Add topicGettingStarted sample (Azure#82)

* Add topicGettingStarted sample

examples/samples/topicsGettingStarted.ts

@@ -0,0 +1,98 @@
+import {
+  OnMessage,
+  OnError,
+  MessagingError,
+  delay,
+  ServiceBusMessage,
+  generateUuid,
+  Namespace,
+  SendableMessageInfo,
+  SubscriptionClient,
+  TopicClient
+} from "../../lib";
+import * as dotenv from "dotenv";
+dotenv.config();
+
+const str = process.env.SERVICEBUS_CONNECTION_STRING || "";
+const topic = process.env.TOPIC_NAME || "";
+const subscription1 = process.env.SUBSCRIPTION_NAME1 || "";
+const subscription2 = process.env.SUBSCRIPTION_NAME2 || "";
+const subscription3 = process.env.SUBSCRIPTION_NAME3 || "";
+
+console.log("str: ", str);
+console.log("path: ", topic);
+console.log("Subscription 1: ", subscription1);
+console.log("Subscription 2: ", subscription2);
+console.log("Subscription 3: ", subscription3);
+
+let ns: Namespace;
+async function main(): Promise<void> {
+  ns = Namespace.createFromConnectionString(str);
+  const client = ns.createTopicClient(topic);
+
+  const subscription1Client = ns.createSubscriptionClient(topic, subscription1);
+  const subscription2Client = ns.createSubscriptionClient(topic, subscription2);
+  const subscription3Client = ns.createSubscriptionClient(topic, subscription3);
+
+  //we are setting up receive handlers here
+  setupReceiveHandlers(subscription1Client);
+  setupReceiveHandlers(subscription2Client);
+  setupReceiveHandlers(subscription3Client);
+
+  await sendMessage(client);
+
+  await delay(2000);
+
+  await subscription1Client.close();
+  await subscription2Client.close();
+  await subscription3Client.close();
+}
+
+async function sendMessage(client: TopicClient): Promise<void> {
+  var 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" }
+  ];
+  for (let index = 0; index < data.length; index++) {
+    const element = data[index];
+    const message: SendableMessageInfo = {
+      body: `${element.firstName} ${element.name}`,
+      label: "Scientist",
+      timeToLive: 2 * 60 * 1000, // 2 minutes
+      messageId: generateUuid()
+    };
+
+    console.log(`Sending ${message.body} \n`);
+    await client.send(message);
+  }
+}
+
+async function setupReceiveHandlers(client: SubscriptionClient): Promise<void> {
+  const onMessage: OnMessage = async (brokeredMessage: ServiceBusMessage) => {
+    console.log(`subscription: ${client.name}  Retrieved: ${brokeredMessage.body}`);
+  };
+  const onError: OnError = (err: MessagingError | Error) => {
+    console.log(">>>>> Error occurred: ", err);
+  };
+  const rcvHandler = client.receive(onMessage, onError);
+  await delay(10000);
+  await rcvHandler.stop();
+}
+
+main()
+  .then(() => {
+    console.log(">>>> Calling close....");
+    return ns.close();
+  })
+  .catch((err) => {
+    console.log("error: ", err);
+    return ns.close();
+  });