Software Architecture

This post is an abstract of some chapters in the book 'Software Systems Architecture' by Eoin Woods and Nick Rozanski

Software Architecture Definition

Software elements that you need to specify and or design in order to meet a particular set of requirements, plus the hardware required to run those software elements on

Key Parts of the definition

• Structure - System’s elements, pieces that can be constructed, and their relationships
• Static structure
• Software classes, Relational entities, Network, Hardware etc
• Dynamic structure
• System response to an external stimulus
• Information flow, parallel/serial execution of tasks, effects on data (create, update, delete)
• Properties - Fundamental properties of a system
• Externally visible properties
• Functional behavior
• Quality properties
• Scalability, Performance, Security etc
• Principles - of its design and evolution
• Fundamental beliefs, approach or intent - that guides the architecture
• Conventions that makes system easily understood and allow extensions in a consistent and logical way fitting naturally into the overall form of the system

Stakeholder

Individual, team organization having an interest in the realization of the system 

Concern

Requirements, objective, constraint, intention, aspiration of a stakeholder

Architectural Description

Documents or representation of an architecture that a stakeholder can understand and demonstrates that the architecture has met their concern

It is not possible to capture all properties of a complex system in a single model that can be understood and of value to all stakeholders.

View

Representation of structural aspects of an architecture that illustrates how the architecture addresses one or more concerns of its stakeholders.

Viewpoint

Conventions for constructing one type of view.

Grouping of Viewpoints

• Context Viewpoint
• The relationship, dependencies, and interactions between the system and its environment (people, system and external entities)
• Functional Viewpoint
• Fundamental organization of a system - Functional elements, their responsibilities, interfaces, and interactions
• Information Viewpoint
• Fundamental organization of a system - Storage, manipulation, management, and distribution of information
• Concurrency Viewpoint
• Fundamental organization of a system - Identification and coordination of system parts that can execute concurrently
• Development Viewpoint
• Supports the construction of a system - Building, testing, fixing, enhancing
• Deployment
• Deployment of a system in its live environment
•  Operational Viewpoint
• Operations, administration, support and running a system in its live environment

Architectural Perspectives

Quality concerns (non-functional requirements) that are cross-cutting in nature. 

• Security
• Performance
• Scalability
• Availability
• Resilience
• UsabilityAccessibility
• Regulation
• Location
• Internationalization
• Evolution

Perspectives are addressed by applying them to Views.

Viewpoints & Perspectives