Eclipse Ditto adapter
Eclipse Ditto is one of the most popular open-source platform for the development of DTs, mantained by the Eclipse Foundation.
The Eclipse Ditto platform follows the Device-as-a-Service paradigm where each Physical Asset is abstracted into its Ditto Thing (the Digital Twin) provinding a Web-based and domain-agnostic abstraction layer for IoT devices.
Ditto metamodel consists of
- Features: handle data and functionalities.
- Attributes: useful to define static properties.
- Messages: enable bidirectional data exchange between the DT and the PA.
A Ditto Thing model is defined via a JSON-based representation or via a WoT Thing Model (TM).
The HWoDT Framework offers a Java-based middleware to make each Ditto Thing compliant with HWoDT ecosystems. The middleware connects to the Eclipse Ditto instance exploiting the native WebSocket connection and converts the Ditto model represented with the WoT TM in a valid DTD, as well as the DT data to the DTKG representation.
The Ditto metamodel seems far from the WoDT one, but within the Ditto HWoDT adapter we adopted a simple mapping that allow us to be able to represent the whole WoDT metamodel. Properties are mapped with both Features and Attributes, relationships are mapped with custom Attributes, actions are mapped with Messages from the Consumer to the DT, and events are mapped with Messages from the DT to the Consumer.
In the current implementation we provide the following interfaces:
- HTTP-based API that implements the HWoDT interaction patterns and uniform interface.
- WebSocket-based DTKG observation endpoint.
In the following a Components and Connectors diagram depicting the Eclipse Ditto HWoDT Adapter modules and interfaces.
The usage and configuration information are available in the README of the GitHub repository.
Limits
Currently one instance of the Eclipse Ditto HWoDT Adapter can handle and adapt only one Ditto Thing.