Objects

The following diagram shows the concepts of the ModelFed vocabulary and their relationships. Objet is the core concept of the ModelFed vocabulary, defined in the Activity vocabulary as an entity of any kind. Every Object, identified by a globally unique URI, falls into one of four main categories (*ModelElements, Activities, Actors, and Grants).

ModelElements

ModelElement, which inherits from Object, is an abstract concept that serves as a general representation of any element within a model. The ModelFed vocabulary provides a pragmatic representation of the UML specification for structural models. Concepts such as Classes, Enumerations, Associations, and Generalizations can be defined to build a domain model. As an example, the following JSON-LD defines a class named ProductPassport with a string attribute (name). Note that every object includes an id for global identification and a type for object classification.

{
"@context": [
    "https://www.w3.org/ns/activitystreams",
    "https://www.modelfed.com/ns/modelfed"
],
"type": "Class",
"id": "https://platformA.com/classes/product_passport",
"name": "ProductPassport",
"attributes": [
    {
    "type": "Property",
    "id": "https://platformA.com/properties/name",
    "name": "name",
    "elementType": "str"
    }
]
}

Activities

Activities enable the specification of actions performed on any Object. ModelFed defines five activities: Create, Update, Delete, Reclassify, and Clone.

The following is the definition of an Activity to create the LifecicleStage class. It includes:

• @context to define the vocabulary used in the JSON-LD document.

• type to define the type of activity (in this case, Create).

• id to define the globally unique identifier of the activity.

• actor to define the actor who performed the activity.

• to to define the actors with whom the activity is federated.

• object to define the object on which the activity is performed (the LifecicleStage class with the start attribute).

• timestamp to define the date and time of the activity.

{
"@context": [
    "https://www.w3.org/ns/activitystreams",
    "https://besser-pearl.github.io/ModelFed/ns/modelfed.jsonld"
],
"type": "Create",
"id": "http://platformA.com/activities/a1c2t3",
"actor": "https://platformC.com/industrialeng/",
"to": [
    "http://platformA.com/admin/"
],
"object": {
    "type": "LifecicleStage",
    "id": "https://platformC.com/classes/life_cicle_stage",
    "name": "LifecicleStage",
    "attributes": [
        {
        "type": "Property",
        "id": "https://platformC.com/properties/lf_start",
        "name": "start",
        "elementType": "date"
        }
    ]
    "owner": "https://platformA.com/domain_model/dpp_model"
},
"timestamp": "2025-02-11T15:42:45Z"
}

Actors

In ModelFed, Actors are the people, organizations, services, or applications that can perform activities within a model.

Each modeling platform participating in Modelverse must manage a basic set of information for every actor, as required by the ModelFed protocol:

• id: A unique identifier

• type: What kind of actor it is (e.g., person, service)

• name: A human-readable name

• inbox: Where the actor receives shared activities

• outbox: Where the actor sends activities to others

The following is an example of a JSON-LD document defining a Person actor called Materials Scientist.

{
"@context": [
"https://www.w3.org/ns/activitystreams",
"https://besser-pearl.github.io/ModelFed/ns/modelfed.jsonld"
],
"type": "Person",
"id": "https://platformB.com/materialsscientist",
"name": "Materials Scientist",
"inbox": "https://platformA.com/materialsscientist/inbox",
"outbox": "https://platformA.com/materialsscientist/outbox"
}

Actors collaborate by sending and receiving activities using their inbox and outbox:

• The outbox is where an actor publishes activities they perform.

• The inbox is where they receive activities shared by others.

This direct actor-to-actor communication is what powers federation in Modelverse, where there’s no central hub, just peers talking to each other.

Grants

In ModelFed, Grants control who can do what. They define permissions for each actor, specifying which model elements an actor can interact with, and what kind of activities they are allowed to perform.

A Grant links:

• An Actor (e.g., a person)

• A Model Element (what they can access)

• A Role (what level of access they have)

There are three different roles defined in ModelFed.

Role	Access Level
Administrator	Full control (can edit, delete, and assign new Grants)
Editor	Read and write access (but cannot delete)
Reader	Read-only access