Implement websocket server

src/http/kernel/HTTPKernel.ts

@@ -35,16 +35,6 @@ export interface ModuleRegistrationFluency {
     core: () => HTTPKernel,
 }
 
-/**
- * Error thrown when a kernel module is requested that does not exist w/in the kernel.
- * @extends Error
- */
-export class KernelModuleNotFoundError extends Error {
-    constructor(name: string) {
-        super(`The kernel module ${name} is not registered with the kernel.`)
-    }
-}
-
 /**
  * A singleton class that handles requests, applying logic in modular layers.
  */
@@ -140,8 +130,6 @@ export class HTTPKernel extends AppClass {
 
                 if ( typeof foundIdx !== 'undefined' ) {
                     this.postflight = this.postflight.put(foundIdx, this.app().make(module))
-                } else {
-                    throw new KernelModuleNotFoundError(other.name)
                 }
 
                 return this
@@ -162,8 +150,6 @@ export class HTTPKernel extends AppClass {
 
                 if ( typeof foundIdx !== 'undefined' ) {
                     this.postflight = this.postflight.put(foundIdx + 1, this.app().make(module))
-                } else {
-                    throw new KernelModuleNotFoundError(other.name)
                 }
 
                 return this

src/http/kernel/module/ExecuteResolvedRoutePreflightHTTPModule.ts

@@ -5,6 +5,7 @@ import {ActivatedRoute} from '../../routing/ActivatedRoute'
 import {ResponseObject} from '../../routing/Route'
 import {AbstractResolvedRouteHandlerHTTPModule} from './AbstractResolvedRouteHandlerHTTPModule'
 import {collect, isLeft, unleft, unright, withErrorContext} from '../../../util'
+import {MountWebSocketRouteHTTPModule} from './MountWebSocketRouteHTTPModule'
 
 /**
  * HTTP Kernel module that executes the preflight handlers for the route.
@@ -13,7 +14,9 @@ import {collect, isLeft, unleft, unright, withErrorContext} from '../../../util'
  */
 export class ExecuteResolvedRoutePreflightHTTPModule extends AbstractResolvedRouteHandlerHTTPModule {
     public static register(kernel: HTTPKernel): void {
-        kernel.register(this).after(MountActivatedRouteHTTPModule)
+        const reg = kernel.register(this)
+        reg.after(MountWebSocketRouteHTTPModule)
+        reg.after(MountActivatedRouteHTTPModule)
     }
 
     public async apply(request: Request): Promise<Request> {

src/http/kernel/module/ExecuteResolvedWebSocketHandlerHTTPModule.ts

@@ -0,0 +1,35 @@
+import {HTTPKernel} from '../HTTPKernel'
+import {Request} from '../../lifecycle/Request'
+import {ActivatedRoute} from '../../routing/ActivatedRoute'
+import {withErrorContext} from '../../../util'
+import {AbstractResolvedRouteHandlerHTTPModule} from './AbstractResolvedRouteHandlerHTTPModule'
+import {ExecuteResolvedRoutePreflightHTTPModule} from './ExecuteResolvedRoutePreflightHTTPModule'
+import {WebSocketBus} from '../../../support/bus'
+
+/**
+ * HTTP kernel module that runs the web socket handler for the socket connection's route.
+ */
+export class ExecuteResolvedWebSocketHandlerHTTPModule extends AbstractResolvedRouteHandlerHTTPModule {
+    public static register(kernel: HTTPKernel): void {
+        kernel.register(this).after(ExecuteResolvedRoutePreflightHTTPModule)
+    }
+
+    public async apply(request: Request): Promise<Request> {
+        const route = <ActivatedRoute<unknown, unknown[]>> request.make(ActivatedRoute)
+        const params = route.resolvedParameters
+        if ( !params ) {
+            throw new Error('Attempted to call route handler without resolved parameters.')
+        }
+
+        await withErrorContext(async () => {
+            const ws = request.make<WebSocketBus>(WebSocketBus)
+            await route.handler
+                .tap(handler => handler(ws, ...params))
+                .apply(request)
+        }, {
+            route,
+        })
+
+        return request
+    }
+}

