软件架构复习笔记7

1、 HYPERLINK http:/blog.sheimi.me/note/2012/06/21/software-architecture-review-8.html 软件架构复习笔记(7) - 体系结构21 Jun 2012At NJU为什么需要有体系结构的设计（高层设计）详细设计的不足关注点偏差（载体失配）程序语言无法描述整理的质量要求无法实现佳偶信息本地化（信息隐藏的局限性）单词匹配的需求是模块见必须依赖与对方的接口无法有效抽象部件的整体特性（无法描述Module itself）接口的定义缺乏结构性模块的众多接口之间太独立了无法实现区别对待不能有效适应大型软件开发的特殊开发方法复用与单词

2、匹配多语言/多泛型与联合编译遗留资产与Module Inside使用Programming in the large 的特点载体复杂度过大：过于依赖单词匹配的导入导出关系导入导出并不适合整体结构设计体系结构设计the set of principal design decision about the system组成部分Components: computation and stateConnector: relation among components (deserve to be first-class)Configuration注意点Components should be inde

3、pendentConnectors should be independentRelations among components are not fixed体系结构设计的关注点Qualities of the systemavailabilitymodifiabilityperformancesecuritytestabilityusabilityProject EnvironmentsDevelop EnvironmentsBusiness EnvironmentsTechnology EnvironmentsBusiness GoalsWhy architectural design d

4、ecisions are important and difficult?Design decisions are cross cutting and intertwined:the design decision information is fragmented across various parts of the design, making it hard to find and change the decisions.Design rules and constraints are violated:designers can easily violate design rule

5、s and constraints arisingfrom previously taken design decisionslead to architectural drift and its associated problemsObsolete design decisions are not removedIn the current design practice removing design decisions is avoided, because of the effort needed, and the unexpected effects this removing c

6、an have on the system.Software Architecture Description4 + 1 View HYPERLINK http:/blog.sheimi.me/note/2012/06/18/software-architecture-review-1.html 传送门Logic to ProcessInside-out: from Logic structuredefine agent tasksObjects executed on that same agentseveral classes that need to be executed in mut

7、ual exclusionOutside-in: from physical structureidentify external stimuli (requests) to the systemdefine client and servers processesdefine the right set of servers,and allocate objects to the client and servers agentsLogic to Developmentvery close, but not the sameA Component is usually implemented

8、 as a module. Large one are decomposed into multiple packagesGrouping to subsystems based on:Strategies and Tactics (Ch5)Availability TacticsFault detectionPing echoHeartbeatExceptionRecovery preparation and repairVotingActive redundancy (hot restart)Passive redundancy (warm restart/dual redundancy/

9、)SpareRecovery reintroductionShadowState resynchronizationRollbackPreventionRemoval from serviceTransactionsProcess monitorModifiability Tactics HYPERLINK http:/blog.sheimi.me/note/2012/06/20/software-architecture-review-6.html 传送门Separate configure dataSeparate hardware-specific componentSeparate t

10、ime-critical componentSeparate domain model from interfacesSeparate domain model from technologiesSeparate monitor from functionSeparate error resume from core logicSeparate external interface adapterPerformance TacticsResource DemandIncrease computation efficiencyreduce computational overheadManage

11、 event rateControl frequency of samplingResource ManagementIntroduce concurrencyMaintain multiple copiesIncrease available resourcesResource AbstractionSheduling policySecurity TacticsResisting AttacksAuthenticate UsersAuthorize UsersMaintain data confidentialityMaintain IntegrityLimit ExposureLimit AccessDetecting AttacksIntrusion detectionRecorvering from an AttackRestoration availabilityIdentification Audi