docs: Update sample code snippets in the main readme (#71)

* Update example code in readme

* comment

Author: tmdiep

README.md

@@ -18,6 +18,14 @@ If you are using Maven, add this to your pom.xml file
   <artifactId>google-cloud-pubsublite</artifactId>
   <version>0.1.3</version>
 </dependency>
+
+<!-- A logging dependency used by the underlying library  -->
+<dependency>
+  <groupId>com.google.flogger</groupId>
+  <artifactId>flogger-system-backend</artifactId>
+  <version>0.5.1</version>
+  <scope>runtime</scope>
+</dependency>
 ```
 If you are using Gradle, add this to your dependencies
 ```Groovy
@@ -85,6 +93,9 @@ publishers. Add the following imports at the top of your file:
 
 ```java
 import com.google.cloud.pubsublite.*;
+import com.google.cloud.pubsublite.proto.Topic;
+import com.google.cloud.pubsublite.proto.Topic.*;
+import com.google.protobuf.util.Durations;
 ```
 Then, to create the topic, use the following code:
 
@@ -93,28 +104,28 @@ CloudRegion region = CloudRegion.of("us-central1");
 TopicPath topicPath =
     TopicPaths.newBuilder()
       .setZone(CloudZone.of(region, 'b'))
-      .setProjectNumber(ProjectNumber.of(123))
+      .setProjectNumber(ProjectNumber.of(123L)) // Your project number.
       .setTopicName(TopicName.of("my-new-topic"))
       .build();
-    
+
 Topic topic =
     Topic.newBuilder()
       .setPartitionConfig(
         PartitionConfig.newBuilder()
           .setScale(1) // Set publishing throughput to 1*4 MiB per sec. This must be 1-4.
-          .setCount(PARTITIONS))
+          .setCount(2)) // The number of partitions.
       .setRetentionConfig(
         RetentionConfig.newBuilder()
           .setPeriod(Durations.fromDays(7))
           .setPerPartitionBytes(100000000000L)) // 100 GiB. This must be 30 GiB-10 TiB.
       .setName(topicPath.value())
       .build();
 
-try (AdminClient client =
-         AdminClientBuilder.builder()
-           .setRegion(region)
-           .build()) {
-  client.createTopic(topic).get();
+AdminClientSettings settings =
+    AdminClientSettings.newBuilder().setRegion(region).build();
+try (AdminClient client = AdminClient.create(settings)) {
+  Topic response = client.createTopic(topic).get();
+  System.out.println(response.getAllFields());
 }
 ```
 
@@ -123,8 +134,12 @@ try (AdminClient client =
 With Pub/Sub Lite, you can publish messages to a topic. Add the following import at the top of your file:
 
 ```java
+import com.google.api.core.*;
 import com.google.cloud.pubsublite.*;
 import com.google.cloud.pubsublite.cloudpubsub.*;
+import com.google.protobuf.ByteString;
+import com.google.pubsub.v1.PubsubMessage;
+import java.util.*;
 ```
 Then, to publish messages asynchronously, use the following code:
 
@@ -139,12 +154,12 @@ public class PublisherExample {
   // Load the topic name from a commandline flag.
   private static final String TOPIC_NAME = "my-new-topic";
 
-  public static List<ApiFuture<String>> runPublisher(PublisherInterface publisher) throws Exception {
+  public static List<ApiFuture<String>> runPublisher(Publisher publisher) throws Exception {
     List<ApiFuture<String>> futures = new ArrayList<>();
     for (int i = 0; i < MESSAGE_COUNT; i++) {
       String message = "message-" + i;
 
-      // convert message to bytes
+      // Convert the message to a byte string.
       ByteString data = ByteString.copyFromUtf8(message);
       PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();
 
@@ -157,25 +172,27 @@ public class PublisherExample {
 
   // Publish messages to a topic.
   public static void main(String[] args) throws Exception {
-    PublisherApiService publisherService =
-        PublisherBuilder.newBuilder()
+    PublisherSettings settings =
+        PublisherSettings.newBuilder()
             .setTopicPath(
                 TopicPaths.newBuilder()
                     .setProjectNumber(ProjectNumber.of(PROJECT_NUMBER))
                     .setZone(CloudZone.parse(ZONE))
                     .setTopicName(TopicName.of(TOPIC_NAME))
                     .build())
             .build();
-    publisherService.startAsync().awaitRunning();
-    List<ApiFuture<String>> futureAckIds = runPublisher(publisherService);
-    publisherService.stopAsync().awaitTerminated();
+    Publisher publisher = Publisher.create(settings);
+    publisher.startAsync().awaitRunning();
+    List<ApiFuture<String>> futureAckIds = runPublisher(publisher);
+    publisher.stopAsync().awaitTerminated();
+
     List<String> ackIds = ApiFutures.allAsList(futureAckIds).get();
     ArrayList<PublishMetadata> metadata = new ArrayList<>();
     for (String id : ackIds) {
       metadata.add(PublishMetadata.decode(id));
     }
     for (PublishMetadata one : metadata) {
-      System.out.println(one.offset());
+      System.out.println(one);
     }
   }
 }
@@ -188,15 +205,17 @@ single, specific topic. Add the following imports at the top of your file:
 
