > 1) {
					oScript.setAttribute(aAttr[0],
					 aAttr[1].match(/^[\s|"|']*([\s|\S]*[^'|"])[\s|"|']*$/)[1]);
				} else {
					oScript.setAttribute(aAttr[0], aAttr[0]);
				}
			}
			// It's important for Safari to assign attributes before appending
			oContr.appendChild(oScript);
		}
	}
};

/**
 * Fetches and parses XML document from the specified URL.
 *
 * <pre>
 * When XML document is fetched and parsed, one of provided callback functions
 * is called: onLoad on success or onError on error. In synchronous mode onLoad
 * callback can be omitted. Instead use returned object.
 *
 * onLoad callback function receives XMLDocument object as argument and may use
 * its documentElement and other properties.
 *
 * onError callback function receives following object:
 * {
 *   errorCode: error code [number],
 *   errorDescription: human readable error description [string]
 * }
 * Error code will be 0 unless Zapatec.Transport.fetch was used to fetch URL
 * and there was a problem during fetching.
 *
 * If method argument is not defined, more efficient XMLDOM in IE and
 * document.implementation.createDocument in Mozilla will be used to fetch
 * and parse document. Otherwise Zapatec.Transport.fetch will be used to fetch
 * document and Zapatec.Transport.parseXml to parse.
 *
 * Note: Some browsers implement caching for GET requests. Caching can be
 * prevented by adding 'r=' + Math.random() parameter to URL.
 *
 * If you use POST method, content argument should be something like
 * 'var1=value1&var2=value'. If you wish to send other content, set appropriate
 * contentType. E.g. to send XML string, you should set contentType: 'text/xml'.
 *
 * If server response contains non-ASCII characters, encoding must be specified.
 * E.g. <?xml version="1.0" encoding="utf-8"?> or 
 * <?xml version="1.0" encoding="windows-1251"?>.
 *
 * If server response contains non-ASCII characters, server must send
 * corresponding content-type header. E.g.
 * "Content-type: text/xml; charset=utf-8" or
 * "Content-type: text/xml; charset=windows-1251".
 *
 * Arguments object format:
 * {
 *   url: [string] relative or absolute URL to fetch,
 *   method: [string, optional] method ('GET', 'POST', 'HEAD', 'PUT'),
 *   async: [boolean, optional] use asynchronous mode (default: true),
 *   contentType: [string, optional] content type when using POST,
 *   content: [string or object, optional] postable string or DOM object data
 *    when using POST,
 *   onLoad: [function, optional] function reference to call on success,
 *   onError: [function, optional] function reference to call on error,
 *   username: [string, optional] username,
 *   password: [string, optional] password,
 *   busyContainer: [object or string, optional] element or id of element where
 *    to put "Busy" animated GIF,
 *   busyImage: [string, optional] standard image name or custom image URL,
 *   busyImageWidth: [number or string, optional] image width,
 *   busyImageHeight: [number or string, optional] image height
 * }
 * </pre>
 *
 * @param {object} oArg Arguments object
 * @return In synchronous mode XMLDocument object or null. In asynchronous mode
 * always null.
 * @type object
 */
Zapatec.Transport.fetchXmlDoc = function(oArg) {
	// Check arguments
	if (oArg == null || typeof oArg != 'object') {
		return null;
	}
	if (!oArg.url) {
		return null;
	}
	if (typeof oArg.async == 'undefined') {
		oArg.async = true;
	}
	if (!oArg.onLoad) {
		oArg.onLoad = null;
	}
	if (!oArg.onError) {
		oArg.onError = null;
	}
	// Try more efficient methods first
	if (!oArg.method && typeof oArg.username == 'undefined' &&
	 typeof oArg.password == 'undefined') {
		if (document.implementation && document.implementation.createDocument) {
			// Mozilla
			var oDoc = null;

			if (!oArg.reliable) {
				oArg.reliable = false;
			}
			// Form argument for fetch
			var oFetchArg = {};
			for (var sKey in oArg) {
				oFetchArg[sKey] = oArg[sKey];
			}
			// Prevent duplicate parseXml call in synchronous mode
			if (oArg.async) {
				oFetchArg.onLoad = function(oRequest) {
					// Prevent onload being called more than once
					oFetchArg.onLoad = null;

					// Parse xml response string
					var parser = new DOMParser();
					oDoc = parser.parseFromString(oRequest.responseText, "text/xml");

					// Remove "Busy" animated GIF
					Zapatec.Transport.removeBusy(oArg);
					// Process response
					Zapatec.Transport.onXmlDocLoad(oDoc, oArg.onLoad,
					 oArg.onError);
				};
			} else {
				oFetchArg.onLoad = null;
			}

			// Fetch URL
			var oRequest = Zapatec.Transport.fetch(oFetchArg);

			// In synchronous mode the result is ready on the next line
			if (!oArg.async && oRequest) {
				// Parse xml response string
				var parser = new DOMParser();
				oDoc = parser.parseFromString(oRequest.responseText, "text/xml");

				// Remove "Busy" animated GIF
				Zapatec.Transport.removeBusy(oArg);
				// Process response
				Zapatec.Transport.onXmlDocLoad(oDoc, oArg.onLoad,
				 oArg.onError);

