The Process of Software Architecting

 

®

IBM Software Group

The Process of Software Architecting Peter Eeles Executive IT Architect IBM UK [email protected]

© 2009 IBM IBM Corporati Corporation on

 

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 Agenda 

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Introduction  Architecture, Architect, Arc Architecting hitecting

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Method fundamentals

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Documenting a software architecture

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Reusable architecture assets

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 A day in the life Summary

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Coming Soon!

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Inspiration 

“If I have seen further it is only by standing on the shoulders of Giants”  

Sir Isaac15Newton, letter to Robert th February Hooke, 1676

www.booch.com/architecture www.handbookofsoftwarearchitecture.com

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 Agenda 

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Introduction  Architecture, Architect, Arc Architecting hitecting



Method fundamentals



Documenting a software architecture

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Reusable architecture assets

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 A day in the life Summary

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Core Concepts

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 Architecture 

 Architecture is the fundamental fundamental organization of a system embodied in its components components,, their relationships to each other, and to the environment  the principles guiding its design and evolution. [IEEE 1471] , and the principles



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 elements, relationships among them. [Bass] 

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[Architecture is] the organizati organizational onal structure and associated behavior  of a system. An architecture can be rec recurs ursive ively ly de decom compos ed into intoparts,  parts that interact through interfaces, relationships thatposed  connect and constraints for assembling parts. Parts that interact through interfaces include classes, components and subsystems. [UML 1.5] 

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 Architecture versus Design

 All architecture is design but bu t not all design is architecture. Architecture represents the significant design decisions that shape a system, where significant is measured by cost of change. - Gr Grad ady y Bo Booc och h

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 An architecture has a particular scop scope e

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The benefits of architecting 

 Architecting helps helps manage complexity

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 Architecting ensures ensures archit architectural ectural integ integrity rity

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 Architecting provides provides a bas basis is for reuse

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 Architecting addresses addresses system qualities

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 Architecting drives drives consensu consensus s

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 Architecting reduces reduces mainte maintenance nance costs

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 Architecting supports supports impa impact ct analysis

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 Architecting supports supports the pl planning anning pro process cess

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 Agenda 



Introduction  Architecture, Architect, Arc Architecting hitecting



Method fundamentals



Documenting a software architecture



Reusable architecture assets

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 A day in the life Summary

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Key Method Concepts

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 A Waterfall Process

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 An Iterative Process

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 Agile 

 Agile Manifesto Individuals

and interactions over processes and tools.

Working

software over comprehensive documentation. Customer collaboration over contract negotiation. Responding



to change over following a plan.

Scrum is a manageme management nt and control process that cuts through complexity to focus on building software to meet business needs. Scrum is superimposed superimpose d on top of and wraps existing engineering practices, development methodologies methodologies and standards. [Schwaber] 

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 Agenda 



Introduction  Architecture, Architect, Arc Architecting hitecting



Method fundamentals



Documenting a software architecture



Reusable architecture assets





 A day in the life Summary

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Views, Diagrams and Models

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Basic Views and Cross-Cutting Views

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Views, Models and Levels of Realization

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 Agenda 



Introduction  Architecture, Architect, Arc Architecting hitecting



Method fundamentals



Documenting a software architecture



Reusable architecture assets





 A day in the life Summary

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 A Metamodel of Architecture Assets

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 Agenda 



Introduction  Architecture, Architect, Arc Architecting hitecting



Method fundamentals



Documenting a software architecture



Reusable architecture assets





 A day in the life Summary

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Inputs 

Business Entity Model

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Business Process Model

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Business Rules

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Existing IT Environmen Environmentt

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Vision

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Types of Requirements 

Functional requireme requirements nts Describe

the behaviors (functions or services) services) of th the e [IT] system system that support support

user goals, tasks or activities. [Malan]  

Non-functional requirements Non-functional

requirements include constraints and qualities. [Malan] 

Constraint 

 A constraint is a restriction on the degree degree of freedom we have in providing a solution. [Leffingwell] 

Quality 

[System] qualities are properties or characteristics of the system that its stakeholders care about and hence will affect their degree of satisfaction with the system. [Malan] 

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Define Requirements

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Task: Collect Stakeholder Requests 

Pitfall: Treating Requests as Requirements

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Pitfall: The Shopping Cart Mentality

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Pitfall: The Questions are too Technical

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Pitfall: Requests Are Too General

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Pitfall: Requests Are Not Measurable

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Pitfall: Talking with the Wrong People

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Pitfall: All Requests Are Equal

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Task: Define System Context

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Task: Outline Functional Requirements

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Task: Outline Non-Functional Requirements 

Usability Requirement Requirements s

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Reliability Requirements

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Performance Requirements

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Supportability Requirements

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Constraints Business

Constraints

 Architecture

Constraints Constraints

Development Physical

Constraints

Constraints

“Brownfield sites are those in which redevelopment or reuse of the site is complicated existing contaminants. contaminants . Greenfield sites areby clean, previously undeveloped land”. [Hopkins]  29

 

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Task: Prioritize Requirements

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Create Logical Architecture

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From Requirements to Solution

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 Approaches 

 Attribute Driven Driven Design (ADD) Method Developed Quality

at the Software Engineering Institute

attributes drive the derivation of the architecture

Underpinned 

by architectural tactics and patterns

Siemens’ Siem ens’ 4 Vi Views ews ((S4V S4V)) me method thod Developed

at Siemens Corporate Research Starts with a global analysis of the t he factors that influence the architecture Iteratively

addresses challenges across four views (conceptual, execution, module and code architecture)



The Rational Unified Process (RUP) Developed Driven

at Rational Software (now IBM Rational)

by architecturally-significant requirements

Each

iteration considers the key architectural elements of the solution, before realizing the requirements using these solution elements 33

 

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How Much Logical Architecture? 

Minimizing Logical Architecture The

logical architecture is simply a means of getting to a physical architecture

as quickly as possible al l In some cases, no logical architecture may be required at all 





E.g. The requirements for the system are similar to those t hose of an existing system E.g. We are using a packaged application or integrating i ntegrating with an existing system

Logical Architecture as an Investment  A

valuable asset if a technology technology change is anticipated anticipated at some point in the future

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Task: Define Architecture Overview

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Task: Outline Functional Elements 

Component identification Business 

Entity Model

Clustering of related entities

Functional 

requirements

Boundary, control and entity components

Non-functional

requirements



Constraints



Components that address specific technical challenges (e.g. security)

Business 

rules

Business rules component(s)

 Architecture 

decisions decisions

Use of particular assets (e.g. packages, patterns)

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Task: Outline Functional Elements

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Task: Outline Functional Elements

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 Assigning NFRs to Components

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Task: Outline Deployment Elements

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Task: Outline Deployment Elements

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Task: Outline Deployment Elements

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Summary 

The process of architecting … Spans

software engineering disciplines

 Applies Draws Is

across the project lifecycle across

upon proven experience (practices, standards and other assets)

built upon solid engineering principles

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