Index: lams_common/src/flash/org/lamsfoundation/lams/common/comms/Communication.as
===================================================================
diff -u -r20c7ecef5985188eb80619a4a636042a6e338eaf -r0f7f1e2d8ccc55f853744613ed1e67187caad20e
--- lams_common/src/flash/org/lamsfoundation/lams/common/comms/Communication.as	(.../Communication.as)	(revision 20c7ecef5985188eb80619a4a636042a6e338eaf)
+++ lams_common/src/flash/org/lamsfoundation/lams/common/comms/Communication.as	(.../Communication.as)	(revision 0f7f1e2d8ccc55f853744613ed1e67187caad20e)
@@ -8,46 +8,72 @@
 * 
 */
 class org.lamsfoundation.lams.common.comms.Communication {
-    private var _serverUrl:String;
-    private var errorCodes:Array;
+    
+    private static var FRIENDLY_ERROR_CODE:Number = 1;  //Server error codes
+    private static var SYSTEM_ERROR_CODE:Number = 2;
+    
+    private static var MAX_REQUESTS:Number = 20;       //Maximum no of simultaneous requests
+    
+    private var _serverURL:String;
     private var ignoreWhite:Boolean;  
     private var responseXML:XML;      //XML object for server response
     private var wddx:Wddx;            //WDDX serializer/de-serializer
     
-    private var requestHandlers:Hashtable;
+    private var queue:Array;
+    private var queueID:Number;
     
-    //TODO DI 11/04/05 Manage key/handler relationship - temp solution
-    private var requestCallBack:Function;
-    private var onXMLData:Function;
-    
+   
     /**
     * Comms constructor
     */
-    function Communication(aServerUrl:String){
+    function Communication(serverURL:String){
         trace('Communication.constructor');
-        //Set up error codes used in communication with server
-        errorCodes=[1,2,3];
+
+        //Set up queue
+        queue=[];
+        queueID=0;
+        
+        
         ignoreWhite = true;
 		//_global.breakpoint();
-		if(aServerUrl == null){
-			_serverUrl = Config.getInstance().serverUrl;
-		}
-		//Debugger.log('_serverUrl:'+_serverUrl,4,'Consturcutor','Communication');
+		if(_serverURL == null){
+			//_serverURL = Config.getInstance().serverUrl;
+            
+		}
+        _serverURL = _root.serverURL;
+        
+		//Debugger.log('_serverURL:'+_serverURL,4,'Consturcutor','Communication');
         wddx = new Wddx();
     }
     
     /**
-    * request a design from the server
-    * @param requestUrl URL on the server for request script
+    * Make a request to the server.  Each request handlers is added to a queue whilst waiting for the (asynchronous) response 
+    * from the server. The server returns a wrapped XML packet that is unwrapped and de-serialised on load and passed back
+    * to the request handler
+    * 
+    * @usage -  var myObject.test = function (deserializedObject) {
+    *               //Code to process object here....
+    *           }
+    *           commsInstance.getRequest('http://dolly.uklams.net/lams/lams_authoring/all_library_details.xml',myObject.test,true)   
+    * 
+    * @param requestURL URL on the server for request script
     * @param handlerFn  a callback function to call with the response object
+    * @returns Void
     */
-    public function getRequest(requestUrl:String,handlerFn:Function,isFullURL){
+    public function getRequest(requestURL:String,handler:Function,isFullURL:Boolean):Void{
         trace('Communication.getRequest()');
-        //Create XML response object (deleting old XML if neccesary), assign data+load events and load XML
-        if(responseXML!=null){
-            delete responseXML;
+        
+        //Create XML response object 
+        var responseXML = new XML();
+        
+        //Add request to queue
+        addToQueue(queueID,handler);
+        
+        //Reset queueID?
+        if(queueID>=MAX_REQUESTS) {
+            queueID=0;
         }
-        responseXML = new XML();
+        
         //Set ondata handler to validate data returned in XML object
         responseXML.onData = function(src){
             if (src != undefined) {
@@ -67,69 +93,109 @@
             }            
         }
         //Assign onLoad handler
-        responseXML.onLoad = Proxy.create(this,xmlOnLoad,responseXML);
+        responseXML.onLoad = Proxy.create(this,onServerResponse,queueID);
         
+        //Increment the queueID for next time
+        queueID++;
+        
         //TODO DI 11/04/05 Stub here for now until we have server implmenting new WDDX structure
         if(isFullURL){
-			Debugger.log('Requesting:'+requestUrl,Debugger.GEN,'getRequest','Communication');			
-			responseXML.load(requestUrl);
+			Debugger.log('Requesting:'+requestURL,Debugger.GEN,'getRequest','Communication');			
+			responseXML.load(requestURL);
 		}else{
-			Debugger.log('Requesting:'+_serverUrl+requestUrl,Debugger.GEN,'getRequest','Communication');			
-			responseXML.load(_serverUrl+requestUrl);
+			Debugger.log('Requesting:'+_serverURL+requestURL,Debugger.GEN,'getRequest','Communication');			
+			responseXML.load(_serverURL+requestURL);
 		}
-        //_global.breakPoint();
-        //responseXML.load('sampleLearningDesign.xml');
-        requestCallBack = handlerFn;
     }
     
