my question is similar to the below one...
How to embed Skype in my App
I have an android application. There we have a option to chat with our google contact user. So, We planned to use the hangout chat to achieve. Now, I just want to use the hangout chat in my android application. I should able to chat with the my google contact users from my own UI using hangout.
It's not possible to do without API. and API for that doesn't exist. I you want to create chat application you can use GCM.
You can write extentions for hangouts : Hangouts API. But android application integration is not possible at this moment. (And i think it never will be, because they have their protocol)
You have only one way to do this. Download
fidler and see what
http requests are sent/received during the chat on your android or web hangouts chat. :)
But still i think they have some authentication and hashing that will make this impossible.