Software Design

• Basic Principles of the Design

  • 从system model出发，设计 system architecture 和 specific system components

  • system --> subsystems + interplay --> components + interfaces

  • System analysis to system design

• System architecture: A system architecture describes the structure of the system by means of software components and the relationships(events等) amongst each other.

  • 设计需要考虑的标准

  • call return pattern

  • pipes and filter Architectures：支持复用，并发，易维护

    • pipe 是连接两个方块的线

    • filter是方块

  • controller控制板块

  • Service Oriented Architecture（SOA）:Architectural style that for software design where services are provided to other componentsthrough a communication protocol over a network.

    • 更好的复用

    • 统一的接口标准

    • 可移植性强，可以跨平台调用

    • Service： A service is a discrete unit of functionality that can be accessed remotely and acted upon and updated independently, such as retrieving a location information online.

    • Evaluation

  • Multi-tier Architectures多层架构：

    • 例如: IOT三层架构

  • MVC架构：

• Analysis the system archtecture:

  • 从每个stakeholder的角度，分析scenarios

  • SAAM方法: 想各种scenarios，并排优先级，分为直接或者间接，分别评估

  • ATAM方法：注意analysis的输入输出

• Design principles：

  • module：可以独立测试，不关心其中的具体实现的模块，如 class, component, library

  • 在设计module的时候，要权衡耦合性，复杂性和module的数量

  • analysis model --> design model

  • System of Systems

• real time：

  • Real-time Design Patterns：

    • Concurrency Patterns：control and scheduling of the architectural elements

    • help to organize, manage, use and share finite resources in real-time andembedded systems

    • Watchdog Pattern：解决死锁等问题

    • Event-driven architectures

    • Time-driven architectures

• Safey：