SAP Hana adapters are Equinox Plugin projects. This means essentially nothing else than writing normal Java code plus an additional Manifest file which contains the dependencies to other plugin projects and libraries.
The easiest way to setup all is by using the Eclipse Plugin Development wizard. By calling the File -> New menu item and selecting the type Plug-in Project, the wizard is started.
After entering a project name, the important part is to change the plug-in type to OSGi Equinox.
A Plug-in project consists of certain standard classes like the activator and has a version, again used for dependency handling. Nothing to be changed here.
Since the OSGi framework was selected before, the Data Provisioning Adapter Wizard is shown and can be selected. Then the created project will have sample implementations of the mandatory classes.
At the end the Java/Plugin Perspective will show something like this
A project with the Activator and Factory classes and the real adapter class.
Adapters for Hana are available in all kinds of facets
Important Adapters are included in the SAP Hana EIM option, e.g. an Adapter for Oracle, SQL Server, DB, etc or SAP ECC and more.
Other SAP products require other adapters and they are developed there.
We have partners writing new adapters
And there is the Open Source approach we just started.
The latter is a good starting point for learning how adapters work internally. For example the Adapter HelloWorld used in the Adapter SDK manual is available there.