This chapter describes the Information System Systems Architecture, including the development of Data and Applications Architectures.

Objective

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.

Approach

Development

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

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:

• Design:
  1. Business Architecture design
  2. Data (or Applications) Architecture design
  3. Applications (or Data) Architecture design
  4. Technology Architecture design
• Implementation:
  1. Technology Architecture implementation
  2. Applications (or Data) Architecture implementation
  3. Data (or Applications) Architecture implementation
  4. 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

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 2 1.0 (detailed), if appropriate
• Target Business Architecture (Business Architecture), Version 2 1.0 (detailed)
• 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)

Steps

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

• Data Architecture ( Phase C: Information Systems Architectures - Data Architecture)
• Applications Architecture (Phase C: Information System Systems Architectures - Applications Architecture )

Outputs

The main outputs are as follows:

• Statement of Architecture Work (Major Output Descriptions), updated if necessary
• Baseline Data Architecture, Version 1.0
• Target Data Architecture Architecture, Version 1.0
• Baseline Applications Architecture, Version 1.0
• Target Applications Architecture 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, Report, summarizing what was done and the key findings
• Applications Architecture report, Report, summarizing what was done and the key findings
• Gap analysis: 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)

The TOGAF document set is designed for use with frames. To navigate around the document:

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Downloads of the TOGAF documentation, are available under license from the TOGAF information web site . The license is free to any organization wishing to use TOGAF entirely for internal purposes (for example, to develop an information system architecture for use within that organization). A hardcopy book is also available from The Open Group Bookstore as document G063 .