Yes it's possible to monitor middle-ware applications. If you have OEM 12c is already installed,
1. got to Setup > Add Targets> Add Targets Manually and then add hosts
2. Follow the prompts and provide all the required host entries
3. Choose Deploy Agents.
4.Choose Continue > Continue, All Hosts
make sure inventory is not locked and set appropriately.
on the node
5. stop agent
6. start agent
7. emctl upload
hope this helps.