9. Phase C: Information Systems Architectures

Chapter Contents
9.1 Objectives | 9.2 Approach | 9.3 Inputs | 9.4 Steps | 9.5 Outputs

This chapter describes the Information Systems Architectures for an architecture project, including the development of Data and Application Architectures.

Requirements Management Phase H Phase G Phase F Phase E Phase D Phase C Phase B Phase A Preliminary Phase
Figure 9-1: Phase C: Information Systems Architectures

9.1 Objectives

The objective of Phase C is to develop Target Architectures covering either or both (depending on project scope) of the data and application systems domains.

Information Systems Architecture focuses on identifying and defining the applications and data considerations that support an enterprise's Business Architecture; for example, by defining views that relate to information, knowledge, application services, etc.

9.2 Approach

9.2.1 Development

Phase C involves some combination of Data and Application Architecture, in either order. Advocates exist for both sequences. For example, Steven Spewak's Enterprise Architecture Planning (EAP) recommends a data-driven approach.

On the other hand, major applications systems - such as those for Enterprise Resource Planning (ERP), Customer Relationship Management (CRM), etc. - often provide a combination of technology infrastructure and business application logic, and some organizations take an application-driven approach, whereby they recognize certain key applications as forming the core underpinning of the mission-critical business processes, and take the implementation and integration of those core applications as the primary focus of architecture effort (the integration issues often constituting a major challenge).

9.2.2 Implementation

Implementation of these architectures may not necessarily follow the same order. For example, one common implementation approach is top-down design and bottom-up implementation:

An alternative approach is a data-driven sequence, whereby application systems that create data are implemented first, then applications that process the data, and finally applications that archive data.

9.3 Inputs

This section defines the inputs to Phase C.

9.3.1 Reference Materials External to the Enterprise

9.3.2 Non-Architectural Inputs

9.3.3 Architectural Inputs

9.4 Steps

Detailed steps for Phase C are given separately for each architecture domain:

9.5 Outputs

The main outputs of Phase C are:


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