Facade

Every caller has to learn the whole subsystem just to do one common thing

Starting a video conversion might mean: open the file, validate the codec, allocate a decoder, configure the encoder, then run the pipeline — five classes, in the right order, with error handling at each step. Most callers just want "convert this file."

One method that knows the right order

The facade exposes a small number of high-level methods. Internally it calls the subsystem's classes in the correct sequence. The subsystem classes are still there and still usable directly for anyone who needs finer control.

One `convert()` call in front of four subsystem classes

Callers who only need the common case use `VideoFacade.convert()`; the individual classes remain available for advanced use.

const Decoder = { open: (f) => console.log(`decoder: opened ${f}`) };
const CodecValidator = { check: (f) => console.log(`validator: codec ok for ${f}`) };
const Encoder = { configure: (fmt) => console.log(`encoder: configured for ${fmt}`) };
const Pipeline = { run: () => console.log(`pipeline: running`) };

class VideoFacade {
  static convert(file, targetFormat) {
    Decoder.open(file);
    CodecValidator.check(file);
    Encoder.configure(targetFormat);
    Pipeline.run();
    console.log(`done: ${file} -> ${targetFormat}`);
  }
}

VideoFacade.convert("clip.mov", "mp4");

Trade-offs

• Lower barrier to entry — Most callers get a one-line, easy-to-remember call instead of learning the subsystem.
• Doesn't remove flexibility — Advanced callers can still reach the subsystem classes directly when the facade is too limiting.
• Can become a dumping ground — Resist adding every subsystem option as a facade parameter — that just rebuilds the complexity it was meant to hide.