Multiple downloads in flex

Question

Hello, can someone help me?

I want to download files from the server side to client side without prompting a window to the user to download when any updates happen at server side.

Right now I am using urlstream class but first file is downloading completely rest of the files contents downloading partially.

edit

Code sample taken from other post. Warning: it's a huuuge chunk o'code.

<?xml version="1.0" encoding="utf-8"?>
<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml" 
    xmlns:MyComp="client.components.*" layout="absolute" height="554" width="817" 
    backgroundGradientAlphas="[1.0, 0.0]" 
    backgroundGradientColors="[#ABA9A7, #03143B]" creationComplete="init();">

<mx:Script>
<![CDATA[
    import flash.system.Capabilities;
    import mx.collections.XMLListCollection;
    import mx.rpc.Fault;
    import mx.rpc.events.ResultEvent;
    import mx.rpc.events.FaultEvent;
    import mx.events.ListEvent;
    import mx.collections.ArrayCollection;
    import flash.data.SQLConnection;
    import flash.errors.SQLError;
    import flash.events.SQLErrorEvent;
    import flash.events.SQLEvent;
    import flash.filesystem.File;
    import flash.errors.SQLError;
    import mx.controls.Alert;
    import mx.events.CloseEvent;
    import flash.net.*;
    import flash.filesystem.*;
    import flash.events.OutputProgressEvent;

    private var urlstring:String="server path";
    private var urlReq:URLRequest; 
    private var urlStream:URLStream; 
    private var fileData:ByteArray = new ByteArray(); 
    private var sqlConnection:SQLConnection =null;
    private var sql:String;
    private var result:SQLResult;
    private var stmt:SQLStatement=null; 
    private var catid:int=0; 
    private var testcollection:Array=new Array();

    [Bindable]
    private var DGArray:ArrayCollection = new ArrayCollection(testcollection);
    private var number:int;
    private var selection:Boolean=false;
    private var timestamp:String;
    private var xmlcol:XMLListCollection; 
    private var categoryid:int=0; 
    private var numbers:int;
    private var index:int=0;
    private var findex:int=0;
    private var nupdates:int=0; 
    private var newfile:String="";
    private var selectstream:int=1; 
    private var startdownload:Boolean=false;

    public function init():void{
     userRequest.send(null);
     sqlConnection= new SQLConnection();
     //create a new db-file in the application storage location 
     var file:File = new File("app:/E-catalog.db");
     sqlConnection.addEventListener(SQLEvent.OPEN,dbOpenedHandler);
     sqlConnection.addEventListener(SQLErrorEvent.ERROR,dbErrorHandler);

     sqlConnection.open(file);

     getData();
    }

    public function loaded(event:Event):void { 
     urlStream.readBytes(fileData, 0, urlStream.bytesAvailable); 

     for(var x:int=0;x<nupdates;x++){
      var filename:Object=xmlcollection.getItemAt(x);
      newfile=filename['pdfimage'];
      writeAirFile(); 
     }

    } 

    public function writeAirFile():void { 
     /*
     var obj:Object=new Object;
     startdownload=true;
     var file:File = File.applicationStorageDirectory.resolvePath(newfile); 
     fileStream = new FileStream(); 

     fileStream.openAsync(file, FileMode.WRITE); 
     fileStream.writeBytes(fileData, 0, fileData.length); 
     fileStream.addEventListener(Event.COMPLETE,progressHandler,true,10,true);

     for(var x:int=0;x<fileData.length;x++){}

     startdownload=false; 
     fileStream.close();
     */
    }

    public function progressHandler(event:Event){
     Alert.show("File downloading");
    }

    public function dbOpenedHandler(event:SQLEvent):void{}

    public function dbErrorHandler(error:SQLError):void{}

    public function getData():void{
     sql = "SELECT STRFTIME('%Y-%m-%d %H:%M:%S',lupdated_dt)as lupdated_dt FROM update_mas where delflag=0 ";
     stmt = new SQLStatement();
     stmt.sqlConnection = sqlConnection;

     stmt.text = sql;

     stmt.addEventListener(SQLEvent.RESULT, selectResult);
     stmt.addEventListener(SQLErrorEvent.ERROR, selectError);
     stmt.execute();
    }

    public function selectResult(event:SQLEvent){
     DGArray.removeAll();
     number=1; 
     var result = stmt.getResult();
     var numRows = result.data.length;

     for (var i = 0; i < numRows; i++){
      for(var col:String in result.data[i]){
       timestamp=result.data[i][col];
      }
     }

     updateRequest.url="serverpath ?time="+timestamp+"";
     updateRequest.send(null);
    }

