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


Chapter 10 Processing VSAM Data Using TIBCO Object Service Broker : Access of TIBCO Object Service Broker VSAM Tables

Access of TIBCO Object Service Broker VSAM Tables
Editing or Browsing
The setting of the Read Only field in the TIBCO Object Service Broker VSAM table definition determines how you can access the VSAM data:
If Read Only=N, you can edit the table using the Table Editor or rules.
You cannot delete records through an ESDS table definition or through a KSDS table definition representing an alternate index of an ESDS data set.
If Read Only=Y, you can only browse the table using the Table Browser or rules.
Using the Table Editor
You can edit a VSAM table in the same way you would edit any other table with the following exceptions:
If your table definition contains fields of syntax C or V that are longer than 260 bytes, or fields of syntax RD or UN that are longer than 130 bytes, you must use SELECT LIKE instead of SELECT to access fields of this length.
You can define and access KSDS and ESDS type definitions via alternate indexes. Full read and update access is available if you define the alternate index as the primary key.
In TIBCO Object Service Broker you cannot cancel changes made in the Table Editor. VSAM changes are immediate; there is no ROLLBACK.
Using the Table Browser
You can browse a VSAM table in the same way you would browse any other table except for the following:
Using the Single Occurrence Editor from the Table Browser begins a dependent transaction in TIBCO Object Service Broker. Therefore, the table must have a unique key because access in the row transaction is by key.
Using Rules
You can access VSAM data using the rules language in the same way you would access data in any other table except for the following:
If you issue a EXECUTE statement within a main (parent) transaction, it creates another transaction stream (child), to a maximum of nine streams.
The number of streams allowed in a transaction depends on the Execution Environment parameter TRANMAXNUM. Each transaction stream accessing external data requires its own server thread. Additional transactions can cause parent-child locking conflicts if more than one transaction stream is in update.
Using TRANSFERCALL or DISPLAY & TRANSFERCALL statements in a rule minimizes server threads and reduces the possibility of locking contention.
Under CICS, write applications that allow pseudo-conversational processing using TRANSFERCALL or DISPLAY & TRANSFERCALL statements. This can minimize recovery problems after an abend.
If you use the default session parameter values, you can access at least 16 VSAM tables per transaction; more, depending on the size of the VSAM table definitions.
VSAM Files with Multiple Record Formats and Repeating Groups
When a file contains multiple record formats, you must use rules to access the data.
Repeating Groups
Note the following about repeating groups:
Retrieval Processing
When a TIBCO Object Service Broker transaction runs in browse mode, locks are not taken on the TIBCO Object Service Broker data; however, locks are taken on the VSAM data in accordance to the transaction mode being set to Browse or No Browse.
The WHERE clause recognizes ranges. For example, if you use the clause WHERE KEY > 5 & KEY < 10, the server skips to > 5 and then stops processing when Key = 10. The following two rules statements differ from regular processing:
VSAM files with multiple record formats cannot be sorted (ORDERED clause) or selected (WHERE clause) by field values because the files are defined by several tables.
GET Statement
A GET statement retrieves the first occurrence in the VSAM table that satisfies the specified selection criteria.
A GET… ORDERED statement must retrieve all VSAM data that satisfies the selection criteria and sort it in the Execution Environment before returning the first occurrence that meets the selection criteria.
FORALL Statement
When using a FORALL statement, occurrences are returned in primary key order. If you require a different order, you must include an ORDERED clause in your FORALL statement. TIBCO Object Service Broker orders only occurrences specified in the selection criteria.
See Also
TIBCO Object Service Broker Managing Data for information on the Table Editor.
TIBCO Object Service Broker Programming in Rules for information on using rules, transactions, and table access statements.

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