📦 rpc-nats-alvamind: Your Go-To RPC Library with NATS

⚡️ Supercharge your microservices with seamless, reliable communication!

🤔 What's the Deal?

rpc-nats-alvamind is a lightweight, flexible RPC (Remote Procedure Call) library built on top of the blazing-fast NATS messaging system. It's designed for building robust, scalable microservices with ease. Think of it as the glue that holds your distributed systems together! 🧩

✨ Key Features

• 💨 NATS Power: Built on top of NATS, leveraging its speed and reliability for high-performance messaging.
• 🔌 Codec Flexibility: Supports json and string codecs. Easily plug in your own!
• 🎯 Type-Safe Proxies: Generate client proxies with strong typing, reducing runtime errors.
  • Choose between ClassTypeProxy or as unknown as ClassName casting for generated proxies.
• 🛡️ Error Handling: Handles errors gracefully with retry logic and dead-letter queue (DLQ) support.
• ⏱️ Customizable Timeouts: Set timeouts for requests to prevent hanging calls.
• 🔄 Prototype Chain Support: Works flawlessly with class inheritance, making your life easier.
• 🪵 Logger Integration: Includes built-in logging with logger-alvamind for easy debugging.
• 🛠️ Easy Setup: Simple to install and use, getting you up and running in minutes.
• ✅ Fully Tested: Comes with a comprehensive test suite for reliability.

🚀 Benefits

• ⚡️ Speed & Efficiency: NATS's performance gives you lightning-fast RPC calls.
• ⚙️ Scalability: Designed for microservices, making it easy to scale your apps.
• 🧱 Modular Design: The code is clean and well-organized, making it easy to maintain and extend.
• ✅ Reliability: Retry logic and DLQ ensure your requests are processed, even when things get bumpy.
• 🧑‍💻 Developer-Friendly: Easy-to-use API with TypeScript support.
• 🥳 Code That's Fun: Built with modern JS, you'll enjoy developing with this!

🛠️ Installation

bun add rpc-nats-alvamind

📖 Usage

1. Setting Up a Server

import { RPCServer } from 'rpc-nats-alvamind';

// Define your service classes
class MyService {
  async hello(name: string): Promise<string> {
    return `Hello, ${name}!`;
  }
    async complexObject(data: any): Promise<any> {
        return data
    }
}

class AnotherService {
  async greet(message: string): Promise<string> {
    return `Server says: ${message}`;
  }
}

async function main() {
  const server = new RPCServer({ url: 'nats://localhost:4222', debug: true }); // Pass in your NATS options
  await server.start();

  // Register your service instances
  await server.handleRequest(new MyService());
  await server.handleRequest(new AnotherService());
    // or with retry
   await server.handleRequest(new MyService(),{ retry: { attempts: 3, delay: 100 } });
   await server.handleRequest(new AnotherService(), { dlq: 'my.dlq', retry: { attempts: 3, delay: 100 } });

  console.log('RPC Server is running!');
}

main();

2. Creating a Client Proxy

import { RPCClient, ClassTypeProxy } from 'rpc-nats-alvamind';

// Define your service interfaces/classes, matching server side
class MyService {
  hello(name: string): Promise<string> {
    throw new Error('Method not implemented.');
  }
    complexObject(data: any): Promise<any> {
        throw new Error('Method not implemented.');
    }
}
class AnotherService {
  greet(message: string): Promise<string> {
      throw new Error('Method not implemented.');
    }
}
async function main() {
  const client = new RPCClient({ url: 'nats://localhost:4222', debug: true, timeout: 5000 }); // Pass in your NATS options
  await client.start();

  // Generate proxies
  const myServiceClient: ClassTypeProxy<MyService> = client.createProxy(MyService);
  const anotherServiceClient: ClassTypeProxy<AnotherService> = client.createProxy(AnotherService);

  // Use the generated proxies to make RPC calls
  const response1 = await myServiceClient.hello('World');
  console.log('Response 1:', response1); // Output: Hello, World!

  const response2 = await anotherServiceClient.greet('Howdy!');
  console.log('Response 2:', response2); // Output: Server says: Howdy!
  const data = { name: "Complex", data: { nested: [{ value: 1, isTrue: true, date: new Date(), bigint: BigInt(9007199254740991) }] } }
    const response3 = await myServiceClient.complexObject(data)
    console.log('Response 3:', response3);

  await client.close();
}

main();

3. Codec Usage

import { RPCServer, RPCClient, ClassTypeProxy, getCodec } from 'rpc-nats-alvamind';

// Server Side
class MyService {
  async hello(name: string): Promise<string> {
    return `Hello, ${name}!`;
  }
}

async function mainServer() {
  const server = new RPCServer({ url: 'nats://localhost:4222', codec: "string" }); // using string codec
  await server.start();
  await server.handleRequest(new MyService());
}
mainServer();

