1 ///////////////////////////////////////////////////////////////////////////////

     2 // The FeedUpdateBroker class implements a simple RSS fetcher and parser.

     3 // Adapted from WRTKit RssReader example

     4 

     5 // Constructor.

     6 function FeedUpdateBroker() {

     7     this.httpReq = null;

     8     this.feedAddress = null;

     9     this.callback = null;

    10 	this.ignoreContent = false;

    11 	this.cancelled = false;

    12 	this.responseParser = this.handleRssResponse;

    13 	this.startFromItem = 0;

    14 	this.maxItems = 0;

    15 }

    16 

    17 // Fetches a feed from the specified URL and calls the callback when the feed

    18 // has been fetched and parsed, or if the process results in an error.

    19 FeedUpdateBroker.prototype.doFetchFeed = function(){    

    20     // create new XML HTTP request

    21     this.httpReq = new Ajax();

    22     

    23     // set callback

    24     var self = this;

    25     this.httpReq.onreadystatechange = function() { self.readyStateChanged(); };

    26 

    27     // initiate the request

    28     this.httpReq.open("GET", nocache(this.feedAddress), true);

    29     this.httpReq.send(null);

    30 }

    31 

    32 // has been fetched and parsed, or if the process results in an error.

    33 FeedUpdateBroker.prototype.fetchFeed = function(feedURL, callback) {

    34     // remember callback

    35     this.callback = callback;

    36     this.feedAddress = feedURL;

    37 	this.doFetchFeed();

    38 }

    39 

    40 // Callback for ready-state change events in the XML HTTP request.

    41 FeedUpdateBroker.prototype.readyStateChanged = function() {

    42     // complete request?

    43     if (this.httpReq.readyState == 4) {

    44         // attempt to get response status

    45         var responseStatus = null;

    46         try {

    47             responseStatus = this.httpReq.status;

    48         } catch (noStatusException) {}

    49         

    50 		// are we being prompted for login?

    51 		var text = this.httpReq.responseText;

    52 		

    53         // handle the response and call the registered callback object

    54 		var response = this.httpReq.responseXML;

    55 		if (response == null) {

    56 			// if the content type is not set correctly, we get the response as text

    57 			var xmlparser = new DOMParser();

    58 		    response = xmlparser.parseFromString(this.httpReq.responseText, "text/xml");

    59 		}

    60         this.callback.feedUpdateCompleted(this.handleResponse(responseStatus, response));

    61     }

    62 }

    63 

    64 // Handles a completed response.

    65 FeedUpdateBroker.prototype.handleResponse = function(responseStatus, xmlDoc){

    66 	if (this.responseParser == null) {

    67 		return this.handleRssResponse(responseStatus, xmlDoc);

    68 	}

    69 	else {

    70 		return this.responseParser.call(this, this, responseStatus, xmlDoc);

    71 	}	

    72 }

    73 

    74 

    75 FeedUpdateBroker.prototype.handleRssResponse = function(broker, responseStatus, xmlDoc){

    76 	if ( this.cancelled ) {

    77         return { status: "cancelled" };

    78 	}

    79     if (responseStatus == 200 && xmlDoc != null) {

    80         // node ref for iterating

    81         var node;

    82         

    83         // get last modified time - default to current time

    84         var lastModified = new Date().getTime();

    85         var channelElements = xmlDoc.getElementsByTagName("channel");

    86         if (channelElements.length > 0) {

    87             node = channelElements[0].firstChild;

    88             while (node != null) {

    89                 if (node.nodeType == Node.ELEMENT_NODE) {

    90                     if (node.nodeName == "pubDate" ||

    91                             node.nodeName == "lastBuildDate" ||

    92                             node.nodeName == "dc:date") {

    93                         lastModified = getTextOfNode(node);

    94                         break;

    95                     }

    96                 }

    97                 node = node.nextSibling;

    98             }

    99         }

   100         

   101         // init feed items array

   102         var items = [];

   103         

   104         // we got the feed XML so now we'll parse it

   105         var itemElements = xmlDoc.getElementsByTagName("item");

   106 		

   107         for (var i = this.startFromItem; i < itemElements.length; i++) {

   108 			if ( this.maxItems > 0 && this.maxItems < i ) {

   109 				break;

   110 			}

   111             // iterate through child nodes of this item and gather

   112             // all the data we need for a feed item

   113             var title = null;

   114             var date = null;

   115             var description = null;

   116             var url = null;

   117             var author = null;

   118             node = itemElements[i].firstChild;

   119             while (node != null) {

   120                 if (node.nodeType == Node.ELEMENT_NODE) {

   121                     if (node.nodeName == "title") {

   122                         // item title

   123                         title = getTextOfNode(node);

   124                     } else if (node.nodeName == "pubDate" || node.nodeName == "dc:date") {

   125                         // item publishing date

   126                         date = getTextOfNode(node);

   127                     } else if (node.nodeName == "description" && !this.ignoreContent ) {

   128                         // item description

   129                         description = getTextOfNode(node);

   130                     } else if (node.nodeName == "link") {

   131                         // link URL

   132                         url = getTextOfNode(node);

   133                     } else if (node.nodeName == "dc:creator" ) {

   134 						author = getTextOfNode(node);

   135 					}

   136                 }

   137                 node = node.nextSibling;

   138             }

   139             

   140             // create the item and add to the items array

   141             items.push({ title: title, date: date, description: description, url: url, author: author });

   142         }

   143         

   144         // update was completed successfully

   145         return { status: "ok", lastModified: lastModified, items: items };

   146     } else {

   147         // update failed

   148         return { status: "error" };

   149     }

   150 }

   151 

   152 // Returns the text of a node.

   153 function getTextOfNode(node) {

   154     var buf = "";

   155 	// iterate through all child elements and collect all text to the buffer

   156 	var child = node.firstChild;

   157 	while (child != null) {

   158 		if (child.nodeType == Node.TEXT_NODE || child.nodeType == Node.CDATA_SECTION_NODE) {

   159 			// append text to buffer

   160 			if (buf != "") {

   161 				buf += " ";

   162 			}

   163 			buf += child.nodeValue;

   164 		}

   165 		child = child.nextSibling;

   166 	}

   167 	

   168 	return buf;

   169 }

   170 

   171 FeedUpdateBroker.prototype.cancel = function() {

   172 	this.cancelled = true;

   173 	this.httpReq.abort();

   174 }