HL7 Acknowledgement (ACK) Messages - Guaranteed Message Delivery
February 1st, 2007 by Mike Stockemer
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The HL7 2.5 standard defines close to 500 different message types. While some are only used occasionally, almost all HL7 interfaces will incorporate the H7 acknowledgment (ACK) message. An HL7 ACK message is used to insure that HL7 messages are delivered from system to system without being lost.
Like any technology company, occasionally we have our own internal IT problems to deal with. This week it happened to be our mail server. For a period of time, we were not receiving any external e-mail, but we were unaware of the problem until a customer called us to let us know his e-mail had bounced. Once we were aware of the problem, fixing it was trivial. This got me thinking about the way HL7 messages are delivered, and the importance of HL7 acknowledgment messages.
In the clinical world, the successful and timely delivery of HL7 messages is critical. Tens of thousands or even hundreds of thousands of messages are transported daily in a typical hospital environment. When a medical application (HIS, LIS, RIS…) sends an HL7 message, it immediately needs to know that message was delivered successfully. Only once the successful delivery of the message has been verified should the next message in the queue be sent.
HL7 integration engines or HL7 enabled applications need to be able to generate properly formatted HL7 responses for all messages that they receive. Also, with HL7 messaging, applications should be configured to wait to receive an HL7 formatted response prior to sending the next message in their queue.
Most applications will take the ACK qualification a few steps further and verify not only that the message they receive is an HL7 ACK message, but also that the data contained within this message matches the data from the previously sent message and that the status of the ACK is a positive response. This is known as original mode acknowledgement. A vast majority of HL7 interfaces today use original mode acknowledgment.
Last 5 posts by Mike Stockemer
- Comparing HL7 Messages to HL7 Documents - January 25th, 2008
- Monitoring and Alerting for HL7 Interfaces - October 22nd, 2007
- Variations of the HL7 ORU^R01 Message Format - September 10th, 2007
- Point-to-Point Interface vs. Interface Engine in Healthcare - August 23rd, 2007
- Getting Started with Your HL7 Interface - August 16th, 2007
[…] In an earlier post on HL7 acknowledgement (ACK) messages, I highlighted the important value of ACKs and defined the concept of original mode acknowledgement. […]
[…] In my last two posts - acknowledgement (ACK) message definition and Original Mode ACK, it is important to remember that not every system will handle acknowledgments the same way. You will interface with systems that send you HL7 messages and do not wait for a response of any kind prior to sending the next message. In this scenario, your system will not be able to send back acknowledgment messages. This type of message delivery is never recommended. […]
[…] - It’s important to have an understanding of how each system will handle acknowledgement (ACK and NACK) messages. Under what circumstances would a receiver connection send back a negative […]
[…] ACK vs NACK […]