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Introduction

Concerto models may be specified using either a JSON document, or using a set of domain-specific language files (the CTO format).

Concerto can convert seamlessly between these two formats. Use the concerto parse command to convert a CTO string to a JSON model, or the concerto print CLI command to convert a JSON model to a CTO string.

Data Serialization and Deserialization​

Concerto includes a runtime library to serialize data to/from JSON and to validate that JSON data conforms to the data model.

JSON data includes basic type information and field names — allowing any JSON library to be used to deserialize the data. To validate that the data conforms to a Concerto data model the reader should have access to the Concerto data model (JSON or CTO) as well as a Concerto runtime.

Objects​

In general the JSON serialization will take the form of a JSON object, with nested objects. 

{
  "$class" : "org.acme@1.0.0.Person",
  "name" : "John Doe",
  "address" : {
    "$class" : "org.acme@1.0.0.Address",
    "street" : "1 Main Street"
  }
}

Corresponding data model:

namespace org.acme@1.0.0

concept Address {
  o String street
}

concept Person {
  o String name
  o Address adress
}

Note that Concerto uses a nominal type system with the type identifiers carried via the $class JSON property.

Enums​

An enum is encoded by their string value.

Arrays​

Arrays are encoded by a JSON array.

Null Values​

Null values are encoded using a JSON null.

DateTime Values​

DateTime values are encoded as a JSON string is ISO-8601 format.

Integer, Long, Double Values​

Integer, Long, Double values are encoded as JSON numbers.

Boolean Values​

Boolean values are encoded as JSON Booleans (true / false).

String Values​

String values are encoded as JSON strings.

Relationship Values​

Relationship values are encoded as JSON strings, using a URI format to capture the fully-qualified type name and identifier of the relationship.