FRAMEWORKS AND STANDARDS
There are a number of architectural frameworks and standards and the number is growing.
Firstly there are frameworks that are used to classify architecures. They form a chest of drawers as it were where each architecture has it’s own spot. Well known examples of these types of architecture frameworks are: Zachman; IAF; DYA framework and Tapscott. Frameworks such as Zachman; IAF and DYA are useful to retain an overview of the different architecture components that an organization usually has. They are used to show the relationships between the architecture components; to monitor the consistency between the architecture components and to identify overlap and white spaces.
There are many others in addition to the abovementioned frameworks. Some more well known and used than others. TOGAF is a framework that is popular in the US especially. It is based on the Zachman framework but adds an architecture development approach and a repository for standards; patterns and best practices. xAF aims at defining a generic architecture framework with which a specific framework can be evaluated, for instance. Finally, in terms of standards, IEEE1471 is the primary one.
Zachman
Zachman was probably the first person to ascertain the importance of architecture frameworks. The framework was first introduced in 1987 and was expanded in 1992. The framework is positioned as a resource for defining enterprise wide architectures for IT systems. The Zachman framework is defined using two dimensions: perceptions and abstractions. The perceptions are linked to parties (roles) that have a function in the realization of IT systems. The abstractions are in fact questions that are referenced to the perceptions listed earlier (what, how, where, when and why).
IAF
The Integrated Architecture Framework (IAF) also distinguishes two dimensions:
- Four architecture domains: organization (business processes); information systems (automated information systems) and technological infrastructure (technical infrastructure).
- Five phases of architectural design: contextual; conceptual; logical; physical and transformation.
The five design phases are the bridge between function and construction. Each phase results in the answer to a design question and results in a segment of the architecture description.
DYA Framework
In the DYA framework the columns indicate the different objects of an architecture:
Business architecture; information architecture and technical architecture. The rows in the framework indicate the different manifestations of the architecture: general principles; policy directives and models.
The architecture framework illustrates that an organization architecture should not be viewed as a monolithic entity but rather divided in components. Some of the components will be detailed in specific instances (the matrix cell will be filled in) while others will not be addressed (the matrix cell is empty). This is perfectly legitimate. As long as the completed portions are consistent with each other and with the business goals and that the portions required for the direction of the actual changes within the organization are completed.
Tapscott
In 1993 Tapscott and Caston introduced a framework consisting of five architectures to be used within an organization to allow business and IT to collaborate. The five architectures each form a perspective on the integral IT architecture. In other words there are five different viewpoints used to define the IT support for the business. These five viewpoints are: business view; process view; information view; application view and technology view.
TOGAF
The first version of “The Open Group’s Architecture Framework – TOGAF” was published in 1995. It was based on the “Technical Architecture Framework for Information Management” developed by the American Defense Department. The first version of TOGAF was understandably focussed on technological architecture. Other architecture domains were added later. TOGAF version 8.1 titled “Enterprise Edition” was published in December 2003. It concerns the development of architecture for all domains of an overal enterprise architecture. TOGAF considers an architecture framework as a resource for developing a broad scala of different architectures. Such a framework is meant as a methodology for describing the design of the information systems in terms of a set of building blocks, whereby the relationship between the building blocks is defined. The framework should also contain supporting resources in addition to a common vocabulary. According to the TOGAF approach, the framework should furthermore provide a list of recommended standards and compliant products.
xAF
The Dutch Architecture Forum NAF propagates and develops the IT architecture vision in the Dutch context. In the NAF there are three categories respresented: the academic world; suppliers of IT products and services; and companies that implement IT products and services.
A yearly National Architecture Congress (LAC) is organized under the auspices of the NAF. The eXtensible Archtecture Framework (xAF) is being defined by a workgroup within the NAF in which all three of the streams are represented.
The xAF approach is generic and not focussed on developing a specific system. This manifests itself in the concepts regarding an architecture framework. Constrained by the generic nature of xAF, the following are defined as being of general import for an architecture framework:
1. The systemtype S to which the framework relates.
2. Design domains D
3. Areas of concern A
These are areas that need to be addressed when system realization becomes an issue. Maintenance or Security for instance.
IEEE 1471
A well known architectural standard is IEEE 1471. This standard is especially well known because of the emphasis it puts on stakeholders and their concerns and in the subsequent definition of viewpoints and associated views.
