1.3 Overview

The MSDTC Connection Manager: OleTx Transaction Protocol Logical Unit Mainframe Extension (DTCLU) is used between an implementation of Logical Unit type 6.2 (LU 6.2) and a transaction manager to provide transaction support. It enables integration of a LU 6.2-based transaction participant into an OleTx transaction, and vice-versa. DTCLU extends the transaction protocol described in OleTx Transaction Protocol [MS-DTCO] with helper messages and abstract state, such as additional mechanisms for identifying a transaction, or support for recovery that does not use the presumed-abort two-phase-commit variant.

An LU 6.2 implementation can use the extension to delegate many of its responsibilities for the transactional features of each logical unit of work (LUW) to a transaction manager. This reduces the amount of work necessary to implement LU 6.2. A transaction manager that implements this protocol extension provides two main areas of support. First, it supports the enlistment of an LUW in, and its completion as part of, an atomic transaction. Second, it supports recovery after a transient failure that affects connectivity between a local LU and a remote LU, or between the local LU and a transaction manager.

The scenarios and roles are described in the following sections as follows:

  • The scenarios that this protocol is intended to support such as enlistment, completion, and transaction recovery.

  • The distinct transaction roles that are played by participants in these scenarios in addition to those described in [MS-DTCO].