+
+    
     /**
-    * XML onLoad handler called after data validation
+    * XML load handler called after data validation on XML returned from server
     * @param success            XML load status
     * @param wrappedPacketXML   The wrapped XML response object 
     */
-    private function xmlOnLoad(success:Boolean,wrappedPacketXML:XML){
+    private function onServerResponse(success:Boolean,wrappedPacketXML:XML,queueID:Number){
         trace('XML loaded success:'+ success);
-        /*
-        * Validate the XML
-        * If No Errors THEN
-        *   Use key to lookup the handler for the object
-        *   fire callback handler passing in server response object
-        * ELSE
-        *   deal with errors
-        * END IF
-        */
-        
         //Load ok?
         if(success){
             var responseObj:Object = wddx.deserialize(wrappedPacketXML);
-            //Call request handler function now that we have a response
-            //Match key with handler and call handler
-            requestCallBack(responseObj.messageValue);
+
+            //Now delete the XML 
+            delete wrappedPacketXML;
+            
+            //Check for errors in message type that's returned from server
+            if(responseObj.messageType == FRIENDLY_ERROR_CODE){
+                //user friendly error
+                //showAlert("Oops", responseObj.body, "sad");
+            }else if(responseObj.messageType == SYSTEM_ERROR_CODE){
+                //showAlert("System error", "<p>Sorry there has been a system error, please try the operation again. If the problem persistes please contact support</p><p>Additional information:"+responseObj.body+"</p>", "sad");
+            }else{
+                //Everything is fine so lookup callback handler on queue 
+                var index:Number = getIndexByQueueID(queueID);
+                //Dispatch handler passing in object stored under messageValue
+                queue[index].handler(responseObj.messageValue);
+                //Now that request has been dealt with remove item from queue
+                removeFromQueue(queueID);
+            }            
         }else {
             //TODO DI 12/04/05 Handle onLoad error
-            trace('XML load failed!');
+            //showAlert("System error", "<p>Communication Error</p>", "sad");
         }
     }
     
     /**
-    * Send an object to the server
+    * Adds a key handler pair to the queue
     */
-    public function sendObject(){
-        
+    private function addToQueue(queueID:Number,handler:Function){
+        queue.push({queueID:queueID,handler:handler});
+    }
+    
+    /**
+    * removes a key handler pair from the queue
+    * @returns boolean indicating success
+    */
+    private function removeFromQueue(queueID:Number):Boolean{
+        //find item and delete it
+        var index:Number = getIndexByQueueID(queueID);
+        if(index!=-1) {
+            //Remove the item from the queue
+            queue.splice(index,1);
+            return true;
+        }else {
+            return false;
+            Debugger.log('Item not found in queue :' + queueID,Debugger.GEN,'removeFromQueue','Communication');
+        }
+    }
+    
+    /**
+    * searches queue for item by key 
+    * @returns Array index value, -1 if key not found
+    */
+    private function getIndexByQueueID(queueID):Number {
+        //Go through handlers and remove key
+        for(var i=0;i<queue.length;i++) {
+            //If key found, delete key/handler object from array 
+            if(queue[i].queueID==queueID) {
+                return i;
+            }
+        }
+        //If we're here then we didn't find it return an error
+        return -1;
     }
     
     /**
 	* Sends a data object to the server and directs response to handler function.
 	* 
     * @param dto		The flash object to send. Will be WDDX serialised    
-	* @param requestUrl the url to send and load the data from
+	* @param requestURL the url to send and load the data from
 	* @param handlerFn  the function that will handle the response (usually an ACK response)
-	* @param isFullURL  Inicates if the requestUrl is fully qualified, if false serverURL will be prepended
+	* @param isFullURL  Inicates if the requestURL is fully qualified, if false serverURL will be prepended
 	* 
 	* @usage: 
 	* 
     */
-    public function sendAndReceive(dto:Object, requestUrl:String,handlerFn:Function,isFullURL){
+    public function sendAndReceive(dto:Object, requestURL:String,handlerFn:Function,isFullURL,overrideKey:String){
       //TODO: Implement!  
     }
 	
@@ -150,14 +216,14 @@
     * returns current server URL  
     */
     function get serverUrl():String{
-        return _serverUrl;
+        return _serverURL;
     }
 
 
     /**
     * sets current server URL  
     */
     function set serverUrl(val:String){
-        _serverUrl = val;
+        _serverURL = val;
     }
 }
\ No newline at end of file