Paper Title: Engineering Models for a Software Architecture Pattern Language Author's Name: Lorraine L. Boyd Author's email address: lorrie_boyd@mail.amsinc.com Authors postal address: American Management Systems 4050 Legato Rd. Fairfax, VA 22003 Author's phone number: 703-267-5497 Subject Area & Keywords: Software Architecture, Business Systems Abstract: This paper defines characteristics of business systems, and, based on user requirements to meet these characteristics, proposes four engineering models for architectural patterns which together define an overall software architecture. First, this paper describes seven primary characteristics of business systems. Different business functions have contradictory user requirements for each of these characteristics. The contradiction and tension in these user requirements become forces for the individual engineering model architecture patterns. Then, this paper presents four engineering model patterns which together meet the main requirements of these characteristics. The four engineering model patterns are: Online Engineering Model , Messaging Engineering Model, Batch Engineering Model and Stream-IO Engineering Model. By delineating and tuning different engineering model architecture patterns to meet different user characteristics, the overall system will meet all the user requirements. In addition, defining these architecture patterns early in the analysis phase provides a framework for individual business functions. Designers can evaluate their particular business function against the system characteristics and determine the best architectural engineering model to use as a framework for their function.