onewaydata
Server sent events for NodeJs, works with raw http, express and polka.
to be used with EventSource API client side.
install
usage
import {
createEventStream,
sendOne,
RECONNECT,
CONNECT,
DISCONNECT,
} from "onewaydata";
import { useDefaultLogging } from "onewaydata/source/defaultLogging.js";
const server = ...
const condition = (request, response) => {
return request.url === `/sse`;
};
const eventStream = createEventStream({server, condition, reconnectionTime: 5000 });
useDefaultLogging({ eventStream });
eventStream.send({ data: `data only`)});
eventStream.send({ data: `something`, event: `eventName`, id: String(Date.now())});
eventStream.on(RECONNECT, ({lastId, response}) => {
if (lastId) {
// opportunity to resume with sendOne
sendOne(response, `here is what you missed since last disconnection`);
}
});
// eventStream.off(RECONNECT); // unsubscribe
// eventStream.close(); // closes all eventStream
// eventStream.setAndSendId(); // shorthand to send id only and saving lastEventId
// same as send but takes a filter function
eventStream.sendWithCondition({
data: `latitude=434521, longitude=23213`,
event: "fire started",
function (request, response) {
// request and response are from http because SSE is built on top of HTTP protocol
// assumes some request have this property set before hand
return request.isFirefighter; // only send to isFirefighter === true
},
);with express/polka
The main difference is that the path is handled at the web framework level.
import { createEventStream } from "onewaydata";
import polka from "polka";
const polkaServer = polka();
const eventStream = createEventStream({ asMiddleWare: true });
polkaServer.use(`/sse`, eventStream.middleWare);
polkaServer.listen(PORT);
eventStream.send({ data: `something`, event: `eventName`});See examples
Extras
More information
https://hpbn.co/server-sent-events-sse/