💡 Software Architecture Foundations

LinkedIn, Allen Holub

🪕 1. The Software Architect

UML: Unified Modeling Language, xmind

📑 Modern Architects

Agile Software Development (incremental design)

An Agile Architect (Servant 仆人 Leader) duty:

• teaching, coaching, coordinating
• main design responsibility: assures coherence(连贯性) across the system (reviews work, makes suggestions, helps refine process)
• guide, direction, collaboratively, make decisions
• Researching is part of job: programmers, conferences, vendors, operations

Daily work

• 9:00am meeting: ba, po, tech leader, scrum master, developers, ui/ux designers, db experts, testers, devops,
• 10:30am: Sprint Review
• 2:00pm: techincal understanding and availibility, trade-offs(权衡), innerconnections, etc(open-source research, license, dependencies, firewall setup, backup, searching engines, kubernates, i18n, cloud/api integration)
• meetup, work collaboratively

Good Architecture

• Simplicity
• Maintainability
• Testability

📑 Thinking Architecturally

• Conway’s law: Architecutre and organization structure
• Story: a description of the user’s work - a story touches every piece of the system
• Agile Incremental Designs: Customer, Stories, Technology
• DDD (Domain-Driven Design): The structure of your code should map to the structure of the problem domain.( =300x200)
• ubiquitous language(无处不在的语言) in DDD: universal notation, such as SKU=order item,
• JIRA, Sticky notes
• -

📑 System vs. enterprise architecture (EA)

Broad architectural patterns

📑 monolith 整体式

• homogeneous (同质) structure, heterogeneous (异质), Protocol Aware Heterogeneous Interoperability (协议感知异构互操作性)
• N-Tier

📑 Microkernel(plugin) architecture

• Isolation prevents big ball-of-mud dependencies
• Plugins are small and easy to write, debug, and maintain

📑 Message-based architectures

• producer, broker, consumer
• Pub/Sub Model
• messaging infrastructure

📑 Microservices and miniservices

• Small (few hundred lines of source codes)
• independently deployable
• fully autonomous(自主性)
• distributed
• Highly observable
• Modeled around business concepts

📑 Reactive and choreographed(编排) systems

🪕 2. Microservices Foundations

• Decompositions, System Decompositions
• polyglot (多种语言) development support
• All communications over ReST/GraphQL
• The stages of evolution in modern software servicce architectures, from oldest to most modern are: N-Tier, SOA, Microservices
• BPEL (Business Process Execution Language) is an XML-based language that allows Web services in a service-oriented architecture (SOA) to interconnect and share data. Programmers use BPEL to define how a business process that involves web services will be executed.
• ACID: atomic, consitent, isolated, durable transaction
• BASE

🪕 3. Node.js: Design Patterns

📑 Creational Patterns

• singleton
• prototype
• factory

• builder

  class Person {
  	constructor(builder) {
  		this.name = name;
  		this.isEmployee = builder.isEmployee;
  		this.shoppingList = builder.shoppingList || [];
  	}
  	toString() {
  		return JSON.stringify(this);
  	}
  }
  class PersonBuilder {
  	constructor(name) {
  		this.name = name;
  	}
  	makeEmployee() {
  		this.isEmployee = true;
  		return this;
  	}
  	build() {
  		return new Person(this);
  	}
  }
  const bill = new PersonBuilder("Bill").makeEmployee().makePartTime().build();
  console.log(bill.toString());

📑 Structural Patterns

• adapter: 兼容不同环境，比如 browser 环境和 nodejs 环境的兼容。
• proxy
• composite 综合
• decorator

See github/test/my-package

📑 Behaviral Patterns

• command
• iterator
• observer
• strategy

See node-js-design-patterns

🪕 4. Software Architecture Patterns

📑 Design Patterns vs. Architecture Patterns (higher level)

📑 Categories of patterns (3)

• Application Landscape Patterns

  • Monolith
  • N-tier (BusinessTier, DataTier, PresentationTier, …)
  • Service-oriented
  • Microservices
  • Serverless
  • Peer-to-peer (discoverable)

• Application Streucture Patterns

  • Layered
  • Microkernel
  • Command Query Responsibility Segregation (CQRS)
  • Event sourcing
  • Command Query Responsibilityy Segregation and event souring combined

• User Interface Patterns

  • Model-view-controller(MVC)
  • Model-view-presenter (MVP)
  • Model-view-viewmodel (MVVM)

📑 Application Landscape Patterns

• SOA: Service-Oriented Architecture

• Microservices

  • Docker, containers
  • No logic-heavy enterprise serivce bus
  • Teams run multiple services independently
  • Each service is a business activity
  • Loosely coupled and easily scalable, reliability, designed to handle failures

• Serverless

  • Backend as a Service
  • Function as a Service
  • Cold Start
  • AWS cloud

• Peer-to-Peer

  • Share resources

📑 Application Structure Patterns

• Layered

  • Easy to organize

• Microkernel: Plugin Pattern, flexibility, separate

  • Taskk scheduler
  • Workflow
  • Data processing
  • Browser
  • Graphic designer

📑 UI Patterns

MVC, MVP, MVVM Similarities:

• Decoupling view and model
• Extra component in between
• Increased testability
• Web: MVC; Desktop: MVP; Morden/Mobile: MVVM