Crossing Chasms: The architectural patterns

This paper is part of a large pattern language (Crossing Chasms) currently under development by Bruce Whitenack of The Object People and myself. The pattern language as a whole addresses the issues faced by teams trying to build large clientserver systems using Object Technology and Relational data stores. This section of Crossing Chasms addresses issues faced by project teams who are just beginning to develop an architecture for client-server systems built using Object Technology. This paper contains four patterns: n Four Layer Architecture addresses how proper division of labor between the objects in a system can result in higher reuse potential and easier manageability. n Three tier architecture shows how systems can be organized to best take advantage of the machine resources of an organization. n Phase-in tiers shows how systems using a four-layer architecture can be built initially for a two-tier architecture, and then moved to a three-tier architecture over time. n Trim and fit Client demonstrates how the objects in a four layer architecture can be best distributed into the tiers of a two or three tier architecture. Together these patterns can help a project team make the right decisions to arrive at an extensible, maintainable, manageable architecture for client-server computing.