An application usually defines steps performed against any given resource in terms of transactions.
A transaction is a complete unit of work in which:
The server has the ability to access multiple data sources and to carry out heterogeneous joins across different data sources. The transaction that describes work done by more than one Resource Manager is called a Global or Distributed Transaction.
Most relational and some non-relational resources are maintained by their Resource Managers. The X/Open Distributed Transaction Processing (DTP) model is a software architecture that allows multiple application programs to access resources provided by multiple resource managers, and allows their work to be coordinated into global transactions.
Read/write applications accessing CICS and IMS transactions, relational data sources, as well as CICS-controlled VSAM data sets are able to perform transactions managed in XA-compliant mode. The Transaction Coordinator component uses a two-phase commit protocol for completion of customer transactions across different database management systems.
Using the XA Transaction Management feature does not require any changes in existing ODBC, JDBC, or WebFOCUS Maintain applications. To activate the XA Transaction Management feature, the server has to be configured in Transaction Coordination Mode, using the Web Console configuration functions. In Transaction Coordination Mode, all requests performed against the listed XA-compliant DBMSs will be processed as XA-distributed transactions, and completed in two-phase commit mode. This guarantees the integrity of data modification on all of the involved DBMSs. It protects part of the data modifications from being committed on one DBMS and terminated on another.