Software Architecture – Definitions, Roles, and Analogies

	John D. McGregor
	Clemson University

Definition from SAP

	The software architecture of a program or computing system is the structure or structures of the system, which comprise software elements, the externally visible properties of those elements, and the relationships among them.

ANSI/IEEE Std 1471-2000

	the fundamental organization of a system, embodied in its components, their relationships to each other and the environment, and the principles governing its design and evolution.

Building Architecture Analogy

	Similarities
	Sense of aesthetics is present in both
	Differences
	Physical laws don’t apply
	Software architecture still immature

Leonardo da Vinci – a basic principle

Leonardo da Vinci - observation

Leonardo da Vinci

At last a genuine Leonardo

FallingWater

Christopher Alexander

Grands Magasins du Bon Marche

Quality without a name

Realization hierarchy

Where do I start?

J2EE v. 1.4 architecture

Architecture as a blender of technologies

Block diagram

4+1 Views - Krutchen

Tactics – decomposition - 1

Tactics – decomposition - 2

Tactics – decomposition - 3

Reasoning - Latency attribute

Reasoning – statistical model

Architecture and People

	Stakeholder – anyone having an interest in the architecture
	Client
	User
	Designers
	…

Influences on the architecture

	Stakeholders
	Developing Organization
	Technical/Deployment environment
	Background of architects

Architecture process

	Understand the requirements
	Create architectures that satisfy the requirements
	Evaluate the trade-offs among the architectures
	Select appropriate architecture
	Repeat as requirements evolve

Architectural pattern

	description of element and relation types and a set of constraints
	Architectural style
	Client/server – implies multiple clients seeking service from a resource

Reference model

	Characteristic of the domain – in this case ecommerce

Reference architecture

Why architecture?

	Communication among stakeholders
	Early design decisions
	Transferable abstraction of the system

Architectural Structures

	Module structures
	Which piece is responsible for what
	Component-connector structures
	how do the major pieces interact at runtime
	Allocation structures
	allocates pieces of the architecture to pieces of the external environment

Module structures

Layered example – OSI Protocol Stack

Component/Connector structures

Common Object Request Broker

Allocation structures

Thread architecture

Eclipse environment

Eclipse requirements

	Edit multiple files
	Select files
	Bind files into a project
	Build a project
	See the individual attributes