Open cart integration with Other systems

Hey All,

I want to know whether we can integrate Opencart with other application built in Java / Mongo-DB.
To be precise, A back end system is developed using Java/ Mysql and Mongo DB. All products will be managed from this application(backend) and orders which are placed have to be pushed to this application from opencart(Frontend).
Can you guys help me to know possibility of how a communication between 2 systems, Opencart(Frontend) and Java application(Backend) can be achieved.

Sounds like you need to write a module to communicate to your back end when an order is placed. See here:

http://docs.opencart.com/developer/module/

for the module development documentation.