				return oDoc;
			}

			return null;
		}
		if (typeof ActiveXObject != 'undefined') {
			// IE
			// Show "Busy" animated GIF
			Zapatec.Transport.showBusy(oArg);
			// Load document
			try {
				var oDoc = new ActiveXObject(Zapatec.Transport.XMLDOM);
				oDoc.async = oArg.async;
				// Prevent duplicate onXmlDocLoad call in synchronous mode
				if (oArg.async) {
					oDoc.onreadystatechange = function () {
						if (oDoc.readyState == 4) {
							// Remove "Busy" animated GIF
							Zapatec.Transport.removeBusy(oArg);
							// Process response
							Zapatec.Transport.onXmlDocLoad(oDoc, oArg.onLoad,
							 oArg.onError);
							// Prevent memory leak
							oDoc.onreadystatechange = {};
						}
					};
				}
				oDoc.load(oArg.url);
				// In synchronous mode the result is ready on the next line
				if (!oArg.async) {
					// Remove "Busy" animated GIF
					Zapatec.Transport.removeBusy(oArg);
					// Process response
					Zapatec.Transport.onXmlDocLoad(oDoc, oArg.onLoad,
					 oArg.onError);
					return oDoc;
				}
				return null;
			} catch (oExpn) {
				// Remove "Busy" animated GIF
				Zapatec.Transport.removeBusy(oArg);
			};
		}
	}
	// Try XMLHttpRequest
	// Form argument for fetch
	var oFetchArg = {};
	for (var sKey in oArg) {
		oFetchArg[sKey] = oArg[sKey];
	}
	// Prevent duplicate parseXml call in synchronous mode
	if (oArg.async) {
		oFetchArg.onLoad = function(oRequest) {
			Zapatec.Transport.parseXml({
				strXml: oRequest.responseText,
				onLoad: oArg.onLoad,
				onError: oArg.onError
			});
		};
	} else {
		oFetchArg.onLoad = null;
	}
	// Fetch URL
	var oRequest = Zapatec.Transport.fetch(oFetchArg);
	// In synchronous mode the result is ready on the next line
	if (!oArg.async && oRequest) {
		return Zapatec.Transport.parseXml({
			strXml: oRequest.responseText,
			onLoad: oArg.onLoad,
			onError: oArg.onError
		});
	}
	return null;
};

/**
 * Parses XML string into XMLDocument object.
 *
 * <pre>
 * When XML string is parsed, one of provided callback functions is called:
 * onLoad on success or onError on error. In synchronous mode onLoad callback
 * can be omitted. Instead use returned object.
 *
 * onLoad callback function receives XMLDocument object as argument and may use
 * its documentElement and other properties.
 *
 * onError callback function receives following object:
 * {
 *   errorCode: error code [number],
 *   errorDescription: human readable error description [string]
 * }
 * Error code will be always 0.
 *
 * Returns XMLDocument object, so onLoad callback function is optional.
 * Returned value and its documentElement property should be checked before
 * use because they can be null or undefined.
 *
 * If XML string contains non-ASCII characters, encoding must be specified.
 * E.g. <?xml version="1.0" encoding="utf-8"?> or 
 * <?xml version="1.0" encoding="windows-1251"?>.
 *
 * Arguments object format:
 * {
 *   strXml: XML string to parse [string],
 *   onLoad: function reference to call on success [function] (optional),
 *   onError: function reference to call on error [function] (optional)
 * }
 * </pre>
 *
 * @param {object} oArg Arguments object
 * @return XMLDocument object or null
 * @type object
 */
Zapatec.Transport.parseXml = function(oArg) {
	if (oArg == null || typeof oArg != 'object') {
		return null;
	}
	if (!oArg.strXml) {
		return null;
	}
	if (!oArg.onLoad) {
		oArg.onLoad = null;
	}
	if (!oArg.onError) {
		oArg.onError = null;
	}
	if (window.DOMParser) {
		// Mozilla
		try {
			var oDoc = (new DOMParser()).parseFromString(oArg.strXml,
			 'text/xml');
			Zapatec.Transport.onXmlDocLoad(oDoc, oArg.onLoad,
			 oArg.onError);
			return oDoc;
		} catch (oExpn) {
			Zapatec.Transport.displayError(0,
			 "Error: Can't parse.\n" +
			 'String does not appear to be a valid XML fragment.',
			 oArg.onError);
		};
		return null;
	}
	if (typeof ActiveXObject != 'undefined') {
		// IE
		try {
			var oDoc = new ActiveXObject(Zapatec.Transport.XMLDOM);
			oDoc.loadXML(oArg.strXml);
			Zapatec.Transport.onXmlDocLoad(oDoc, oArg.onLoad,
			 oArg.onError);
			return oDoc;
		} catch (oExpn) {};
	}
	return null;
};

/**
 * Checks if there were errors during XML document fetching and parsing and
 * calls onLoad or onError callback function correspondingly.
 *
 * @private
 * @param {object} oDoc XMLDocument object
 * @param {function} onLoad Callback function provided by user
 * @param {function} onError Callback function provided by user
 */
Zapatec.Transport.onXmlDocLoad = function(oDoc, onLoad, onError) {
	var sError = null;
	if (oDoc.parseError) {
		// Parsing error in IE
		sError = oDoc.parseError.reason;
		if (oDoc.parseError.srcText) {
			sError += 'Location: ' + oDoc.parseError.url +
			 '\nLine number ' + oDoc.parseError.line + ', column ' +
			 oDoc.parseError.linepos + ':\n' +
			 oDoc.parseError.srcText + '\n';
		}
	} else if (oDoc.documentElement &&
	 oDoc.documentElement.tagName == 'parsererror') {
		// If an error is caused while parsing, Mozilla doesn't throw an exception.
		// Instead, it creates an XML string containing the details of the error:
		// <parsererror xmlns="http://www.w3.org/1999/xhtml">XML Parsing Error: ...
		// Check if strings has been generated.
		sError = oDoc.documentElement.firstChild.data + '\n' +
		 oDoc.documentElement.firstChild.nextSibling.firstChild.data;
	} else if (!oDoc.documentElement) {
		sError = 'String does not appear to be a valid XML fragment.';
	}
	if (sError) {
		// Parsing error
		Zapatec.Transport.displayError(0,
		 "Error: Can't parse.\n" + sError,
		 onError);
	} else {
		// Success
		if (typeof onLoad == 'function') {
			onLoad(oDoc);
		}
	}
};

