sfenig
November 7, 2025, 8:13pm
1
Would there be interest in adding support to SSE Trigger node for Graphql over SSE. Currently it’s restricted to only listen for messages, where as graphql sse sends ‘next’ and ‘complete’ evenns:
# GraphQL over Server-Sent Events Protocol
## Introduction
We live in a connected world where real-time needs are ever-growing. Especially in the world's most connected "world", the internet. When talking about real-time, there are two main players in the game: [WebSockets](https://datatracker.ietf.org/doc/html/rfc6455) and [Server-Sent Events](https://html.spec.whatwg.org/multipage/server-sent-events.html).
Using Server-Sent Events (abbr. SSE) for your next real-time driven endeavour sounds appealing because of many reasons spanning from simplicity to acceptance. However, you're soon to find out that SSE suffers from a limitation to the maximum number of open connections when dealing with HTTP/1 powered servers (more details below).
This documents aims to elevate HTTP/1 limitations through a "single connection mode" and back up HTTP/2+ powered servers using the "distinct connections mode" with a unified GraphQL over SSE transport protocol.
## Distinct connections mode
Operation requests need to conform to the [GraphQL over HTTP spec](https://github.com/graphql/graphql-over-http/blob/main/spec/GraphQLOverHTTP.md), with two key observations:
1. The `Content-Type` MUST always be `text/event-stream` as per the [Server-Sent Events spec](https://www.w3.org/TR/eventsource/#text-event-stream).
1. Validation steps that run before execution of the GraphQL operation MUST report errors through an accepted SSE connection by emitting `next` events that contain the errors in the data field.
<br>One reason being, the server should agree with the client's `Accept` header when deciding about the response's `Content-Type`.
<br>Additionally, responding with a `400` (Bad Request) will cause the user agent to fail the connection. In some cases, like with the browser's native `EventSource`, the error event will hold no meaningful information helping to understand the validation issue(s).
Streaming operations, such as `subscriptions` or directives like `@stream` and `@defer`, are terminated/completed by having the client simply close the SSE connection.
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