Add ScheduledMessages sample (Azure#79)

examples/samples/scheduledMessages.ts

@@ -0,0 +1,66 @@
+import { ReceiveMode, Namespace, generateUuid, QueueClient } from "../../lib";
+import * as dotenv from "dotenv";
+dotenv.config();
+
+const str = process.env.SERVICEBUS_CONNECTION_STRING || "";
+const path = process.env.QUEUE_NAME || "";
+console.log("str: ", str);
+console.log("path: ", path);
+
+let ns: Namespace;
+
+async function sendMessages(queueClient: QueueClient, data: any[]): Promise<void> {
+  for (let index = 0; index < data.length; index++) {
+    const element = data[index];
+    const message = {
+      body: `${element.firstName} ${element.name}`,
+      label: "Scientist",
+      timeToLive: 2 * 60 * 1000, // 2 minutes
+      messageId: generateUuid()
+    };
+    const scheduledEnqueueTimeUtc = new Date(Date.now() + 30000 + index * 1000); // scheduling message to be sent (30 + index) seconds from now
+    console.log(
+      `>>>> Sending message:\t ${message.body}, scheduled for UTC: ${scheduledEnqueueTimeUtc}`
+    );
+    await queueClient.scheduleMessage(message, scheduledEnqueueTimeUtc);
+  }
+}
+
+async function main(): Promise<void> {
+  ns = Namespace.createFromConnectionString(str);
+  const client = ns.createQueueClient(path, { receiveMode: ReceiveMode.peekLock });
+  const data = [
+    { name: "Einstein", firstName: "Albert" },
+    { name: "Heisenberg", firstName: "Werner" },
+    { name: "Curie", firstName: "Marie" },
+    { name: "Hawking", firstName: "Steven" },
+    { name: "Newton", firstName: "Isaac" },
+    { name: "Bohr", firstName: "Niels" },
+    { name: "Faraday", firstName: "Michael" },
+    { name: "Galilei", firstName: "Galileo" },
+    { name: "Kepler", firstName: "Johannes" },
+    { name: "Kopernikus", firstName: "Nikolaus" }
+  ];
+
+  // schedule messages to appear on Queue at a later time.
+  await sendMessages(client, data);
+
+  // retrieve all the messages that were sent to the queue
+  for (let index = 0; index < data.length; index++) {
+    // retrieve one message at a time.
+    const msg = await client.receiveBatch(1, 30 + index); // (30 + index) is the maximum wait time in seconds for which the Receiver will wait to receive the message.
+
+    console.log(`Retrieved: ${msg[0].body} - ${msg[0].label}`);
+  }
+
+  await client.close();
+}
+
+main()
+  .then(() => {
+    console.log(">>>> Calling close....");
+    return ns.close();
+  })
+  .catch((err) => {
+    console.log("error: ", err);
+  });