Microservices ...

on frontend

Rafał Warzycha

@rwarzycha

  • fullstack JS dev
  • speaker
  • podcast co-host - just4fun.io 
  • conference maniac

Rafał Warzycha

Why micro-services?

  • loosely coupled
  • reduce time-to-market
  • release new feature quickly
  • ability to innovate independently

Who is using it?

  • Spotify
  • Zalando
  • ConopyTax
  • ...
  • Allegro :)

Pros

  • each service maintained by separate team
  • best tools for different jobs
  • single responsibility
  • better scaling and composability

Cons

  • large complexity up front - (architecture, APIs, separation of concerns)
  • writing your own framework
  • challenging cross-component
  • communication 

Modern frontend isn't easy

  • managing multiple dependencies (JS bundle, CSS, etc)
  • interaction between fragments (scaling)
  • telemetry done in consistent way (headers tracking)
  • customer plugins / later customization
  • A/B testing
  • error handling/performance issue tracability
  • many devices: browsers, mobile, smartTV
  • omnichannel - excellent UI across all places

Principles

  • dynamic page creation - CMS-like
  • reusable components
  • separation Data vs View
    • many Views: Web, Mobile, other
    • many Data-Source: REST, decoupled
  • conditional Rendering - testability (A/B), time specific events, user-profile based rendering 
  • consistent telemetry
  • separate page definition from renderer
  • single integration with backend (API, Event Bus)
  • dependency management

Building blocks

  • browser APIs
    • IFrame, postMessages, broadcastChannel, storage events
  • components API
    • React
  • server side rendering
    • NodeJS, PM2
  • HTTP cache
    • Varnish
  • event bus, event emmiters
    • eev

Approaches

  • multiple SPA, multiple URLs
    • apps live under different URls
  • isolated micro-apps
    • IFrame :(
    • Windows.postMessages API for communication
  • multiple WebComponents/Polymer
    • API support over browsers
  • reverse proxy Varnish Cache
    • conditional rendering
  • service oriented async loader - requireJS, Sofe
  • server side rendering

API gateway pattern

SSR Loader

Comparison by complexity level

Router-based components

  • separate apps
  • simple setup
  • universal router

IFrame API

  • plain HTML API
  • cross-browser compatibility issues
  • loading and bundling imprints

WebComponents API / Polymer

  • Custom Elements
  • Shadow DOM
  • HTML Imports
  • HTML Templates

WebComponents support

Varnish reverse cache proxy

  • more cache focused
  • simple if/switch template loaders using Edge Side Includes (ESI)
  • render separation

SSR React component loader

  • stable stack - nodejs, 
  • homogeneous components (React only)
  • cache/crawlers friendly
  • bundle consideration - shared lib, version handling

The End

Q&A

Sources

Microservices

By Rafał Warzycha

Microservices

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