If client applications invoke an RSP through the Access Service Library, you need to be aware of how some of the DirectConnect configuration properties affect both client application and RSP processing. This section explains the following information:
Datatype conversion
Preventing inconsistencies in SQL transformation
Managing COMMIT/ROLLBACK
Adaptive Server Enterprise applications are designed to manipulate data in Adaptive Server Enterprise datatypes. When these applications execute an RSP to retrieve host data, DirectConnect converts the result rows into the corresponding Adaptive Server Enterprise datatypes.
Adaptive Server Enterprise uses the Transact-SQL™ query language, while DB2 uses IBM’s version of SQL. Consequently, SQL statements written for Adaptive Server Enterprise generally do not perform as expected when executed against DB2. To prevent SQL inconsistencies, each DirectConnect Access Service is configured either for native SQL or for Transact-SQL transformation.
DirectConnect Access Service is a specific set of configuration properties
working with the Access Service Library. The Access Service Library
is the program component that works with MainframeConnect to provide
access to DB2 data.
The corresponding DirectConnect Access Service transformation modes are PASSTHROUGH for native DB2 SQL and SYBASE for Transact-SQL.
TSQL transformation modes (TSQL0, TSQL1 and TSQL2) are supported
to provide backward compatibility.
If you write a client application to invoke an RSP, you must be aware of how the SQL transformation level is configured for the Access Service because it determines the format of the RSP invocation command you use. See Figure 5-3 for more information.
TRS always uses PASSTHROUGH.
When you write an RSP, be aware of how DirectConnect configuration property settings affect COMMIT/ROLLBACK management under normal and error conditions. The following table shows the interaction of the configuration property settings under normal processing conditions.
Transaction mode DirectConnect configuration property setting |
Outcome |
|---|---|
SHORT |
MainframeConnect issues COMMIT/ROLLBACK after each batch |
LONG |
Client application or RSP issues COMMIT/ROLLBACK |
Therefore, if TRS invokes an RSP, the transaction is committed (unless the transaction failed) because TRS always runs in SHORT.
The client application uses standard SQL statements to issue COMMITs and ROLLBACKs; the RSP uses the special RSP COMMIT and ROLLBACK commands.
If the RSP invokes through Access Service Library, COMMIT and ROLLBACK processing under error conditions is also affected by the DirectConnect Stop Condition configuration property.
This property can be set as follows:
None – If an error occurs, the RSP continues processing despite error status messages.
Error – If an error occurs, the RSP receives a STATUS message from MainframeConnect and RSP processing stops.
Err/Warn – If either an error or a DB2 warning message occurs, RSP processing stops (for Database Gateway release 2.03 only).
The client application can override the DirectConnect StopCondition configuration
property with the following set statement: set
StopCondition {error|none|warning}.
