Using Link3270 single transaction mode

Single transaction mode allows a client to run a single transaction.

The bridge facility is automatically created, then deleted at the end of the transaction. This mechanism is more efficient and easier to program than session mode, if only one transaction is being run. It is particularly suited to inquiry transactions.

To run in single transaction mode, your client program must supply the name of the user transaction in the BRIH_TRANSACTIONID field of the bridge message header (BRIH). See Link3270 message header (BRIH) for a description of the BRIH. The following parameters may also be optionally defined:
  • BRIH-DATALENGTH (if BRIV vectors are appended to the message)
  • BRIH-FACILITYLIKE
  • BRIH-TERMINAL
  • BRIH-NETNAME
  • BRIH-ADSDESCRIPTOR
  • BRIH-ATTENTIONID
  • BRIH-STARTCODE
  • BRIH-CURSORPOSITION

Your client program must also create BRIV vectors for any input commands. If you add data to a BRIV, you must also update the BRIH-DATALENGTH field. See Updating data length fields.

To use single transaction mode your application must satisfy the following restrictions, otherwise session mode should be used:
  • Only one input and one output message are allowed. To run conversational transactions, you must provide all the input data in sequential BRIV structures in the input message. The BRIH-CONVERSATIONALTASK and BRIH-GETWAITINTERVAL parameters in the BRIH are ignored.
  • The COMMAREA should be large enough to receive the output message. If it is not, the message is truncated at the last complete vector, and the rest of the message is discarded. BRIH-REMAININGDATALENGTH is set to a non zero value to indicate there has been truncation.
  • If a communications link breaks, you can not obtain the output using a resend message request. For this reason it is recommended that single transaction mode is mainly used for inquiry type transactions.