What is Systems Architecture ?

 
  • Systems Architecture is a generic discipline to handle objects (existing or to be created) called "systems", in a way that supports reasoning about the structural properties of these objects.

  • Systems Architecture is a response to the conceptual and practical difficulties of the description and the design of complex systems.
 

On this page, you will find three sections:

  • a unified definition of Systems Architecture (outlining what are systems, their architecture and the justifications for Systems Architecture)
  • fundamental principles underlying Systems Architecture (in all acceptions of the term)
  • socio-cognitive aspects of Systems Architecture to take into account the reality of men (cognitive limitations) and teams (social behaviors).

>> A Unified Definition

  • You have said "architecture" ?

    Systems Architecture is a generic discipline to handle objects (existing or to be created) called "systems", in a way that supports reasoning about the structural properties of these objects.

    Depending on the context, Systems Architecture can in fact refer to:

    • the architecture of a system, i.e. a model to describe/analyze a system
    • architecting a system, i.e. a method to build the architecture of a system
    • a body of knowledge* for "architecting" systems while meeting business needs, i.e. a discipline to master systems design. 
      * consisting in: concepts, principles, frameworks, tools, methods, heuristics, practices

    At this point, we can only say that the "architecture of a system" is (similarly to the one of a building) a global model of this system consisting of:

    • a structure
    • properties (of various elements involved)
    • relationships (between various elements)
    • behaviors & dynamics
    • multiple views of the system (complementary and consistent).

  • But what is a "complex system" ?

    Systems are typically objects designed by men, involving heterogeneous components (e.g. hardware, software, humans) working together to perform a mission. The complexity of a system will mainly come from two aspects:

    • integration of components: there are many interrelations between a possibly huge number of components, and there are recursive levels of integration
    • heterogeneity of components: several specialized fields are involved in the design of a complex system, making it difficult to keep a unified vision of this system and to manage its design.

    You can read further explanations on complex systems. We will not describe here the numerous issues raised (at every level of a company: corporate strategy, marketing, product definition, engineering, manufacturing, operations, support, maintenance, etc) by the design and management of such complex systems. But every experienced business leader, manager, consultant or engineer will perfectly know what we are talking about. These issues can be summarized as:

    • going from local to global, i.e. mastering integration and emergence
    • building an invariable architecture in a moving environment.

  • And so, Systems Architecture is ... ?

    In this context, Systems Architecture is a response to the conceptual and practical difficulties of the description and the design of complex systems. Systems Architecture helps to describe consistently and design efficiently complex systems such as:

    • an industrial system (the original meaning of Systems Architecture)
    • an IT infrastructure (Enterprise Architecture)
    • an organization (Organizational Architecture)
    • a business (Business Architecture)
    • a project (Project Architecture?).

    Systems Architecture will often rely on a tool called an architecture framework, i.e. a reference model to organize the various elements of the architecture of a system into complementary and consistent predefined views allowing to cover all the scope of Systems Architecture. Famous architecture frameworks are for example DoDAFMoDAF or AGATE.

    Finally, Systems Architecture will consider any system with a socio-technical approach (even when dealing with a "purely technical" system). In particular, during the design (or transformation) of a system, the systems in the scope of this design (or transformation) can be divided in two separated systems in interaction :

    • the product, i.e. the system being designed or transformed
    • the project, i.e. the socio-technical system* in charge of the design or transformation of the product. 
      * teams, tools, other resources and their organization following strategies & methods

>> Fundamental Principles

Whatever the type of system and the acception considered (model, method or discipline), Systems Architecture is based on 9 fundamental principles :

