[¤2] Introduction to Building Blocks

[¤3] Overview    Generic Characteristics    Architectural Building Blocks    Solution Building Blocks

[¤4] Overview

[¤5] This subsection describes the characteristics of building blocks. The uses of building blocks in the ADM is described separately, under Building Blocks and the TOGAF Architecture Development Method.

[¤6] Generic Characteristics of Building Blocks

[¤7] Building Blocks have generic characteristics as follows:

• [¤8] A Building Block is a package of functionality defined to meet the business needs across an organization
• [¤9] A Building Block has published interfaces to access the functionality
• [¤10] A Building Block may interoperate with other, interdependent, Building Blocks.
• [¤11] A good Building Block has the following characteristics:
  • [¤12] It considers implementation and usage, and evolves to exploit technology and standards
  • [¤13] It may be assembled from other Building Blocks
  • [¤14] It may be a subassembly of other Building Blocks
  • [¤15] Ideally a Building Block is reusable and replaceable, and well specified
• [¤16] A Building Block may have multiple implementations but with different interdependent Building Blocks

[¤17] A Building Block is therefore simply a package of functionality defined to meet business needs. The way in which functionality, products and custom developments are assembled into building blocks will vary widely between individual architectures. Every organization must decide for itself what arrangement of building blocks works best for it. A good choice of building blocks can lead to improvements in legacy system integration, interoperability, and flexibility in the creation of new systems and applications.

[¤18] Systems are built up from collections of building blocks, so most building blocks have to interoperate with other building blocks. Wherever that is true, it is important that the interfaces to a building block are published and reasonably stable.

[¤19] Building blocks can be defined at various levels of detail, depending on what stage of architecture development has been reached.

[¤20] For instance, at an early stage, a building block can simply consist of a grouping of functionality such as a customer database and some retrieval tools. Building blocks at this functional level of definition are described in TOGAF as Architecture Building Blocks (ABBs). Later on, real products or specific custom developments replace these simple definitions of functionality, and the building blocks are then described as Solution Building Blocks (SBBs).

[¤21] More detail on each of these aspects of building blocks is given below.

[¤22] Architectural Building Blocks

[¤23] Architectural Building Blocks (ABBs) relate to the Architecture Continuum, and are defined or selected as a result of the application of the Architecture Development Method.

[¤24] Characteristics

[¤25] Architectural Building Blocks:

• [¤26] define what functionality will be implemented
• [¤27] capture business and technical requirements
• [¤28] are technology aware
• [¤29] direct and guide the development of Solution Building Blocks

[¤30] Specification Content

• [¤31] Architectural Building Block specifications include the following as a minimum:
• [¤32] Fundamental Functionality and Attributes - semantic, unambiguous, including security capability and manageability
• [¤33] Interfaces - chosen set, supplied (APIs, data formats, protocols, hardware interfaces, standards)
• [¤34] Dependent BBs with required functionality and named used interfaces
• [¤35] Map to business / organizational entities and policies

[¤36] Solution Building Blocks

[¤37] Solution Building Blocks (SBBs) relate to the Solutions Continuum, and may be either procured or developed.

[¤38] Characteristics

[¤39] Solution Building Blocks:

• [¤40] define what products and components will implement the functionality
• [¤41] define the implementation
• [¤42] fulfil business requirements
• [¤43] are product or vendor aware

[¤44] Specification Content

[¤45] Solution Building Block specifications include the following as a minimum:

• [¤46] Specific Functionality and Attributes
• [¤47] Interfaces - the implemented set
• [¤48] Required Solution Building Blocks used with required functionality and names of the interfaces used
• [¤49] Mapping from the Solution Building Blocks to the IT topology and operational policies
• [¤50] Specifications of attributes shared across the environment (not to be confused with functionality) such as security, manageability, localizability, scalability,
• [¤51] performance, configurability
• [¤52] Design drivers and constraints, including the physical architecture
• [¤53] Relationships between Solution Building Blocks and Architectural Building Blocks

[¤54] Copyright © The Open Group, 1998, 1999