/**
 * Serializes XMLDocument object into XML string.
 *
 * @param {object} oDoc XMLDocument object
 * @return XML string
 * @type string
 */
Zapatec.Transport.serializeXmlDoc = function(oDoc) {
	if (window.XMLSerializer) {
		// Mozilla
		return (new XMLSerializer).serializeToString(oDoc);
	}
	if (oDoc.xml) {
		// IE
		return oDoc.xml;
	}
};

/**
 * Fetches and parses JSON object from the specified URL.
 *
 * <pre>
 * When JSON object is fetched and parsed, one of provided callback functions
 * is called: onLoad on success or onError on error. In synchronous mode onLoad
 * callback can be omitted. Instead use returned object.
 *
 * onLoad callback function receives JSON object as argument.
 *
 * onError callback function receives following object:
 * {
 *   errorCode: error code [number],
 *   errorDescription: human readable error description [string]
 * }
 * Error code will be 0 unless there was a problem during fetching.
 *
 * Note: Some browsers implement caching for GET requests. Caching can be
 * prevented by adding 'r=' + Math.random() parameter to URL.
 *
 * If you use POST method, content argument should be something like
 * 'var1=value1&var2=value'. If you wish to send other content, set appropriate
 * contentType. E.g. to send XML string, you should set contentType: 'text/xml'.
 *
 * If server response contains non-ASCII characters, server must send
 * corresponding content-type header. E.g.
 * "Content-type: text/plain; charset=utf-8" or
 * "Content-type: text/plain; charset=windows-1251".
 *
 * Arguments object format:
 * {
 *   url: [string] relative or absolute URL to fetch,
 *   reliable: [boolean, optional] false (string will be parsed) or true
 *   (evaluated) (default: false),
 *   method: [string, optional] method ('GET', 'POST', 'HEAD', 'PUT'),
 *   async: [boolean, optional] use asynchronous mode (default: true),
 *   contentType: [string, optional] content type when using POST,
 *   content: [string or object, optional] postable string or DOM object data
 *    when using POST,
 *   onLoad: [function, optional] function reference to call on success,
 *   onError: [function, optional] function reference to call on error,
 *   username: [string, optional] username,
 *   password: [string, optional] password,
 *   busyContainer: [object or string, optional] element or id of element where
 *    to put "Busy" animated GIF,
 *   busyImage: [string, optional] standard image name or custom image URL,
 *   busyImageWidth: [number or string, optional] image width,
 *   busyImageHeight: [number or string, optional] image height
 * }
 * </pre>
 *
 * @param {object} oArg Arguments object
 * @return In synchronous mode JSON object or null. In asynchronous mode always
 * null.
 * @type object
 */
Zapatec.Transport.fetchJsonObj = function(oArg) {
	// Check arguments
	if (oArg == null || typeof oArg != 'object') {
		return null;
	}
	if (!oArg.url) {
		return null;
	}
	if (typeof oArg.async == 'undefined') {
		oArg.async = true;
	}
	if (!oArg.reliable) {
		oArg.reliable = false;
	}
	// Form argument for fetch
	var oFetchArg = {};
	for (var sKey in oArg) {
		oFetchArg[sKey] = oArg[sKey];
	}
	// Prevent duplicate parseXml call in synchronous mode
	if (oArg.async) {
		oFetchArg.onLoad = function(oRequest) {
			Zapatec.Transport.parseJson({
				strJson: oRequest.responseText,
				reliable: oArg.reliable,
				onLoad: oArg.onLoad,
				onError: oArg.onError
			});
		};
	} else {
		oFetchArg.onLoad = null;
	}
	// Fetch URL
	var oRequest = Zapatec.Transport.fetch(oFetchArg);
	// In synchronous mode the result is ready on the next line
	if (!oArg.async && oRequest) {
		return Zapatec.Transport.parseJson({
			strJson: oRequest.responseText,
			reliable: oArg.reliable,
			onLoad: oArg.onLoad,
			onError: oArg.onError
		});
	}
	return null;
};

/**
 * Parses JSON string into object.
 *
 * <pre>
 * When JSON string is parsed, one of provided callback functions is called:
 * onLoad on success or onError on error.
 *
 * onLoad callback function receives JSON object as argument.
 *
 * onError callback function receives following object:
 * {
 *   errorCode: error code [number],
 *   errorDescription: human readable error description [string]
 * }
 * Error code will be always 0.
 *
 * Returns JSON object, so onLoad callback function is optional.
 * Returned value should be checked before use because it can be null.
 *
 * Arguments object format:
 * {
 *   strJson: JSON string to parse [string],
 *   reliable: false (string will be parsed) or true (evaluated) [boolean]
 *   (optional, false by default),
 *   onLoad: function reference to call on success [function] (optional),
 *   onError: function reference to call on error [function] (optional)
 * }
 * </pre>
 *
 * @param {object} oArg Arguments object
 * @return JSON object or null
 * @type object
 */
Zapatec.Transport.parseJson = function(oArg) {
	if (oArg == null || typeof oArg != 'object') {
		return null;
	}
	if (!oArg.reliable) {
		oArg.reliable = false;
	}
	if (!oArg.onLoad) {
		oArg.onLoad = null;
	}
	if (!oArg.onError) {
		oArg.onError = null;
	}
	var oJson = null;
	try {
		if (oArg.reliable) {
			if (oArg.strJson) {
				oJson = eval('(' + oArg.strJson + ')');
			}
		} else {
			oJson = Zapatec.Transport.parseJsonStr(oArg.strJson);
		}
	} catch (oExpn) {
		var sError =
		 "Error: Can't parse.\nString doesn't appear to be a valid JSON fragment: ";
		sError += oExpn.message;
		if (typeof oExpn.text != 'undefined' && oExpn.text.length) {
			sError += '\n' + oExpn.text;
		}
		sError += '\n' + oArg.strJson;
		Zapatec.Transport.displayError(0, sError, oArg.onError);
		// onLoad should not be called in this case
		return null;
	};
	if (typeof oArg.onLoad == 'function') {
		oArg.onLoad(oJson);
	}
	return oJson;
};

