We are looking to create an app that will be like WhatsApp support for multiple platforms. For chatting functionalities, we are looking to setup XMPP Server on one of our dedicated servers & setup properly.
XMPP Server will keep copies of contact discovery list, contacts & message delivery but all contacts will also part of web services & online database too.
Basically, everything will save inside database & synchronized with XMPP to operate the charting functionality.
More, we need to setup file transfer functionalities, where files will remains on server during transfer.
All clients will use PUBSUB way to wait for messages. We need some one who can do this part.
In case you are not willing to do Web Services Part, no problem, we can use in-house resources to build that up.
We do not need xmpp client programming but xmpp sever side programming required.