In most cases, you will not just be running just an Oracle database on AWS. You will be running a web based application. For Oracle focused developers and engineers, running web applications on AWS is not an area of expertise. Here are the best documents, documentation, and diagrams to review for developing web based applications on AWS:
Support for session state and database failover when application server goes down are a couple of details that most Oracle folks ask about. Information can be found here:
Session state: Good blog post here: http://harish11g.blogspot.com/2012/10/web-session-synchronization-aws-ec2.html . The last option is DynamoDB which is the method used most often.
- Using RDS this is automatic: When automatic failover occurs, your application can remain unaware of what's happening behind the scenes. The CNAME record for your DB instance will be altered to point to the newly promoted standby. Your client library must be able to close and reopen the connection in the event of a failover.
- Using Oracle on EC2 : You would use Elastic Ips and use this pattern : http://aws.amazon.com/articles/2127188135977316 . You cloud use ENIs so private Ips could be used http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html#create-a-low-budget-high-availability-solution