src/http/kernel/module/MonitorWebSocketConnectionHTTPModule.ts

@@ -0,0 +1,96 @@
+import {HTTPKernelModule} from '../HTTPKernelModule'
+import {HTTPKernel} from '../HTTPKernel'
+import {Request} from '../../lifecycle/Request'
+import {Inject, Injectable} from '../../../di'
+import {Config} from '../../../service/Config'
+import {setInterval} from 'timers'
+import {Logging} from '../../../service/Logging'
+import {WebSocketCloseEvent} from '../../lifecycle/WebSocketCloseEvent'
+import Timeout = NodeJS.Timeout;
+import {Bus} from '../../../support/bus'
+import * as WebSockets from 'ws'
+import {Maybe} from '../../../util'
+
+@Injectable()
+export class MonitorWebSocketConnectionHTTPModule extends HTTPKernelModule {
+    @Inject()
+    protected readonly config!: Config
+
+    @Inject()
+    protected readonly logging!: Logging
+
+    public static register(kernel: HTTPKernel): void {
+        kernel.register(this).core()
+    }
+
+    async apply(request: Request): Promise<Request> {
+        const ws = request.make<WebSockets.WebSocket>(WebSockets.WebSocket)
+
+        // Time to wait between pings
+        const pollIntervalMs = this.config.safe('server.socket.pollIntervalMs')
+            .or(30000)
+            .integer()
+
+        // Time to wait for a response
+        const pollResponseTimeoutMs = this.config.safe('server.socket.pollResponseTimeoutMs')
+            .or(3000)
+            .integer()
+
+        // Max # of failures before the connection is closed
+        const maxFailedPolls = this.config.safe('server.socket.maxFailedPolls')
+            .or(5)
+            .integer()
+
+        let failedPolls = 0
+        let interval: Maybe<Timeout> = undefined
+
+        await new Promise<void>(res => {
+            let gotResponse = false
+
+            // Listen for pong responses
+            ws.on('pong', () => {
+                this.logging.verbose('Got pong response from socket.')
+                gotResponse = true
+            })
+
+            // Listen for close event
+            ws.on('close', () => {
+                this.logging.debug('Got close event from socket.')
+                res()
+            })
+
+            interval = setInterval(async () => {
+                // Every interval, send a ping request and set a timeout for the response
+                this.logging.verbose('Sending ping request to socket...')
+                gotResponse = false
+                ws.ping()
+
+                await new Promise<void>(res2 => setTimeout(res2, pollResponseTimeoutMs))
+
+                // If no pong response is received before the timeout occurs, tick the # of failed response
+                if ( !gotResponse ) {
+                    this.logging.verbose('Socket failed to respond in time.')
+                    failedPolls += 1
+                } else {
+                    // Otherwise, reset the failure counter
+                    failedPolls = 0
+                }
+
+                // Once the failed responses exceeds the threshold, kill the connection
+                if ( failedPolls > maxFailedPolls ) {
+                    this.logging.debug('Socket exceeded maximum # of failed pings. Killing.')
+                    res()
+                }
+            }, pollIntervalMs)
+        })
+
+        if ( interval ) {
+            clearInterval(interval)
+        }
+
+        // Tell the server to close the socket connection
+        const bus = request.make<Bus>(Bus)
+        await bus.push(new WebSocketCloseEvent())
+        return request
+    }
+}

