1.3.2 OpenTP1 and the X/Open DTP model
In the X/Open DTP model, transaction processing is an interaction among:
- a UAP (user application program)
- a transaction manager
- a resource manager
- a communication resource manager
- interfaces among the UAP, TM, RM, and CRM
The UAP specifies the contents of the transaction and directs a transaction manager to start or terminate a transaction. A transaction manager manages the transaction and coordinates the completion of a transaction across a set of resource managers. A resource manager manages a particular shared resource. A communication resource manager manages inter-application components. Figure 1-10 illustrates the relation among the components of the model and their interfaces.
Figure 1-10 The X/Open DTP model
![[Figure]](figure/zu010900.gif)
- Organization of this subsection
- (1) Configuration of DTP models
- (2) Interface between elements
- (3) Resource managers provided by OpenTP1
(1) Configuration of DTP models
The DTP models are composed of the following elements.
- AP (Application Program)
- An application program created by the system user using a high-level language. This application program is known as a UAP of OpenTP1.
- Transaction Manager
- Manages system transactions and supports consistency according to the update information of resources.
- RM (Resource Manager)
- Manages system resources such as user data.
- CRM (Communication Resource Manager)
Manages resources concerning the communication between the systems.
(2) Interface between elements
Each element that composes a DTP model can be linked with the following interfaces.
- TX interface
- Instructs the start and end of a transaction from AP to Transaction Manager.
- XATMI and TxRPC interfaces
- Instruct the communication from AP to CRM.
- XA interface
- Synchronizes according to the update information of resources with Transaction Manager and RM.
- XA+ interface
- Extends the transaction managed by Transaction Manager to other system processing when communicating with other system using CRM.
- Interface provided by RM
Instructs update of resources from AP to RM. The API to RM contains an SQL.
(3) Resource managers provided by OpenTP1
The following shows RMs that can be used in OpenTP1.
- RMs that manage user resources such as files
An RM that conforms to TP1/FS/Direct Access, TP1/FS/Table Access, ISAM (ISAM/B), and X/Open
- RMs that manage communications by using messages
- TP1/Message Control, TP1/NET/Library, and TP1/Message Queue.
Figure 1-11 shows the relationship between the X/Open DTP model and the OpenTP1 system.
Figure 1-11 Relationship between the X/Open DTP model and the OpenTP1 system
![[Figure]](figure/zu011000.gif)