nvb

This utility lets you write or launch a process that will wait for a given set of clients to connect to it. HTTP-based Promise.all() for the console!

Each client ("part") is identified by a name. When all clients have connected, the listener ends its job and yields success (for CLI, this means exit 0; for nvb.listen() it's a resolved promise).

Install

# for a global install as root, use:
npm install -g nvb
# or if you prefer a local install for use in your project, with CLI tools in ./node_modules/.bin :
npm install nvb --save

Use from CLI

In one terminal:

nvb clientA clientB
# The process does not exit until you've called both clients
# Also, on timeout, the exit code will be 2 - you can inspect the last command's exit code by executing the below:
echo $?

In another:

nvb-client clientA
nvb-client clientB

The main nvb process should exit after you've called both clientA and clientB. Try that again, but call the client with the same name twice or a name that has not been declared on the server and observe what happens.

Also add some auth and configure a custom port, and pass two fancy names to wait for:

export NVB_PORT=15678
export NVB_TOKEN=super-secret-stuff
export NVB_TIMEOUT=10000
nvb mainApp backgroundWorker &
# Børk børk
NVB_TOKEN=totally-forgot nvb-client backgroundWorker
# Only the main app is having a good day today:
nvb-client mainApp
# In a sec, you're going to see nvb complain about the background worker missing

Use from Node

// On the server that will listen to the minions waking up:
require('nvb').listen({ parts: [ 'minion1', 'minion2' ] }).then(onFulfilled, onRejected);

// On the clients:
require('nvb').notify({ name: 'minion1' });

nvb.listen([ options ]) → Promise

Start listening for all clients to connect.

nvb.notify([ options ]) → Promise

Connect to an nvb server and indicate the client's presence.

Options

options.parts : Array.<string>

The set of client names to await. When all of them have connected, the promise resolves. Only used on the server.

options.address : string

The address to listen on or to connect to. By default, :: is used on the server (all interfaces) and ::1 on the client (localhost).

options.port : number

The port to listen on or to connect to. By default, 6786 or whatever is passed in environment variable NVB_PORT.

options.token : string

If passed, uses a string value to authenticate against the server using an X-NVB-Token. On the server, this parameter sets the required token. Defaults to env variable NVB_TOKEN - unused if empty.

options.timeout : number

Sets the timeout (ms) for connecting and listening. By default, 10000 on the client and 60000 on the server.

License

MIT