Software Engineering Institute

This report provides an overview of two standards that are used for data specification and representation in distributed systems. The standards considered are the Abstract Syntax Notation One (ASN.1) and the external data representation (XDR). Standards for data representation are appropriate for the development of real-time distributed systems, particularly loosely coupled, heterogeneous systems. The report presents an example of the use of each standard. Several performance metrics are also introduced that are suitable for comparing the space and time costs of using the different standards. Several issues are discussed that are appropriate to a system designer. an ADA implementation of ASN.1 encode and decode routines for floating point types is included in an appendix.