Declaring Data Sources

If your mashup script invokes SQL queries or statements directly, you typically refer to named datasources that have already been configured in the Presto Server called implicit datasources. If needed, you can explicitly declare a <datasource> with connection information for a database directly in the mashup script. You can use several named datasources in a mashup script as well as a single, explicitly declared, default datasource.

Datasource

Advantages

Disadvantages

Configuration

Implicit

Configured in the Presto Server by Presto administrators.

Tip:	It is a best practice to use implicit datasources.

Single, consistent configuration.

Easily managed in clustered environments.

Credentials for database access are secure (encrypted in the Presto Repository).

Supports 'hot' updates to drivers without restarting the Presto Server.

Does not support dynamic connection information.

Connection and credential information is static in the Presto Repository.

Explicit

Declared in the mashup script using the <datasource> element.

Can support dynamic connection information or credentials using Presto attributes or input parameters to the mashup script.

Credentials and connection information is less secure, as clear text within the mashup script or defined as input parameters or Presto attributes.

Configuration is in individual mashup scripts, and thus harder to manage and maintain consistency.

If datasources are named, connection information must be consistent across all mashup scripts in the Presto Repository.

You must add and configure drivers in the Presto Server for explicit datasources. See Configuring Datasource Drivers for instructions.