How to Create an Architecture Overview

Transcription

1 by Gerrit Muller University of South-Eastern Norway-NISE Abstract A short specific overview of an architecture is a powerful means during product creation. This article addresses how to create such an overview. One of the main issues is the need for breadth, what needs to be included and for whom, and the balancing act of providing sufficient depth, what are crucial details that are part of this top-level description. Also the way of describing is discussed, from stakeholder needs to ambiguity and the level of formalism. Distribution This article or presentation is written as part of the Gaudí project. The Gaudí project philosophy is to improve by obtaining frequent feedback. Frequent feedback is pursued by an open creation process. This document is published as intermediate or nearly mature version to get feedback. Further distribution is allowed as long as the document remains complete and unchanged. status: draft Customer objectives Customer Operations Application customers application experts marketing, sales maintainers other systems auditors quality officers managers Functional Conceptual software engineers hardware engineers testers architecture overview internal Operational view Realization production engineers service engineers purchasing managers

2 Approach to Create Architecture Overview Identify scope: product, market, system, context Bottom-up fact finding and quantification Top-down identify stakeholders, concerns, views and models Determine most relevant issues: important, valuable, critical, costly,... Define overview structure and presentation Iterate and communicate many times 2 Gerrit Muller OHTapproach

3 CAFCR model What does Customer need in Product and Why? Customer What Customer How drives, justifies, needs enables, supports Product What Product How Customer objectives Application Functional Conceptual Realization internal Operational view (process, organization, people, sales, service, purchasing, manufacturing, suppliers) 3 Gerrit Muller OHTannotatedCAFCR

4 Bottom up fact finding and quantification Customer Application Functional Conceptual Realization objectives figures of merit typical quantities critical specs working ranges critical numbers patients/physician physician income success rate failure rate integral cost # patients # physicians # exams/day # exams/patient # information/ patient productivity response time capacity # transactions # queries peak&average network speed CPU speed memory size power consumption query duration transaction overhead internal Operational view market size market share growth rate product life cycle business model market segments maintenance effort update frequency service crew # suppliers partners competitors effort cost time project size # engineers/discipline # teams 4 Gerrit Muller OHTbottomup

5 IEEE 1471 top level mission system has architecture Described by fulfills environment influences architecture description provides rationale 5 Gerrit Muller OHTieee1471top

6 IEEE 1471 view level System has Architecture Described by Architecture Description Consists of Stakeholder has concern covers viewpoint conforms 1 to 1 view model covers defines 6 Gerrit Muller VCieee1471model

7 Architecture Overview Architecture Subset of which architect is aware Flattened into Architecture description overview Actually written by architect(s) 7 Gerrit Muller OHTarchitectureOverview

8 Role of Architecture Description problem space solution space "real world" highly simplified very incomplete communication documentation archiving... architecture description system system system system instance instance instance instance stakeholder stakeholder stakeholder stakeholder stakeholder stakeholder 8 Gerrit Muller SAFSOParchitectureDescription

9 Stakeholder of an Architecture Overview Customer objectives Application customers application experts marketing, sales Functional Conceptual software engineers hardware engineers testers Realization maintainers other systems architecture overview Customer Operations auditors quality officers managers production engineers service engineers purchasing managers internal Operational view 9 Gerrit Muller OHTstakeholders

10 Form and Medium Architecture description book mock-up player prototype Mozilla Firefox architecture description The system static view dynamic view The wonderful view on...? active content dynamic content 10 Gerrit Muller OHToverviewForm

11 Payload: the Ratio between Content and Overhead front page title identification author distribution status review history changes diagrams tables 1. aap 2. noot 3. mies lists and ca 50% text meta information max 2 pages contents pages 11 Gerrit Muller DGpayload

12 Language Recommendations * Keep your sentences short * Prefer active verbs * Use 'you' and 'we' * Choose words appropriate for the reader * Don't be afraid to give instructions * Avoid nominalisations * Use positive language * Use lists where appropriate from Plain English Campaign 12 Gerrit Muller OHTlanguage

13 Ideal Structure does not Exist function 1 function 2 function m view 1 view 2 view n object 1 object 2 object i application 2 application n quality 1 application 1 quality 2 quality k technology k subsystem 1 subsystem 2 technology 1 subsystem n technology 2 13 Gerrit Muller OHTstructure