GraphQL subscriptions over SSE

graphql-transport-sse serves GraphQL operations over Server-Sent Events using the distinct-connections mode of the GraphQL over SSE protocol. It accepts GET and POST operations with Accept: text/event-stream, emits next events, and terminates each operation with complete. Other requests are passed to the wrapped HTTP handler.

Getting Started

schema := graphql.MustParseSchema(schemaString, resolver)
sse := graphqlsse.NewHandler(schema, relay.Handler{Schema: schema})
http.Handle("/graphql", sse)
log.Fatal(http.ListenAndServe(":8080", nil))

Example

Run the standalone counter example with:

go run ./example

Then open http://localhost:8080 for a GraphiQL UI wired up to the SSE endpoint at /graphql (queries/mutations use plain JSON POST responses via relay.Handler; subscription { counter } streams live ticks over SSE).

Security

Requests without an Origin header and same-origin browser requests are allowed by default. Cross-origin requests are rejected unless WithCheckOrigin explicitly allows them.

Options

• WithReadLimit bounds POST bodies and the raw GET query string.
• WithWriteTimeout bounds each write,
• WithHeartbeatInterval sends keepalive comments,
• WithMaxConcurrentOperations limits open streams,
• WithMaxOperationDuration bounds stream lifetime,
• WithContextGenerator injects request-derived context, and
• WithCheckOrigin configures browser origin checks.

Limitations

SSE streams do not resume after reconnecting. Use application-level cursors or offsets when resumption is required. Reverse proxies must disable response buffering for the endpoint.

The single-connection multiplexed mode is intentionally not part of v1.