/**
 * Parses JSON string into object.
 *
 * <pre>
 * Was taken with changes from http://json.org/json.js.
 *
 * Throws exception if parsing error occurs.
 *
 * JSON format is described at http://json.org/js.html.
 * </pre>
 *
 * @private
 * @param {string} text JSON string to parse
 * @return JSON object
 * @type object
 */
Zapatec.Transport.parseJsonStr = function(text) {
	var p = /^\s*(([,:{}\[\]])|"(\\.|[^\x00-\x1f"\\])*"|-?\d+(\.\d*)?([eE][+-]?\d+)?|true|false|null)\s*/,
			token,
			operator;
	function error(m, t) {
			throw {
					name: 'JSONError',
					message: m,
					text: t || operator || token
			};
	}
	function next(b) {
			if (b && b != operator) {
					error("Expected '" + b + "'");
			}
			if (text) {
					var t = p.exec(text);
					if (t) {
							if (t[2]) {
									token = null;
									operator = t[2];
							} else {
									operator = null;
									try {
											token = eval(t[1]);
									} catch (e) {
											error("Bad token", t[1]);
									}
							}
							text = text.substring(t[0].length);
					} else {
							error("Unrecognized token", text);
					}
			} else {
					// undefined changed to null because it is not supported in IE 5.0
					token = operator = null;
			}
	}
	function val() {
			var k, o;
			switch (operator) {
			case '{':
					next('{');
					o = {};
					if (operator != '}') {
							for (;;) {
									if (operator || typeof token != 'string') {
											error("Missing key");
									}
									k = token;
									next();
									next(':');
									o[k] = val();
									if (operator != ',') {
											break;
									}
									next(',');
							}
					}
					next('}');
					return o;
			case '[':
					next('[');
					o = [];
					if (operator != ']') {
							for (;;) {
									o.push(val());
									if (operator != ',') {
											break;
									}
									next(',');
							}
					}
					next(']');
					return o;
			default:
					if (operator !== null) {
							error("Missing value");
					}
					k = token;
					next();
					return k;
			}
	}
	next();
	return val();
};

/**
 * Serializes JSON object into JSON string.
 *
 * Was taken with changes from http://json.org/json.js.
 *
 * @param {object} v JSON object
 * @return JSON string
 * @type string
 */
Zapatec.Transport.serializeJsonObj = function(v) {
	var a = [];
	/*
		Emit a string.
	*/
	function e(s) {
			a[a.length] = s;
	}
	/*
		Convert a value.
	*/
	function g(x) {
			var c, i, l, v;
			switch (typeof x) {
			case 'object':
					if (x) {
							if (x instanceof Array) {
									e('[');
									l = a.length;
									for (i = 0; i < x.length; i += 1) {
											v = x[i];
											if (typeof v != 'undefined' &&
															typeof v != 'function') {
													if (l < a.length) {
															e(',');
													}
													g(v);
											}
									}
									e(']');
									return;
							} else if (typeof x.toString != 'undefined') {
									e('{');
									l = a.length;
									for (i in x) {
											v = x[i];
											if (x.hasOwnProperty(i) &&
															typeof v != 'undefined' &&
															typeof v != 'function') {
													if (l < a.length) {
															e(',');
													}
													g(i);
													e(':');
													g(v);
											}
									}
									return e('}');
							}
					}
					e('null');
					return;
			case 'number':
					e(isFinite(x) ? +x : 'null');
					return;
			case 'string':
					l = x.length;
					e('"');
					for (i = 0; i < l; i += 1) {
							c = x.charAt(i);
							if (c >= ' ') {
									if (c == '\\' || c == '"') {
											e('\\');
									}
									e(c);
							} else {
									switch (c) {
											case '\b':
													e('\\b');
													break;
											case '\f':
													e('\\f');
													break;
											case '\n':
													e('\\n');
													break;
											case '\r':
													e('\\r');
													break;
											case '\t':
													e('\\t');
													break;
											default:
													c = c.charCodeAt();
													e('\\u00' + Math.floor(c / 16).toString(16) +
															(c % 16).toString(16));
									}
							}
					}
					e('"');
					return;
			case 'boolean':
					e(String(x));
					return;
			default:
					e('null');
					return;
			}
	}
	g(v);
	return a.join('');
};

/**
 * Displays error message.
 *
 * <pre>
 * Calls onError callback function provided by user. If there is no onError
 * callback function, displays alert with human readable error description.
 * onError callback function receives following object:
 * {
 *   errorCode [number]: error code,
 *   errorDescription [string]: human readable error description
 * }
 * </pre>
 *
 * @private
 * @param {number} iErrCode Error code
 * @param {string} sError Human readable error description
 * @param {function} onError Callback function provided by user
 */
Zapatec.Transport.displayError = function(iErrCode, sError, onError) {
	if (typeof onError == 'function') {
		onError({
			errorCode: iErrCode,
			errorDescription: sError
		});
	} else {
		alert(sError);
	}
};

