What's JCA? Here's from the IronJacamar page:
The connector architecture also defines a Common Client Interface (CCI) for EIS access. The CCI defines a client API for interacting with heterogeneous EISs.
The connector architecture enables an EIS vendor to provide a standard resource adapter for its EIS. A resource adapter is a system-level software driver that is used by a Java application to connect to an EIS. The resource adapter plugs into an application server and provides connectivity between the EIS, the application server, and the enterprise application. The resource adapter serves as a protocol adapter that allows any arbitrary EIS communication protocol to be used for connectivity. An application server vendor extends its system once to support the connector architecture and is then assured of seamless connectivity to multiple EISs. Likewise, an EIS vendor provides one standard resource adapter which has the capability to plug in to any application server that supports the connector architecture.
So I guess it's like JDBC except generic, so you'd be able to connect to other types of things. the JCA 1.6 spec even says JCA is like JDBC, except it's not meant for relational databases. from page 38:
The connector architecture is a standard architecture for integrating Java EE applications with EISs that are not relational databases. Each of these EISs currently provides a native function call API for identifying a function to call, specifying its input data, and processing its output data. The goal of the Common Client Interface (CCI) is to provide an EIS independent API for coding these EIS function calls.
JCA provides for conection management, transaction management, security, work lifecycles, inbound and outbound dataflow. And even caching.
There's a reference implementation that's part of glassfish, but IronJacamar includes tools and looks to be really nice. You can imagine using this to connect to or manage almost anything, which is kinda neat when you think about it.