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Schema Salad

From: Peter Amstutz <peter.amstutz@curoverse.com>
Date: Mon, 7 Sep 2015 21:33:59 -0400
Message-ID: <CAEXjzRv0o=qu4mKmyzZDDDWkfx8rPLaq2MabxtXxmXQU40BziA@mail.gmail.com>
To: public-linked-json@w3.org
Hello everyone,

I wanted to introduce a project I am working on, "Schema Salad":

https://github.com/common-workflow-language/schema_salad

Salad is a schema language for describing structured linked data
documents in JSON or YAML documents. A Salad schema provides rules for
preprocessing, structural validation, and link checking for documents
described by a Salad schema. Salad builds on JSON-LD and the Apache
Avro data serialization system, and extends Avro with features for
rich data modeling such as inheritance, template specialization,
object identifiers, and object references. Salad was developed to
provide a bridge between the record oriented data modeling supported
by Apache Avro and the Semantic Web.

The JSON data model is an extremely popular way to represent
structured data. It is attractive because of it's relative simplicity
and is a natural fit with the standard types of many programming
languages. However, this simplicity means that basic JSON lacks
expressive features useful for working with complex data structures
and document formats, such as schemas, object references, and
namespaces.

JSON-LD is a W3C standard providing a way to describe how to interpret
a JSON document as Linked Data by means of a "context". JSON-LD
provides a powerful solution for representing object references and
namespaces in JSON based on standard web URIs, but is not itself a
schema language. Without a schema providing a well defined structure,
it is difficult to process an arbitrary JSON-LD document as idiomatic
JSON because there are many ways to express the same data that are
logically equivalent but structurally distinct.

Several schema languages exist for describing and validating JSON
data, such as the Apache Avro data serialization system, however none
understand linked data. As a result, to fully take advantage of
JSON-LD to build the next generation of linked data applications, one
must maintain separate JSON schema, JSON-LD context, RDF schema, and
human documentation, despite significant overlap of content and
obvious need for these documents to stay synchronized.

Schema Salad is designed to address this gap. It provides a schema
language and processing rules for describing structured JSON content
permitting URI resolution and strict document validation. The schema
language supports linked data through annotations that describe the
linked data interpretation of the content, enables generation of
JSON-LD context and RDF schema, and production of RDF triples by
applying the JSON-LD context. The schema language also provides for
robust support of inline documentation.

This is a work in progress, and any comments, suggestions, or pointers
to related/similar technologies would be very much appreciated.  Here
are a couple of example schemas:

https://github.com/common-workflow-language/schema_salad/blob/master/schema_salad/metaschema.yml

https://github.com/common-workflow-language/common-workflow-language/blob/salad_schema/schemas/draft-3/cwl-avro.yml

Thanks,
Peter
Received on Tuesday, 8 September 2015 01:34:28 UTC

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