Some of the differences between APPC mapped and MRO conversations are shown in the command sequence in Table 52.
Commands | APPC mapped | MRO |
---|---|---|
|
sending is deferred | data1 is sent |
|
syncpoint request added to data1, and both are sent | syncpoint request is sent with null data |
|
sending of data2, with INVITE, is deferred | data2 with INVITE is sent |
|
data2, with INVITE, is sent | (nothing to send) |
|
||
|
sending of data3, with LAST indicator, is deferred | data3 is sent, but without LAST indicator |
|
syncpoint request and LAST indicator added to data3 and sent | syncpoint request and LAST indicator are sent with null data |
The WAIT option can, of course, be added to the SEND command to cause immediate transmission on APPC links; for example:
SEND CONVID(REM1)
FROM(data2)
LENGTH(251)
INVITE
WAIT
RECEIVE SESSION(REM1)
There are no significant differences between the MRO and APPC mapped implementations of this command sequence. However, with MRO, a SEND command with the WAIT option causes CICS® to suspend the transaction until the partner system has received the data.
Unlike APPC, MRO allows only one outstanding SEND to be transmitted. This means that when a transaction issue two successive SEND commands (without the WAIT option) to transmit data, the second piece of data does not flow until the partner system has received the first.
A further implementation difference arises between APPC mapped and MRO for command sequences that contain an implicit change of direction. For MRO, a RECEIVE command must not be issued unless the conversation is in receive state (state 5).
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