In a typical real-world situation, you have an application with access to patient information which is periodically updated. Examples of updates could include when a patient is discharged or a lab result is issued.

Other applications are interested in knowing when this information changes, but do not have direct access to your application's data. In particular, they do not have access to the way the data is structured internally by your application, and are likely to have their own customized methods of handling data.

To communicate data from your application to these other applications, you need to encode it as an HL7 message. HL7 is a widely-used standard for transmitting healthcare-related information. If your application and an application with which it is communicating can both process HL7 messages, your application can successfully transmit data to the other application.

The problem is that the structure of the data inside your application may not resemble the data format specified by the HL7 standard. What is needed is an interface between your application and the HL7 message - a way to efficiently and reliably map the desired information out of the application's data structures and into an HL7 message, which can then be sent to other interested applications.

Chameleon solves this problem. It provides a flexible and intuitive means of designing HL7 messages and mapping the desired data into the messages, thus making the data available to the recipient in a standardized format.