Very Computer

Dear Group,

I am calling a webService asynchronously, using a pattern similar to this:
private void button2_Click(object sender, System.EventArgs e)
{
    // Disable the Async button and clear the ListView of any data
    // Create an instance of XML Web service proxy class
    BookCatalog.Service1 ws = new BookCatalog.Service1();
    // Create a reference to the callback delegate
    AsyncCallback cb = new AsyncCallback(ServiceCallback);
    // Call the Begin method, passing the callback delegate and
    // this proxy class instance as the AsyncState object.
    ws.BeginGetItems(cb,ws);

Quote:}

private void ServiceCallback(IAsyncResult ar)
{
    // Cast the AsyncState object to the proxy object
    BookCatalog.Service1 ws = (BookCatalog.Service1)ar.AsyncState;
    // Call the End method and assign the response to a DataSet
    this.ds = ws.EndGetItems(ar);    //forces to updates the ui in the
corresponding thread    this.Invoke(new
EventHandler(this.DataGridUpdater));}

private void DataGridUpdater(object sender, EventArgs ea)

{

      this.pctbSalir.Enabled=true;

      this.dgSanatorios.DataSource=this.ds.Tables["prestadores"];

      this.dgSanatorios.RowHeadersVisible=false;

      this.dgSanatorios.Visible=true;

Quote:}

But I have problems when exceptions rise, I have tried to add a try/cath
block in te line: ws.BeginGetItems(cb,ws), but exceptions still arise and
make me crash the app. The exceptions I wanna catch are
ObjectDisposedException, and InvalidOperationException and some more which
are thrown when the call to the web service has not been successful.

Diwik

You'll need to place the try...catch block around the EndGetItems call.  It
is from there that most exceptions due to a failing web service call are
thrown.

Hope this helps.

Mike Boilen
Developer
NET Compact Framework

This posting is provided "AS IS" with no warranties, and confers no rights.
http://www.gotdotnet.com/team/netcf/FAQ.aspx

--------------------

| Subject: Exceptions when Making Asynchronous Web Service Calls
| Date: Mon, 5 May 2003 09:25:34 -0700
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microsoft.public.dotnet.framework.compactframework:22304
| X-Tomcat-NG: microsoft.public.dotnet.framework.compactframework
|
| Dear Group,
|
|
| I am calling a webService asynchronously, using a pattern similar to this:
| private void button2_Click(object sender, System.EventArgs e)
| {
|     // Disable the Async button and clear the ListView of any data
|     // Create an instance of XML Web service proxy class
|     BookCatalog.Service1 ws = new BookCatalog.Service1();
|     // Create a reference to the callback delegate
|     AsyncCallback cb = new AsyncCallback(ServiceCallback);
|     // Call the Begin method, passing the callback delegate and
|     // this proxy class instance as the AsyncState object.
|     ws.BeginGetItems(cb,ws);
| }
|
| private void ServiceCallback(IAsyncResult ar)
| {
|     // Cast the AsyncState object to the proxy object
|     BookCatalog.Service1 ws = (BookCatalog.Service1)ar.AsyncState;
|     // Call the End method and assign the response to a DataSet
|     this.ds = ws.EndGetItems(ar);    //forces to updates the ui in the
| corresponding thread    this.Invoke(new
| EventHandler(this.DataGridUpdater));}
|
| private void DataGridUpdater(object sender, EventArgs ea)
|
| {
|
|       this.pctbSalir.Enabled=true;
|
|       this.dgSanatorios.DataSource=this.ds.Tables["prestadores"];
|
|       this.dgSanatorios.RowHeadersVisible=false;
|
|       this.dgSanatorios.Visible=true;
|
| }
|
|
| But I have problems when exceptions rise, I have tried to add a try/cath
| block in te line: ws.BeginGetItems(cb,ws), but exceptions still arise and
| make me crash the app. The exceptions I wanna catch are
| ObjectDisposedException, and InvalidOperationException and some more which
| are thrown when the call to the web service has not been successful.
|
|
|
|
|
| Diwik
|
|
|