 ```java
 import com.google.cloud.pubsublite.*;
+import com.google.cloud.pubsublite.proto.Subscription;
+import com.google.cloud.pubsublite.proto.Subscription.*;
+import com.google.cloud.pubsublite.proto.Subscription.DeliveryConfig.*;
 ```
 Then, to create the subscription, use the following code:
 
 ```java
-// CloudZone must be equivalent to the topic.
-CloudRegion cloudRegion = CloudRegion.of("us-central1");
-CloudZone zone = CloudZone.of(cloudRegion, 'b');
-// ProjectNumber must the equivalent to the topic.
-ProjectNumber projectNum = ProjectNumber.of(123);
+// CloudZone must be the zone of the topic.
+CloudRegion region = CloudRegion.of("us-central1");
+CloudZone zone = CloudZone.of(region, 'b');
+ProjectNumber projectNum = ProjectNumber.of(123L);
 TopicName topicName = TopicName.of("my-new-topic");
 SubscriptionName subscriptionName = SubscriptionName.of("my-new-sub");
 
@@ -223,11 +242,11 @@ Subscription.newBuilder()
   .setTopic(topicPath.value())
   .build();
 
-try (AdminClient client =
-         AdminClientBuilder.builder()
-           .setRegion(region)
-           .build()) {
-  client.createSubscription(subscription).get();
+AdminClientSettings settings =
+    AdminClientSettings.newBuilder().setRegion(region).build();
+try (AdminClient client = AdminClient.create(settings)) {
+  Subscription response = client.createSubscription(subscription).get();
+  System.out.println(response.getAllFields());
 }
 ```
 
@@ -237,29 +256,37 @@ With Pub/Sub Lite you can receive messages from a subscription. Add the
 following imports at the top of your file:
 
 ```java
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
 import com.google.cloud.pubsublite.*;
 import com.google.cloud.pubsublite.cloudpubsub.*;
-import com.google.pubsub.v1.MessageReceiver;
-import com.google.pubsub.v1.SubscriberInterface;
+import com.google.common.util.concurrent.MoreExecutors;
+import com.google.pubsub.v1.PubsubMessage;
+import java.util.*;
 ```
 Then, to pull messages asynchronously, use the following code:
 
 ```java
+CloudZone zone = CloudZone.parse("us-central1-b");
+ProjectNumber projectNum = ProjectNumber.of(123L);
+SubscriptionName subscriptionName = SubscriptionName.of("my-new-sub");
+
 SubscriptionPath subscriptionPath =
-SubscriptionPaths.newBuilder()
-  .setZone(zone)
-  .setProjectNumber(projectNum)
-  .setSubscriptionName(subscriptionName)
-  .build();
-// Connect to partition 0.
-Partition PARTITION = Partition.of(0);
+    SubscriptionPaths.newBuilder()
+      .setZone(zone)
+      .setProjectNumber(projectNum)
+      .setSubscriptionName(subscriptionName)
+      .build();
 
 FlowControlSettings flowControlSettings =
     FlowControlSettings.builder()
-      .setBytesOutstanding(10_000_000) // 10 MB per partition.
-      .setMessagesOutstanding(Long.MAX_VALUE)
-      .build();
+        .setBytesOutstanding(10 * 1024 * 1024L) // 10 MiB per partition.
+        .setMessagesOutstanding(Long.MAX_VALUE)
+        .build();
 
+// Connect to partitions 0, 1. Note that we configured the topic with 2
+// partitions.
+List<Partition> partitions = Arrays.asList(Partition.of(0), Partition.of(1));
 
 MessageReceiver receiver =
   new MessageReceiver() {
@@ -276,19 +303,20 @@ MessageReceiver receiver =
     }
   };
 
-SubscriberInterface subscriber = null;
+Subscriber subscriber = null;
 try {
-  subscriber = Subscriber.create(SubscriberSetttings.newBuilder()
+  subscriber = Subscriber.create(SubscriberSettings.newBuilder()
          .setSubscriptionPath(subscriptionPath)
-         .setFlowControlSettings(flowControlSettings)
+         .setPerPartitionFlowControlSettings(flowControlSettings)
          .setReceiver(receiver)
-         .setPartitions(List.of(Partition.of(0)))
+         .setPartitions(partitions)
          .build());
   subscriber.addListener(
     new Subscriber.Listener() {
       @Override
       public void failed(Subscriber.State from, Throwable failure) {
-        // Handle failure. This is called when the Subscriber encountered a fatal error and is shutting down.
+        // Handle failure. This is called when the Subscriber encountered a
+        // fatal error and is shutting down.
         System.err.println(failure);
       }
     },
@@ -302,6 +330,10 @@ try {
 }
 ```
 
+## Samples
+
+More sample code can be found in the [samples](samples) folder.
+
 ## Troubleshooting
 
 To get help, follow the instructions in the [shared Troubleshooting document][troubleshooting].