/**
 * Translates a URL to the URL relative to the specified or to absolute URL.
 *
 * <pre>
 * Arguments object format:
 * {
 *   url [string]: absolute or relative URL to translate; if absolute, will be
 *    returned as is,
 *   relativeTo [string, optional]: "url" will be translated to the URL relative
 *    to this absolute or relative URL; default: current page URL
 * }
 * </pre>
 *
 * @param {object} oArg Arguments object
 * @return Translated URL
 * @type string
 */
Zapatec.Transport.translateUrl = function(oArg) {
	if (!oArg || !oArg.url) {
		return null;
	}
	// Cut arguments part from url
	var aFullUrl = oArg.url.split('?', 2);
	var sUrl = aFullUrl[0];
	// Check url
	if (sUrl.indexOf(':') >= 0) {
		// Return absolute URL as is
		return oArg.url;
	}
	var oLocation = document.location;
	var sPort = oLocation.port;
	if (sPort) {
		sPort = ':' + sPort;
	}
	if (sUrl[0] == '/') {
		// Add hostname and return absolute URL as is
		return [oLocation.protocol, '//', oLocation.hostname, sPort, sUrl].join('');
	}
	// Get relativeTo
	var sLocation;
	if (sPort) {
		sLocation = [oLocation.protocol, '//', oLocation.hostname, sPort,
		 oLocation.pathname].join('');
	} else {
		sLocation = oLocation.toString();
	}
	var sRelativeTo;
	if (typeof oArg.relativeTo != 'string') {
		// By default relative to current page URL
		sRelativeTo = sLocation.split('?', 2)[0];
	} else {
		// Remove arguments from relativeTo
		sRelativeTo = oArg.relativeTo.split('?', 2)[0];
		// Check relativeTo
		if (sRelativeTo.indexOf('/') < 0) {
			// Relative to current page URL
			sRelativeTo = sLocation.split('?', 2)[0];
		} else if (sRelativeTo.charAt(0) != '/' &&
		 sRelativeTo.indexOf(':') < 0) {
			// Transform relativeTo to absolute URL to be able to translate URLs
			// starting from ../
			sRelativeTo = Zapatec.Transport.translateUrl({
				url: sRelativeTo
			});
		}
	}
	// Remove #
	sRelativeTo = sRelativeTo.split('#')[0];
	// Split URLs
	var aUrl = sUrl.split('/');
	var aRelativeTo = sRelativeTo.split('/');
	// Remove file name
	aRelativeTo.pop();
	// Form new URL
	for (var iToken = 0; iToken < aUrl.length; iToken++) {
		var sToken = aUrl[iToken];
		if (sToken == '..') {
			aRelativeTo.pop();
		} else if (sToken != '.') {
			aRelativeTo.push(sToken);
		}
	}
	aFullUrl[0] = aRelativeTo.join('/');
	// Restore arguments part
	return aFullUrl.join('?');
};

/**
 * Holds currently loading URLs to prevent duplicate loads.
 * @private
 */
Zapatec.Transport.loading = {};

/**
 * Prevents duplicate loads of the same URL when second request is done before
 * first request is completed.
 *
 * <pre>
 * Arguments object format:
 * {
 *   url: [string] absolute URL,
 *   force: [boolean, optional] force reload if it is already loaded,
 *   onLoad: [function, optional] function reference to call on success,
 *   onError: [function, optional] function reference to call on error
 * }
 *
 * Returned object format:
 *
 * If this URL is already loading by another process:
 * {
 *   loading: [boolean] always true
 * }
 *
 * Otherwise:
 * {
 *   onLoad: [function, optional] replacement for function to call on success,
 *   onError: [function, optional] replacement for function to call on error
 * }
 * </pre>
 *
 * @private
 * @param {object} oArg Arguments object
 * @return Returned object
 * @type object
 */
Zapatec.Transport.setupEvents = function(oArg) {
	// Check arguments
	if (!oArg) {
		return {};
	}
	// If loading is forced, we don't need to check if it is already loading
	// If EventDriven is not available, operate as in older versions
	// Check if URL is passed
	if (oArg.force || !Zapatec.EventDriven || !oArg.url) {
		return {
			onLoad: oArg.onLoad,
			onError: oArg.onError
		};
	}
	var sUrl = oArg.url;
	// Add onLoad listener
	if (typeof oArg.onLoad == 'function') {
		Zapatec.EventDriven.addEventListener('zpTransportOnLoad' + sUrl,
		 oArg.onLoad);
	}
	// Add onError listener
	if (typeof oArg.onError == 'function') {
		Zapatec.EventDriven.addEventListener('zpTransportOnError' + sUrl,
		 oArg.onError);
	}
	// Check if it is already loading
	if (Zapatec.Transport.loading[sUrl]) {
		return {
			loading: true
		};
	} else {
		// Flag
		Zapatec.Transport.loading[sUrl] = true;
		// Replace original callbacks
		return {
			onLoad: new Function("Zapatec.EventDriven.fireEvent('zpTransportOnLoad" +
			 sUrl + "');Zapatec.EventDriven.removeEvent('zpTransportOnLoad" +
			 sUrl + "');Zapatec.EventDriven.removeEvent('zpTransportOnError" +
			 sUrl + "');Zapatec.Transport.loading['" + sUrl + "'] = false;"),
			onError: new Function('oError',
			 "Zapatec.EventDriven.fireEvent('zpTransportOnError" +
			 sUrl + "',oError);Zapatec.EventDriven.removeEvent('zpTransportOnLoad" +
			 sUrl + "');Zapatec.EventDriven.removeEvent('zpTransportOnError" +
			 sUrl + "');Zapatec.Transport.loading['" + sUrl + "'] = false;")
		};
	}
};

/**
 * Holds URLs of already loaded JS files to prevent duplicate loads.
 * @private
 */
Zapatec.Transport.loadedJS = {};

/**
 * Checks if specified JS file is already loaded.
 *
 * @private
 * @param {string} sUrl Absolute or relative URL of JS file
 * @param {string} sAbsUrl Optional. Absolute URL of JS file
 * @return Loaded or not
 * @type boolean
 */
Zapatec.Transport.isLoadedJS = function(sUrl, sAbsUrl) {
	// Get absolute URL of the JS file
	if (typeof sAbsUrl == 'undefined') {
		sAbsUrl = Zapatec.Transport.translateUrl({url: sUrl});
	}
	// Check in the list of loaded
	if (Zapatec.Transport.loadedJS[sAbsUrl]) {
		return true;
	}
	// Try to find script tag
	var aScripts = document.getElementsByTagName('script');
	for (var iScript = 0; iScript < aScripts.length; iScript++) {
		var sSrc = aScripts[iScript].getAttribute('src') || '';
		if (sSrc == sUrl) {
			// Add this URL to the list of loaded
			Zapatec.Transport.loadedJS[sAbsUrl] = true;
			return true;
		}
	}
	// Not found
	return false;
};

