How Java implements message communication using Apache Pulsar
Apache Pulsar is an open source distributed messaging system that can be used to reliably store and transmit large-scale data streams. It has high scalability and can provide low latency and high throughput message delivery.
The following are some advantages of the Apache Pulsar framework:
1. Distributed architecture: Pulsar adopts a layered architecture, which is conducive to high reliability and scalability.
2. Persistent storage: Messages are stored in persistent storage and can be delayed and data persisted as needed.
3. Flexible message delivery guarantee: Pulsar supports multiple message delivery guarantee levels to meet various application requirements.
4. Multi tenant support: Multiple tenants can be isolated in different namespaces to ensure data security and isolation.
5. Support rich client APIs: Pulsar provides various client APIs such as Java, Python, and C++, making it easy for developers to use.
The following is the complete sample code for using Apache Pulsar to send and receive messages in Java:
Firstly, you need to add the maven dependency of Apache Pulsar.
<dependency>
<groupId>org.apache.pulsar</groupId>
<artifactId>pulsar-client</artifactId>
<version>2.8.0</version>
</dependency>
2. Example of message sending code:
import org.apache.pulsar.client.api.*;
public class PulsarProducerExample {
public static void main(String[] args) throws PulsarClientException {
PulsarClient client = PulsarClient.builder()
.serviceUrl("pulsar://localhost:6650")
.build();
Producer<byte[]> producer = client.newProducer()
.topic("my-topic")
.create();
String message = "Hello, Pulsar!";
producer.send(message.getBytes());
producer.close();
client.close();
}
}
In the above code example, we first created a PulsarClient object and set the URL of the Pulsar service. Then, create a Producer object and specify the topic to send the message to. Finally, send the message by calling the 'send' method.
3. Example of message receiving code:
import org.apache.pulsar.client.api.*;
public class PulsarConsumerExample {
public static void main(String[] args) throws PulsarClientException {
PulsarClient client = PulsarClient.builder()
.serviceUrl("pulsar://localhost:6650")
.build();
Consumer<byte[]> consumer = client.newConsumer()
.topic("my-topic")
.subscriptionName("my-subscription")
.subscribe();
while (true) {
Message<byte[]> msg = consumer.receive();
try {
System.out.println(new String(msg.getData()));
consumer.acknowledge(msg);
} catch (Exception e) {
//Handling exceptions
}
}
}
}
In the above code example, we first created a PulsarClient object and set the URL of the Pulsar service. Then, create a Consumer object and specify the topic and subscription name to receive. Then, you can receive messages by calling the 'receive' method in the loop.
Configuration example:
In the configuration file of Pulsar (such as' conf/pulsar. conf '), the following example configurations can be added to start the Pulsar service:
brokerServicePort=6650
webServicePort=8080
For more information about Apache Pulsar, please refer to the official website: https://pulsar.apache.org/
