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Chat

Holi chat is built on top of Matrix and uses Synapse as a Matrix Server.

The frontend client is custom built in react native, but uses the Matrix JavaScript SDK to talk to Matrix. The frontend uses Jotai to manage local state and state updates. State changes are pushed from the matrix server to the frontend as events. Technically the Matrix SDK uses long polling to handle server pushed events.

The client applications connect to the matrix server directly. Authentication is managed via single sign on. See

In addition, there is a service holi-chat-integration that connects to the Matrix Server to control chat rooms that are created for Spaces. holi-chat-integration does not use the Matrix SDK, but instead sends REST calls "manually". The reason for this is, that the chat-integration is not listening to matrix events. It is only sending commands to the Matrix server or queries the Matrix server explicitly. Some of the calls are done via the Synapse Admin API. In addition the chat integration also uses it's own user to create and manage rooms. The chat-integration listens for events published by Okuna via pubsub.

Chat Frontend general Structure​

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The SDK does all the communication with the Matrix Server. Sending commands to the Matrix server happens, because a user is interaction with a Component e.g. send a message or start a new chat. For this, chat components can have "actions", which call our chat client, which internally uses the SDK to communicate the command to the Matrix server.

The other for of communication is Matrix Events, that are pushed from the Matrix server to the client. We register an EventTransformer to the SDK, that transforms incoming Matrix events into a form that is more suited to our needs. The transformed events are passed on to the store, that manages the local state in Jotai Atoms.

Components read Jotai Atoms to display Chat content, like received messages or room data, like names etc.

Chat Frontend Atom structure​

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In addition to Jotai, Chat also uses Immer to detect partial updates and prevent unnecessary rerendering.