Phase C: Information Systems Architectures
Two sub-domains, one phase
Phase C covers Data Architecture and Application Architecture. They may be developed in either order, though data is often first because applications are justified by the data they manage. Each runs baseline to target with gap analysis, and both trace upward to the Business Architecture.
Data artifacts: Data Entity/Data Component catalog, Data Entity/Business Function matrix, Application/Data matrix, Conceptual and Logical Data diagrams, plus Data Dissemination, Data Lifecycle, Data Security and Data Migration diagrams. Application artifacts: Application Portfolio and Interface catalogs; Application/Organization, Role/Application, Application/Function and Application Interaction matrices; plus Application Communication, Application and User Location, Application Use-Case, Process/Application Realization, Software Engineering and Application Migration diagrams.
Traps
- Matrix versus diagram: the Application Interaction matrix records relationships; the Application Communication diagram shows them pictorially. Questions swap these deliberately.
- The Data Migration diagram belongs here even though migration scheduling happens later; it models data movement, not the timetable.
- Phase C does not select platforms or infrastructure; that is Phase D.
- The Architecture Requirements Specification grows here and must not be confused with the Architecture Definition Document.
Worked rule of thumb
If an artefact name pairs an application with something else (function, organization, role, data entity), it is almost certainly a Phase C matrix. If it names hardware, platform or network, it belongs to Phase D.