ETC Labs Core

shane.j@etclabs.org

General Internet-Draft JSON Template Language is a simple, compact template language to substitute JSON into a template. It is derived from the template literals of Javascript, as defined in the ECMAScript Programming Language Standard, Ninth Edition ECMA-262. It has uses not limited to: specifying interfaces, runtime expression mapping, and other forms of programmatically interacting with JSON and templates.

JSON Template Language provides a mechanism for describing various parts of a template by using familiar syntax from Javascript and JSON. By using a familiar syntax we can get interoperability within the JSON and URI specifications. The terms “string”, “object” and “array” are from the conventions of Javascript and JSON. A JSON Template provides a structural description of a template, and when JSON is provided, machine-readable instructions on how to construct a string corresponding to those values. A template is transformed into a string by replacing each of the template literals with the corresponding JSON values.

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

When considering runtime security of JSON Template Language, the surface area is only expanding JSON value by key. No loops or operator grammar is defined and should be avoided in runtime contexts.

This document has no IANA actions.

for the given JSON:

and the given template:

expansion:

for the given JSON

and the given template:

expansion:

for the given JSON

and the given template:

expansion:

Language Grammar defined in ABNF

The contents within the Template literal should be valid a key-value object mapping or array-index mapping for JSON.

A template literal is represented within a URIs as a pair of curly braces starting with a $.

An identifier is a valid JSON key.

MUST be a valid nested JSON key that will be resolved with the identifier.

MUST be a valid index of a JSON array are represented within square brackets and MUST be a valid number.

Head represents the characters before template-head, this could be beginning of the template or the last tail.

Head represents the characters after the template-tail until the end of the template or the next instance of a template literal.

In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.