src/http/kernel/module/MountWebSocketRouteHTTPModule.ts

@@ -0,0 +1,51 @@
+import {Injectable, Inject} from '../../../di'
+import {HTTPKernelModule} from '../HTTPKernelModule'
+import {HTTPKernel} from '../HTTPKernel'
+import {Request} from '../../lifecycle/Request'
+import {Routing} from '../../../service/Routing'
+import {ActivatedRoute} from '../../routing/ActivatedRoute'
+import {Logging} from '../../../service/Logging'
+import {apiEvent, error} from '../../response/api'
+import {Bus, WebSocketBus} from '../../../support/bus'
+import {WebSocketCloseEvent} from '../../lifecycle/WebSocketCloseEvent'
+
+/**
+ * HTTP kernel middleware that tries to find a registered route matching the request's
+ * path and creates an ActivatedRoute instance from it, limited to websocket handling
+ * routes.
+ */
+@Injectable()
+export class MountWebSocketRouteHTTPModule extends HTTPKernelModule {
+    public readonly executeWithBlockingWriteback = true
+
+    @Inject()
+    protected readonly routing!: Routing
+
+    @Inject()
+    protected readonly logging!: Logging
+
+    public static register(kernel: HTTPKernel): void {
+        kernel.register(this).before()
+    }
+
+    public async apply(request: Request): Promise<Request> {
+        const route = this.routing.match('ws', request.path)
+        if ( route ) {
+            this.logging.verbose(`Mounting activated WebSocket route: ${request.path} -> ${route}`)
+            const activated = <ActivatedRoute<unknown, unknown[]>> request.make(ActivatedRoute, route, request.path)
+            request.registerSingletonInstance<ActivatedRoute<unknown, unknown[]>>(ActivatedRoute, activated)
+        } else {
+            this.logging.debug(`No matching WebSocket route found for: ${request.method} -> ${request.path}`)
+
+            // Send an error response on the socket to the client
+            const ws = request.make<WebSocketBus>(WebSocketBus)
+            await ws.push(apiEvent(error('Endpoint is not a configured socket listener.')))
+
+            // Then, terminate the request & socket connections
+            await request.make<Bus>(Bus).push(new WebSocketCloseEvent())
+            request.response.blockingWriteback(true)
+        }
+
+        return request
+    }
+}

src/http/lifecycle/WebSocketCloseEvent.ts

@@ -0,0 +1,11 @@
+import {Event} from '../../support/bus'
+import {uuid4} from '../../util'
+
+/** Event used to tell the server to close the websocket connection. */
+export class WebSocketCloseEvent implements Event {
+    eventName = '@extollo/lib:WebSocketCloseEvent'
+
+    eventUuid = uuid4()
+
+    shouldBroadcast = false
+}

src/http/response/api.ts

@@ -1,7 +1,12 @@
 /**
  * Base type for an API response format.
  */
+import {BaseSerializer, Event, ObjectSerializer} from '../../support/bus'
+import {Awaitable, ErrorWithContext, hasOwnProperty, JSONState, uuid4} from '../../util'
+
 export interface APIResponse<T> {
+    eventName?: string,
+    eventUuid?: string,
     success: boolean,
     message?: string,
     data?: T,
@@ -12,6 +17,61 @@ export interface APIResponse<T> {
     }
 }
 
+export function isAPIResponse(what: unknown): what is APIResponse<unknown> {
+    return typeof what === 'object' && what !== null
+        && hasOwnProperty(what, 'success')
+        && typeof what.success === 'boolean'
+        && (!hasOwnProperty(what, 'message') || typeof what.message === 'string')
+        && (!hasOwnProperty(what, 'error') || (
+            typeof what.error === 'object' && what.error !== null
+                && hasOwnProperty(what.error, 'name') && typeof what.error.name === 'string'
+                && hasOwnProperty(what.error, 'message') && typeof what.error.message === 'string'
+                && (!hasOwnProperty(what.error, 'stack') || (
+                    Array.isArray(what.error.stack) && what.error.stack.every(x => typeof x === 'string')
+                )
+                )
+        )
+        )
+}
+
+export function apiEvent<T>(response: APIResponse<T>): APIResponse<T> & Event {
+    if ( !response.eventName ) {
+        response.eventName = '@extollo/lib:APIResponse'
+    }
+
+    if ( !response.eventUuid ) {
+        response.eventUuid = uuid4()
+    }
+
+    return response as APIResponse<T> & Event
+}
+
+/**
+ * Serializer implementation that can encode/decode APIResponse objects.
+ */
+@ObjectSerializer()
+export class APIResponseSerializer extends BaseSerializer<APIResponse<unknown>, JSONState> {
+    protected decodeSerial(serial: JSONState): Awaitable<APIResponse<unknown>> {
+        if ( isAPIResponse(serial) ) {
+            return serial
+        }
+
+        throw new ErrorWithContext('Could not decode API response: object is malformed')
+    }
+
+    protected encodeActual(actual: APIResponse<unknown>): Awaitable<JSONState> {
+        return actual as unknown as JSONState
+    }
+
+    protected getName(): string {
+        return '@extollo/lib:APIResponseSerializer'
+    }
+
+    matchActual(some: APIResponse<unknown>): boolean {
+        return isAPIResponse(some)
+    }
+}
+
 /**
  * Formats a mesage as a successful API response.
  * @param {string} displayMessage
@@ -56,7 +116,7 @@ export function many<T>(records: T[]): APIResponse<{records: T[], total: number}
  * @return APIResponse
  * @param thrownError
  */
-export function error(thrownError: string | Error): APIResponse<void> {
+export function error(thrownError: string | Error): APIResponse<undefined> {
     if ( typeof thrownError === 'string' ) {
         return {
             success: false,

