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RTR Nested Transactions & XA Interface
Topic Area:
Track: eBusiness
Topic: Electronic Commerce
Type:  Breakout Session

11/10/99   10:00 AM     Duration: 90 Min.     Room: 15A

Shu-Tsui Tu
Principal Engineer , Compaq Computer Corp.  

The XA interface is part of the X/Open DTP (Distributed Transaction Processing)specification. It defines the interface that transaction managers (TM) and resource managers (RM) use to perform the two-phase commit protocol. (Resource managers are underlying database systems such as ORACLE RDBMS, Microsoft SQL Server and others.) RTR, as a transaction manager, implements the XA interface so that it can directly communicate with an XA-compliant resource manager to commit a distributed transaction in a true two-phase manner. As a result, RTR and the underlying resource manager become tightly integrated with respect to committing a transaction. In addition, RTR can also act as a resource manager exporting the XA-compliant API to other foreign transaction mangers to implement the notion of the nested transaction. For example, an RTR transaction can be included in (or joined to) a global transaction that is coordinated by a parent transaction manager. This RTR transaction is called a nested transaction or subtransaction. The parent (or foreign) transaction manager could be Microsoft DTC, Tuxedo or Encina, etc. When a global transaction commits, it communicates with the underlying resource manager (RTR, in this case) by calling RTR's XA-compliant API to make sure that those nested transactions managed by RTR are ready to commit. Or, the global transaction has to ask RTR to abort those nested transactions. In this presentation, an example will be provided to discuss how RTR is acting as a TM talking to underlying SQL Server (RM) and, in the same time, also acting as an RM communicating with a foreign TM to process a global/nested transaction.

Understand how RTR transactions can be joined with a transaction that is managed by a non-RTR transaction manager (TM) such as Microsoft DTC, Tuxedo, etc.
Understand how RTR using X/Open XA protocol to communicate with different vendors' database systems to support distributed transactions.
Understand the essential concept, architecture of RTR nested transactions.  

Prerequisites for attendees:
General knowledge about transaction, two-phase commit protocol, and recovery procedure is necessary. Having a working knowledge of RTR concept and RTR application programming is very helpful.

Required Skill Level:
Assumes general knowledge of topic, familiarity w/basic terms & procedures


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