    public function selectError(event):void{
     stmt.removeEventListener(SQLEvent.RESULT, selectResult);
     stmt.removeEventListener(SQLErrorEvent.ERROR, selectError);
     Alert.show("SELECT error:");
    }

    public function displayPOPUP(event:ResultEvent):void{
     nupdates=((int)(event.result));
     if(nupdates==0){
     }else{
      selection=Alert.show(""+nupdates+"Updates available", "UPDATES", Alert.YES|Alert.NO, this, alertClickHandler);
     }
    } 

    private function alertClickHandler(event:CloseEvent):void {
     if (event.detail==Alert.YES){ 
      downloadRequest.url="serverpath ?time="+timestamp;
      downloadRequest.send(null);
     }else
      Alert.show("download cancelled");
    }

    public function displayResult(event:ResultEvent):void{
     var record:String="";
     sql="";
     for(index=0;index<xmlcollection.length;index++){
      var category:Object=xmlcollection.getItemAt(index);
      sql="select Id FROM CATEGORY where delflag=0 and cat_name='"+category['catname']+"'";
      stmt = new SQLStatement();
      stmt.sqlConnection = sqlConnection;
      stmt.text = sql;
      stmt.addEventListener(SQLEvent.RESULT,checkRecord);
      stmt.addEventListener(SQLErrorEvent.ERROR,checkError);
      stmt.execute();
     }
    }

    public function checkRecord(event:Event):void{
     var category:Object=xmlcollection.getItemAt(index); 
     var path:String="";
     var result:SQLResult = stmt.getResult();
     if(result.data==null){ 
      var sql:String= "INSERT INTO CATEGORY (cat_name, created_user,created_dt,updated_user,updated_dt,image_jpg,image_pdf) ";
      sql += "VALUES ('"+category['catname']+"',";
      sql +="'admin','"+category['cdate']+"','admin','"+category['udate']+"'"+category['pictimage']+"','"+category['pdfimage']+"' )";
      stmt = new SQLStatement();
      stmt.sqlConnection = sqlConnection;
      stmt.text = sql;
      stmt.addEventListener(SQLEvent.RESULT,insertRecord);
      stmt.addEventListener(SQLErrorEvent.ERROR,insertError);

      stmt.execute(); 
     }else{
      sql="";
      sql="update CATEGORY set created_dt='"+category['cdate']+"', updated_dt='"+ category['udate']+"',image_jpg='"+category['pictimage']+"', image_pdf='"+category['pdfimage']+"' where delflag=0 and cat_name='"+category['catname']+"'";
      stmt = new SQLStatement();
      stmt.sqlConnection = sqlConnection;
      stmt.text = sql;
      stmt.addEventListener(SQLEvent.RESULT,updateResult);
      stmt.addEventListener(SQLErrorEvent.ERROR,updateError);
      stmt.execute();
     }

     userRequest.send(null);

     var ludt_dt:Object=xmlcollection.getItemAt((xmlcollection.length-1));
     timestamp="";
     timestamp=ludt_dt['udate'];
     sql="";
     sql="update update_mas set lupdated_dt='"+timestamp+"' where delflag=0 ";
     stmt = new SQLStatement();
     stmt.sqlConnection = sqlConnection;
     stmt.text = sql;
     stmt.addEventListener(SQLEvent.RESULT,updateResult);
     stmt.addEventListener(SQLErrorEvent.ERROR,updateError);
     stmt.execute();
     var temp:int=0;
     for(var x:int=0;x<=xmlcollection.length-1;){
      var urlstring:String="http://sidssoldc:81/lessons/ravi/";
      var url:Object=xmlcollection.getItemAt(x);
      urlstring+=url['pdfimage'];
      path=url['pdfimage'];
      while((path.indexOf('/',0)!=-1)){
       path=path.slice(path.indexOf('/',0)+1,path.length);
      }

      urlReq=new URLRequest(urlstring);
      var filename:Object=xmlcollection.getItemAt(x);
      var loader:URLLoader=new URLLoader();
      loader.dataFormat="binary";

      selectstream=2;
      loader.load(urlReq);

