Instantiating and Invoking Web Services

Select Start, Programs, Microsoft Visual Studio .NET, Visual Studio .NET Tools, Visual Studio .NET Command Prompt. This opens a command prompt window and sets the environment up so that you can use any of the command-line tools from the .NET Framework SDK.

Navigate to the folder that contains the WSDL file that you created in Step-by-Step 4.7.

Enter the following command to create a proxy class to call the Airport Weather Web service:

wsdl /language:CS /out:AirportWeatherProxy.cs AirportWeather.wsdl

The tool reads the WSDL file and creates a new file named AirportWeatherProxy.cs.

Add the AirportWeatherProxy.cs file to your Visual Studio .NET Windows application project by selecting File, Add Existing Item.

Add a new Windows form to your Visual C# .NET project.

Place a Label control, a TextBox control (txtCode), a Button control (btnGetWeather), and a Listbox control (lbResults) on the form. Refer to Figure for the design of this form.

Double-click the Button control and enter the following code to invoke the Web service when the user clicks the Get Weather button:

private void btnGetWeather_Click(object sender,

    System.EventArgs e)

{

    // Connect to the Web service by declaring

    // a variable of the appropriate type

    // available in the proxy

    AirportWeather aw = new AirportWeather();



    // Invoke the service to get a summary object

    WeatherSummary ws = aw.getSummary(txtCode.Text);



    // And display the results

    lbResults.Items.Clear();

    lbResults.Items.Add(ws.location);

    lbResults.Items.Add("Wind " + ws.wind);

    lbResults.Items.Add("Sky " + ws.sky);

    lbResults.Items.Add("Temperature " + ws.temp);

    lbResults.Items.Add("Humidity " + ws.humidity);

    lbResults.Items.Add("Barometer " + ws.pressure);

    lbResults.Items.Add("Visibility " +

       ws.visibility);

}

Insert the Main() method to launch the form. Set the form as the startup object for the project.

Run the project and fill in a value for the airport code. Click the Get Weather button. After a brief pause while the Web service is invoked, you'll see some information in the ListBox control, as shown in Figure. This information is delivered from the server where the Web service resides, as properties of the WeatherSummary object. The difference between this and the version in Step-by-Step 4.1 is that this code explicitly defines the objects that it uses rather than discovering them at runtime. The AirportWeather and WeatherSummary objects are proxy objects that pass calls to the Web service and return results from the Web service. This information is delivered from the server where the Web service resides, as properties of the WeatherSummary object.

Download the .NET WebService Studio tool from www.gotdotnet.com/team/tools/web_svc/default.aspx and install it on your computer.

Launch the WebServiceStudio.exe application.

Enter http://live.capescience.com/wsdl/AirportWeather.wsdl as the WSDL endpoint and click the Get button.

The tool reads the WSDL file from the Web service and constructs the necessary proxy classes to invoke it. Click the getSummary entry on the Invoke tab to use the getSummary Web method.

In the Input section, select the arg0 item. You can now enter a value for this item in the Value section. Enter an airport code such as KSEA for the value.

Click the Invoke button. The tool sends a SOAP message to the Web service, using your chosen parameters, and then displays the results, as shown in Figure.

Click the Request/Response tab to view the outgoing and incoming SOAP messages.

Click the WSDLs & Proxy tab to see the WSDL file and the generated proxy class for this Web service.