// Client Side
class MyService {
    hello(name: string): Promise<string> {
        throw new Error('Method not implemented.');
    }
}
async function mainClient() {
  const client = new RPCClient({ url: 'nats://localhost:4222', codec: "string"}); // using string codec
  await client.start();
  const myServiceClient: ClassTypeProxy<MyService> = client.createProxy(MyService);
    const response1 = await myServiceClient.hello('World');
    console.log('Response 1:', response1); // Output: Hello, World!
  await client.close();
}
mainClient();

4. Custom Codec Usage

import { RPCServer, RPCClient, ClassTypeProxy, NatsCodec } from 'rpc-nats-alvamind';

// Server Side
//Custom Codec
class MyCustomCodec implements NatsCodec<any>{
  encode(data: any): Uint8Array {
    return new TextEncoder().encode(JSON.stringify(data));
  }
  decode(data: Uint8Array): any {
    const value = new TextDecoder().decode(data)
    return JSON.parse(value);
  }
}

class MyService {
  async hello(name: string): Promise<string> {
    return `Hello, ${name}!`;
  }
}

async function mainServer() {
  const codec = new MyCustomCodec();
  const server = new RPCServer({ url: 'nats://localhost:4222', codec: codec });
  await server.start();
  await server.handleRequest(new MyService());
}
mainServer();

// Client Side
class MyService {
  hello(name: string): Promise<string> {
    throw new Error('Method not implemented.');
  }
}

async function mainClient() {
  const codec = new MyCustomCodec()
  const client = new RPCClient({ url: 'nats://localhost:4222', codec: codec});
  await client.start();
  const myServiceClient: ClassTypeProxy<MyService> = client.createProxy(MyService);
  const response1 = await myServiceClient.hello('World');
  console.log('Response 1:', response1);
  await client.close();
}
mainClient();

5. Error Handling

import { RPCServer, RPCClient, ClassTypeProxy } from 'rpc-nats-alvamind';

// Define your service classes
class MyService {
  async error(): Promise<string> {
   throw new Error("this is test error");
  }
}

async function main() {
  const server = new RPCServer({ url: 'nats://localhost:4222', debug: true });
  await server.start();

  // Register your service instances
  await server.handleRequest(new MyService());
  console.log('RPC Server is running!');
  const client = new RPCClient({ url: 'nats://localhost:4222', debug: true, timeout: 5000 });
  await client.start();
  const myServiceClient: ClassTypeProxy<MyService> = client.createProxy(MyService);
  try{
    await myServiceClient.error();
  }catch(err){
    console.log("error", err) // catch the error
  }
  await server.close();
    await client.close();
}

main();

6. Retry with DLQ (Dead Letter Queue)

import { RPCServer, RPCClient, ClassTypeProxy } from 'rpc-nats-alvamind';

interface DLQMessage {
  className: string;
  methodName: string;
  data: any;
  error: string;
  errorType: string
}

// Define your service classes
class MyService {
  async flakyCall(): Promise<string> {
   throw new Error("flaky error");
  }
}

async function main() {
  const dlqSubject = 'my.dlq'; // dlq subject
  let dlqMessage: DLQMessage | undefined;
  const server = new RPCServer({ url: 'nats://localhost:4222', debug: true, dlq: dlqSubject, retry: { attempts: 2, delay: 100 } }); // retry logic
  await server.start();

  const dlqPromise = new Promise<DLQMessage>((resolve) => {
    const nc = server['natsClient'].getNatsConnection();
    nc?.subscribe(dlqSubject, {
      callback: (err, msg) => {
        if (!err) {
          const decoded = server['natsClient'].getCodec().decode(msg.data);
          resolve(decoded);
        }
      }
    });
  });
  // Register your service instances
  await server.handleRequest(new MyService());
  console.log('RPC Server is running!');
  const client = new RPCClient({ url: 'nats://localhost:4222', debug: true, timeout: 5000 });
  await client.start();
  const myServiceClient: ClassTypeProxy<MyService> = client.createProxy(MyService);
  try{
   await myServiceClient.flakyCall();
  }catch(err){
   console.log("error", err) // catch the error
  }
  dlqMessage = await dlqPromise;
  console.log("DLQ Message", dlqMessage); // DLQ message
  await server.close();
    await client.close();
}

main();

7. Generating Client Proxies with rpc-nats CLI

The rpc-nats-alvamind package includes a CLI tool to automatically generate the rpc-services.ts file containing client proxies. This tool is particularly useful for large projects.

