PROTOCOL

`TransportDriver`

public protocol TransportDriver: AnyObject

Abstract Transport Driver API

Describes anything capable of sending messages and subscribing to incoming messages (e.g. udp socket). Despite some complications due to not tracking message delivery, this is the most simple approach to bidirectional message transfer, which may be implemented via any kind of socket, http+sse etc.

Methods

`send(meta:data:)`

func send(meta: TransportMeta, data: TransportData) async throws

Send a message via transport

This method awaits until the message is sent (not until it's delivered) and throws if sending is impossible. Specific destination and delivery is handled by implementation.

Parameters

Name	Description
meta	message identifiers
data	message data

Returns

void

`on(filter:callback:)`

func on(filter: TransportFilter, callback: @escaping TransportCallback) -> String

Subscribe to specific kinds of messages

It is possible to subscribe to the same message twice, which may be used in advanced message filtering strategies.

Parameters

Name	Description
filter	incoming message filter
callback	to be invoked with messages matching to a provided filter

Returns

String

subscription identifier, used to cancel this subscription

`off(id:data:)`

func off(id: String, data: TransportData?)

Cancel an existing subscription

Does not throw if there were no subscriptions with this id. If current subscriber is actively awaiting a message one may use the optional data field to resolve that.

Parameters

Name	Description
id	subscription identifier returned upon creation
data	(optional) message data to be sent to a current subscriber’s callback

Returns

void