Micro Frontends “Extending the microservice idea to frontend development”. What does it really mean? Is it just abusing a certain hype? Should I consider it? How should I approach it? These are just some of the questions one might ask when presented with this notion. Long story short – Micro front-ends are a reality! However, it is not for everyone. In this session, we’re going to demystify micro frontends. We’re going to establish what it is, when it should be considered and the decisions to be made

1. Micro Frontends
Myth or Reality?
Amir Zuker
Senior Software Architect
Founder, Web Division Leader
Twitter: @AmirZuker

2. About Me
2
Amir Zuker
 Senior software architect, instructor, speaker and developer
 Over 20 years of experience in the field
 Designed and developed various systems, both backend and frontend
 Mentored and lead large teams and R&D divisions
 Publications
 Book: HandsOn Full-Stack Web Development with ASP.NET Core
 Open source: WCF Contrib
 WCF Microsoft Official Curriculum (MOC)
 Leads the WEB division at CodeValue

3. The Idea of Micro Frontends
3

4. 4
What is
Micro Frontends?

5. 5
"Extending the microservice idea
to frontend development"
https://micro-frontends.org/

6. Microservices
 A vast subject
 Out of scope
 In relevance to this talk
 Decompose the monolith to smaller parts
 Each part is independently managed, versioned and deployed
 Tailor parts together to form features
 And well.. polyglot
6

7. 7
"Web app as a composition of
features which are owned by
independent teams.
..using different JavaScript
frameworks"
https://micro-frontends.org/
not necessarily

8. Why though? It's Frontend!
 It normally boils down to the same technology (JavaScript mostly)
 It all runs in the same host and process (browser mostly)
 It's.. well.. UI!
8

9. 9
The bigger you are
and more versatile and
agile you need to be..
The more likely you are
to benefit from micro-frontends

10. Not an Entirely New Concept
 Having small parts which are managed independently
 ..plugged into the entire app
 ..able to integrate and interact
 Not a new concept
 Composite or Widget-based Apps
 Facebook
 WordPress
 SharePoint
10

11. Let's Get Practical
11

12. 12
Decompose, How?

13. Decomposition Strategies
 There are various ways to decompose apps
 Functional feature-based verticality
 Domain driven and business concerns
 Organizational, team structure and responsibility
 Can consider some parity with the backend
 It really depends
13
App Svc1 Svc2

14. Decomposition
 Effective decomposition is crucial
 Beware of the Big Ball of Mud (BBOM)
 A "distributed monolith" in backend semantics
 Difficult to get it completely right
 Observe and change accordingly
14

15. 15
Checkout
Exploration
Decompose
Apps

16. 16
Let's Get Technical

17. No Single Truth
 There are always multiple ways to achieve your goal
 Essentially, determine the shared foundation for integration
 Key approaches
 Technology agnostic
 Technology specific
 A big spectrum in between
17

18. Technology Agnostic
 "New" interoperable standards have solidified
 Web Components!
 Basically, leverage the HTML DOM as the shared foundation
 Custom Elements
 Input and Events
 More complex
 Requires higher discipline
18
HTML DOM
JS, TS
Core SDK
Micro
App
Micro
App
Micro
App

19. 19
Custom Elements
<shell>
<exploration-category-page category="art">
<checkout-offerings id="232">
offerElem.addEventListener(
'selected',
() => { … });
Input
Events

20. Technology Specific
 Expand the shared foundation
 Settle on a specific set of additional frameworks
 Manage it across teams and products
 Easier when applicable
 Less flexible
20
HTML DOM
JS, TS
Vue.js, Vuex, Vue Router
Core SDK
Micro App Micro App Micro App

21. 21
Wait, does it mean that my Vue apps,
split into separate packages which are
independently managed and integrated..
Technically, in a sense, YES!
AM I DOING MICRO FRONTENDS?

