Ubend

Wraps a NodeJS stream pipe chain in a Duplex stream.

Ubend is a light wrapper around pump.

The problem

I often write NodeJS transform streams that are designed to work together as a pipeline:

function pipeline(handlers) {
    var first = transformer1();
    var second = transformer2();
    var third = transformer3();
 
    first.pipe(second).pipe(third)
        .on("data", handlers.onData)
        .on("error", handlers.onError)
        .on("end", handlers.onEnd);
 
    return first;
}
 
pipeline({
        onData: /* something smart */,
        onError: /* something smart */,
        onEnd: /* something smart */
    })
    .write("some super cool input data")
    .pipe(process.stdout);

This is nice because each intermediate stream can be tested and reused separately, but it is also cumbersome:

1. I need to keep a handle on (at least) first
2. I have no satisfying way of getting the data out of third
3. Error handling is a nightmare

What I really want is to be able to treat the entire pipeline as a Duplex stream with sane error handling built in.

Installing

npm install --save ubend

Usage

const ubend = require("ubend");
 
function pipeline() {
    return ubend(
        transformer1(),
        transformer2(),
        transformer3()
    );
}
 
pipeline()
    .on("data", /* something smart */)
    .on("error", /* something smart */)
    .on("end", /* something smart */)
    .write("some super cool input data")
    .pipe(process.stdout);

Much more elegant.

ubend is based on pump and has the exact same API, except that it returns a Duplex stream instead of returning the last stream in the pipeline.

Ubend ONLY works with Duplex streams, obviously, and is specifically intended for use with Transform streams.

Roadmap

1. More tests