In a typical real-world situation, you have a stream of HL7 messages arriving over a network and an application that is interested in some or all of the data encoded in the messages. The problem is that the format of the data preferred by the application bears little relation to the format of the data in the HL7 message. What is needed is an interface between the data stream and the application - a way to efficiently and reliably map the desired information out of the HL7 message and into the application's data structures.

Chameleon solves this problem. It provides a flexible and intuitive means of parsing HL7 messages, mapping the desired data into user-defined data structures, and making the data available to an application.