Data Transformation Engine Services Guide

Chapter 19 – Advanced Topics for Mercator Command Server Adapters
114
quantity parameter (passed in uUnitSize) which must be observed. Since handles and
other context information can be maintained in the adapter parameter structures which are
passed to the adapter on each call, the adapter does not need to maintain any additional
state information.
The following is the sequence of calls that will be made to a source adapter which is in
burst mode. Note that when the adapter has no more data to return, it should set bBurst
to FALSE.
If the transactional scope is BURST:
1. ValidateCommand (bBurst = TRUE)
2. Connect (bBurst = TRUE)
3. Get (bBurst = TRUE)
4. Get (bCleanup = TRUE)
5. Get (bBurst = TRUE)
6. Get (bCleanup = TRUE)
7. Get (adapter sets bBurst = FALSE)
8. Get (bCleanup = TRUE)
9. Disconnect
10. FreeAdapterParms
If the transactional scope is MAP:
1. ValidateCommand (bBurst = TRUE)
2. Connect (bBurst = TRUE)
3. Get (bBurst = TRUE)
4. Get (bBurst = TRUE)
5. Get (adapter sets bBurst = FALSE)
6. Get (bCleanup = TRUE)
7. Get (bCleanup = TRUE)
8. Disconnect
9. FreeAdapterParms
Retry
An adapter can be implemented to provide retry capability. It is the responsibility of the
developer to add the processing necessary to implement the retry.
The EXITPARAM structure has been designed to provide the information for passing to
the adapter the data necessary to support retry.
The AdapterRetry settings specified for the source or target are included in
EXITPARAM
as uRetryCount and uRetryInterval indicating how many times to attempt to retry
unavailable resources and at what interval (in seconds). If desired, the adapter can
incorporate retry capability using these retry settings for the data sources or targets.