As part of an ongoing project I am just about to finish, I had a need to use a 3rd party web service. Now I am quite a cautious sort of chap when it comes to using web services. So I generally try and ensure that I try and make my code as robust as possible when dealing with such code.
For example when calling a web service, there is no guarantee that the web server is not going to die, after all it could be a web service that is hosted on a single server. Of course if the web service is from a reputable source, it's probably going to be a web farm that you're dealing with. Nevertheless, it’s good to plan for problems such as a timeout, lack of results, remote connection denials, security issues. These calls all lead into problems when dealing with a web service.
To this end, I have written the following bit of code to allow me to call a method asynchronously but have a timeout. This code does not use a web service, but rather shows the pattern that could be used to call any method asynchronously with a timeout. Which of course fits well with the idea of calling a web service, call the web service asynchronously, wait for a reasonable time, then see if the results are available. If they are use them, if not alert the user in whatever manner you have opted for.
Anyway the code is fairly simple and is as follows:
fetchNumberOfUsersDelegate fetchUsers = getNumberOfUsers;
IAsyncResult asynchResult = fetchNumberOfUsersDelegate.BeginInvoke(1000000,
while (!asynchResult.AsyncWaitHandle.WaitOne(5000, false))
usersFetched = fetchUsers.EndInvoke(asynchResult);