Question

This should be pretty easy , but i couldn’t find a adequated term to search for… Well I’m new to C# and i’m trying to make a simple App to write the return of a webservice.

I came across the need to use a Thread… passing parameters to the thread is fairly easy , I couldn’t find a way to return from the Threaded method and update my UI to show the result (well actually no the real result for now)

The event:

    private void TextBox_TextChanged_1(object sender, TextChangedEventArgs e)
    {
        minhaSigla = Sigla.Text;
        Task.Factory.StartNew(() => GetQuoteAndUpdateText(minhaSigla));
        tb1.Text = "UIElement-TO-UPDATE";

    }

And then the Threaded method

    private string GetQuoteAndUpdateText(string sign)
    {
        string SoapEnvelope = "";
        SoapEnvelope = "<?xml version=\"1.0\" encoding=\"utf-8\"?>";
        SoapEnvelope += "<soap:Envelope ";
        SoapEnvelope += "xmlns:xsi = \"http://www.w3.org/2001/XMLSchema-instance\" ";
        SoapEnvelope += "xmlns:xsd= \"http://www.w3.org/2001/XMLSchema\" ";
        SoapEnvelope += "xmlns:soap= \"http://schemas.xmlsoap.org/soap/envelope/\">";
        SoapEnvelope += "<soap:Body>";
        SoapEnvelope += "   <GetQuote xmlns=\"http://www.webserviceX.NET/\"> ";
        SoapEnvelope += "       <symbol>" + sign + "</symbol> ";
        SoapEnvelope += "   </GetQuote> ";
        SoapEnvelope += "</soap:Body>";
        SoapEnvelope += "</soap:Envelope>";

        EndpointAddress endpoint = new EndpointAddress("http://www.webservicex.net/stockquote.asmx");
        BasicHttpBinding basicbinding = new BasicHttpBinding();
        basicbinding.SendTimeout = new TimeSpan(3000000000);
        basicbinding.OpenTimeout = new TimeSpan(3000000000);

        stockbyname.StockQuoteSoapClient sbn = new stockbyname.StockQuoteSoapClient(basicbinding, endpoint);

        XmlDocument xmlDocument = new XmlDocument();
        return sbn.GetQuote(SoapEnvelope);
    }

Also any information will be much appreciated, even comments about how awful my code is 😛

Answer 1

Without getting into all the fun async/await stuff, you can use the ContinueWith method of Task to handle the returned information.

private void TextBox_TextChanged_1(object sender, TextChangedEventArgs e)
{
    minhaSigla = Sigla.Text;
    var quoteGetterTask = Task.Factory.StartNew(() => GetQuoteAndUpdateText(minhaSigla));
    quoteGetterTask.ContinueWith(task => 
    {
        var theResultOfYourServiceCall = task.Result;
        //You'll need to use a dispatcher here to set the value of the text box (see below)
        tb1.Text = theResultOfYourServiceCall;     //"UIElement-TO-UPDATE";
    });
}

As I mention in the above code sample, depending on which UI technology you’re using you’ll need to use a dispatcher to avoid getting an illegal cross thread access exception.

WinForms example of the expression inside the .ContinueWith (using the Invoke method of Control)

task =>
{
    var theResultOfYourServiceCall = task.Result;
    tb1.Invoke(new Action(() => tb1.Text = theResultOfYourServiceCall));
}

WPF example of the expression inside the .ContinueWith (using WPF’s Dispatcher)

task =>
{
    var theResultOfYourServiceCall = task.Result;
    tb1.Dispatcher.Invoke(DispatcherPriority.Normal, 
                          new Action(() => tb1.Text = theResultOfYourServiceCall));
}

Silverlight/Windows Phone example of the expression inside the .ContinueWith (using Silverlight’s Dispatcher)

task =>
{
    var theResultOfYourServiceCall = task.Result;
    tb1.Dispatcher.BeginInvoke(() => tb1.Text = theResultOfYourServiceCall);
}

Windows Store example of the expression inside the .ContinueWith (using CoreDispatcher)

task =>
{
    var theResultOfYourServiceCall = task.Result;
    tb1.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => tb1.Text = theResultOfYourServiceCall);
}