I am setting request parameter as request.setAttribute("abc", "test123"); in calling servlet.
The same has to be read in called servlet.
That's not possible. Request attributes are a concept that's internal to a servlet engine - they're not part of an HTTP call that you make to some other URL. You'll need to use HTTP parameters instead. Using a library like Apache HttpClient for this is easier than using URLConnection directly.
subject: Call servlet from servlet passing request parameters