Message pubish in goolge cloud pubsub topic with java client

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Table Of Contents

  1. What is Pub/Sub?
  2. What are the benefits of using Pub/Sub?
  3. Core concepts of Pub/sub.
  4. How to publish a message in pub/sub topic in java with credentials?
  5. Shutdown publisher when application stop or no need publisher. 
  6. GitHub project link of reusable module. 
  7. How to publish and receive a message in pub/sub in cloud console?
  8. Conclusion.

 What is Pub/Sub?

Cloud Pub/Sub is a fully-managed messaging service provided by Google Cloud Platform. It is designed to provide reliable, scalable, and real-time messaging between applications and services.

Cloud Pub/Sub allows you to publish and consume messages from any application or service, regardless of the language or platform they are built on. It provides a simple and flexible architecture that decouples your systems and allows them to work independently.

In Cloud Pub/Sub, you can create one or more topics to which you can publish messages. Subscribers can then subscribe to the topic and receive all published messages in real-time. Cloud Pub/Sub guarantees the delivery of each message at least once, ensuring that every message is received by at least one subscriber.

Cloud Pub/Sub provides many features, including filtering and delivery control, which allow you to control which messages are delivered to which subscribers, as well as rate-limiting and message retention policies to help you manage your data. Additionally, Cloud Pub/Sub integrates with many other services in the Google Cloud Platform, making it easy to build complex applications and workflows.

What are the benefits of using Pub/Sub?

There are many benefits to using Pub/Sub, including the ability to:
-Easily scale your message processing
-Decouple your message producers from your message consumers
-Guarantee delivery of messages by using Google’s global infrastructure
-Monitor the health of your message processing system with built-in metrics and logs

Pub/Sub is a flexible, reliable, and cost-effective way to process large volumes of messages. it is extremely efficient at moving data between databases and in storage. A large queue of tasks can be easily distributed among multiple devices for the most balanced workload. And because Pub/Sub decouples your message producers from your message consumers, you can add or remove consumers without affecting your producers.

Core concepts of Pub/sub

  • Topic: A named resource to which messages are sent by publishers.
  • Subscription: In order to get the data published on the topic, we must subscribe to that topic. Subscription represents the streaming message from a unique topic to be delivered to the subscribing application.
  • Message: A data that is going to be published and subscribed.
  • Message attribute: Depending on the receiver’s language, the publisher can define a key-value pair for the message.
  • Publisher: An application that creates and sends messages to single or multiple topics.
  • Subscriber:  An application with a subscription to single or multiple topics to receive messages from it.
  • Push and pull: The two message delivery methods. A subscriber receives messages either by Pub/Sub pushing them to the subscriber-chosen endpoint or by the subscriber pulling them from the service.

How to publish a message in pub/sub topic in java with credentials?

 To publish a message to a Google Cloud Pub/Sub topic using Java with credentials, follow these steps:

  • Ensure that you have created a Google Cloud project, enabled the Cloud Pub/Sub API, and created a topic.
  •   Add the Google Cloud Pub/Sub client library to your Java project. You can do this by adding the following dependency to your project's pom.xml file if you are using Maven:  
                <dependency>
                      <groupId>com.google.cloud</groupId>
                      <artifactId>google-cloud-pubsub</artifactId>
                      <version>1.123.2</version>
                </dependency>
  • In your Java code, create an instance of the Credentials class to authenticate with Google Cloud Platform: 

         CredentialsProvider credentialsProvider = null;
         try {
            credentialsProvider = FixedCredentialsProvider
        .create(ServiceAccountCredentials
        .fromStream(new ByteArrayInputStream(
        StandardCharsets.UTF_8.encode("AccountCredential").array()
        )));

            } catch (Exception e) {
            }     

         Replace <AccountCredential> with your credentials.

         You can download this file from the Google Cloud Console.

  • Create an instance of the Publisher class from the Google Cloud Pub/Sub client library, passing the credentials and the name of the topic you want to publish to:
                 ProjectTopicName topic = ProjectTopicName.of("ProjectId", "Topic"); 

         Publisher publisher = Publisher.newBuilder(topic)

.setCredentialsProvider(credentialsProvider)

.build()

                 Replace <ProjectId> and <Topic> with your project and topic name.
  • Create a PubsubMessage object to represent the message you want to publish:

         ByteString data = ByteString.copyFromUtf8("Message Content");

         PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();

 
         Replace <Message Content> with your message body.
  • Publish the message to the topic using the publish method of the Publisher instance:
              try {
                    ApiFuture<String> messageIdFuture = publisher.publish(pubsubMessage);
                    String messageId = messageIdFuture.get();
                    ApiFutures.addCallback(messageIdFuture, new ApiFutureCallback<String>() {
                       public void onSuccess(String messageId) {
                        }
                       public void onFailure(Throwable t) {
                       }
                     }, MoreExecutors.directExecutor());
                 } catch (Exception e) {
                 } 
  • Close the Publisher instance after publishing the message: 
         try {
                 publisher.shutdown();
                 publisher.awaitTermination(1, TimeUnit.MINUTES);
           } catch (Exception e) {
           }

GitHub project link of reusable module. 

 
Steps to use this module:
 
1. Clone Repository.
  git clone https://github.com/tariqulgithub/gcloud-pubsub.git 

2. Compile and Install.

  mvn clean install
3. Dependency Setup
    <dependency>
       <groupId>org.simpleton</groupId>
       <artifactId>gcloud-pubsub</artifactId>
       <version>1.0.0</version>
   </dependency>
4. Usage Example Code
    String credentialString =  "";
    JSONObject messageBody = new JSONObject();
    messageBody.put("Hello", "Hello From Inline");
    GAccountCredentials gAccountCredentials = GAccountCredentials.builder()
        .accountCredential(credentialString)
	.projectId("projectId")
	.topic("myTopic")
	.build();
    GCloudMessagePublisher publisher = GCloudMessagePublisher.getInstance();
    publisher.publishMessage(MessageContainer.builder()
    		.content(messageBody.toString())
    		.build(), gAccountCredentials); 
    publisher.shutdown(); 

How to publish and receive a message in pub/sub in cloud console?

First, we need to Set up a Google Cloud console project.

  • Create or select a project.
  • Enable the Pub/Sub API for that project.

Create a Topic:

  1. In a google cloud console, navigate to the pub-sub page.
  2. Click on create topic button and enter a unique name

 

Subscribe to the Topic:

 

Publish a message on the topic:

  1. To publish a message on the created topic, click on a topic
  2. Click on the message tab
  3. Select Subscription
  4. Click Publish Message
  5. In the Message body, add the message
  6. Click Publish. A message at the bottom of the page says “Message published” if the publication was successful.

 

Pull the data Published:

  1. Go to subscriptions, and click on subscription Id
  2. In the Messages tab, click Pull.

  

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