[FEAT] [CORE] added the ability to publish/respond by providing a Msg…

… argument. This is useful downstream to some applications.

nats-base-client/core.ts

@@ -556,6 +556,13 @@ export interface NatsConnection {
    */
   publishMessage(msg: Msg): void;
 
+  /**
+   * Replies using the reply subject of the specified message, specifying the
+   * data, headers in the message if any.
+   * @param msg
+   */
+  respondMessage(msg: Msg): boolean;
+
   /**
    * Subscribe expresses interest in the specified subject. The subject may
    * have wildcards. Messages are delivered to the {@link SubOpts#callback |SubscriptionOptions callback}

nats-base-client/nats.ts

@@ -133,6 +133,17 @@ export class NatsConnectionImpl implements NatsConnection {
     });
   }
 
+  respondMessage(msg: Msg) {
+    if (msg.reply) {
+      this.publish(msg.reply, msg.data, {
+        reply: msg.reply,
+        headers: msg.headers,
+      });
+      return true;
+    }
+    return false;
+  }
+
   subscribe(
     subject: string,
     opts: SubscriptionOptions = {},

tests/basics_test.ts

@@ -1381,7 +1381,7 @@ Deno.test("basics - sync subscription", async () => {
   await cleanup(ns, nc);
 });
 
-Deno.test("basics - respond message", async () => {
+Deno.test("basics - publish message", async () => {
   const { ns, nc } = await setup();
   const sub = nc.subscribe("q");
 
@@ -1403,6 +1403,28 @@ Deno.test("basics - respond message", async () => {
   await cleanup(ns, nc);
 });
 
+Deno.test("basics - respond message", async () => {
+  const { ns, nc } = await setup();
+  const sub = nc.subscribe("q");
+
+  const nis = new MM(nc);
+  nis.data = new TextEncoder().encode("not in service");
+
+  (async () => {
+    for await (const m of sub) {
+      if (m.reply) {
+        nis.reply = m.reply;
+        nc.respondMessage(nis);
+      }
+    }
+  })().then();
+
+  const r = await nc.request("q");
+  assertEquals(r.string(), "not in service");
+
+  await cleanup(ns, nc);
+});
+
 class MM implements Msg {
   data!: Uint8Array;
   sid: number;