22. Demo
Custom Element
22

23. Writing Web Components
 Controversial
 Can be tedious and convoluted
 Don't have to implement web components directly
 Higher level frameworks still provide incredible value
 Going with web components is not a problem free path
 Prefer to register components quickly
 Shadow DOM and theme-ability
 Server-side rendering (web components are a browser phenomenon)
 Accessibility
 SEO
23

24. Frameworks and Custom Elements
 Can be built using several frameworks, e.g. –
 Vue CLI Build Target / vue-web-component-wrapper / vue-custom-element
 Svelte 'customElement' compiler option
 Angular Elements
 Stencil
 Polymer
 Etc.
 Check integrability of frameworks with custom elements
 https://custom-elements-everywhere.com/
24

25. Which? It Depends
25
x50

26. Demo
micro-frontends
26

27. But Wait, There's More
27

28. Crosscutting Concerns
 Data and State
 Separate / Namespaced / Shared
 Events BUS
 Routing and Links
 Internationalization
 Network
 Logging
 Error Handling
 Dialogs
28
 Busy / Spinner
 Undo / Redo
 Notifications
 Configuration
 AUTH
 Theming
 Responsiveness
 Style Guide
 Storage and cookies
 Etc..

29. Crosscutting Concerns
 Data and State
 Separate / Namespaced / Shared
 Events BUS
 Routing and Links
 Internationalization
 Network
 Logging
 Error Handling
 Dialogs
29
 Busy / Spinner
 Undo / Redo
 Notifications
 Configuration
 AUTH
 Theming
 Responsiveness
 Style Guide
 Storage and cookies
 Etc..

30. Core SDK (shared code)
 Keep it minimal and as needed
 Try to keep it on top of the chosen foundation
 HTML DOM or Frameworks
 Creates a technical debt
 Requires proper management and mandate control
30

31. Code Splitting
 Size matters in Web
 The more frameworks and code, the bigger the assets
 Consider effective..
 Tree-shaking
 Lazy loading
 Preloading
 Invest in code splitting enabler patterns and pick the right tools
 E.g. Webpack externals / Webpack module federation / Rollup for micro parts /
Webpack for shell / etc.
31

32. Encapsulation Isolation
 Micro apps still run in the same host (browser window)
 Think about different framework versions
 Require true isolation?
 Consider <iframe> and window.postMessage
 Caveats
 Integration is more complex
 More so in case of intertwined micro apps
 Shared assets can be downloaded multiple times
 Seamless UX is difficult
32

33. Server-side Rendering
 Working with <iframe> can get you there
 However, has its drawbacks
 Consider server-side includes (web server feature)
 Or other edge-side include (ESI) enabler frameworks
 E.g. Tailor, nodesi, ESI, compoxure
33
<checkout-offerings id="232">
<!--#include virtual="/checkout/offerrings?id=232" -->
</checkout-offerings>

34. Productivity
 Productivity is paramount
 Process, Collaboration, Integration, Sharing, Testing and Distribution
 Care about..
 Feature flags
 Repo management, methodologies and tools
 Test and Automation
 Showcases
 Self executable micro apps
 Versioning
 Releases
 DevOps
34

35. You're Not Alone
 Tools and frameworks can help of course
 Project Mosaic
 https://www.mosaic9.org/
 Single-SPA
 https://single-spa.js.org/
35

36. 36
Micro Frontends
Comes at a cost..

37. 37
Micro Frontends
Don't blindly ride hype trains

38. 38
Micro Frontends
Do what is right for you..

39. Ask Yourself..
 Do you have an excessively large or multiple frontend products?
 Do you need to scale and effectively manage dozens of developers?
 Do you require high agility and versatility in your frontend products?
 Do you need to support flexible pluggability (widget / micro-apps style)
 Are you willing to invest and adjust?
 Organization-wise, process, development, ecosystem, DevOps pipelines, etc.
39

40. 41
Micro Frontends
It's a journey..

41. Resources
 WebComponents.org
 https://www.webcomponents.org/
 Micro-Frontends.org
 https://micro-frontends.org/
 Integrability of frameworks with custom elements
 https://custom-elements-everywhere.com/
 Project Mosaic
 https://www.mosaic9.org/
 Single SPA
 https://single-spa.js.org/
 Demos
 https://github.com/azuker/micro-frontends
42

42. Amir Zuker
Senior Software Architect
Founder, Web Division Leader
Twitter: @AmirZuker