I have implemented GCM in my application and I have tested via two android devices and it works. I am implementing a simple chat application within my app. My app is actually selling or buying products. 

When a user wants to give a bid, then he types his message and send it to server and gcm is activated and seller receives the potential customer's message. When seller clicks on the received push notification message, it should take him to the chat activity. With this simple text message, how do I know which corresponding product?