A resource adapter is a deployable Jakarta EE component that provides communication between a Jakarta EE application and an Enterprise Information System (EIS) using the Java Connector Architecture (JCA) specification. A resource adapter is often provided by EIS vendors to allow easy integration of their products with Jakarta EE applications.
An Enterprise Information System can be any other software system within an organization. Examples include Enterprise Resource Planning (ERP) systems, database systems, e-mail servers and proprietary messaging systems.
A resource adapter is packaged in a Resource Adapter Archive (RAR) file which can be deployed to the server. A RAR file may also be included in an Enterprise Archive (EAR) deployment.