src/http/routing/Route.ts

@@ -9,6 +9,7 @@ import {RouteGroup} from './RouteGroup'
 import {Config} from '../../service/Config'
 import {Application} from '../../lifecycle/Application'
 import {Logging} from '../../service/Logging'
+import {WebSocketBus} from '../../support/bus/WebSocketBus'
 
 /**
  * Type alias for an item that is a valid response object, or lack thereof.
@@ -140,8 +141,8 @@ export class Route<TReturn extends ResponseObject, THandlerParams extends unknow
      * Create a new WebSocket route on the given endpoint.
      * @param endpoint
      */
-    public static socket(endpoint: string): Route<void, [void]> {
+    public static socket(endpoint: string): Route<Awaitable<void>, [WebSocketBus]> {
-        return new Route<void, [void]>('ws', endpoint)
+        return new Route<Awaitable<void>, [WebSocketBus]>('ws', endpoint)
     }
 
     /**

src/index.ts

@@ -35,6 +35,7 @@ export * from './http/kernel/HTTPCookieJar'
 
 export * from './http/lifecycle/Request'
 export * from './http/lifecycle/Response'
+export * from './http/lifecycle/WebSocketCloseEvent'
 export * from './http/RequestLocalStorage'
 
 export * from './make'

src/service/WebsocketServer.ts

@@ -5,6 +5,20 @@ import {HTTPServer} from './HTTPServer'
 import {Logging} from './Logging'
 import {ErrorWithContext} from '../util'
 import {Request} from '../http/lifecycle/Request'
+import {AsyncResource, executionAsyncId} from 'async_hooks'
+import {HTTPKernel} from '../http/kernel/HTTPKernel'
+import {InjectSessionHTTPModule} from '../http/kernel/module/InjectSessionHTTPModule'
+import {ExecuteResolvedRoutePreflightHTTPModule} from '../http/kernel/module/ExecuteResolvedRoutePreflightHTTPModule'
+import {ParseIncomingBodyHTTPModule} from '../http/kernel/module/ParseIncomingBodyHTTPModule'
+import {InjectRequestEventBusHTTPModule} from '../http/kernel/module/InjectRequestEventBusHTTPModule'
+import {RequestLocalStorage} from '../http/RequestLocalStorage'
+import {MountWebSocketRouteHTTPModule} from '../http/kernel/module/MountWebSocketRouteHTTPModule'
+import {SetSessionCookieHTTPModule} from '../http/kernel/module/SetSessionCookieHTTPModule'
+import {MonitorWebSocketConnectionHTTPModule} from '../http/kernel/module/MonitorWebSocketConnectionHTTPModule'
+import {Bus, WebSocketBus} from '../support/bus'
+import {WebSocketCloseEvent} from '../http/lifecycle/WebSocketCloseEvent'
+import {ExecuteResolvedWebSocketHandlerHTTPModule} from '../http/kernel/module/ExecuteResolvedWebSocketHandlerHTTPModule'
+import {InjectRequestLocale} from '../i18n'
 
