I am developing an android application using Koha Restful API. the issue I am facing is that I cannot find anything API for item checkout(book issue) or item checkin(book return). I have installed the koha on ubuntu(Linux)
This sounds like a support request rather than a bug. Questions about Koha should be asked on the Koha mailing list (http://koha-community.org/support/koha-mailing-lists/) or in the #koha IRC channel (http://koha-community.org/get-involved/irc/). Hopefully you've already seen the Koha documentation: http://koha-community.org/documentation/ You can also find options for paid support here: https://koha-community.org/support/