diff --git a/server/client.test.ts b/server/client.test.ts
index 28d172a..cfbf96a 100644
--- a/server/client.test.ts
+++ b/server/client.test.ts
@@ -1,12 +1,13 @@
 import { assertEquals } from "jsr:@std/assert";
+import { createSession } from "#/server/handler.ts";
 import handler from "./handler.ts";
 import { close, connect, flush, href, setup } from "./testSetup.ts";
 
 Deno.test(
 	"test",
 	setup(async () => {
-		const t1 = "123-abc";
-		const [s1, m1] = await connect(`${href}?ticket=${t1}`);
+		const sessionId = createSession();
+		const [s1, m1] = await connect(`${href}?sessionId=${sessionId}`);
 		await flush();
 		assertEquals(m1, []);
 		await close(s1);
diff --git a/server/handler.ts b/server/handler.ts
index 2c7ab98..8c5dfaa 100644
--- a/server/handler.ts
+++ b/server/handler.ts
@@ -2,14 +2,12 @@ import { STATUS_CODE, STATUS_TEXT, type StatusCode } from "jsr:@std/http";
 
 const ALLOWED_ORIGIN = "http://0.0.0.0:8042";
 
-const sessions = new Map<string, WebSocket>();
-
-function createSession(socket: WebSocket): string {
-	const session = crypto.randomUUID();
-	sessions.set(session, socket);
-
-	return session;
-}
+type Session = {
+	id: string;
+	connId: number;
+	createdAt: number;
+	lastSeenAt: number;
+};
 
 function createResponse(
 	status: StatusCode,
@@ -18,32 +16,66 @@ function createResponse(
 	return new Response(body, { status, statusText: STATUS_TEXT[status] });
 }
 
+const sessions = new Map<string, Session>();
+const connections = new Map<number, WebSocket>();
+
+export function createSession(): string {
+	const id = crypto.randomUUID();
+	const now = Date.now();
+	sessions.set(id, {
+		id,
+		connId: 0,
+		createdAt: now,
+		lastSeenAt: 0,
+	});
+
+	return id;
+}
+
+let currentId = 1;
+const nextId = (): number => {
+	return currentId++;
+};
+
+const connectSession = (session: Session, request: Request): Response => {
+	const { response, socket } = Deno.upgradeWebSocket(request);
+	const connId = nextId();
+
+	socket.onopen = () => {
+		session.lastSeenAt = Date.now();
+		session.connId = connId;
+		connections.set(connId, socket);
+	};
+	socket.onclose = () => {
+		session.lastSeenAt = Date.now();
+		connections.delete(connId);
+	};
+	socket.onmessage = () => {
+		session.lastSeenAt = Date.now();
+	};
+	socket.onerror = (e) => {
+		session.lastSeenAt = Date.now();
+		console.error(e);
+	};
+
+	return response;
+};
+
 export default function (request: Request): Response {
 	if (request.headers.get("upgrade")?.toLowerCase() !== "websocket") {
 		return createResponse(STATUS_CODE.UpgradeRequired);
 	}
 
 	const url = new URL(request.url);
-	if (url.origin !== ALLOWED_ORIGIN) {
+	const sessionId = url.searchParams.get("sessionId");
+	if (url.origin !== ALLOWED_ORIGIN || sessionId === null) {
 		return createResponse(STATUS_CODE.BadRequest);
 	}
 
-	const sessionId = url.searchParams.get("sessionId");
-
-	if (sessionId === null) {
-		const upgrade = Deno.upgradeWebSocket(request);
-		createSession(upgrade.socket);
-
-		return upgrade.response;
-	} else {
-		const session = sessions.get(sessionId);
-		if (session === null) {
-			return createResponse(STATUS_CODE.Unauthorized);
-		}
-
-		// TODO
-		// I need a new socket every time
+	const session = sessions.get(sessionId);
+	if (session === undefined) {
+		return createResponse(STATUS_CODE.Unauthorized);
 	}
 
-	return createResponse(STATUS_CODE.InternalServerError);
+	return connectSession(session, request);
 }