 @Singleton()
 export class WebsocketServer extends Unit {
@@ -14,8 +28,36 @@ export class WebsocketServer extends Unit {
     @Inject()
     protected readonly logging!: Logging
 
+    @Inject()
+    protected readonly requestLocalStorage!: RequestLocalStorage
+
+    @Inject()
+    protected readonly bus!: Bus
+
+    protected kernel?: HTTPKernel
+
     protected server?: WebSocket.Server
 
+    protected getKernel(): HTTPKernel {
+        if ( !this.kernel ) {
+            const kernel = this.app().makeNew<HTTPKernel>(HTTPKernel)
+
+            SetSessionCookieHTTPModule.register(kernel)
+            InjectSessionHTTPModule.register(kernel)
+            MountWebSocketRouteHTTPModule.register(kernel)
+            ExecuteResolvedRoutePreflightHTTPModule.register(kernel)
+            ExecuteResolvedWebSocketHandlerHTTPModule.register(kernel)
+            ParseIncomingBodyHTTPModule.register(kernel)
+            InjectRequestEventBusHTTPModule.register(kernel)
+            MonitorWebSocketConnectionHTTPModule.register(kernel)
+            InjectRequestLocale.register(kernel)
+
+            this.kernel = kernel
+        }
+
+        return this.kernel
+    }
+
     public async up(): Promise<void> {
         // Make sure the HTTP server is started. Otherwise, this is going to fail anyway
         if ( this.http.status !== UnitStatus.Started ) {
@@ -30,20 +72,58 @@ export class WebsocketServer extends Unit {
             server: this.http.getServer(),
         })
 
+        // Turns out that the websocket server was causing context loss bc of the way
+        // its callback structure works. So, to allow us to access the global container
+        // from w/in the server handler, we need to give Node some guidance on which
+        // async context we're using.
+        const resource = new AsyncResource('WebsocketServer', {
+            triggerAsyncId: executionAsyncId(),
+            requireManualDestroy: false,
+        })
+
         // Register the websocket handler
         this.server.on('connection', (ws, request) => {
-            this.logging.info('Got WebSocket connection! ' + request.method)
+            resource.runInAsyncScope(() => {
-            const extolloReq = new Request(request)
+                this.logging.info('Got WebSocket connection! ' + request.method)
-            this.logging.debug(ws)
+                const extolloReq = new Request(request)
-            this.logging.debug(request)
+
+                this.requestLocalStorage.run(extolloReq, async () => {
+                    this.logging.info(`WebSocket connection: ${extolloReq.path}`)
+
+                    // Register the websocket with the request container
+                    extolloReq.registerSingletonInstance(WebSocket.WebSocket, ws)
+
+                    // Register the websocket bus with the request container
+                    const wsBus = extolloReq.makeNew<WebSocketBus>(WebSocketBus)
+                    await wsBus.up()
+                    extolloReq.registerSingletonInstance(WebSocketBus, wsBus)
+
+                    // Register the listener to clean up this connection when it dies
+                    extolloReq.onResolve<Bus>(Bus)
+                        .then(bus => bus.subscribe(WebSocketCloseEvent, () => {
+                            extolloReq.destroy()
+                            ws.terminate()
+                        }))
+
+                    // Run the request through the kernel to get the setup
+                    await this.getKernel().handle(extolloReq)
+                })
+            })
         })
     }
 
     public down(): Promise<void> {
+        // Stop the websocket server, if it exists
         return new Promise(res => {
-            // Stop the websocket server, if it exists
             if ( this.server ) {
-                this.server.close(() => res())
+                // Since all the request busses connect to the global app bus,
+                // we can broadcast a global close event to get all in-progress
+                // connections to close their sockets.
+                const event = new WebSocketCloseEvent()
+                event.shouldBroadcast = true
+
+                this.bus.push(event)
+                    .then(() => this.server?.close?.(() => res()))
             }
         })
     }

