[¤3] Introduction Foundation Architecture Common System Architectures
Industry Architectures Organization
Enterprise Architectures
[¤5] There is a continuum of architectures, architectural building blocks, and architectural models, that are relevant to the task of constructing an enterprise-specific architecture.
[¤6] The Architecture Continuum, and the relative positioning of different types of architectures within it, is illustrated in Figure 1.
[¤8] Figure 1: The Architecture Continuum
[¤9] Figure 1 illustrates how architectures are developed across a continuum ranging from foundational architectures such as TOGAF's, through common systems architectures, and industry-specific architectures, to an enterprise's own individual architectures.
[¤10] The arrows in Figure 1 represents the bi-directional relationship that exists between the different architectures in the Architecture Continuum. The leftwards direction focuses on meeting enterprise needs and business requirements, while the rightwards direction focuses on leveraging architectural components and building blocks.
[¤11] The enterprise needs and business requirements are addressed in increasing detail from left to right. The architect will typically look to find re-usable architectural elements toward the left of the continuum. When elements are not found, the requirements for the missing elements are passed to the left of the continuum for incorporation. Those implementing architectures within their own organizations can use the same continuum models specialized for their business.
[¤12] The four particular architectures illustrated in Figure 1 are intended to indicate the range of different types of architecture that may be developed at different points in the continuum: they are not fixed stages in a process. Many different types of architecture may occur at points in-between those illustrated in Figure 1.
[¤13] Although the continuum illustrated in Figure 1 does not represent a formal process, it does represent a progression, which occurs at several levels:
[¤15] Logical to physical
[¤17] Horizontal (IT technology focused) to vertical (business focused)
[¤19] Generalization to specialization
[¤21] At each point in the continuum, an architecture is designed in terms of the design concepts and building blocks available and relevant to that point.
[¤22] The four architectures illustrated in Figure 1 represent main classifications of potential architectures, and will be relevant and familiar to many architects. They are analyzed in detail in the following subsections.
[¤24] A Foundation Architecture is an architecture of building blocks and corresponding
standards that supports all the common systems architectures, and,
therefore, the complete computing environment.
[¤25] For The Open Group, this Foundation Architecture is the TOGAF Technical Reference Model and Standards Information Base. The TOGAF ADM explains how to get from that foundation architecture to an enterprise specific one.
[¤26] The TOGAF TRM and SIB describe a fundamental architecture upon which other, more
specific, architectures can be based. The As a TOGAF Foundation
Architecture, it contains many alternatives in each of the architectural
building blocks. Other characteristics of the TOGAF foundation architecture include the
following:
[¤35] Common Systems Architectures guide the selection and integration of specific services from the Foundation Architecture to create an architecture useful for building common (i.e., reusable) solutions across a wide number of relevant domains.
[¤36] Examples of Common Systems Architectures include: a Security Architecture, a Management Architecture, a Network Architecture, etc. Each is incomplete in terms of overall information system functionality, but is complete in terms of a particular problem domain (security, manageability, networking, etc.), so that solutions implementing the architecture constitute reusable building blocks for the creation of functionally complete information systems.
[¤37] Other characteristics of Common Systems Architectures include:
[¤42] The TOGAF Integrated Information Infrastructure Reference Model is a Common Systems Architecture that focuses on the requirements, building blocks, and standards relating to the vision of Boundaryless Information Flow.
[¤44] Industry Architectures guide the integration of common systems components with industry-specific components, and guide the creation of industry solutions for targeted customer problems within a particular industry.
[¤45] A typical example of an industry-specific component is a Data Model representing the business functions and processes specific to a particular vertical industry, such as the Retail industry's "Active Store" architecture, or an industry architecture that incorporates the Petrotechnical Open Software Corporation (POSC) Data Model.
[¤46] Other characteristics of Industry Architectures include the following:
[¤54] Enterprise Architectures are the most relevant to the IT customer community, since they describe and guide the final deployment of user-written or third-party components that constitute effective solutions for a particular enterprise or enterprises that have a need to share information.
[¤55] IEEE Std 1003.23, Guide for Developing User Organization Open System Environment (OSE) Profiles, provides a method for identifying and documenting an organization’s operational requirements, the Information Systems services and Information Technology services needed to support those requirements, and the standards, standards options, interim solutions and products that will provide the needed services.
[¤56] There may be a continuum of Enterprise Architectures that are needed to effectively cover the organization’s requirements by defining the Enterprise Architecture in increasing levels of detail. Alternatively, this might result in several more detailed Enterprise Architectures for specific entities within the global enterprise.
[¤57] The Enterprise Architecture guides the final customization of the solution, and has the following characteristics:
[¤65] Copyright © The Open Group, 1998, 2000, 2002
