Examples
GraphQL Subscription
Building a Subscription
GraphQL subscription streams new comments in real-time.
What is a GraphQL Subscription?
GraphQL Subscriptions are a crucial part of the GraphQL specification that enables developers to listen for real-time updates. They are particularly useful for applications that require immediate data updates, like chat applications or live dashboards. Subscriptions allow clients to maintain a long-lived, persistent connection to the server, receiving data whenever a specified event occurs.
Setting Up a Basic Subscription Server
To implement GraphQL subscriptions, you need a server that supports WebSocket connections. Popular libraries like Apollo Server or graphql-yoga provide built-in support for WebSockets, making it easier to set up a subscription server. Below is a basic example using Apollo Server.
Publishing Events to the Subscription
Once the subscription server is set up, you need to publish events to the specific topic so that subscribed clients can receive updates. This can be done using the PubSub instance. Here's an example of how to publish a new comment event:
Subscribing to Events on the Client-Side
On the client-side, you need to subscribe to the events published by the server. Libraries like Apollo Client offer easy-to-use APIs for managing subscriptions. Below is an example using Apollo Client:
Conclusion
GraphQL Subscriptions provide a powerful way to handle real-time data in your applications. By setting up a subscription server and managing client-side subscriptions, you can create dynamic applications that respond immediately to data changes. This is particularly useful in scenarios where real-time updates are critical, such as collaborative apps, live feeds, and notifications.
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