Recoverable communication manager

WebSphere Application Server for z/OS itself is not a recoverable resource manager. It is a recoverable communication manager. This means that the application server has no recoverable locks of its own and it doesn't need to manage locks nor manage lock states in a log. Instead, the application server needs to make sure that both callers and callees are connected in each of the communications sessions of a distributed transaction.

This example outlines the organization of servers in a recoverable communication manager setup. Use the following diagram to understand the sysplex layout:

Diagram that lays out the organization of servers in a recoverable communication manager setup

Suppose there is a client that talks to server A. Server A then talks to server B, which in turn talks to servers C and D. In this example, server A is the superior, server B is the superior subordinate, and servers C and D are subordinates. With respect to server B, there is a communication session from server A and one each to servers C and D. OTS logs each of these communication sessions as recoverable resource references and prepares them for recovery so that, in the event of a failure, server B can reestablish the communication sessions to these servers.

When server B fails, server A and servers C and D cannot communicate to each other since server B is the intermediary between them. So, when server B recovers, it reads the log and reestablishes the communication sessions to the other servers. Further, once connectivity is reestablished, servers B, C, and D can determine the outcome of the transaction.


Related tasks
Setting up peer restart and recovery



Searchable topic ID:   cprrcommgr
Last updated: Jun 21, 2007 9:56:50 PM CDT    WebSphere Application Server for z/OS, Version 5.0.2
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