src/support/bus/RedisBus.ts

@@ -101,9 +101,7 @@ export class RedisBus implements EventBus, AwareOfContainerLifecycle {
 
         await this.subscriptions
             .where('eventName', '=', name)
-            .pluck('handler')
+            .awaitMapCall('handler', event)
-            .map(handler => handler(event))
-            .awaitAll()
     }
 
     isConnected(): boolean {

src/support/bus/WebSocketBus.ts

@@ -0,0 +1,123 @@
+import {AwareOfContainerLifecycle, Container, Inject, Injectable, StaticInstantiable} from '../../di'
+import {
+    EventBus,
+    Event,
+    EventHandler,
+    EventHandlerSubscription,
+    BusSubscriber,
+    EventHandlerReturn,
+} from './types'
+import * as WebSocket from 'ws'
+import {NoSerializerError, Serialization} from './serial/Serialization'
+import {Logging} from '../../service/Logging'
+import {Awaitable, Collection, Pipeline, uuid4} from '../../util'
+import {getEventName} from './getEventName'
+import {Bus} from './Bus'
+import {WebSocketCloseEvent} from '../../http/lifecycle/WebSocketCloseEvent'
+import {apiEvent, error} from '../../http/response/api'
+import {AsyncResource, executionAsyncId} from 'async_hooks'
+
+@Injectable()
+export class WebSocketBus implements EventBus, AwareOfContainerLifecycle {
+    awareOfContainerLifecycle: true = true
+
+    @Inject()
+    protected readonly ws!: WebSocket.WebSocket
+
+    @Inject()
+    protected readonly bus!: Bus
+
+    @Inject()
+    protected readonly serial!: Serialization
+
+    @Inject()
+    protected readonly logging!: Logging
+
+    public readonly uuid = uuid4()
+
+    private connected = false
+
+    /** List of local subscriptions on this bus. */
+    protected subscriptions: Collection<BusSubscriber<Event>> = new Collection()
+
+    /** Get a Promise that resolves then the socket closes. */
+    onClose(): Promise<WebSocketCloseEvent> {
+        return new Promise<WebSocketCloseEvent>(res => {
+            this.bus.subscribe(WebSocketCloseEvent, event => res(event))
+        })
+    }
+
+    pipe<T extends Event>(eventKey: StaticInstantiable<T>, line: Pipeline<T, EventHandlerReturn>): Awaitable<EventHandlerSubscription> {
+        return this.subscribe(eventKey, event => line.apply(event))
+    }
+
+    async push(event: Event): Promise<void> {
+        this.logging.verbose(`Pushing event to WebSocket: ${event.eventName}`)
+        this.logging.verbose(event)
+
+        await this.ws.send(await this.serial.encodeJSON(event))
+    }
+
+    async subscribe<T extends Event>(eventKey: StaticInstantiable<T>, handler: EventHandler<T>): Promise<EventHandlerSubscription> {
+        const uuid = uuid4()
+        const subscriber: BusSubscriber<Event> = {
+            eventName: getEventName(eventKey),
+            eventKey,
+            handler,
+            uuid,
+        } as unknown as BusSubscriber<Event>
+
+        this.logging.verbose(`Creating WebSocket subscriber ${uuid}...`)
+        this.logging.verbose(subscriber)
+
+        this.subscriptions.push(subscriber)
+
+        return {
+            unsubscribe: () => {
+                this.subscriptions = this.subscriptions.where('uuid', '!=', uuid)
+            },
+        }
+    }
+
+    protected async onMessage(message: string): Promise<void> {
+        const payload = await this.serial.decodeJSON<Event>(message)  // FIXME validation
+
+        await this.subscriptions
+            .where('eventName', '=', payload.eventName)
+            .awaitMapCall('handler', payload)
+    }
+
+    up(): void {
+        const resource = new AsyncResource('WebSocketBus', {
+            triggerAsyncId: executionAsyncId(),
+            requireManualDestroy: false,
+        })
+
+        this.ws.on('message', async data => {
+            await resource.runInAsyncScope(async () => {
+                this.logging.verbose(`Got data from websocket: ${data}`)
+                try {
+                    Container.getContainer()
+                    await this.onMessage(`${data}`)
+                } catch (e: unknown) {
+                    if ( e instanceof NoSerializerError ) {
+                        this.logging.warn(`Discarding message as no validator could be found to deserialize it: ${data}`)
+                        this.push(apiEvent(error('Invalid message format or serializer.')))
+                    } else {
+                        throw e
+                    }
+                }
+            })
+        })
+
+        this.connected = true
+    }
+
+    down(): void {
+        this.connected = false
+    }
+
+    isConnected(): boolean {
+        return this.connected  // FIXME: monitor for bad connections
+    }
+}

