Copyright © TIBCO Software Inc. All Rights Reserved
Copyright © TIBCO Software Inc. All Rights Reserved


Chapter 2 Operating Service Gateway for IDMS/DB : Implementing Fail Safe Processing

Implementing Fail Safe Processing
Fail Safe level‑1 processing guarantees consistency when updating both TDS and CA‑IDMS data from a single instance of TIBCO Service Gateway for IDMS/DB in a single transaction. At the end of a transaction, the Data Object Broker requests that the Gateway commit outstanding updates. As part of CA‑IDMS commit processing, the Gateway initiates another run unit for the transaction database, updates the database to record the successful commit, issues a FINISH for the transaction database run unit, and then issues a FINISH for the original run unit. If the Gateway does not respond to the Data Object Broker in a reasonable amount of time, the transaction is flagged as being in doubt. Locks held on TDS data remain in place until the problem is resolved.
When a connection is re-established between the Data Object Broker and an instance of TIBCO Service Gateway for IDMS/DB with the same configuration as the one that failed, the Data Object Broker asks the Gateway if the in-doubt transaction completed. The Gateway checks the CA‑IDMS transaction database to determine this. If CA‑IDMS has completed the update, the TDS updates are applied and the locks are released.
You can resolve in-doubt transactions only by starting an instance of TIBCO Service Gateway for IDMS/DB with exactly the same parameter settings as the Gateway in use when the transaction was placed in doubt.
See Also
TIBCO Object Service Broker for z/OS Managing Backup and Recovery for more information on Fail Safe processing.
Procedure
To implement Fail Safe processing, you must complete the following tasks:
1.
2.
3.
4.
5.
These tasks are described in the following sections.
 
Task A Define a transaction database
To implement Fail Safe level‑1 processing, you must define a CA‑IDMS transaction database. The DDL required to define the database is located in the CNTL data set, in members XIDMTRX1, XIDMTRX2, XIDMTRX3, and XIDMTRX4.
These members contain definitions to create the following
Do not change the CA‑IDMS record name; however, you can change the schema and subschema names. If the subschema name is changed, ensure you include the TRXDB parameter (specifying the new subschema name) when the Gateway is started. This transaction table holds a maximum of one record for each combination of TIBCO Service Gateway for IDMS/DB and Data Object Broker.
Task B Extract the CA‑IDMS transaction database
Use the CA‑IDMS extract program S6BIDUTL or S6BIDU12 to extract the CA‑IDMS element, record, set, and index information from the IDD that you defined in Define a transaction database. For more information, refer to Task A, Extracting CA‑IDMS data dictionary information.
Task C Load the CA‑IDMS subschema definition into TIBCO Object Service Broker
After extracting the information from the IDD, you must load the CA‑IDMS subschema definition into TIBCO Object Service Broker. For more information, refer to Task B, Loading a CA‑IDMS subschema definition into TIBCO Object Service Broker.
Task D Define a TIBCO Object Service Broker IDMS/DB transaction table
After loading the CA‑IDMS subschema definition into TIBCO Object Service Broker, you must define a TIBCO Object Service Broker IDMS/DB transaction table to contain the CA‑IDMS data in these fields. By default this table is called @IDMFSTRXDB and its fields must match the fields in the CA‑IDMS transaction database.
The transaction table can be managed in TIBCO Object Service Broker like any other IDM table. For example, you can write a TIBCO Object Service Broker rule to clean up the Fail Safe database on shutting down the Gateway.
Task E Define TIBCO Service Gateway for IDMS/DB Fail Safe startup parameters
Ensure that the following TIBCO Service Gateway for IDMS/DB startup parameters are included in your startup JCL:
For more information on these TIBCO Service Gateway for IDMS/DB startup parameters, refer to Supplying Service Gateway for IDMS/DB Startup Parameters.
At startup, the Gateway asks the Data Object Broker for the TIBCO Object Service Broker IDMS/DB transaction table definition specified in the FSTABLENAME startup parameter. This table definition is bound for the life of the Gateway and is used at transaction end and at intermediate COMMITs, to update the CA‑IDMS transaction database.

Copyright © TIBCO Software Inc. All Rights Reserved
Copyright © TIBCO Software Inc. All Rights Reserved