  • "Thinking with a systemic approach"
    1. the objects of the reality are modelled as systems (i.e. a box performing a function and defined by its perimeter, inputs, outputs and an internal state)
      Ex: a mobile phone is a system which takes in input a voice & keystrokes and outputs voices & displays. Moreover, it can be on, off or in standby. Overall, the phone allows to make phone calls (among other functions).
    2. a system can be broken down into a set of smaller subsystems, which is less than the whole system (because of emergence)
      Ex: a mobile phone is in fact a screen, a keyboard, a body, a microphone, a speaker, and electronics. But the phone is the integration of all those elements and cannot be understood completely from this set of elements.
    3. a system must be considered in interaction with other systems, i.e. its environment
      Ex: a mobile phone is in interaction with users, relays (to transmit the signal), reparators (when broken), the ground (when falling), etc. All these systems constitue its environment and shall be considered during its design.
    4. a system must be considered through its whole lifecycle
      Ex: a mobile phone will be designed, prototyped, tested, approved, manufactured, distributed, selled, used, repaired, and finally recycled. All these steps are important (and not only the moment when it is used).
  • "Reasoning according to an architecture paradigm"
    1. a system can be linked to another through an interface, which will model the properties of the link
      Ex: when phoning, our ear is in direct contact with the phone, and there is therefore a link between the two systems (the ear and the phone). However, there is a hidden interface : the air! The properties of the air may influence the link between the ear and the phone (imagine for example if there is a lot of noise).
    2. a system can be considered at various abstraction levels, allowing to consider only relevant properties and behaviors
      Ex: do you consider your phone as a device to make phonecalls (and other functions of modern phones), a set of material and electronics components manufactured together, or a huge set of atoms ? All these visions are realistic, but they are just at different abstraction levels, whose relevancy will depend on the context.
    3. a system can be viewed according to several layers (usually three: its sense, its functions, and its composition)
      Ex: a phone is an object whose sense is to accomplish several missions for its environment : making phone calls, being a fashionable object, offering various features of personal digital assistants, etc. But it is also a set of functions organized to accomplish these missions (displaying on the screen, transmitting signal, delivering power supply, looking for user inputs, making noise if necessary, etc). And finally, all these functions are implemented through physical components organized to perform these functions.
    4. a system can be described through interrelated models with given semantics (properties, structure, states, behaviors, datas, etc)
      Ex: from the point of view of properties, the phone is a device expected to meet requirements like "a phone must resist to falls from a height of one meter". But a phone will also change state : when a phone is off and that the power button is pressed, the phone shall turn on. Function dynamics of the phone are also relevant: when receiving a call, the screen will display the name and the speaker will buzz, but if the user presses no button the phone will stop after 30 secondes... This will typically be described with diagrams in SysML (an evolution of UML).
    5. a system can be described through different viewpointscorresponding to various actors concerned by the system.
      Ex: commercials, designers, engineers (in charge of software, electronics, acoustics, materials, etc) users, repairers... All these people will have different visions of the phone. When the designer will see the phone as an easy-to-use object centered on the user, the engineer will see it as a technological device which has to be efficient and robust. A commercial may rather see it as a product which must meet clients' needs and market trends to be sold. All these visions are important and define the system in multiple and complementary ways.

>> Socio-Cognitive Aspects

Systems Architecture involves multiple views (sometimes partial or conflictual) of the same system by multiple actors. These views can be understood as "projections" of the system in the spaces of those different actors:

  • this is the set of all those views (themselves involving several interrelated models at different abstraction levels) which define the system. But it is in general impossible to define a system in an objective, unified and exhaustive way.
  • each view is an analytical description of the system. However, complexity of systems and their architecture cannot be grasped by an analytical decomposition. Considering multiple viewpoints allows to compensate the weaknesses of analytical decomposition (which is the only one we can handle as humans), following the ideas of Edgard Morin and Jean-Louis Le Moigne.

Moreover, social and cognitive aspects of Systems Architecture are absolutely critical to carry out a successful design. Indeed, Systems Architecture is key to make individual and collective work more efficient in projects, in order to meet business needs (quality, delays, performances, costs, risk):

  • for individuals, Systems Architecture is a powerful tool helping to overcome the complexity of systems and to keep a vision of their work. It allows to describe, model and design systems in a rich and diverse way, while keeping a good usability of the objects handled and improving decision making. For instance, cognitive rules as "7x7x7" (i.e. for one model, there must be at most 7 elements per level and at most 3 recursive levels) will allow people to work efficiently with their cognitive limitations.
  • for teams, Systems Architecture proposes a common language to understand and be understood. It is also a strong tool & method to facilitate collaboration in projects and to create transversality between departments of a company, while allowing to make the right questions emerge in the discussion. In particular, it can help actors to create a shared vision of the system and to converge on various issues. For example, the rule "Every element of the architecture of a system must have an owner" will help teams to advance their work without losing traceability of responsabilities.

Finally, Systems Architecture is not only a model or a method to design complex systems. It is more of a discipline, allowing to consider at the same time the system and the project in charge of it, while overcoming the difficulties related to the complexities (technical, social and cognitive) of the system and its design
As a discipline, Systems Architecture has its own practical rules & heuristics, as much as powerful best practices coming from various fields. These points have not been addressed in the scope of this introduction, and can be found for instance in this book.

Click here to learn more about my research on Systems Architecture.

For more information on Systems Architecture as a discipline, you can check this book chapter (in French). For a quality academic introduction to Systems Architecture (centered on industrial systems), you can read this paper from MIT.

***https://www.lix.polytechnique.fr/~golden/systems_architecture.html

What is Systems Architecture ?的更多相关文章

  1. 谈谈我理解的SA——Systems Architecture

    什么是SA? SA即Systems Architecture,是系统体系结构. 系统体系结构是定义系统的结构.行为和系统视图的概念模型.架构师将其系统的形式化描述或表示出来,以支持结构和行为的推理的方 ...

