I want to create a mobile app for android(first) with back end server on AWS.I will use DynamoDB and other services.The backend application I think should be more easy to build on Elastic Beanstalk maybe in Java-Tomacat.The question is this :
Can I use Android SDK to comunicate the mobile users to the server code deployed on Elastic Beanstalk? How is that possible?
AWS SDK for Android(http://aws.amazon.com/sdkforandroid/) helps you make those calls. You can build the back-end using Elastic beanstalk. Build REST APIs here and those can be called from your Android Application directly (don't even need AWS SDK on Android).
If you are looking for something specifically for Mobile app backend, checkout:
1. https://parse.com/
2. https://www.firebase.com/
They will give easy SDK - Primarily for Data storage and retrieval. I have explored Parse SDK and it even supports the offline/online case - will take care of writing back data "when the connection is available".