[Discussion] UI aggregator / gateway / fragment service

First at all that project seems really promising, far better then Zuul 1 version!

Last day I was talking with @dsyer about designing/prototyping a kind of layout service / ui composition service (whatever the name) inspired from Zalando Tailor project (from global Mosaic project - Microservices for the Frontend).

Goal of such service is to avoid getting a well designed and decoupled backend service used by a big monster monolith (SPA?) frontend. Each microservices could be responsible on their own frontend/ui fragments, layout service / ui composition service will be only responsible to aggregate every fragments using a base/master template and returns it.

I wanted to develop by myself a kind of closely inspired fork to Zalando Tailor but using Java + Spring 5 + Spring Boot 2.0 + Reactor. Though I really need such piece of service on my current stack, at start that project was also a good candidate for training myself to Spring 5 + Spring Boot 2.0 + Reactor.

When I spoke that to @dsyer I also proposed an possible architecture based on Zalando one

And mine (Yes is a totally a clone of Zalando one :trollface: )(Attention is a prototype, any box is not necessary a dedicated services. Is more a logical view)

At this point, @dsyer ask me why I have separated gateway and layout service. I don't really have a clear answer but in my mind, only reasons was separation of concerns and resilience (if layout service get down, you can continue using API). But I didn't think more.

That why I open you an issue (is more a discussion, I'm not asking feature request) to

1. Have your feedback to such service in microservices/cloud architecture
2. Your point about integrating it inside gateway or should be a dedicated services

Existing alternative or similar project to Zalando Tailor

• https://www.facebook.com/notes/facebook-engineering/bigpipe-pipelining-web-pages-for-high-performance/389414033919/ (BigPipe from Facebook)
• https://github.com/opentable/oc
• https://github.com/acesinc/convergent-ui
• https://github.com/lsm/micromono#doc_render_page
• (Play Framework) https://www.youtube.com/watch?v=4b1XLka0UIw

Here some sources of inspirations about Microservices for Frontend topic:

• https://www.mosaic9.org/
• http://scs-architecture.org/
• https://www.youtube.com/watch?v=vCzTK4XPfX8
• https://www.youtube.com/watch?v=jJxmi8nrHwg&index=83&list=PLe1TplHMknuLAvTNaAqvqHchuZqC-70Gr
• http://allegro.tech/2016/03/Managing-Frontend-in-the-microservices-architecture.html
• http://blog.xebia.com/the-monolithic-frontend-in-the-microservices-architecture/
• https://www.infoq.com/presentations/html-components-services

This is an architectural discussion about a UI aggregator or gateway, not an implementation request, and it names no project files, tests, or code entry points. Start by reviewing the proposed Zalando Tailor-inspired architectures and the question of integrating the layout service into the gateway. Done would require a maintainer decision on scope and architecture before implementation can be defined.