  2. Architecture Patterns

    This chapter provides guidelines for using architecture patterns. Introduction Patterns for system a ...

  3. (转) [it-ebooks]电子书列表

    [it-ebooks]电子书列表   [2014]: Learning Objective-C by Developing iPhone Games || Leverage Xcode and Obj ...

  4. Streaming data from Oracle using Oracle GoldenGate and Kafka Connect

    This is a guest blog from Robin Moffatt. Robin Moffatt is Head of R&D (Europe) at Rittman Mead, ...

  5. 面向服务体系架构(SOA)和数据仓库(DW)的思考基于 IBM 产品体系搭建基于 SOA 和 DW 的企业基础架构平台

    面向服务体系架构(SOA)和数据仓库(DW)的思考 基于 IBM 产品体系搭建基于 SOA 和 DW 的企业基础架构平台 当前业界对面向服务体系架构(SOA)和数据仓库(Data Warehouse, ...

  6. [Z]CS权威会议

    CS Conference TOP 40 计算机会议TOP40 一.A 类 15 个 ASPLOS: Architecture Support for Programming Languages an ...

  7. CCF推荐国际学术期刊

    中国计算机学会推荐国际学术期刊 (计算机系统与高性能计算) 一.A类 序号 刊物简称 刊物全称 出版社 网址 1 TOCS ACM Transactions on Computer Systems A ...

  8. 【转】为什么很多看起来不是很复杂的网站,比如 Facebook、淘宝,都需要大量顶尖高手来开发?

    先说你看到的页面上,最重要的几个:[搜索商品]——这个功能,如果你有几千条商品,完全可以用select * from tableXX where title like %XX%这样的操作来搞定.但是— ...

  9. Docker基础技术:AUFS

    AUFS是一种Union File System,所谓UnionFS就是把不同物理位置的目录合并mount到同一个目录中.UnionFS的一个最主要的应用是,把一张CD/DVD和一个硬盘目录给联合 m ...

随机推荐

  1. [转载+补充][PY3]——环境配置(2)——windows下安装pycharm并连接Linux的python环境

    原文地址:<你所会用到的Python学习环境和工具> 1. 下载安装Pycharm专业版 具体方法略.Pycharm5激活方法参考http://www.cnblogs.com/snsdzj ...

  2. C指针总结

    取内容* 从右至左 取地址& 从右至左 同类型指针变量关系运算是有意义的. 指针变量和数组名都表示数组的地址,但是数组名是地址常量. *p++和(*p)++不同.*p++的赋值结果跟*p相同, ...

  3. 很小的一个函数执行时间调试器Timer

    对于函数的执行性能(这里主要考虑执行时间,所耗内存暂不考虑),这里写了一个简单的类Timer,用于量化函数执行所耗时间. 整体思路很简单,就是new Date()的时间差值.我仅仅了做了一层简单的封装 ...

  4. Silverlight & Blend动画设计系列十一:沿路径动画(Animation Along a Path)

    Silverlight 提供一个好的动画基础,但缺少一种方便的方法沿任意几何路径对象进行动画处理.在Windows Presentation Foundation中提供了动画处理类DoubleAnim ...

  5. php多进程实现 亲测

    php多进程实现 PHP有一组进程控制函数(编译时需要–enable-pcntl与posix扩展),使得php能在nginx系统中实现跟c一样的创建子进程.使用exec函数执行程序.处理信号等功能. ...

  6. springboot+mybatis+thymeleaf+docker构建的个人站点开源项目(集成了个人主页、个人作品、个人博客)

    前言 My Site 主要功能有:个人首页.个人作品.个人博客为一体的站点,网站的文章和作品均由markdown进行编写,可以满足你的基本需求.如果觉得这个项目不错,请为它点赞支持. 项目架构 JDK ...

  7. Light OJ 1422 - Halloween Costumes(区间DP 最少穿几件)

    http://www.cnblogs.com/kuangbin/archive/2013/04/29/3051392.html http://www.cnblogs.com/ziyi--caolu/a ...

  8. Windows下RSA密钥生成工具openssl

    下载openssl.zip 1. 生成原始 RSA私钥文件 private_key.pem openssl genrsa -out private_key.pem 1024 2. 将原始 RSA私钥转 ...

  9. FLASK日志记录

    from flask import Flask from flask_restful import Resource, Api import logging app = Flask(__name__) ...

  10. [ZOJ1015]:Fishing Net

    题面 Vjudge Sol 给出一个n个点的无向图,询问是否为弦图 做法见上上上篇博客 # include <bits/stdc++.h> # define RG register # d ...