      loader.addEventListener(Event.COMPLETE,function(event:Event){
       var loader:URLLoader=(URLLoader)(event.target);
       loader.dataFormat="binary";
       var ofstream2:FileStream= new FileStream();
       var ofstream1:FileStream= new FileStream();
       var ofstream3:FileStream= new FileStream(); 
       if(selectstream==1){
        var ofile1:File = File.applicationStorageDirectory.resolvePath('images/pdf/'+path); 
        ofstream1.openAsync(ofile1, FileMode.WRITE); 
        ofstream1.writeBytes(loader.data, 0, loader.bytesTotal);
        selectstream++;
       }else if(selectstream==2){
        ofstream1.close();
        var ofile2:File = File.applicationStorageDirectory.resolvePath('images/pdf/'+path); 
        ofstream2.openAsync(ofile2, FileMode.WRITE); 
        ofstream2.writeBytes(loader.data, 0, loader.bytesTotal);
        selectstream++;
       }else if(selectstream==3){
        ofstream2.close();
        var ofile3:File = File.applicationStorageDirectory.resolvePath('images/pdf/'+path); 
        ofstream3.openAsync(ofile3, FileMode.WRITE); 
        ofstream3.writeBytes(loader.data, 0, loader.bytesTotal);
       }

       if(selectstream==3){
        ofstream3.close();
       }
      });

      x++;

      temp=loader.bytesTotal;

      checkStream.close();
     }

     /*urlStream=new URLStream();
     urlStream.addEventListener(Event.COMPLETE, function(event:Event){

     urlStream.readBytes(fileData, 0, urlStream.bytesAvailable); 

     for(var x:int=0;x<nupdates;x++){
      var filename:Object=xmlcollection.getItemAt(x);
      newfile=filename['pdfimage'];
      var obj:Object=new Object;
      startdownload=true;
      var file:File = File.applicationStorageDirectory.resolvePath(newfile); 
      var fileStream:FileStream = new FileStream(); 

      fileStream.openAsync(file, FileMode.WRITE); 
      fileStream.writeBytes(fileData, 0, fileData.length); 
      fileStream.addEventListener(Event.COMPLETE,progressHandler,true,10,true);

      for(var x:int=0;x<fileData.length;x++){
       startdownload=false; 
       fileStream.close(); 
      }
     });

     urlStream.load(urlReq);
     x++;*/
    }

    public function insertRecord(event:Event):void{}

    public function insertError(event:Event):void{}

    public function updateResult(event:Event):void{}

    public function updateError(event:Event):void{
     Alert.show("update failed");
    }

    public function checkError(event:Event):void{
     Alert.show("error");
    }
    public function showError(event:FaultEvent):void{
     Alert.show(""+event.fault);
    }

    public function itemClick(event:ListEvent):void{}
]]>
</mx:Script>

<mx:DataGrid id="dgUserRequest" sortableColumns="false" x="99" y="115" width="364" textAlign="left" itemClick="itemClick(event);" rowHeight="30" doubleClickEnabled="false" height="297" themeColor="#ACF4F8" visible="true" editable="false" dataProvider="{catxmlcollection}" color="#000C0E" fontSize="11" >
    <mx:columns>
     <mx:DataGridColumn id="ID" headerText="Id" visible="false" dataField="catid" />
     <mx:DataGridColumn id="snumber" width="70" headerText="SerialNo" dataField="sno" visible="true" />
     <mx:DataGridColumn id="CATEGORY3" width="250" headerText="CATEGORY" dataField="catname" visible="true" />
    </mx:columns>
</mx:DataGrid>

<mx:XMLListCollection id="catxmlcollection" source="{userRequest.lastResult.categories.category}"/>

<mx:HTTPService id="userRequest" url="http://192.168.10:81/lessons/ravi/cat.php" fault="showError(event);" useProxy="false" method="GET" resultFormat="e4x" />
<mx:HTTPService id="updateRequest" result="displayPOPUP(event);" fault="showError(event);" method="GET" > </mx:HTTPService>

<mx:XMLListCollection id="xmlcollection" source="{downloadRequest.lastResult.Categories.Category}" />

<mx:HTTPService id="downloadRequest" result="displayResult(event);" fault="showError(event);" useProxy="false" method="GET" resultFormat="e4x" ></mx:HTTPService>
<mx:HTTPService id="categoryRequest"></mx:HTTPService>

<mx:Label x="216" y="53" text="Category Master" fontWeight="bold" fontSize="12" width="151"/>

</mx:WindowedApplication>

Answer 1

You need to provide more details. I can't even understand whether you want to refresh data from the server or want to download files without the user's permission. If it's the former, polling is the way to go. For the latter, you might as well shut shop because nobody's going to use an app that downloads stuff without asking first.

.p

Answer 2

I have had some issues when sending multiple requests simultaneously... when, for example, trying to load twenty images at the same time only some of them were received properly. I am not sure what was causing this, but I would suggest you try doing the transfers in a sequence since it solved all of my problems. In practice you might put them in an array and always take and remove the top one when the previous one completes.