diff --git a/packages/core-realtime/src/realtime-broadcaster.interface.ts b/packages/core-realtime/src/realtime-broadcaster.interface.ts
new file mode 100644
index 0000000..89b1444
--- /dev/null
+++ b/packages/core-realtime/src/realtime-broadcaster.interface.ts
@@ -0,0 +1,9 @@
+import type { z } from "zod";
+import type { RealtimeChannelDescriptor } from "./realtime-channel";
+
+export interface IRealtimeBroadcaster {
+  broadcast<T>(
+    descriptor: RealtimeChannelDescriptor<string, z.ZodType<T>>,
+    payload: T,
+  ): Promise<void>;
+}
diff --git a/packages/core-realtime/src/symbols.ts b/packages/core-realtime/src/symbols.ts
new file mode 100644
index 0000000..a5c1663
--- /dev/null
+++ b/packages/core-realtime/src/symbols.ts
@@ -0,0 +1,6 @@
+export const CORE_REALTIME_SYMBOLS = {
+  IRealtimeBroadcaster: Symbol.for("core-realtime:IRealtimeBroadcaster"),
+  IRealtimeServer: Symbol.for("core-realtime:IRealtimeServer"),
+  IRealtimeAuthenticator: Symbol.for("core-realtime:IRealtimeAuthenticator"),
+  IRealtimeHandlerRegistry: Symbol.for("core-realtime:IRealtimeHandlerRegistry"),
+} as const;