Question

My code is for sending Emails to multiple users.User will click on send button,and rpc will be called. Now if user clicks on Cancel button .Ongoing rpc should be cancelled. . Can anyone help ?

I googled a lot, they have introduced the concept of Request Builder. But I am not getting any perfect idea.

Answer 1

Make your async method return a Request instead of void so you can call cancel() on it.

For the same reason, asynchronous methods do not have return types; they generally return void. Should you wish to have more control over the state of a pending request, return Request instead.

— Source: https://developers.google.com/web-toolkit/doc/latest/DevGuideServerCommunication#DevGuideCreatingServices

FYI, you can also use RequestBuilder as the return type, you’ll then have to call the send() method by yourself (after possibly customizing the request, e.g. adding headers) to actually make the request to the server.

And of course, if you need to tell the server to abort the processing, you’ll have to make another RPC call.