17.3.1 About REST Enabled SQL Service References

Create REST Enabled SQL Service references to execute SQL or PL/SQL defined on a remote Oracle database.

Oracle Application Express installations that meet the minimum Oracle REST Data Services (ORDS) requirements can execute any SQL through a REST endpoint.

Developers create REST Enabled SQL references by defining a name, the endpoint URL, and authentication information within Shared Components. Oracle Application Express passes the SQL or PL/SQL query to ORDS over REST, and a self-describing JSON response is returned. The JSON object contains result set meta data, the result data, and pagination details.

Because REST Enabled SQL services are stored at the workspace-level within Application Express components, they are available to all applications within a workspace. Developers can utilize REST Enabled SQL references for interactive reports, interactive grids, classic reports, forms, master detail forms, calendars, JET charts, trees, and PL/SQL processes. References can also be used with Calendars, JET Charts, Trees, and PL/SQL processes.

REST Enabled SQL Service Reference Requirements

Requirements for using REST Enabled SQL Service references include:

How Do REST Enabled SQL Service References Differ from Database Links?

Both REST Enabled SQL Service references and database links enable developers to access data remotely. However, these features access remote data differently. Key differences between database links and REST Enabled SQL Service references include:

  • Database Link:

    • Functions at the SQL-level which enables developers to use remote tables and local tables in the same SQL query.

    • Works over SQL*Net, which can be problematic when connecting to a Cloud instance over the internet.

  • REST Enabled SQL Service References:

    • Functions at the workspace-level. Developers can create an Application Express component with a query on a REST enabled SQL Service but cannot join it to a local table.

    • Works with JSON over HTTP(s) which makes it easy-to-use it in Cloud environments or over the internet.

Both Database Links and REST Enabled SQL fetch data over the network which is significantly slower than fetching data from a table in the local database. When evaluating the best approach for your environment, be sure to evaluate the impact on page view performance and always consider replicating remote data in local tables, with an appropriate refresh algorithm.

Exporting and Importing REST Enabled SQL Services

When you export an application, used REST Enabled SQL references are added to the export file. If you export an application and import it into another workspace, Application Express checks whether the target workspace already contains REST Enabled SQL references with the same static ID. If a REST Enabled SQL reference already exists, the application uses the existing reference. If the reference does not exist, it is created in the target workspace.