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New Message on BDOTNET
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From: Nasha
Message 1 in Discussion
Hey Group,
Today we will checkout how to consume our web service using SOAP in Synchronous
and Asynchronous modes.
To consume to our web service we need to create our web service client.
Let us go ahead and create our web service client.
Open a new windows application and Select References Right click and select Add
Web Reference. Select our Trigonometry web service.
WebReference to this web service will be added and along with it you will
notice the reference.map , .disco and .wsdl files will be added for the web
service. Our client interacts with our web service using a proxy class.
To view the proxy class ... Select the solution in the Solution Explorer and
click on Show All Files ... You will notice a file under the Reference map node
called as Reference.cs.
Open the Reference.cs file and Checkout the BASE CLASS for our webservice proxy
class, it should be SoapHttpClientProtocol.
You should also notice that for each method in our webservice there are three
methods in the webservice proxy class.
For Example these are the the three methods for Sine.
public System.Double Sine(System.Double angel)
public System.IAsyncResult BeginSine(System.Double angel, System.AsyncCallback
callback, object asyncState)
public System.Double EndSine(System.IAsyncResult asyncResult)
Out of these three the first one is used for Synchronous communication and
latter two for Asyncrhomous communication.
Let us checkout Synchrounous Communication.
Add a Form and add a button and a label to that Form
Declare a class level variable for our webservice
localhost.Service1 trigoService = new localhost.Service1();
Write the following code in the button Click event
private void button1_Click(object sender, System.EventArgs e)
{
label1.Text = Convert.ToString(trigoService.Sine(90));
}
Execute the apllication and checkout the results.
One of methods of Asynchronous communication with web service is using
Callbacks.
To start with declare a class level variable for IAyncResult
private IAsyncResult oIAsyncResult;
To consume our web service in asynchronous mode let us add another button to
our form and add the below code. When we communicate with our web service in a
asynchronous mode we will have to call the BeginSine method and pass a CALLBACK
function to it. After our web service is done with its processing it will
callback our function to return the result.
private void button2_Click(object sender, System.EventArgs e)
{
oIAsyncResult = trigoService.BeginSine(90,new
AsyncCallback(CallBackForEndSine),null);
}
public void CallBackForEndSine(IAsyncResult oIAsyncResult)
{
double sineVal = trigoService.EndSine(oIAsyncResult);
label1.Text = Convert.ToString(sineVal);
}
Here I am calling the BeginSine method and passing it the reference of our
CallBack method CallBackForEndSine. You should notice that on Calling the
BeginSine method I am returned an IAysncResult object. This object acts as a
TOKEN between the client and the webservice. Hence when the Webservice is
through with its processing and Callback method is called, to get the result
from the webserivce we need to call EndSine method in the CallBack method
passing IAsyncResult Token.
The Difference between Asynchronous & Synchronous consumption of webservices
can be noticed when there is a lot of processing done by a webservice. Thus if
our webservice is consumed in a synchronous mode then our clients will have to
wait for the processing to complete.
To get a good taste of Asynchronous processing with our webservice we will make
a little change in our methods. Before returning the result we will make the
thread sleep for 20 secs.
public double Sine(double angel)
{
Thread.Sleep(20000); // make a similar change in all
the methods
return System.Math.Sin(angel);
}
Compile the webservice. Update the webservice reference in your Client project
and Execute your Client.
Now if our web service is consumed synchrounsouly our client will have to wait
for the result. Click on Button1 and check it out. The control will come back
after 20 secs and till then your application will not respond to any other
events. Now let us consume the webservice in an ansychronous mode by clicking
on Button2. Since the communication is asynchronous the control will return
back immediately rather than waiting for 20 seconds. Later the call back
function will be called to deliver the results.
Tommorrow we will checkout some other asynchronous methods of consuming our web
service.
-- Please post your queries and comments for my articles in the user group for
the benefit of all. I hope this step from my end is helpful to all of us.
Regards,
Namratha (Nasha) <o:p></o:p>
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