How to asynchronously call a web service from an ASP.NET application?

I need to asychronously call a web service from an ASP.NET application. The aspx does not need the answer from the web service. It's just a simple notification.

I'm using the ...Async() method from web service stub and <%@Page Async="True" %>.

ws.HelloWorldAsync();

My problem: the web page request is waiting for the web service response.

How to solve this problem? How to avoid any r开发者_如何学JAVAesource leak when the web service is down or when there is an overload?

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A Web Service proxy normally has a Begin and End method too. You could use these. The example below shows how you can call the begin method and use a callback to complete the call. The call to MakeWebServiceAsynCall would return straight away. The using statement will make sure the object is disposed safely.

void MakeWebServiceAsynCall()
    {
        WebServiceProxy proxy = new WebServiceProxy();
        proxy.BeginHelloWorld(OnCompleted, proxy);
    }
    void OnCompleted(IAsyncResult result)
    {
        try
        {
            using (WebServiceProxy proxy = (WebServiceProxy)result.AsyncState)
                proxy.EndHelloWorld(result);
        }
        catch (Exception ex)
        {
            // handle as required
        }
    }

If you need to know whether the call was successful or not you would need to wait for the result.

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In your scenario you may use ThreadPool ThreadPool.QueueUserWorkItem(...) to call web service in pooled thread.

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I have used simple threads to do this before. ex:

Thread t = new Thread(delegate()
{
    ws.HelloWorld();
});
t.Start();

The thread will continue to run after the method has returned. Looking around, it seems that the ThreadPool approach isn't always recommended

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Starting a new thread is probably the easiest solution since you don't care about getting notified of the result.

new Thread(() => ws.HelloWorld()).Start