NATS proxy service

Simple tool to forward specific topics from one nats.io cluster to the same server or another. Provides support to process messages with deno Javascript or TypeScript code.

Example

Imagine that we use nats.io to relay events for every confirmed or canceled order in our shopping platform:

sh ./naps --source nats://aws:4222 --destination nats://aks:4222 --topics "orders.>"

If the --script flag is present, naps will spawn a Deno runtime with all v8 capabilities plus promises and all event loop goodies, allowing you to, for example, only keep the confirmed ones and relay them to the myapp.orders.confirmed. You only have to code a recv function with the following signature:

```typescript interface RecvResult { topic: string, msg: string };

function recv(topic: string, data: Uint8Array): boolean | RecvResult { //... your code here... } ```

Processing Example

```sh ./naps --source nats://aws:4222 --destination nats://aks:4222 --topics "myapp.v1.orders" --script " import { Buffer } from 'http://deno.land/x/node_buffer/index.ts';

interface Order {
    status: 'confirmed' | 'canceled',
    user: string,
    amount: number,
    item: any
};

function processOrder(data: Buffer): RecvResult {
    const orderRaw = data.toString();
    const order = JSON.parse(orderRaw) as Order;

    // Skip orders that are not confirmed
    if (order.status !== 'confirmed') {
        return false;
    }
    return {
        topic: 'myapp.v1.orders.confirmed',
        msg: orderRaw
    };
}

function recv(topic, uint8array) {
    switch (topic) {
        case "myapp.v1.orders":
            return processOrder(Buffer.from(uint8array))
        default:
            // nothing to do...
    }
}

" ```

Thanks

TODOs