This chapter provides an overview of the contents of Part III.
The Architecture Development Method (ADM) process can be adapted to deal with a number of different usage scenarios, including different process styles (e.g., the use of iteration) and also specific specialist architectures (such as security). Guidelines included within this part of TOGAF are as follows:
- Applying Iteration to the ADM (see 19. Applying Iteration to the ADM) discusses the concept of iteration and shows potential strategies for applying iterative concepts to the ADM.
- Applying the ADM across the Architecture Landscape (see 20. Applying the ADM across the Architecture Landscape) discusses the different types of architecture engagement that may occur at different levels of the enterprise. This section then also discusses how the ADM process can be focused to support different types of engagement.
- Security Architecture and the ADM (see 21. Security Architecture and the ADM) provides an overview of specific security considerations that should be considered during different phases of the ADM.
- Using TOGAF to Define & Govern SOAs (see 22. Using TOGAF to Define & Govern SOAs) shows how SOA concepts can be supported by the TOGAF framework and the specific SOA considerations for different phases of the ADM.
The following techniques are described within Part III: ADM Guidelines and Techniques to support specific tasks within the ADM:
- Architecture Principles (see 23. Architecture Principles) - principles for the use and deployment of IT resources across the enterprise - describes how to develop the set of general rules and guidelines for the architecture being developed.
- Stakeholder Management (see 24. Stakeholder Management) describes Stakeholder Management, an important discipline that successful architecture practitioners can use to win support for their projects.
- Architecture Patterns (see 25. Architecture Patterns) provides guidance on using architectural patterns.
- Business Scenarios (see 26. Business Scenarios and Business Goals) describes the Business Scenarios technique, a method for deriving business requirements for architecture and the implied technical requirements.
- Gap Analysis (see 27. Gap Analysis) describes the technique known as gap analysis. It is widely used in the TOGAF ADM to validate an architecture that is being developed.
- Migration Planning Techniques (see 28. Migration Planning Techniques) describes a number of techniques to support migration planning in Phases E and F.
- Interoperability Requirements (see 29. Interoperability Requirements) describes a technique for determining interoperability requirements.
- Business Transformation Readiness Assessment (see 30. Business Transformation Readiness Assessment) describes a technique for identifying business transformation issues.
- Risk Management (see 31. Risk Management) describes a technique for managing risk during an architecture/business transformation project.
- Capability-Based Planning (see 32. Capability-Based Planning) describes the technique of capability-based planning.
TOGAF is designed to be flexible and it can be used with various architectural styles. This part of TOGAF includes two chapters that are intended as useful examples.
- Security Architecture and the ADM (see 21. Security Architecture and the ADM)
- Using TOGAF to Define & Govern SOAs (see 22. Using TOGAF to Define & Govern SOAs)
Architectural styles differ in terms of focus, form, techniques, materials, subject, and time period. Some styles can be considered as fashionable, others focused on particular aspects of enterprise architecture. TOGAF is a generic framework and intended to be used in a wide variety of environments. It is a flexible and extensible framework that can be readily adapted to a number of architectural styles.
An organization's Architecture Landscape can be expected to contain architecture work that is developed in many architectural styles. TOGAF ensures that the needs of each stakeholder are appropriately addressed in the context of other stakeholders and the Baseline Architecture.
When using TOGAF to support a specific architectural style the practitioner must take into account the combination of distinctive features in which architecture is performed or expressed. As a first step, the distinctive features of a style must be identified.
For example, The Open Group definition for SOA identifies the following distinctive features:
- It is based on the design of the services - which mirror real-world business activities - comprising the enterprise (or inter-enterprise) business processes.
- Service representation utilizes business descriptions to provide context (i.e., business process, goal, rule, policy, service interface, and service component) and implements services using service orchestration.
- It places unique requirements on the infrastructure - it is recommended that implementations use open standards to realize interoperability and location transparency.
- Implementations are environment-specific - they are constrained or enabled by context and must be described within that context.
The second step is determining how these distinctive features will be addressed. Addressing a distinctive style should not call for significant changes to TOGAF; instead it should adjust the models, viewpoints, and tools used by the practitioner.
In Phase B, Phase C, and Phase D the practitioner is expected to select the relevant architecture resources, including models, viewpoints, and tools, to properly describe the architecture domain and demonstrate that stakeholder concerns are addressed (see Part II, 8.4.1 Select Reference Models, Viewpoints, and Tools, 10.4.1 Select Reference Models, Viewpoints, and Tools, 11.4.1 Select Reference Models, Viewpoints, and Tools, and 12.4.1 Select Reference Models, Viewpoints, and Tools). Depending upon the distinctive features, different architectural styles will add new elements that must be described, highlight existing elements, adjust the notation used to describe the architecture, and focus the architect on some stakeholders or stakeholder concerns.
Addressing the distinctive features will usually include extensions to the Architecture Content Metamodel and the use of specific notation or modeling techniques and the identification of viewpoints. Whether the style is dominant will determine whether it is necessary to revisit the Preliminary Phase and make changes to the Architecture Capability or whether support for the distinctive feature is possible within the scope of selection expected within a single ADM cycle.
Style-specific reference models and maturity models are commonly used tools that support a practitioner.
Over time new architectural styles are expected to arise to address the key problems facing practitioners. Some styles will be transitory, some will endure in a niche, and some will merge into the mainstream. The Open Group Forums and Work Groups exist to address the challenges facing the industry. These bodies produce a wide range of material that is useful to a practitioner interested in adapting TOGAF, or a particular ADM cycle, to a particular architectural style for current materials, including White Papers and Standards that are applicable (see www.opengroup.org/togaf_docs).