I want to connect my GAE Java project (Paas) to third party Cloud SQL (DaaS), I just want to know is it possible or not!
Details:
With my basic fundamental knowledge on J2EE I'm doing some hacks onGoogle App Engine (Java) PaaS, since Google cloud-sql for GAE is paid I want connect the GAE to any third party cloud SQL service (DaaS) like nuvola which offers free service for limited time period. Developers pain point is Google Cloud storage/ sql doesn't allow free space for developers unlike other platforms like Parse, kinvey etc will do.
update: URL Fetch API we can do that, I'm not sure it's the right way or not! also URL Fetch API Calls are Outgoing Bandwidth are billable!!
If you want to connect to external systems, the recommended way to integrate with them would be via Web Services.
You have 2 options:
Look out for a Web Service (typical REST with JSON/XML data) for your chosen data service provider in the cloud. You can then integrate your GAE app via URL Fetch API.
There is also a likelihood that your data provider also provides client libraries (Java, Python, etc) which you can easily integrate into your application. That would ease the integration.
App Engine also supports Sockets, but they are currently in Preview and available only for Paid Applications.