/**
 * Returns path to the specified js file. Iterates over all loaded script
 * elements starting from the end. Finds specified js file in src attribute of
 * the script element. Splits src attribute value and returns path without js
 * file name.
 *
 * @param {string} sScriptFileName Script file name, e.g. 'zpmywidget.js'
 * @return Path to the script, e.g. '../src/' or '' if path is not found
 * @type string
 */
Zapatec.Transport.getPath = function(sScriptFileName) {
	// Get all script elements
	var aScripts = document.getElementsByTagName('script');
	// Find the script in the list
	for (var iScript = aScripts.length - 1; iScript >= 0; iScript--) {
		var sSrc = aScripts[iScript].getAttribute('src') || '';
		var aTokens = sSrc.split('/');
		// Remove last token
		var sLastToken = aTokens.pop();
		if (sLastToken == sScriptFileName) {
			return aTokens.length ? aTokens.join('/') + '/' : '';
		}
	}
	// Search in loaded JS files
	for (var sSrc in Zapatec.Transport.loadedJS) {
		var aTokens = sSrc.split('/');
		// Remove last token
		var sLastToken = aTokens.pop();
		if (sLastToken == sScriptFileName) {
			return aTokens.length ? aTokens.join('/') + '/' : '';
		}
	}
	// Not found
	return '';
};

/**
 * Writes script tag to the document. Checks if specified JS file is already
 * loaded unless bForce argument is true.
 *
 * <pre>
 * Note: This function must be invoked during page load because it uses
 * document.write method.
 *
 * If special Zapatec.doNotInclude flag is set, this function does nothing.
 * </pre>
 *
 * @param {string} sSrc Src attribute value of the script element
 * @param {string} sId Optional. Id of the script element
 * @param {boolean} bForce Optional. Force reload if it is already loaded
 */
Zapatec.Transport.include = function(sSrc, sId, bForce) {
	// Check flag
	if (Zapatec.doNotInclude) {
		return;
	}
	// Get absolute URL of the JS file
	var sAbsUrl = Zapatec.Transport.translateUrl({url: sSrc});
	// Check if it is already loaded
	if (!bForce && Zapatec.Transport.isLoadedJS(sSrc, sAbsUrl)) {
		return;
	}
	// Include file
	document.write('<script type="text/javascript" src="' + sSrc +
	 (typeof sId == 'string' ? '" id="' + sId : '') + '"></script>');
	// Add this URL to the list of loaded
	Zapatec.Transport.loadedJS[sAbsUrl] = true;
};

/**
 * Shortcut. The same as {@link Zapatec.Transport#include}.
 */
Zapatec.include = Zapatec.Transport.include;

/**
 * Includes JS file into the page. Allows URLs from foreign domains. Doesn't
 * check if the JS file is already included. File is loaded asynchronously.
 *
 * @param {string} sSrc Src attribute value of the script element
 * @param {string} sId Optional. Id of the script element
 */
Zapatec.Transport.includeJS = function(sSrc, sId) {
	// Make sure it is asynchronous in all browsers
	setTimeout(function() {
		// Include file
		var oContr = document.body;
		if (!oContr) {
			oContr = document.getElementsByTagName('head')[0];
			if (!oContr) {
				oContr = document;
			}
		}
		var oScript = document.createElement('script');
		oScript.type = 'text/javascript';
		oScript.src = sSrc;
		if (typeof sId == 'string') {
			oScript.id = sId;
		}
		// This is important for Safari to assign attributes before appending
		oContr.appendChild(oScript);
	}, 0);
};

/**
 * Fetches JS file using fetch and evaluates it in global scope.
 *
 * <pre>
 * When JS file is loaded successfully, onLoad callback function is called
 * without arguments. URL is added into Zapatec.Transport.loadedJS array
 * and will not be fetched again on next function call unless force argument is
 * set to true.
 *
 * onError callback function receives following object:
 * {
 *   errorCode: [number] server status number (404, etc.),
 *   errorDescription: [string] human readable error description
 * }
 *
 * One of the arguments: module or url is required. When url is passed,
 * module argument is ignored.
 *
 * If module argument is used, function gets all "script" elements using
 * getElementsByTagName and searches for the first element having "src"
 * attribute value ending with (relativeModule + ".js") (default relativeModule
 * value is "transport"). Path to the module is taken from that src attribute
 * value and will be the same as path to relativeModule file.
 *
 * Arguments object format:
 * {
 *   url: [string, optional] absolute or relative URL of JS file,
 *   module: [string, optional] module name (file name without .js extension);
 *    ignored when "url" is defined,
 *   path: [string, optional] path where to search "module" (default is
 *    Zapatec.zapatecPath if it is defined); ignored when "url" is defined,
 *   async: [boolean, optional] use asynchronous mode (default: true),
 *   force: [boolean, optional] force reload if it is already loaded,
 *   onLoad: [function, optional] function reference to call on success,
 *   onError: [function, optional] function reference to call on error
 * }
 *
 * Note: If "force" is used, you should add 'r=' + Math.random() parameter to
 * URL to prevent loading from browser cache.
 *
 * <b>
 * Note: Global variables must be declared without "var" keyword. Otherwise
 * they will be ignored by Safari.
 * </b>
 *
 * If special Zapatec.doNotInclude flag is set, this function just calls onLoad
 * callback function.
 * </pre>
 *
 * @param {object} oArg Arguments object
 */
Zapatec.Transport.loadJS = function(oArg) {
	// Check arguments
	if (!(oArg instanceof Object)) {
		return;
	}
	if (typeof oArg.async == 'undefined') {
		oArg.async = true;
	}
	// Get URL of JS file
	var sUrl = null;
	if (oArg.url) {
		sUrl = oArg.url;
	} else if (oArg.module) {
		var sPath = '';
		if (typeof oArg.path != 'undefined') {
			sPath = oArg.path;
		} else if (typeof Zapatec.zapatecPath != 'undefined') {
			sPath = Zapatec.zapatecPath;
		}
		sUrl = sPath + oArg.module + '.js';
	} else {
		return;
	}
	// Get absolute URL of the JS file
	var sAbsUrl = Zapatec.Transport.translateUrl({url: sUrl});
	// Check arguments
	if (!oArg.onLoad) {
		oArg.onLoad = null;
	}
	if (!oArg.onError) {
		oArg.onError = null;
	}
	// Check if it is already loaded
	if (Zapatec.doNotInclude ||
	 (!oArg.force && Zapatec.Transport.isLoadedJS(sUrl, sAbsUrl))) {
		// onLoad callback
		if (typeof oArg.onLoad == 'function') {
			oArg.onLoad();
		}
		return;
	}
	// Setup onLoad and onError events
	var oHandlers = Zapatec.Transport.setupEvents({
		url: sAbsUrl,
		force: oArg.force,
		onLoad: oArg.onLoad,
		onError: oArg.onError
	});
	// Don't need to continue if this url is already loading by another process
	if (oHandlers.loading) {
		return;
	}
	// Load JS file
	Zapatec.Transport.fetch({
		url: sUrl,
		async: oArg.async,
		onLoad: function(oRequest) {
			// Can be loaded in two processes simultaneously
			if (oArg.force || !Zapatec.Transport.loadedJS[sAbsUrl]) {
				var aTokens = sUrl.split('/');
				// Remove last token
				var sLastToken = aTokens.pop();
				// Store path to current module
				Zapatec.lastLoadedModule = aTokens.join('/') + '/';
				// Evaluate code in global scope
				Zapatec.Transport.evalGlobalScope(oRequest.responseText);
				// clear path to last loaded module
				Zapatec.lastLoadedModule = null;
				// Add this URL to the list of loaded
				Zapatec.Transport.loadedJS[sAbsUrl] = true;
			}
			// onLoad callback
			if (typeof oHandlers.onLoad == 'function') {
				oHandlers.onLoad();
			}
		},
		onError: oHandlers.onError
	});
};

