A declarative implementation of the DICOM-3 network protocol

We describe a new design for programs using the Digital Imaging and Communications in Medicine (DICOM) protocol, which we have implemented in a DICOM image storage server and a radiation treatment plan transfer facility for our locally developed radiation treatment planning system, Prism. This design is declarative, representing DICOM as a language for describing messages and sequencing of messages. The coding involved implementing an interpreter for this language. The DICOM protocol specifies messages, message formats, and sequencing. In our design, the specification translates almost directly into computer-readable declarative expressions that closely resemble the relevant tabulated DICOM specifications. The resulting programs are small, simple, and extensible, because most of the details of the DICOM protocol are not coded in the procedural control statements but are in the expressions and state table that the interpreter uses to perform all its functions. This approach provides a way to validate the consistency of a specification and the correctness of the implementation. The same method can be generalized to other such protocols. It may also be used to assist the design of new protocols.