src/support/bus/index.ts

@@ -4,10 +4,13 @@ export * from './serial/BaseSerializer'
 export * from './serial/SimpleCanonicalItemSerializer'
 export * from './serial/Serialization'
 export * from './serial/decorators'
+export * from './serial/NamedEventPayload'
+export * from './serial/JSONMessageEvent'
 
 export * from './Bus'
 export * from './LocalBus'
 export * from './RedisBus'
+export * from './WebSocketBus'
 
 export * from './queue/event/PushingToQueue'
 export * from './queue/event/PushedToQueue'

src/support/bus/serial/JSONMessageEvent.ts

@@ -0,0 +1,35 @@
+import {BaseSerializer} from './BaseSerializer'
+import {Awaitable, JSONState, uuid4} from '../../../util'
+import {ObjectSerializer} from './decorators'
+import {Event} from '../types'
+
+export class JSONMessageEvent<T extends JSONState> implements Event {
+    constructor(
+        public readonly value: T,
+    ) {}
+
+    eventName = '@extollo/lib:JSONMessageEvent'
+
+    eventUuid = uuid4()
+}
+
+@ObjectSerializer()
+export class JSONMessageEventSerializer extends BaseSerializer<JSONMessageEvent<JSONState>, { value: JSONState }> {
+    protected decodeSerial(serial: { value: JSONState }): Awaitable<JSONMessageEvent<JSONState>> {
+        return new JSONMessageEvent(serial.value)
+    }
+
+    protected encodeActual(actual: JSONMessageEvent<JSONState>): Awaitable<{ value: JSONState }> {
+        return {
+            value: actual.value,
+        }
+    }
+
+    protected getName(): string {
+        return '@extollo/lib:JSONMessageEventSerializer'
+    }
+
+    matchActual(some: JSONMessageEvent<JSONState>): boolean {
+        return some instanceof JSONMessageEvent
+    }
+}

src/support/bus/serial/NamedEventPayload.ts

@@ -0,0 +1,36 @@
+import {Event, SerialPayload} from '../types'
+import {ObjectSerializer} from './decorators'
+import {BaseSerializer} from './BaseSerializer'
+import {JSONState} from '../../../util'
+
+export class NamedEventPayload {
+    constructor(
+        public readonly eventName: string,
+        public readonly event: Event,
+    ) {}
+}
+
+@ObjectSerializer()
+export class NamedEventPayloadSerializer extends BaseSerializer<NamedEventPayload, { eventName: string, event: SerialPayload<Event, JSONState> }> {
+    protected async decodeSerial(serial: { eventName: string; event: SerialPayload<Event, JSONState> }): Promise<NamedEventPayload> {
+        return new NamedEventPayload(
+            serial.eventName,
+            await this.getSerialization().decode(serial.event),
+        )
+    }
+
+    protected async encodeActual(actual: NamedEventPayload): Promise<{ eventName: string; event: SerialPayload<Event, JSONState> }> {
+        return {
+            eventName: actual.eventName,
+            event: await this.getSerialization().encode(actual.event),
+        }
+    }
+
+    protected getName(): string {
+        return '@extollo/lib:NamedEventPayloadSerializer'
+    }
+
+    matchActual(some: NamedEventPayload): boolean {
+        return some instanceof NamedEventPayload
+    }
+}