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3.2 Namespace

It's compulsory to specify a unique namespace for a Component Container. The namespace of a Component Container helps to make sure the Component Container state store & actions dispatch won't interfere other Component Container.

A Component Container namespace is a string that may contain / character as namespace parts sperator. It's recommended that to construct the Component Container Namespace as Reverse domain name notation of your registered domain + / + Component Name to avoid name-space collisions. e.g. io.github.t83714/RandomGif as shown in sample above.

Please note: Here, the Component Container Namespace (e.g. io.github.t83714/RandomGif) is NOT the full runtime namespace (or we call Full Namespace Path). The Full Namespace Path will be automatically created for each Component Container instance using the following parts:

  • Namespace Prefix: fractal-component will lookup this value from react component's namespacePrefix property (default value is empty string). It's an interface reserved for component users. A component user can use it to put component namespace to a particular position (of the Namespace Tree) to control action delivery without impacting component's internal logic.
  • Component Container Namespace: That's the namespace we specified when register component. e.g. io.github.t83714/RandomGif
  • Component ID: It's a unique ID auto-generated to make sure any two Component Containers' Full Namespace Paths are different.

One example of the Full Namespace Path could be:

`Namespace Prefix`          `Namespace`                 `Component ID`
  exampleApp          /  io.github.t83714/RandomGif   /       c0

3.2.1 Namespace Tree & Action Dispatch

The namespace system in fractal-component is similar to file system path. It consists of namespace path parts that are seperated by / delimiting character. It also supports relative path calculation:

Suppose the Full Namespace Path of a component is exampleApp/io.github.t83714/RandomGif/c0 A relative path: ../.. will be resolve to exampleApp/io.github.t83714 for this component.

All registered (in an AppContainer) components' Full Namespace Paths forms a Namespace Tree. Below is an example of the Namespace Tree structure:

Namespace Tree structure diagram

The namespace of the containers included in the diagram are:

  • Component Container A:
    • Full namespace Path: ExampleApp/GifPair/io.github.t83714/RandomGif/c0
    • Namespace: io.github.t83714/RandomGif
    • Namespace Prefix: ExampleApp/GifPair
  • Component Container B:
    • Full namespace Path: ExampleApp/GifPair/io.github.t83714/RandomGif/c1
    • Namespace: io.github.t83714/RandomGif
    • Namespace Prefix: ExampleApp/GifPair
  • Component Container C:
    • Full namespace Path: ExampleApp/io.github.t83714/Counter/c0
    • Namespace: io.github.t83714/Counter
    • Namespace Prefix: ExampleApp

fractal-component allows actions to be dispatched from any namespace node in the namespace tree by specify the relativeDispatchPath. The relativeDispatchPath is calculated from Full namespace Path of a Component Container. i.e. Suppose Component Container A dispatches an action from relativeDispatchPath:

../../..  (Up 3 levels from "ExampleApp/GifPair/io.github.t83714/RandomGif/c0")

Then, the actual action dispatch namespace node would be ExampleApp/GifPair in the Namespace Tree.

If the relativeDispatchPath is specified as ../../../*, the action is a multicast action. For multicast actions, all lower levels namespace nodes will receive the actions. i.e. multicast actions will always be sent down the Namespace Tree. In this case, Container A & Container B will receive the multicast action as they are lower level nodes of dispatch point ExampleApp/GifPair. Container C won't receive the actions.

There are two ways to dispatch namespaced actions in component: