6 Things You Should Know About MicroFrontends @ngCopenhagen, Juni 2020

@ManfredSteyer ManfredSteyer 6 Things You Should Know About Micro Frontends
Manfred Steyer, ANGULARarchitects.io Angular Copenhagen

@ManfredSteyer Do you remember her? Bonnie Barstow, PhD

@ManfredSteyer Software Engineering is a Team Sport

@ManfredSteyer Coordination b/w Teams

@ManfredSteyer Monolith Flight System

@ManfredSteyer Booking Service Check-in Service Boarding Service Luggage Service Microservices
Sub-Domains (DDD)

@ManfredSteyer Booking App Check-in App Boarding App Luggage App Microfrontends

@ManfredSteyer Lots of Questions …

@ManfredSteyer About me… Manfred Steyer, ANGULARarchitects.io (Remote) Angular Workshops and
Consulting Google Developer Expert for Angular Trusted Collaborator in the Angular Team Manfred Steyer

@ManfredSteyer How to implement Microfrontends? ?

@ManfredSteyer Several Options • Hyperlink-Integration • Loading Web Components into
your index.html • Loading separate SPAs into your index.html • Loading separately compiled Angular Modules • Webpack 5 Module Federation

@ManfredSteyer DEMO: Webpack 5 Module Federation

@ManfredSteyer How To Identify Good Sub-Domains and hence Microfrontends?

@ManfredSteyer Request Product Specify Order Approve Order Send Order Budget
Hierarchy Employee IT-Expert Manager Buying Agent Product Organizational boundaries like departments or different domain experts Different models or same entities w/ different meaning

@ManfredSteyer "Right" Domain Size Should mirror a real-world domain Large
enough: Most use cases don't overlap domains Small enough: One team per domain

@ManfredSteyer Domain Driven Design gives a lot of advice! Also
see blog at: http://angulararchitects.io

@ManfredSteyer Monorepo or Polyrepo?

@ManfredSteyer Catalog Approval Shared Feature Feature Feature Feature Feature …
… … … … … … … … @ManfredSteyer Catalog App Approval App Option 1: One Monorepo w/ several Domains

@ManfredSteyer Consequences Easy to share code Decoupling b/w domains: Conventions
or Tools (Linting) Easy to enforce one version policy Different technologies: possible

@ManfredSteyer Catalog Approval Shared Feature Feature Feature Feature Feature …
… … … … … … … … @ManfredSteyer Catalog App Approval App Option 2: One Repo per Domains Publish shared libs seperately via npm

@ManfredSteyer Consequences Enforces decoupling b/w domains Allows different versions (good
or bad?) Allows different technologies Needs lots of automation Sharing Code via npm and versioning might be a pain

@ManfredSteyer Recommentation, if you are not sure Start with a
monorepo Enforce decoupling via linting Reconsider splitting into several repos later

@ManfredSteyer Pro Tip: Tooling for Monorepos https://nrwl.io/nx

@ManfredSteyer Communication

@ManfredSteyer Communication is a Trade-Off Decoupled Sub-Domains Communication b/w Sub-Domains

@ManfredSteyer Ideas As little as possible! Messaging/ Eventing: Loosly Coupling
Trigger a (Domain) Event Don't expect an answer!

@ManfredSteyer Very Simple Message Bus @Injectable({ providedIn: 'root' }) export
class MessageBus { events$ = new ReplaySubject<DomainEvent>(1); }

@ManfredSteyer Also Consider: Server-Side Messaging µService µFrontend µService µFrontend µService
µFrontend

@ManfredSteyer Redux for Communication?

@ManfredSteyer Well … Don't directly share state b/w sub-domains (coupling!)
You might use Redux for eventing (like a Message Bus)

@ManfredSteyer Sharing Widgets

@ManfredSteyer Sharing Widgets is a Trade-Off too Decoupled Sub-Domains Shared
Widgets Prevent duplicate code (DRY) Separate Ways

@ManfredSteyer Recommentation Technical Widgets (e. g. Design System): Sharing ok
Use Case-specific widgets: Try to avoid (coupling!)

@ManfredSteyer You can't have both: Decoupling and DRY ! Know
your Architecture Goals!

@ManfredSteyer Good Message: Very often, Separate Ways DOES NOT mean
duplicate code!

@ManfredSteyer Catalog Approval Bounded Context Ubiquitous Language

@ManfredSteyer Bounded Context per Sub-Domain Also see blog at: http://angulararchitects.io

@ManfredSteyer Web Components

@ManfredSteyer Web Components can be useful, esp. if you have
to mix several technologies

@ManfredSteyer Shadow DOM helps to isolate styles (emulated by default
in Angular)

@ManfredSteyer Also, lazy loading separately deployed web components is easy

@ManfredSteyer µService µApp3 µApp2 µApp1 Shell Web Components for Macro-Architecture
Shared Widget Shared Widget Shared Widget Web Components for shared Widgets

@ManfredSteyer Authentication and Authorization

@ManfredSteyer Possibilities HTTP Only Cookie: Tunnel through one origin (+XSRF
Token) Token via Header: Different origins (consider OAuth2/OIDC) • Share token via message bus or session storage

@ManfredSteyer Microservice per Microfrontend?

@ManfredSteyer Recommendation: Verticals µService µFrontend µService µFrontend µService µFrontend

@ManfredSteyer Backend for Frontend (BFF) BFF µFrontend BFF µFrontend BFF
µFrontend µServices µServices µServices µServices

@ManfredSteyer Nevertheless, try this approach if possible! µService µFrontend µService
µFrontend µService µFrontend

@ManfredSteyer Dashboards

@ManfredSteyer Dashboard: Special Forces Decoupled Sub-Domains Dashboard Data and widgets
from each subdomain

@ManfredSteyer Approaches Dashboard loads widgets from each sub-domain • Flexibility
• Needs stable contracts • Agreements on common look and feel • Lots HTTP Calls Dashboard as a own sub-domain • Pros and Cons are inversed

@ManfredSteyer Backend for Frontend (BFF) Dashboard µBFF Dashboard µFrontend BFF
µFrontend BFF µFrontend µServices µServices µServices µServices Messaging

@ManfredSteyer Free eBook ANGULARarchitects.io/book Updated for Module Federation and Alternatives

@ManfredSteyer Challenge

@ManfredSteyer ngx-Snake MIT License Credits: Samir Hodzic

@ManfredSteyer DEMO

@ManfredSteyer Conclusion Main Purpose of µFrontends: Scaling Teams Decoupling Federation:
Import From Other App Know Your Domain! Communication & Sharing → Trade-off Monorepo vs. Polyrepo

@ManfredSteyer Contact and Downloads [web] ANGULARarchitects.io [twitter] ManfredSteyer d Slides
& Examples Remote Company Workshops and Consulting

6 Things You Should Know About MicroFrontends @...

6 Things You Should Know About MicroFrontends @ngCopenhagen, Juni 2020

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