I’m writing application for android where two devices should communicate between each other via internet. In addition to this task they also communicate with the EJB3 server via REST. So I decided to kill two birds with one stone and use REST+EJB3 for transferring data between two paired android devices.
So the scenario I implemented is something like this:
- Both devices connect to the server and acquire session id.
- First device sends data to the second device
- Server gets the data but does not end the http request, instead it puts into a waiting pool
- Second device asks for data
- Server transfers the data to the second device and releases waiting connection (and thread) for first device.
- If there are no first or second device requests then opponent waits for a timeout on a server side, then sends the request again. We need to wait for the data on the server side to give immediate respose after data is arrived.
So in this schema I see two drawbacks:
– Waiting thread on the server side – they consume server resources and as the result limit server throughput
– If the server thread will not wait for an answer with timeout, then the client should repeat requests on and on and spend a lot of traffic.
What is the best practice solution for such problem?
P.S: Forgot to mention that two devices should exchange data as smoothly and quickly as possible.
You will need to use C2DM
http://android-developers.blogspot.com/2010/05/android-cloud-to-device-messaging.html
When message needs to be sent from A to B – A should connect to server and depending on data kind/amount – server will either push data via C2DM or just tell device B to come back and grab data.
I would store data on server anyway. If push fails – you can retry it. No need to reinvent wheel. Most issues/problems already solved in C2DM