I was thinking, &quot;wow, reading in data, processing it, and outputting data. Reminds me of Interface Engines in healthcare.&quot; Then I saw &quot;HL7&quot; on the diagram.<p>That&#x27;s what I did for a long time. HL7 contains information such as &quot;Admissions, Discharges, and Transfers (ADT)&quot; which is sent from the Hospital Information System (HIS) to other department&#x27;s systems (radiology, pharmacy, medical records, and possibly dozens more) and vice versa (LAB results back to HIS, for example).<p>HL7 interface engines unpack the HL7 data into separate segments, fields, and subfields, identify the type&#x2F;subtype of message, route to various destinations based on the type and any other fields, map the data and reformat as necessary for the destination, encode back into HL7, and send it. It also needs to queue the messages as needed, re-transmit or set aside the message, or just stop sending depending on what it gets back in the form of response codes.  So you can see in the diagram some of those steps. The also handle input&#x2F;output either in the form of TCP&#x2F;IP ports, reading&#x2F;writing files (for batch processing), or pretty much any other method you can send and receive data (serial ports, in some old cases).<p>I&#x27;m kind of curious how (and how easy it is) to define which fields in the input for a given event goes to the output (and do certain transformations on those fields if needed).