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enchannel-zmq-backend offers the ZeroMQ backend implementation for
enchannel.
As a refresher for the reader, enchannel details nteract's lightweight, implementation-flexible specification for communication between a user frontend and a backend, such as a language kernel. The enchannel specification offers a simple description of "what" messages may be passed between frontends and backends, while leaving a developer freedom in "how" to achieve message communication.
enchannel-zmq-backend takes a classic design approach using ZeroMQ, the foundation messaging protocol for the Jupyter project. enchannel-zmq-backend implements backend support for the messaging channels described in the Jupyter messaging specification. This spec explains how front end clients should communicate with backend language kernels which implement the Jupyter messaging specification.
enchannel-zmq-backend implements the "how" to communicate messages to and from a backend.
We provide functions to create RxJS Subjects (two way Observables for four of the channels described in the Jupyter messaging specification):
shellcontroliopubstdin
That's it. Functions for four channels; simplicity in action.
Prerequisite: Node.js and npm
You may use whichever package manager (npm or yarn) best suits your workflow. The nteract team internally uses yarn.
npm install enchannel-zmq-backend
# OR
yarn add enchannel-zmq-backendTo get access to all of the channels for messaging (shell, control,
iopub, and stdin), import and use the createChannels function:
import { createChannels } from 'enchannel-zmq-backend'The createChannels function accepts two things:
-
an identity
You'll want to set up your identity, relying on the node
uuidpackage:const uuidv4 = require('uuid/v4'); const identity = uuidv4();
-
a runtime object, such as a kernel (which matches the on-disk JSON). Using
spawnteractwith this project helps streamline spawning a kernel.const runtimeConfig = { stdin_port: 58786, ip: '127.0.0.1', control_port: 58787, hb_port: 58788, signature_scheme: 'hmac-sha256', key: 'dddddddd-eeee-aaaa-dddd-dddddddddddd', shell_port: 58784, transport: 'tcp', iopub_port: 58785 }
To create the channels object:
const channels = createChannels(identity, runtimeConfig)
const { shell, iopub, stdin, control } = channels;enchannel-zmq-backend also gives access to all of the channels via a
single multipled channel exposed via createMainChannel.
import { createMainChannel } from 'enchannel-zmq-backend';Similar to the createChannels function, the createMainChannel function
accepts both an identity and a runtime object.
const channel = createMainChannel(identity, runtimeConfig);Messages that are sent via the mutliplexed channel need to define a type
property that outlines which channel they should be sent under.
const body = {
header: {
msg_id: `execute_9ed11a0f-707e-4f71-829c-a19b8ff8eed8`,
username: "rgbkrk",
session: "00000000-0000-0000-0000-000000000000",
msg_type: "execute_request",
version: "5.0"
},
content: {
code: 'print("woo")',
silent: false,
store_history: true,
user_expressions: {},
allow_stdin: false
}
};
const message = { type: "shell", body };enchannel-zmq-backend also offers four convenience functions to
easily create the messaging channels for control, stdin, iopub,
and shell :
import {
createControlSubject,
createStdinSubject,
createIOPubSubject,
createShellSubject,
} from 'enchannel-zmq-backend';Creating a subject for the shell channel:
const shell = createShellSubject(identity, runtimeConfig)Here's an example about how to subscribe to iopub messages:
const iopub = createIOPubSubject(identity, runtimeConfig);
var subscription = iopub.subscribe(msg => {
console.log(msg);
}
// later, run subscription.unsubscribe()Since these channels are RxJS Observables, you can use filter, map,
scan and many other RxJS operators:
iopub.filter(msg => msg.header.msg_type === 'execute_result')
.map(msg => msg.content.data)
.subscribe(x => { console.log(`DATA! ${util.inspect(x)}`)})Executing code will rely on sending an execute_request to the shell channel.
var message = {
header: {
msg_id: `execute_9ed11a0f-707e-4f71-829c-a19b8ff8eed8`,
username: 'rgbkrk',
session: '00000000-0000-0000-0000-000000000000',
msg_type: 'execute_request',
version: '5.0',
},
content: {
code: 'print("woo")',
silent: false,
store_history: true,
user_expressions: {},
allow_stdin: false,
},
};Currently, you'll need to have at least one subscription activated before you can send on a channel.
> shell.subscribe(console.log)> shell.next(message)
> Message {
header:
{ username: 'rgbkrk',
msg_type: 'execute_reply',
msg_id: '0f6d37f3-56a2-41fd-b3ed-90cc189ac423',
version: '5.1',
session: '40472e70-e008-48d1-9537-55837a905c05',
date: '2016-01-12T00:39:44.686986' },
parent_header:
{ username: 'rgbkrk',
session: '00000000-0000-0000-0000-000000000000',
version: '5.0',
msg_id: 'execute_9ed11a0f-707e-4f71-829c-a19b8ff8eed8',
msg_type: 'execute_request' },
metadata:
{ dependencies_met: true,
engine: '34d73425-4f04-4b57-9bc7-b46e3100e1fd',
status: 'ok',
started: '2016-01-12T00:39:44.684534' },
content:
{ status: 'ok',
execution_count: 60,
user_expressions: {},
payload: [] } }If you plan to contribute to this project or extend it, you will need
to have ZeroMQ installed on
your system. The easiest way to do this is to install nteract's
zmq-prebuilt binary for your operating system.
To set up a development environment, you'll need to install:
Then, fork and clone this repo:
git clone https://github.com/nteract/enchannel-zmq-backend.git
cd enchannel-zmq-backend
yarnDevelop! We welcome new and first time contributors.
- Visit our website https://nteract.io/.
- See our organization on GitHub https://github.com/nteract
- Join us on Slack if you need help or have questions. If you have trouble creating an account, either email rgbkrk@gmail.com or post an issue on GitHub.
