Dflow

A minimal Dataflow programming engine

Documentation

How it works

What is a Dflow graph

A node is a block of code that can have inputs and outputs.

A link connects an input to an output.

A graph represents a program. It can contain nodes and links. Nodes are executed, sorted by their connections.

About inputs and outputs

An input is just a reference to its connected output, if any.

An output can be connected to multiple inputs, and hold a data value that can be undefined or any value that can be serialized into JSON.

Usage

This is a graph that will compute sin(π / 2) = 1 and print the result.

   ----------------
  | number = π / 2 |
   ----------------
   |
   |
   ---------
  | mathSin |
   ---------
    \
     \
     ------------
    | consoleLog |
     ------------

You can run the following code with any of the following by cloning this repo and launching npm run example:usage.

You should see a number 1 printed on output.

import { Dflow, type DflowNode } from "dflow";

const { input, output } = Dflow;

const MathSin: DflowNode = {
  kind: "mathSin",
  inputs: [input("number")],
  outputs: [output("number")],
  run(input: number) {
    return Math.sin(input);
  }
};

const ConsoleLog: DflowNode = {
  kind: "consoleLog",
  inputs: [input()],
  run(input: unknown) {
    console.log(input);
  }
};

// Create a Dflow instance with the given nodes.
const dflow = new Dflow([MathSin, ConsoleLog]);

// Create nodes.
const sinNodeId = dflow.node("mathSin");
const consoleLogNodeId = dflow.node("consoleLog");

// Create a data node.
// It will create an instance of a node with kind "data"
// This is a special node, which is built-in into every Dflow instance.
const numNodeId = dflow.data(Math.PI / 2);

// Connect numNode to sinNode and sinNode to consoleLog
dflow.link(numNodeId, sinNodeId);
dflow.link(sinNodeId, consoleLogNodeId);

// run graph
dflow.run();

A graph can be executed asynchronously with await dflow.run(): see async nodes example.

Available examples are listed here.