/**
 * Includes CSS file into the page. Allows URLs from foreign domains. Doesn't
 * check if the CSS file is already included. File is loaded asynchronously.
 * Requires that head section of the page already exists because link tag
 * may appear only inside head.
 *
 * @param {string} sHref Href attribute value of the link element
 */
Zapatec.Transport.includeCSS = function(sHref) {
	// May appear only inside head
	var oContr = document.getElementsByTagName('head')[0];
	if (!oContr) {
		return;
	}
	var oLink = document.createElement('link');
	oLink.setAttribute('rel', 'stylesheet');
	oLink.setAttribute('type', 'text/css');
	oLink.setAttribute('href', sHref);
	oContr.appendChild(oLink);
};

/**
 * Holds URLs of already loaded CSS files to prevent duplicate loads.
 * @private
 */
Zapatec.Transport.loadedCss = {};

/**
 * Fetches style sheet using fetch and loads it into the document. Requires
 * utils/stylesheet.js module.
 *
 * <pre>
 * When stylesheet is loaded successfully, onLoad callback function is called
 * without arguments. URL is added into Zapatec.Transport.loadedCss array
 * and will not be fetched again on next function call unless force argument is
 * set to true.
 *
 * onError callback function receives following object:
 * {
 *   errorCode: server status number (404, etc.) [number],
 *   errorDescription: human readable error description [string]
 * }
 *
 * Arguments object format:
 * {
 *   url: absolute or relative URL of CSS file [string],
 *   async: [boolean, optional] use asynchronous mode (default: true),
 *   force: [boolean, optional] force reload if it is already loaded,
 *   onLoad: [function, optional] function reference to call on success,
 *   onError: [function, optional] function reference to call on error
 * }
 *
 * Note: If "force" is used, you should add 'r=' + Math.random() parameter to
 * URL to prevent loading from browser cache.
 * </pre>
 *
 * @param {object} oArg Arguments object
 */
Zapatec.Transport.loadCss = function(oArg) {
	// Check arguments
	if (!(oArg instanceof Object)) {
		return;
	}
	if (!oArg.url) {
		return;
	}
	if (typeof oArg.async == 'undefined') {
		oArg.async = true;
	}
	// Get absolute URL of the CSS file
	var sAbsUrl = Zapatec.Transport.translateUrl({url: oArg.url});
	// Check if it is already loaded
	if (!oArg.force) {
		if (Zapatec.Transport.loadedCss[sAbsUrl]) {
			// onLoad callback
			if (typeof oArg.onLoad == 'function') {
				oArg.onLoad();
			}
			return;
		}
		var aLinks = document.getElementsByTagName('link');
		for (var iLnk = 0; iLnk < aLinks.length; iLnk++) {
			var sHref = aLinks[iLnk].getAttribute('href') || '';
			// Make it absolute
			sHref = Zapatec.Transport.translateUrl({url: sHref});
			if (sHref == sAbsUrl) {
				// Add this url to the list of loaded
				Zapatec.Transport.loadedCss[sAbsUrl] = true;
				// onLoad callback
				if (typeof oArg.onLoad == 'function') {
					oArg.onLoad();
				}
				return;
			}
		}
	}
	// Setup onLoad and onError events
	var oHandlers = Zapatec.Transport.setupEvents({
		url: sAbsUrl,
		force: oArg.force,
		onLoad: oArg.onLoad,
		onError: oArg.onError
	});
	// Don't need to continue if this url is already loading by another process
	if (oHandlers.loading) {
		return;
	}
	// Load CSS file
	Zapatec.Transport.fetch({
		url: oArg.url,
		async: oArg.async,
		onLoad: function(oRequest) {
			// Parse CSS file.
			// Find URLs and translate them to absolute.
			// Find @import rules and load corresponding CSS files.
			var sCss = oRequest.responseText;
			var aResultCss = [];
			// Will hold image URLs to preload
			var aImgUrls = [];
			// Will hold CSS URLs to load
			var aCssUrls = [];
			// Move first cursor to the beginning of the string
			var iPos = 0;
			// Move second cursor to the pattern
			var iNextPos = sCss.indexOf('url(', iPos);
			while (iNextPos >= 0) {
				// Move first cursor to the URL
				iNextPos += 4;
				// Check if this is @import rule
				var sToken = sCss.substring(iPos, iNextPos);
				var bIsImport = /@import\s+url\($/.test(sToken);
				// Add part of the string before URL
				aResultCss.push(sToken);
				// Move second cursor to the new location to start the search from
				iPos = iNextPos;
				// Search the end of URL
				iNextPos = sCss.indexOf(')', iPos);
				if (iNextPos >= 0) {
					// Remove quotes
					var sImgUrl = sCss.substring(iPos, iNextPos);
					sImgUrl = sImgUrl.replace(/['"]/g, '');
					// Translate image URL relative to CSS file URL
					sImgUrl = Zapatec.Transport.translateUrl({
						url: sImgUrl,
						relativeTo: oArg.url
					});
					// Convert to absolute URL
					sImgUrl = Zapatec.Transport.translateUrl({
						url: sImgUrl
					});
					// Add translated URL
					aResultCss.push(sImgUrl);
					// Add URL to the list
					if (bIsImport) {
						// Add CSS URL to load list
						aCssUrls.push(sImgUrl);
					} else {
						// Add image URL to preload list
						aImgUrls.push(sImgUrl);
					}
					// Move second cursor to the new location to start the search from
					iPos = iNextPos;
					// Search next pattern
					iNextPos = sCss.indexOf('url(', iPos);
				}
			}
			// Add the rest of string
			aResultCss.push(sCss.substr(iPos));
			// Get translated CSS text
			sCss = aResultCss.join('');
			// Load CSS files
			Zapatec.Transport.loadCssList({
				urls: aCssUrls,
				async: oArg.async,
				onLoad: function() {
					// Add style sheet rules into the page
					(new Zapatec.StyleSheet()).addParse(sCss);
					// Fire event
					if (typeof oHandlers.onLoad == 'function') {
						oHandlers.onLoad();
					}
				}
			});
			// Add this URL to the list of loaded
			Zapatec.Transport.loadedCss[sAbsUrl] = true;
			// Preload images
			Zapatec.Transport.preloadImages({
				urls: aImgUrls,
				timeout: 60000 // 1 minute
			});
		},
		onError: oHandlers.onError
	});
};

