cddl

CDDL

Concise data definition language (RFC 8610) implementation and JSON validator in Node.js.

CDDL expresses Concise Binary Object Representation (CBOR) data structures (RFC 7049). Its main goal is to provide an easy and unambiguous way to express structures for protocol messages and data formats that use CBOR or JSON.

There are also CDDL parsers for other languages:

• Rust: anweiss/cddl

The package is currently mostly used to help generate typed interfaces for the WebDriver Bidi specification in the following projects:

• WebdriverIO - via the cddl2ts package and this script
• Selenium - via the cddl2java package

Note: this is work in progress, feel free to have a look at the code or contribute but don't use this for anything yet!

Install

To install this package run:

$ npm install cddl

Using this package

This package exposes a CLI as well as a programmatic interface for parsing and transforming CDDL.

CLI

The cddl CLI offers a validate command that helps identify invalid CDDL formats, e.g.:

npx cddl validate ./path/to/interface.cddl
✅ Valid CDDL file!

Programmatic Interface

You can also use this package to parse a CDDL file into an abstract syntax tree (AST). For example, given the following CDDL file:

person = {
    identity,       ; an identity
    employer: tstr, ; some employer
}

It parses the content into an AST:

import { parse } from 'cddl'

const ast = parse('./spec.cddl')
console.log(ast)
/**
 * outputs:
 * [
 *   {
 *     Type: 'group',
 *     Name: 'person',
 *     Properties: [ [Object], [Object] ],
 *     IsChoiceAddition: false
 *   }
 * ]
 */

Read the full documentation on this AST in the /docs directory.

If you are interested in this project, please feel free to contribute ideas or code patches. Have a look at our contributing guidelines to get started.