Phase C: Information Systems Architectures
This chapter describes the Information Systems Architecture, including the development of Data and Applications
Figure: Phase C: Information Systems Architectures
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.
The scope of the business processes supported in Phase C is limited to those that are supported by IT, and the interfaces of
those IT-related processes to non-IT-related processes.
Phase C involves some combination of Data and Applications 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, 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).
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:
- Business Architecture design
- Data (or Applications) Architecture design
- Applications (or Data) Architecture design
- Technology Architecture design
- Technology Architecture implementation
- Applications (or Data) Architecture implementation
- Data (or Applications) Architecture implementation
- Business Architecture 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.
Inputs to Phase C are:
- Application principles (Application Principles), if existing
- Data principles (Data Principles), if existing
- Request for Architecture Work (Request for Architecture Work)
- Statement of Architecture Work (Major Output Descriptions)
- Architecture Vision (Business Scenario/Architecture Vision)
- Enterprise Continuum (Introduction to the Enterprise Continuum)
- Baseline Business Architecture, Version 1.0 (detailed), if appropriate
- Target Business Architecture (Business Architecture), Version 1.0
- Baseline Data Architecture, Version 0.1
- Target Data Architecture, Version 0.1
- Baseline Applications Architecture, Version 0.1
- Target Applications Architecture, Version 0.1
- Relevant technical requirements that will apply to Phase C
- Gap analysis results (from Business Architecture)
- Re-usable building blocks (from organization's Architecture Continuum, if available)
Detailed steps for Phase C are given separately for each architecture domain:
The main outputs are as follows:
- Statement of Architecture Work (Major Output Descriptions), updated if
- Baseline Data Architecture, Version 1.0
- Target Data Architecture, Version 1.0
- Baseline Applications Architecture, Version 1.0
- Target Applications Architecture, Version 1.0
- Data Architecture views corresponding to the selected viewpoints addressing key stakeholder concerns
- Applications Architecture views corresponding to the selected viewpoints addressing key stakeholder concerns
- Data Architecture Report, summarizing what was done and the key findings
- Applications Architecture Report, summarizing what was done and the key findings
- Gap analysis results:
- Areas where the Business Architecture may need to change to cater for changes in the Data and/or Applications Architecture
- Constraints on the Technology Architecture about to be designed
- Impact Analysis (see Impact Analysis)
- Updated business requirements (if appropriate)
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