Phase C: Information Systems Architectures

Objective | Approach | Inputs | Steps | Outputs

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

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:

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:


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


The main outputs are as follows:

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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.

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