Working With Distributed Transactions

In accordance with the X/Open distributed transaction model, Message Queue C-API support for distributed transactions relies upon a distributed transaction manager. The distributed transaction manage tracks and manages distributed transactions, coordinating the decision to commit them or roll them back, and coordinating failure recovery. The Message Queue C-API supports the X/Open XA interface, qualifying it as an XA-compliant resource manager. This support allows C-API clients running in a distributed transaction processing environment to participate in distributed transactions.

In particular, two C-API functions support the participation of C-API clients in distributed transactions:

MQGetXAConnection()
MQCreateXASession()

If a C-client application is to be used in the context of a distributed transaction, then it must obtain a connection by using MQGetXAConnection() and create a session for producing and consuming messages by using MQCreateXASession(). The start, commit, and rollback, of any distributed transaction is managed by the distributed transaction manager.

For more information on XA resource managers, see the XA Specification.

Message Queue Resource Manager Information

In accordance with the X/Open XA interface specification, a distributed transaction manager needs the following information regarding the Message Queue XA-compliant resource manager:

• Name of the xa_switch_t structure: sun_my_xa_switch

• Name of the Resource Manager: SUN_RM

• The MQ C-API library to be linked: mqcrt

• The xa_close string and format: none

• The xa_open string and format: semicolon (“;”)-separated name/value pairs

The following name/value pairs are supported:

Table 2–12 Message Queue Resource Manager Name/Value Pairs

Name	Value	Description	Default
address	host:port	The host:port of the broker's Portmapper service.	localhost:7676
username	string	The username for connecting to the broker	guest
password	string	The username's password	guest
conntype	TCP or SSL	The protocol type of the connection to the broker	TCP
trustedhost	true/false	Whether the broker host is trusted (only applicable for conntype=SSL)	true
certdbpath	string	The full path to the directory that contains NSS certificate and key database files	not set
clientid	string	Required only for JMS durable subscriptions	not set
reconnects	integer	The number of re-connection attempts to broker (0 means no reconnect)	0

Programming Examples

To help you program an application that uses distributed transactions, Message Queue provides programming examples based on the Tuxedo distributed transaction manager. A description of the sample programs and their location is provided in Table 1–5.