App - Host Boundary Interfaces

The interfaces that lie at the boundary between the Host and the App are stored in this package. This package is intentionally very simple because we want to avoid changes in the boundary over time.

Architecture

The goal of this package is to establish a robust, future proof form of communication between a Host and any number of Plugin Apps. All messages that need to pass through the boundary (regardless of the direction) are formed into a Request and then dispatched to a Handler. The Handler is responsible for determining which Action this Request should be sent to.

If the message is being passed from the Host to the App, then the Host will be resposible for forming the Request and Dispatching it to a Handler, which is owned by the App.

If the message is being passed from the App to the Host, then the App will be resposible for forming the Request and Dispatching it to a Handler, which is owned by the Host.

Requests

The Request interface defines object that is allowed to pass across the boundary either from the App to the Host or vice versa. It is composed of the following:

type: string

This is the type of the request. For example: "START_APP"

version: number

This is the version of the payload for this particular request. This is used to future-proof the boundary from future changes in the Payload, particulaly in the Host handler. It allows the Host to adjust how it parses the Payload based on the version number.

payload?: uknown

This is an optional object that can be used to wrap up the data being passed through the boundary

Handler

The Handler is a simple type that defines the signature of a function that recieves a Request and retuns void.

VIVED App

This is the basic interface that any Plugin App must satisfy

mount

Mount is called when you App needs to be initialized. The App will be passed the host request handler, which is the Handler that this app should dispatch all Requests to. The App will need to return it's Handler back to whatever has mounted the app. The App can assume that must handle any Requests that are dispatched to this handler.

moundDev

This is called when the App is being developed. This should mount the Sandbox instead of the App. Later the Sandbox will mount the App.

Versioning

This package version will follow typical semantic versioning. What is important to note is that a change in the Major version indicates a breaking change. Therefore, for Hosts and Apps to be compatible, they must be built with matching major version numbers.