To generate RPC services, use the following command:

rpc-nats generate --includes="src/**/*.controller.ts" --output="src/common/rpc/rpc-services.ts"

Options:

• --includes: Glob patterns for including files (required).
• --excludes: Glob patterns for excluding files.
• --output: Output file path.
• --watch: Watch for file changes and regenerate.
• --logLevel: Log level (debug, info, warn, error).
• --proxyType: Type of proxy generation, proxy (default), generate proxies using ClassTypeProxy or cast to generate proxies with casting with as unknown as ClassName

Examples:

# Generate rpc-services.ts using ClassTypeProxy
rpc-nats generate --includes="src/**/*.controller.ts" --output="src/common/rpc/rpc-services.ts"

# Generate rpc-services.ts with casting
rpc-nats generate --includes="src/**/*.controller.ts" --output="src/common/rpc/rpc-services.ts" --proxyType=cast

# Multiple includes and excludes with watch mode
rpc-nats generate \
  --includes="src/**/*.controller.ts" "src/**/*.service.ts" \
  --excludes="src/**/*.spec.ts" "src/**/*.test.ts" \
  --output="src/common/rpc/rpc-services.ts" \
  --watch

🧪 Testing

To run the test suite:

bun test test/*.test.ts

📜 API Reference

RPCServer

• constructor(options: RPCServerOptions): Creates a new RPC server instance.
• start(): Promise<void>: Connects to the NATS server.
• close(): Promise<void>: Closes the NATS connection.
• handleRequest<T extends ClassType>(instance: T, retryConfig?: { retry?: {attempts: number, delay: number }, dlq?: string}): Promise<void>: Registers an instance to handle requests.
• isConnected(): boolean: Checks whether nats client is connected
• getRegisteredMethods(): Map<string, Set<string>>: get all registered methods.
• isMethodRegistered(className: string, methodName: string): boolean: check if method is registered.

RPCClient

• constructor(options: RPCClientOptions): Creates a new RPC client instance.
• start(): Promise<void>: Connects to the NATS server.
• close(): Promise<void>: Closes the NATS connection.
• createProxy<T extends ClassType>(classConstructor: new (...args: any[]) => T): ClassTypeProxy<T>: Creates a proxy for a class.
• isConnected(): boolean: Checks if the client is connected.
• getAvailableMethods(className: string): string[]: Gets available methods for class.
• isMethodAvailable(className: string, methodName: string): boolean: check if method is available.
• setTimeout(timeout: number): void: Sets request timeout.
• getTimeout(): number: Gets the current timeout.
• clearMethodCache(className?: string): void: Clears method cache.
• getStats(): { isConnected: boolean; cachedClasses: number; totalCachedMethods: number; timeout: number; }: Gets client stats.

NatsOptions

• url?: string: NATS server URL (nats://localhost:4222 by default).
• codec?: "json" | "string": Choose codec, default is json.
• debug?: boolean: Enable debug logs.

RPCServerOptions

• retry?: { attempts: number; delay: number; }: Configure retries.
• dlq?: string: Dead Letter Queue Subject.

ClassTypeProxy<T>

• A type for dynamic client proxy, that will expose method of class T.

getCodec

• getCodec<T = unknown>(codec: SupportedCodec | NatsCodec<T> = "json"): NatsCodec<T>: A function to get codec instance either json or string or instance of custom codec.

⚙️ Advanced Usage

🛠️ Custom Codecs

You can create your own codec by implementing the NatsCodec interface:

import { NatsCodec } from 'rpc-nats-alvamind';

class MyCustomCodec<T> implements NatsCodec<T> {
  encode(data: T): Uint8Array {
    // Your custom encoding logic here
    return new TextEncoder().encode(JSON.stringify(data));
  }

  decode(data: Uint8Array): T {
     // Your custom decoding logic here
    const value = new TextDecoder().decode(data)
    return JSON.parse(value);
  }
}

Then you can pass the codec instance to RPCServer and RPCClient options like:

  const codec = new MyCustomCodec<any>();
  const server = new RPCServer({ url: 'nats://localhost:4222', codec: codec });
  const client = new RPCClient({ url: 'nats://localhost:4222', codec: codec });

🪵 Logging

This library use logger-alvamind to provide logging functionality, to see debug logs pass {debug: true} to constructor options of RPCServer and RPCClient or set process.env.DEBUG or set NODE_ENV=test.

🤝 Contributing

Contributions are welcome! Feel free to submit pull requests or open issues on the GitHub repository.

Contribution Guidelines

1. Fork the repository.
2. Create a new branch.
3. Make your changes and ensure that tests pass
4. Submit a pull request.

🙏 Donations

If you find this library helpful, consider making a donation to support further development:

• PayPal: your-paypal-link
• GitHub Sponsors: your-github-sponsors-link

⚠️ Disclaimer

This library is provided "as is" without any warranties. Use at your own risk!

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

Thank you and Happy Coding! 🚀🎉