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Fastify SSE Plugin
Fastify plugin for sending Server-sent events.
For `fastify@2.x` use fastify-sse-v2@1.x!
How to use?
yarn add fastify-sse-v2Register fastify-sse-v2 plugin into your fastify instance:
import { FastifySSEPlugin } from "fastify-sse-v2";
const server = fastify();
server.register(FastifySSEPlugin);Sending events from AsyncIterable source
import { FastifySSEPlugin } from "fastify-sse-v2";
const server = fastify();
server.register(FastifySSEPlugin);
server.get("/", function (req, res) {
res.sse(
(async function* source() {
for (let i = 0; i < 10; i++) {
sleep(2000);
yield { id: String(i), data: "Some message" };
}
})()
);
});Sending individual events
import { FastifySSEPlugin } from "fastify-sse-v2";
const server = fastify();
server.register(FastifySSEPlugin);
server.get("/", async function (req, res) {
for (let i = 0; i < 10; i++) {
await sleep(2000);
res.sse({ id: String(i), data: "Some message" });
}
});
fastify.get("/listenForChanges", {}, (request, reply) => {
const listenStream = fastify.db
.watch("doc-uuid")
.on("data", (data) => reply.sse({ data: JSON.stringify(data) }))
.on("delete", () => reply.sse({ event: "close" }));
request.socket.on("close", () => listenStream.end());
});Note
- When sending individual events, the connection is kept open until you call
reply.sseContext.source.end()to terminate the stream.
Sending events from EventEmmiters
import { FastifySSEPlugin } from "fastify-sse-v2";
import { on } from "events";
const server = fastify();
server.register(FastifySSEPlugin);
server.get("/", function (req, res) {
res.sse(
(async function* () {
for await (const [event] of on(eventEmmitter, "update")) {
yield {
event: event.name,
data: JSON.stringify(event),
};
}
})()
);
});Note
- to remove event listeners (or some other cleanup) when client closes connection,
you can listen on connection closing event:
request.socket.on('close', () => abortController.abort());
Change server send retry behavior
import { FastifySSEPlugin } from "fastify-sse-v2";
const server = fastify();
server.register(FastifySSEPlugin) // retryDelay default 3000
server.register(FastifySSEPlugin, {
retryDelay: false // disable retryDelay
retryDelay: 5000 // override 5000
})Change default highWaterMark
import { FastifySSEPlugin } from "fastify-sse-v2";
const server = fastify();
server.register(FastifySSEPlugin) // highWaterMark defaults to 16384 bytes (16kb)
server.register(FastifySSEPlugin, {
highWaterMark: 1024 // override default setting of 16384 (16kb) with 1024 (1kb)
})Note
- You can set parameter
retryDelaytofalseto disable the default behavior of sending retry, or set parameterretryDelaytomillisecondsoverride the default 3000 retry interval . - You can set parameter
highWaterMarkto define the buffer size (in bytes) that determines when the buffer is full and a 'flush' should be performed. Default is 16kb. ()