What Is Hermes Ambassador?

Hermes Ambassador is a powerful tool for building scalable, asynchronous APIs in Node.js. It allows you to create microservices that can communicate with each other using a publish/subscribe messaging pattern. With Hermes, you can build complex systems that are loosely coupled and fault-tolerant.

How does Hermes work?

Hermes uses the AMQP (Advanced Message Queuing Protocol) messaging protocol to send and receive messages between nodes. Each node in the system can act as both a publisher and a subscriber, and messages are sent to named queues.

When a node wants to send a message, it publishes it to a queue. Other nodes that are subscribed to that queue will receive the message and can then process it. This allows for asynchronous communication between nodes, which is essential for building scalable systems.

Benefits of using Hermes

One of the main benefits of using Hermes is that it allows you to build systems that are highly scalable and fault-tolerant. Because each node in the system is loosely coupled, you can add or remove nodes as needed without affecting the rest of the system.

Another benefit of using Hermes is that it provides a high level of reliability. Messages are durable by default, which means they will be persisted even if the server crashes or restarts. This ensures that no messages are lost and that all nodes in the system receive all necessary information.

• Scalability: Hermes allows you to build systems that can scale horizontally by adding additional nodes.
• Fault-tolerance: Because each node is loosely coupled, failures in one part of the system won’t affect other parts.
• Reliability: Messages are durable by default, ensuring that no data is lost.
• Flexibility: You can use Hermes to build a wide range of systems, from simple microservices to complex distributed systems.

Getting started with Hermes

To get started with Hermes, you’ll need to install the package via npm:

npm install hermesjs

Once you’ve installed the package, you can start building your first Hermes application. Here’s a simple example that demonstrates how to send and receive messages:

// Require the Hermes module
const hermes = require('hermesjs');

// Create a new instance of Hermes
const app = hermes();

// Define a handler for incoming messages
app.use((message, next) => {
  console.log(message.body);
  next();
});

// Start listening for messages on the 'example' queue
app.listen('example', () => {
  console.log('Listening for messages on the "example" queue..');
});

// Publish a message to the 'example' queue
app.publish('example', { foo: 'bar' });

In this example, we’re creating a new instance of Hermes and defining a handler that logs incoming messages. We’re then starting the server and listening for messages on the ‘example’ queue. Finally, we’re publishing a message to that queue.

Conclusion

Hermes is an excellent tool for building scalable and fault-tolerant systems in Node. By using asynchronous messaging patterns and durable messaging queues, you can build complex applications that are both reliable and flexible. If you’re looking to build distributed systems or microservices, be sure to give Hermes a try!