/**
 * Loads several CSS files one by one it into the document.
 *
 * <pre>
 * This function behaves differently from other Zapatec.Transport functions.
 * onLoad callback function will be called in any case, even if errors occured
 * during loading. If there are multiple errors, onError callback function will
 * be called once for every passed URL that wasn't loaded successfully.
 *
 * onLoad callback function is called without arguments.
 *
 * onError callback function receives following object:
 * {
 *   errorCode: server status number (404, etc.) [number],
 *   errorDescription: human readable error description [string]
 * }
 *
 * Arguments object format:
 * {
 *   urls: array of absolute or relative URLs of CSS files to load [object]
 *    (files will be loaded in order they appear in the array),
 *   async: [boolean, optional] use asynchronous mode (default: true),
 *   force: [boolean, optional] force reload if it is already loaded,
 *   onLoad: function reference to call on completion [function] (optional),
 *   onError: function reference to call on error [function] (optional)
 * }
 *
 * Note: If "force" is used, you should add 'r=' + Math.random() parameter to
 * URL to prevent loading from browser cache.
 * </pre>
 *
 * @param {object} oArg Arguments object
 */
Zapatec.Transport.loadCssList = function(oArg) {
	// Check arguments
	if (!(oArg instanceof Object)) {
		return;
	}
	if (typeof oArg.async == 'undefined') {
		oArg.async = true;
	}
	if (!oArg.onLoad) {
		oArg.onLoad = null;
	}
	if (!oArg.onError) {
		oArg.onError = null;
	}
	if (!oArg.urls || !oArg.urls.length) {
		// onLoad callback
		if (typeof oArg.onLoad == 'function') {
			oArg.onLoad();
		}
		return;
	}
	// Get first URL in the array
	var sUrl = oArg.urls.shift();
	// CSS file onLoad handler
	var funcOnLoad = function() {
		// Load the rest of URLs
		Zapatec.Transport.loadCssList({
			urls: oArg.urls,
			async: oArg.async,
			force: oArg.force,
			onLoad: oArg.onLoad,
			onError: oArg.onError
		});
	};
	// Load CSS file
	Zapatec.Transport.loadCss({
		url: sUrl,
		async: oArg.async,
		force: oArg.force,
		onLoad: funcOnLoad,
		onError: function(oError) {
			Zapatec.Transport.displayError(oError.errorCode, oError.errorDescription,
			 oArg.onError);
			funcOnLoad();
		}
	});
};

/**
 * Holds image preloads.
 * @private
 */
Zapatec.Transport.imagePreloads = [];

/**
 * Preloads one or several images at once. Requires utils/preloadimages.js
 * module. See Zapatec.PreloadImages class (utils/preloadimages.js) for details.
 *
 * <pre>
 * Arguments object format:
 * {
 *   urls: [object] array of absolute or relative image URLs to preload,
 *   onLoad: [function, optional] onload event handler,
 *   timeout: [number, optional] number of milliseconds to wait for onload
 *    event before forcing it
 * }
 * </pre>
 *
 * @param {object} oArg Arguments object
 */
Zapatec.Transport.preloadImages = function(oArg) {
	Zapatec.Transport.imagePreloads.push(new Zapatec.PreloadImages(oArg));
};