support for subscriptions

[markhamnr]

Am I wrong in thinking that subscriptions aren't supported currently?

The README implies that they are, or at least it mentions registering a Subscription class as well as a Query class and a Mutation class.

But I can't see any examples, nor can I get it to work myself. The GraphQL Java site says that a subscription should return a Publisher, but when I try that with AnnotationsSchemaCreator I get an InvalidSchemaException: "Publisher" must define one or more fields.

Is there a way to handle subscriptions I haven't figure out yet? Or if not, is this something that could be added?

[jkevan]

Hello @markhamnr,

Subscriptions are supported—we are using them in our implementation. This support is not directly related to graphql-java-annotations but rather to graphql-java. However, I agree that this specific case lacks documentation and examples.

I'll try to help:

1. WebSocket Endpoint

First, you need a WebSocket endpoint to receive subscription requests. You can find an example in our implementation:
🔗 [OsgiGraphQLWsEndpoint.java](https://github.com/Jahia/graphql-core/blob/master/graphql-dxm-provider/src/main/java/org/jahia/modules/graphql/provider/dxm/OsgiGraphQLWsEndpoint.java)

2. Base Schema Endpoint

You also need a base schema endpoint to register your subscriptions:

@GraphQLName("Subscription")
public static class Subscription {
}

3. Subscription Implementation Example

Here’s an example of a Subscription implementation:
🔗 [GqlWorkflowSubscriptionExtension.java](https://github.com/Jahia/graphql-core/blob/master/graphql-dxm-provider/src/main/java/org/jahia/modules/graphql/provider/dxm/workflow/GqlWorkflowSubscriptionExtension.java)

A key part that might be missing on your side is that the Publisher should carry a GraphQL object, like this:

Publisher<GqlWorkflowEvent>

Where GqlWorkflowEvent is a GraphQL object annotated with GraphQL annotations:

@GraphQLField
@GraphQLDescription("Workflow that has just been started")
public GqlWorkflow getStartedWorkflow() {
    return startedWorkflow;
}

Hope this helps! Feel free to explore the repository—it’s public and serves as the GraphQL API for our project. 🚀

[markhamnr]

OK, this is about the simplest example I can come up with:

https://gist.github.com/markhamnr/7a516ef640f353791165ef3f75478eae

When run, it gives me the InvalidSchemaException I mentioned above. Is there some way I can modify it to make it a valid schema?