why ?gwt.codesvr=127.0.0.1:9997 is appended to url?

Question

I am using ExtGWT. in development mode we append ?gwt.codesvr=127.0.0.1:9997 to url. please help what it means and why we should append?

Thanks!

Answer 1

When you're running your application in Development Mode, the browser (more precisely: The GWT plugin) needs to connect to a so-called "code server". The "gwt.codesvr" part is evaluated by that plugin, so it knows, how to connect to that code server.

The job of the code server is to emulate the JavaScript behaviour of the final code. It runs your client-side Java code, which is compiled to class files, but not yet to JavaScript files. This is a) a lot faster than compiling to JavaScript, and b) it allows you to use a Java debugger for the (emulated) client side code.