jsontron

Schematron based JSON Semantic Validator

Overview

Jsontron is a Schematron based JSON semantic rules engine. It implements phase, pattern, rule, context and assert elements of Schematron. It also provides a detailed reporting mechanism for semantic validation results.

Jsontron module was developed by Amer Ali as part of DPS dissertation supervised by Dr. Lixin Tao at School of Computer Science and Information Systems Pace University, New York.

Here is an abstract from the study:

JavaScript Object Notation (JSON) has emerged as a popular format for business data exchange. It has a grammar-based schema language called – JSON Schema (IETF draft 7). The JSON Schema provides facilities to specify syntax constraints on the JSON data. There are a number of tools available in a variety of programming languages for JSON Schema validation. However, JSON does not have a standard or a framework to specify the semantic constraints, neither it has any reusable validation tool for semantic rules. In order for JSON data validation to be effective, it needs both syntax and semantic specification standards/frameworks and validation toolset.

XML is another popular format for business data exchange that preceded JSON. XML has a mature ecosystem for specifying and validating syntax and semantic constraints. It has XML Schema and several other syntax constraints specification standards. It has Schematron as a semantic constraints specification language which is an ISO standard [ISO/IEC 19757-3].

This study proposes a framework for specifying semantic constraints for JSON data in JSON format, drawing upon the power, simplicity, and semantics of Schematron standard. A reusable JavaScript/NodeJS based validation tool was also developed to process the JSON semantic rules.

The framework assumes that due to inherent differences between XML and JSON data formats, not all Schematron concepts will be applicable to this study.

What Problem Jsontron Solves?

Jsontron - Schematron based JSON semantic validator solves problems similar to one posted on StackOverflow:

Excerpt from StackOverflow:

Here is a JSON instance showing the start-time and end-time for a meeting:

{
    "start time": "2015-02-19T08:00:00Z",
    "end time": "2015-02-19T09:00:00Z"
}

I can specify the structure of that instance using JSON Schema: the instance must contain an object with a "start time" property and an "end time" property and each property must be a date-time formatted string. See below for the JSON schema. But what I cannot specify is this: the meeting must start before it ends. That is, the value of "start time" must be less than the value of "end time". Some people call this data dependency a co-constraint. In the XML world there is a wonderful, simple technology for expressing co-constraints: Schematron. I am wondering if there is an equivalent technology in the JSON world? What would you use to declaratively describe the relationship between the value of "start time" and "end time"? (Note: writing code in some programming language is not what I mean by "declaratively describe the relationships". I am seeking a declarative means to describe the data dependencies that are present in JSON documents, not procedural code.)

{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "definitions": {
        "meeting": {
            "type": "object",
            "properties": {
                "start time": { "type": "string", "format": "date-time"},
                "end time": { "type": "string", "format": "date-time"}
            },
            "required": [ "start time", "end time" ],
            "additionalProperties": false
        }
    },
    "$ref": "#/definitions/meeting"
}

Same thread on StackOverflow contains the solution provided by Jsontron.

Presentation Deck

Here is a pdf version of Presentation Deck that summarizes the study.

Highlights of Presentation

Jsontron Tutorial

Here is the pdf version of the Jsontron Tutorial.

Highlights of Jsontron Tutorial

Resources

TBD