@solace-community/graphql-solace-subscriptions
v1.0.6
Published
A graphql-subscriptions PubSub Engine using the Solace PubSub+ APIs
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graphql-solace-subscriptions
Overview
This package implements the AsyncIterator Interface and PubSubEngine Interface from the graphql-subscriptions package. It allows you to connect your subscriptions manager to the Solace PubSub+ broker to support a horizontally scalable subscriptions setup. You can also take advantage of many Solace features such as EventMesh, TopicToQueueMapping etc to liberate your GraphQL events to outside your GraphQL ecosystem.
Installation
npm install @solace-community/graphql-solace-subscriptions
Using the AsyncIterator Interface
Define your GraphQL schema with a Subscription
type.
schema {
query: Query
mutation: Mutation
subscription: Subscription
}
type Subscription {
somethingChanged: Result
}
type Result {
id: String
}
Now, create a SolacePubSub
instance.
import { SolacePubSub } from '@solace-community/graphql-solace-subscriptions';
const pubsub = await SolacePubSub.startWithDefaultOptions("GRAPH_QL_QUEUE"); // connecting to ws://localhost:8080 by default
Now, implement the Subscriptions type resolver, using pubsub.asyncIterator
to map the event you need.
const SOMETHING_CHANGED_TOPIC = 'SOMETHING/CHANGED';
export const resolvers = {
Subscription: {
somethingChanged: {
subscribe: () => pubsub.asyncIterator(SOMETHING_CHANGED_TOPIC)
}
}
}
Subscriptions resolvers are not a function, but an object with
subscribe
method, that returnsAsyncIterable
.
The AsyncIterator
method will tell the Solace client to listen for messages from the Solace broker on the topic provided via a Queue, and wraps that listener in an AsyncIterator
object.
When messages are received from the topic, those messages can be returned back to connected clients.
pubsub.publish
can be used to send messages to a given topic.
pubsub.publish(SOMETHING_CHANGED_TOPIC, { somethingChanged: { id: "123" }});
Dynamically Create a Topic Based on Subscription Args Passed on the Query:
export const resolvers = {
Subscription: {
somethingChanged: {
subscribe: (_, args) => pubsub.asyncIterator(`${SOMETHING_CHANGED_TOPIC}/${args.relevantId}`),
},
},
}
Using Arguments and Payload to Filter Events
import { withFilter } from 'graphql-subscriptions';
export const resolvers = {
Subscription: {
somethingChanged: {
subscribe: withFilter(
(_, args) => pubsub.asyncIterator(`${SOMETHING_CHANGED_TOPIC}/${args.relevantId}`),
(payload, variables) => payload.somethingChanged.id === variables.relevantId,
),
},
},
}
Passing your own properties object
The basic usage is great for development and you will be able to connect to a locally hosted Solace PubSub+ event broker. But if you wanted to connect to a specific host, you can inject your own Solace properties.
import { SolacePubSub, SolacePubSubOptions } from '@solace-community/graphql-solace-subscriptions';
let solacePubSubOptions = new SolacePubSubOptions("wss://host:8081","vpn1","user","password");
const pubsub = await SolacePubSub.startWithSolaceOptions("GRAPH_QL_QUEUE",solacePubSubOptions);
Passing your own Solace Session
If you want to take advantage of a different authentication mechanism, you have the ability to inject a fully instantiated Solace session into the SolacePubSub object.
import { SolacePubSub } from '@solace-community/graphql-solace-subscriptions';
import solace from 'solclientjs';
let session: solace.Session;
//instantiate your solace session
const pubsub = await SolacePubSub.startWithSolaceSession("GRAPH_QL_QUEUE",session);
Resources
This is not an officially supported Solace product.
For more information try these resources:
- Ask the Solace Community
- The Solace Developer Portal website at: https://solace.dev
Contributing
Contributions are encouraged! Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.
Authors
See the list of contributors who participated in this project.
License
See the LICENSE file for details.