A websocket client for Mercurius subscriptions.
npm i @mercuriusjs/subscription-client
SubscriptionClient
: class extends EventEmitter
-
The SubscriptionClient class constructor takes two parameters:
-
uri
:string
The uri of the websocket server. -
config
:object
the configuration object.-
protocols
:Array<string>
The WebSocket sub-protocol. default:graphql-transport-ws
. -
reconnect
:boolean
Enables the client to attempt to reconnect if the connection is interrupted. default:false
. -
maxReconnectAttempts
:number
The maximum amount of attempts the client should perform when reconnecting. default:Infinity
. -
serviceName
:string
The service name. -
connectionCallback
:(params: any) : Promise<void>
A callback that is executed when the client is successfully connected to the server. -
failedConnectionCallback
:(params: any) : Promise<void>
A callback that is executed when the client fails connecting to the server. -
failedReconnectCallback
:(params: any) : Promise<void>
A callback that is executed when the client fails reconnecting to the server. -
connectionInitPayload
:any
The connection init payload or a function that returns it. -
rewriteConnectionInitPayload
:(connectionInit, context) => void
A function that allows to rewrite the default connection init payload. -
keepAlive
:number
The milliseconds value of the connection keep-alive interval. default:false
-
-
-
subscriptionClient.connect()
:void
Creates a connection to the server. -
subscriptionClient.close(tryReconnect, closedByUser?)
:void
Closes the connection to the server. -
unsubscribe(operationId, forceUnsubscribe)
:void
Unsuscribes from the topic with the providedoperationId
. -
subscriptionClient.unsubscribeAll()
:void
Unsuscribes from all topics. -
subscriptionClient.createSubscription(query, variables, publish, context)
:string
. Creates a subscription to a query. Returns theSubscriptionOperationId
SubscriptionClient
extends EventEmitter
class from node:events
, and it is possibile add listeners to the following events:
-
SocketOpen
Emits when the connection is open. -
ready
Emits when theconnection_ack
is received and it is ready to communicate. -
SocketError
Emits when an error occurred. -
SocketClose
Emits when the socket is closed.
Examples:
const { SubscriptionClient } = require( "@mercuriusjs/subscription-client")
const { once } = require('events')
const client = new SubscriptionClient('ws://localhost:3000', {
protocols: ["graphql-transport-ws"],
reconnect: true,
maxReconnectAttempts: 10,
serviceName: "test-service",
connectionCallback: () => {
// executes callback on connection
},
failedConnectionCallback: (err) => {
// executes callback on connection error
},
failedReconnectCallback: () => {
// executes callback on reconnection error
},
connectionInitPayload: 'foo', // connection payload
rewriteConnectionInitPayload: (connectionInit, context) => {
// rewrite the connection init payload
},
keepAlive: 1000
});
client.connect()
await once(client, 'ready')
const operationId1 = client.createSubscription('query', {}, (data)=> {
// data returned from the query
})
client.unsubscribe(operationId1)
const operationId2 = client.createSubscription('query', {}, (data)=> {
// data returned from the query
})
client.unsuscribeAll()
client.close()