Micro-Frontend微前端

微前端

https://microfrontends.com/

誕生于微服務的思想和架構之上。

1）應對日志增長的前端複雜度。

2）支援按照微服務團隊，建構對應的前端代碼的獨立建構分發系統。

Web applications are getting more and more complex. Many organisations are struggling to maintain monolithic frontend codebases, and to scale their frontend development processes across multiple teams.

Micro frontends are just one approach to managing that complexity, by splitting products up into smaller, simpler applications that can be delivered all the way to production by independent, autonomous teams.

The pattern has been documented on the ThoughtWorks Tech Radar since late 2016, and has moved steadily from Assess to Trial and finally to Adopt in 2019.

https://medium.com/@tomsoderlund/micro-frontends-a-microservice-approach-to-front-end-web-development-f325ebdadc16

The monolithic approach doesn’t work for larger web apps

Having a monolithic approach to a large front-end app becomes unwieldly. There needs to be a way of breaking it up into smaller modules that can act independently.

Example:

• myapp.com/

  - landing page built with static HTML.

• myapp.com/settings

  - old settings module built in AngularJS 1.x.

• myapp.com/dashboard

  - new dashboard module built in React.

I would imagine the following is needed:

1. A shared codebase in pure JavaScript e.g. managing routing and user sessions. Also some shared CSS. Both should be as thin as possible.
2. A collection of separate modules, “mini-apps”, built in various frameworks. Stored in different code repositories.
3. A deployment system that bundles all the modules together from different repositories and deploys to a server, whenever a module is updated.

實作方案

https://medium.com/@tomsoderlund/micro-frontends-a-microservice-approach-to-front-end-web-development-f325ebdadc16

Implementing micro frontends

Here’s a few different approaches to implementing micro frontends:

1. The best solution I’ve seen is the Single-SPA “meta framework” to combine multiple frameworks on the same page without refreshing the page (see this demo that combines React, Vue, Angular 1, Angular 2, etc). See Bret Little’s explanation here.
2. Multiple single-page apps that live at different URLs. The apps use NPM/Bower components for shared functionality.
3. Isolating micro-apps into IFrames using libraries and Window.postMessage APIs to coordinate. IFrames share APIs exposed by their parent window.
4. Make the different modules communicate over a shared events bus (e.g. chrisdavies/eev). Each module can be built using its own framework, as long as it handles incoming and outgoing events.
5. Using Varnish Cache to integrate different modules.
6. Web Components as the integration layer.
7. “Blackbox” React components.

single-spa（微前端架構）

https://single-spa.js.org/docs/getting-started-overview/

優點：

1）技術無關， 可以任意選擇團隊熟悉的前端技術

2）獨立部署

3）使用新的技術，很容易。不用重構之前應用的代碼。 例如jquery，向vue的技術過度。

4）懶加載，優化初始頁面加載時間。

single-spa is a framework for bringing together multiple javascript microfrontends in a frontend application. Architecting your frontend using single-spa enables many benefits, such as:

• Use multiple frameworks on the same page without page refreshing (React, AngularJS, Angular, Ember, or whatever you're using)
• Deploy your microfrontends independently.
• Write code using a new framework, without rewriting your existing app
• Lazy load code for improved initial load time.

例子：

同一個應用，加載不同的元件，根據URL位址變化，動态加載， vue實作的元件 和  react實作的元件。

https://github.com/dabit3/micro-frontend-example

https://dev.to/dabit3/building-micro-frontends-with-react-vue-and-single-spa-52op

The tool we will be using to create our project is Single SPA - A javascript framework for front-end microservices.

Single SPA enables you to use multiple frameworks in a single-page application, allowing you to split code by functionality and have Angular, React, Vue.js, etc. apps all living together.