Multithreading with HttpWebRequest

[Fieldadvice]

Hi,

Im starting a new thread in my main aspx page, but when I run it, it always
runs through the main code first THEN the workerthread. Can somebody shed
some light on the problem??

Here is the code:

public class WebForm1 : System.Web.UI.P age

{

private FeedAsync Feed1;

public XmlDocument state = new XmlDocument();

private void Page_Load(objec t sender, System.EventArg s e)

{

Feed1 = new
FeedAsync("http ://www.bbc.co.uk/syndication/feeds/news/ukfs_news/technology/
rss091.xml", state);

Feed1.WorkerThr ead.Join();

System.DateTime start = DateTime.Now;

while (Feed1.Complete d == false && ((TimeSpan)(Dat eTime.Now -
start)).Seconds < 20)

{}

if (((TimeSpan)(Da teTime.Now - start)).Seconds > 20)

{

Response.Write( "TimeOut");

}

else

{

Response.Write( Feed1.Result.In nerText); // <-------Feed1.Result is ALWAYS
NULL

}

}

public class FeedAsync

{

public bool Completed = false;

private HttpWebRequest HTTPRequest = null;

public HttpWebResponse HTTPResponse = null;

public XmlDocument Result = null;

private AsyncCallback cb = null;

public Thread WorkerThread;

public FeedAsync(strin g URL)

{

state = nstate;

cb = new AsyncCallback(B eginGetResponse AsyncCallback);

HTTPRequest = (HttpWebRequest )HttpWebRequest .Create(URL);

WorkerThread = new Thread(new ThreadStart(Exe cute));

WorkerThread.St art();

}

public void Execute()

{

HTTPRequest.Beg inGetResponse(c b, null);

}

private void BeginGetRespons eAsyncCallback( IAsyncResult ar) // <------THIS
FUNCTION ONLY SEEMS TO GET CALLED AFTER THE MAIN THREAD HAS COMPLETED

{

if (ar.IsCompleted )

{

HTTPResponse = (HttpWebRespons e)HTTPRequest.E ndGetResponse(a r);

System.Text.Enc oding encode = System.Text.Enc oding.GetEncodi ng("utf-8");

StreamReader sr = new StreamReader(HT TPResponse.GetR esponseStream() ,
encode);

Result = new XmlDocument();

Result.Load(sr) ;

sr.Close();

HTTPResponse.Cl ose();

Completed = true;

}

}

}

[MSFT]

Hello,

I think this there are three threads in your program:

1. ASP.NET working thread which will wait for WorkerThread of class
FeedAsync
2. WorkerThread of class FeedAsync which call HttpWebRequest asynchronously.
3. Thread created by "HTTPRequest.Be ginGetResponse( cb, null);" which wait
for response from HttpWebRequest object.

The Join method only force 2 will be executed before 1, but this do nothing
with thread 3.
Luke
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)

[Fieldadvice]

Yeah I get what you mean, but I get exactly the same behaiviour when I
remove the thread.join().

The way I see it, thread1 should kick-off thread2 and then wait for
thread2/thread3 to flag the completed variable.

Interestingly, if I remove the timeout mechanism, the loop runs
indefinately, because I never get the async callback until thread1
completes.

Fletch

"MSFT" <lu******@onlin e.microsoft.com > wrote in message
news:0k******** ******@cpmsftng xa06.phx.gbl...

Hello,

I think this there are three threads in your program:

1. ASP.NET working thread which will wait for WorkerThread of class
FeedAsync
2. WorkerThread of class FeedAsync which call HttpWebRequest asynchronously. 3. Thread created by "HTTPRequest.Be ginGetResponse( cb, null);" which wait
for response from HttpWebRequest object.

The Join method only force 2 will be executed before 1, but this do nothing with thread 3.
Luke
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)

[MSFT]

If you remove the Join method, thread 2 (WorkerThread) will be executed at
same time as Thread 1. The result will can't be predicted. I think you may
only use two thread, send the webrequest synchronously in WorkerThread. How
about this soultion?

Luke
Microsoft Online Support

Get Secure! www.microsoft.com/security
(This posting is provided "AS IS", with no warranties, and confers no
rights.)