What is the recommended way to install a JDBC driver in EAP 6/7

Environment

• Red Hat JBoss Enterprise Application Platform (EAP)
  • 6
  • 7

Issue

• Should drivers be packaged/bundled with the application?
• Are there advantages to installing JDBC driver using a module?
• Is it recommended to install a JDBC driver as a simple jar deployment or is it better to use a module-based deployment?

Resolution

Driver JAR files should NOT be packaged in the application.

• EAP datasources are dependent on and cannot be successfully loaded without the driver.
• Core EAP functionality (e.g. datasources configured in the standalone*.xml or domain.xml) should not depend on deployment of applications which may, themselves, depend on datasources to have already been successfully configured/loaded.
• Note that bundling a driver in the application when that driver is already deployed in EAP will often lead to class loading conflicts
  • Classes loaded by the application class loader are not interchangeable/compatible with those loaded by a JAR or module class loader

A JDBC driver may be installed either as a simple JAR deployment or as part of a module depending on specific use cases/requirements.

Simple JAR Deployment

• This is the simplest approach for installing a driver and is recommended for most single-JAR driver implementations.
  • JAR based deployments cannot be used if the JDBC driver implementation consists of/requires multiple JAR files.
• JAR based deployments can be created and managed using the web-based administration console.
• In domain configurations, JAR based deployments are automatically published/distributed to all hosts.

Driver Module

• Supports drivers that consist of multiple distinct JAR files or which require custom dependencies.
• Supports lazy/optional loading of the driver only if/at the point it is used by a datasource or by an application.
• May facilitate more structured/clear management of multiple versions of a single driver type (e.g. when using a module per driver version).
  • This is a matter of preference and relates primarily to naming/readability
• NOTE: Modules cannot be created or managed using the web-based administration console.
  • Modules may be created using CLI (in standalone configurations only) or via manual file system operations (in standalone and domain configurations).
• In domain configurations, the module must be explicitly installed on every host for any profile with datasources or applications which require the driver.

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