The Persistence Service is an abstraction layer built into the Application Runtime Container that provides access to virtualized databases hosted in the cloud. It actually plays more of a behind the scenes role, taking care of low-level technical details like recovery and database backup, load balancing and scaling and connection management.
For SAP HANA XS application, there’s no need for a separate persistence service, since SAP HANA XS applications naturally have a direct connection to the backend SAP HANA database.
Building Schemas with Java Applications
Initially database schemas are just empty partitions. In order to put a database schema to work, you need to bind the schema with a Java web application. This allows you to utilize JPA or JDBC APIs to create tables and fill them with data.
Much like schema creation process, schemas can be bound explicitly or implicitly. You can explicitly bind a database schema to an application using SAP HCP Cockpit or the Console Client via bind-screen command.
In SAP HCP Cockpit, you can bind schemas within the same SCHEMAS and DATABASES tab used to create schemas in the first place. Simply, select the target schema in the DATABASE and SCHEMAS panel at the top of the main content area and then create a binding by clicking on NEW BINDING button in the lower-level schema editor panel.
At this point, there are two main attributes you should configure:
- DATA SOURCE: In order for your Java application to be able to address and access a binding, you must assign binding a data source name. The name can also be used to allocate data sources using dependency injections.
- JAVA APPLICATION: In the JAVA APPLICATION dropdown list, select target application that you wish to define the binding for. List is automatically populated based on Java applications that are currently deployed within the account.