HL7 V2 Standard Inbound Message Mode Data Flow over MLLPV2 — Part 1

Once the message is received, the Collaboration determines whether the message needs to be validated. The HL7 V2 message is then validated making sure that the message structure is correct. Various fields in the MSH segment of the message are also validated, such as Version ID and Sending Facility. If these fields do not match the configuration, a NAK is returned.

If sequence numbering is enabled the Collaboration checks to see if the messages sequence number is valid. If the sequence number is not valid, the adapter sends a NAK.

The validated HL7 V2 message moves on to processInitialHandshake() and the sequence numbers are synchronized. The sequence number within the message is checked against the expected sequence number. If the numbers match, the Collaboration sends an ACK, if not it sends a NAK. The ACK or NAK includes information from various fields of the incoming MSA segment. The ACKs level of acknowledgement is set to A (acknowledgement is sent when the message is successfully received), or C (acknowledgement is sent after the message is successfully processed).

Figure 1–32 HL7 V2 Standard Inbound Message Mode Data Flow over MLLPV2 — Part 1