sse.js•3.81 kB
import { JSONRPCMessageSchema } from "../types.js";
/**
* Client transport for SSE: this will connect to a server using Server-Sent Events for receiving
* messages and make separate POST requests for sending messages.
*
* This uses the EventSource API in browsers. You can install the `eventsource` package for Node.js.
*/
export class SSEClientTransport {
constructor(url) {
this._url = url;
}
start() {
if (this._eventSource) {
throw new Error("SSEClientTransport already started! If using Client class, note that connect() calls start() automatically.");
}
return new Promise((resolve, reject) => {
this._eventSource = new EventSource(this._url.href);
this._abortController = new AbortController();
this._eventSource.onerror = (event) => {
var _a;
const error = new Error(`SSE error: ${JSON.stringify(event)}`);
reject(error);
(_a = this.onerror) === null || _a === void 0 ? void 0 : _a.call(this, error);
};
this._eventSource.onopen = () => {
// The connection is open, but we need to wait for the endpoint to be received.
};
this._eventSource.addEventListener("endpoint", (event) => {
var _a;
const messageEvent = event;
try {
this._endpoint = new URL(messageEvent.data, this._url);
if (this._endpoint.origin !== this._url.origin) {
throw new Error(`Endpoint origin does not match connection origin: ${this._endpoint.origin}`);
}
}
catch (error) {
reject(error);
(_a = this.onerror) === null || _a === void 0 ? void 0 : _a.call(this, error);
void this.close();
return;
}
resolve();
});
this._eventSource.onmessage = (event) => {
var _a, _b;
const messageEvent = event;
let message;
try {
message = JSONRPCMessageSchema.parse(JSON.parse(messageEvent.data));
}
catch (error) {
(_a = this.onerror) === null || _a === void 0 ? void 0 : _a.call(this, error);
return;
}
(_b = this.onmessage) === null || _b === void 0 ? void 0 : _b.call(this, message);
};
});
}
async close() {
var _a, _b, _c;
(_a = this._abortController) === null || _a === void 0 ? void 0 : _a.abort();
(_b = this._eventSource) === null || _b === void 0 ? void 0 : _b.close();
(_c = this.onclose) === null || _c === void 0 ? void 0 : _c.call(this);
}
async send(message) {
var _a, _b;
if (!this._endpoint) {
throw new Error("Not connected");
}
try {
const response = await fetch(this._endpoint, {
method: "POST",
headers: {
"Content-Type": "application/json",
},
body: JSON.stringify(message),
signal: (_a = this._abortController) === null || _a === void 0 ? void 0 : _a.signal,
});
if (!response.ok) {
const text = await response.text().catch(() => null);
throw new Error(`Error POSTing to endpoint (HTTP ${response.status}): ${text}`);
}
}
catch (error) {
(_b = this.onerror) === null || _b === void 0 ? void 0 : _b.call(this, error);
throw error;
}
}
}
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