Toolkit architecture

The toolkit consists of a set of packages, the idea being you can use whatever you want out of it and swap out pieces for alternative implementations. For example, if you don’t want to use Fluid Framework for transport, you just need to provide some other implementation of ITransport and everything else should still work.

Here is the dependency diagram of the various packages:

flowchart TD
    A[primitives] --> B
    A[primitives] --> C
    A[primitives] --> D
    A[primitives] --> F
    A[primitives] --> G
    B[state-machine] --> G
    C[action-queue] --> G
    D[singed-transport] --> G
    E[fluid-client] --> G
    F[cryotography] --> G
    G[types]

The primitives package depends on most other packages since it aims to implement some common operations you can plug into your own games “off the shelf” (see the demos).

All other packages depend only on the types package, which declares common types and interfaces.

Conceptually, the layering of the toolkit is:

flowchart TD
    A[State Machine] --> B
    B[Action Queue] --> C
    C[Transport]

At the bottom, we have the transport. The transport just sends messages (actions) and emits events for incoming messages (actions). This maps closely to and is informed by the way Fluid works. See Total order broadcast & eventual consistency.

The toolkit offers an abstraction over the transport, which encapsulates consuming already received message, eventing on incoming new messages, and posting messages from our clients in to a simple async queue which provides only a dequeue(): Promise<T> and an enqueue(value: T): Promise. This significantly simplifies using the transport.

The state machine helps modeling games. In general, a game is modeled as a sequence of steps. Sometimes we need to run some code locally (and usually send a message over the transport when we’re done), sometimes we expect to receive a message and run some code in reaction to that. The state machine helps us declare such sequences and run them given a queue and some context.

See modeling games for details on how to consume the toolkit.