How is the data processing in a pipeline organized?

The data processing pipeline process, typical for streams in Node.js, is based on passing data from one processing stage to another in small chunks.

Main stages:

1. Source: Reads data from a source (file1, socket2, HTTP request3).
2. Transformations: Sequentially applies processing operations to the data. Each stage receives data from the previous one, processes it, and passes it on.
3. Destination: Writes the processed data to the final node.

Example of using pipeline in Node.js:

const { createReadStream, createWriteStream } = require('node:fs');
const { Transform, pipeline } = require('node:stream');

const sourceStream = createReadStream('input.txt');
const destinationStream = createWriteStream('output.txt');

// Transformation: add a prefix to each line
const transformStream = new Transform({
  transform(chunk, encoding, callback) {
    this.push(`Prefix: ${chunk}`);
    callback();
  }
});

pipeline(
  sourceStream, // Source
  transformStream, // Transformation
  destinationStream, // Destination
  (err) => { // Callback on completion
    if (err) {
      console.error('Pipeline failed.', err);
    } else {
      console.log('Pipeline succeeded.');
    }
  }
);

Advantages of pipeline:

• Memory efficiency: Processes data in chunks without loading everything into memory at once.
• Composition: Easily combines multiple processing stages.
• Error handling: Built-in error handling mechanism that propagates through all streams.
• Logging: Allows attaching event handlers for process monitoring.