Ontology

Introduction

Dédalo is an open-source cultural heritage management system designed to handle both tangible and intangible assets, including oral histories, archaeological asses and properties, ethnological objects, etc documented with multimedia archives. At the heart of Dédalo lies its Ontology, a dynamic, modular framework that defines the structure, behaviour, and interactions of all data and components within the system.

What Dédalo Ontology is?

The Ontology in Dédalo serves as the foundational schema that governs how information is organised, stored, and presented. It defines every element of the application, from data models and user interfaces to workflows and outputs. This abstraction layer allows for flexible and scalable management of diverse cultural heritage data.

Dédalo's Ontology employs a correspondence system based on models (elements) and nodes (definitions or instances). For example, to define a section (analogous to an SQL table), a node is created in the Ontology with the model section. This setup enables the system to manage records associated with that section in the database, with specific data processors defined as child nodes of that node, like components (analogous to an SQL fields), groups, view definitions, and more.

Key Features of the Ontology

Model-Node Structure: The Ontology uses a model-node structure where 'models' represent data types (e.g., sections, components), and 'nodes' are specific instances or definitions of these models. This structure allows for dynamic and hierarchical organisation of data elements.

TLD Organisation: All terms in the Ontology are organised using Top-Level Domains (TLDs), which are identifying codes that help adapt the Ontology's growth to specific needs without conflicts. This system ensures scalability and customisation. Every TLD defines a specific part of the ontology with a meaning:

TLD	definition
dd	Dédalo core definition, is used to general aspects as Cultural heritage fields as Tangible or Oral History, Administration, Dédalo users, etc.
rsc	Resource, used to define media elements as Audiovisual, Image, SVG, PDF, etc. including Publications, Restoration processes, and other common sections shared across the system
ontology	Ontology definition, used to create the ontology definition
hierarchy	Thesaurus definition, used to manage any kind of thesaurus and taxonomies as Onomastic, Material, Techniques, etc. as well Tipology catalogues.
lg	Languages, Definition for the languages in the thesaurus (used in all application to translate data and interface)
utoponymy	Unofficial toponymy. Section definition for unofficial toponymy (unofficial places names), used to add places that are not inside the official toponymy of countries or the installation don't want import the official toponymy (use to point the place without the official term in some sections as Publications, to define any place of publication around the world)
oh	Oral History, the definition sections and tools to be used for oral history projects such as Interviews, Transcription, Indexation, etc.
ich	Intangible Cultural Heritage, the definition sections and tools to use for intangible heritage, such as elements, processes, communities, symbolic acts, etc.
tch	Tangible Heritage, the definition of sections and tools to use for tangible heritage, such as objects, collectors, informants, etc
tchi	Tangible Heritage Immovable, the definition of sections and tools to use for tangible heritage immovable, such as archeological sites, finds, alqueries, etc

Unique identification for every node (tipo): Each node in the ontology is defined with uniquely identified by a combination of the Top-Level Domain (TLD) and a sequential number. For example, dd5 represents the fifth node within the dd TLD (dd being the TLD and 5 the sequence). This identifier enables the creation of a uniquely instantiated object based on a specific modelo (model).

Dynamic Object Creation: During execution, Dédalo builds programming objects in real-time based on the Ontology. This means that changes to the Ontology can dynamically alter the application's behaviour without modifying the underlying code.

Format abstraction: The Ontology enables Dédalo to interpret and translate data into multiple formats, including RDF, JSON-LD, SQL, CSV, XML, Dublin Core, HTML, etc. This flexibility facilitates data sharing and integration with other systems.

Linked Data Model: Dédalo is based on a linked data model and uses a relative, multi-reference, universal locator. This locator can find entities, sections, components, and tags, allowing for precise data retrieval and management.

Practical Applications

Dédalo's Ontology supports various cultural heritage domains, including:

• Oral History: Managing interviews and personal narratives.
• Archaeology: Documenting excavation records and artefacts.
• Numismatics: Cataloguing coin collections and monetary artefacts.
• Ethnology: Recording cultural practices and traditions.
• Memory: Managing archives, documentation, people and social events.

The system's flexibility allows institutions to tailor the Ontology to their specific needs, ensuring accurate representation and management of diverse cultural heritage materials .

Benefits of Using Dédalo's Ontology

Customisation: Organisations can adapt the Ontology to fit their unique data structures and workflows.

Scalability: The TLD system and dynamic object creation support the growth and evolution of the Ontology alongside institutional needs.

Interoperability: Multiformat output and a linked data model facilitate integration with other systems and platforms.

Efficiency: Real-time object creation and dynamic behaviour adjustment reduce the need for extensive coding, streamlining the management process.

Managing ontology

Shared, standardized and common ontologies

Any Dédalo installation can implement a shared ontology. Shared ontologies are common definitions to manage specific cultural heritage. They are defined by the community and are used in different projects and institutions. Shared ontologies allows to create inventories, catalogs, archives and researches without the complexity of start from scratch. This common definitions has been refined by years with the curators and researches experience that are using Dédalo, and they are the result of large discussions, meetings about how Dédalo can manage the assets. Implement shared ontologies is a very good way to start using Dédalo.

Benefits of shared ontologies

• As the definition is ready to be used, you can start to use Dédalo and create your data fast.
• The ontology has a lots of features that cover practically any needs.
• You can shared your data with other Dédalo installation easily.
• You can get new definitions/configurations and updates automatically.
• Data changes are implemented into the update process, so, your data will be coherent with the changes.
• They are developed and maintained by the community. Projects doesn't needs to spend time and money to create new one.

drawbacks of shared ontologies

• A shared ontology only changes when the community has consents about the change. It take time and could be large process.
• They could not cover specific aspects or needs.

Local ontology

It is possible to create a local ontology by users or institutions not necessarily aligned with shared, global or standardized ontologies.

Dédalo provide two ways to add local ontology:

1. Creating a custom TLD for the ontology.
2. Overwriting specific nodes of a shared / standard ontology.

Creating a custom TLD

Users and institutions can create their own TLDs to build their own ontology definitions. Note that the custom TLD must be unique and not conflict with existing shared and shared TLDs. Therefore, do not use dd, tch or any other defined shared and common TLD. A good practice could be to use the name of the institution/museum such as: mupreva(Museu de Pehistòria de València).

Creating a new TLD

1. Login as root user or with an user with right privileges to access to the Ontology.
2. Navigate to Ontology->Ontologies main in menu.
3. Create new record.
4. Set the new TLD and fill the fields with your custom ontology name, main language, typology, etc.
5. Ensure that Real section tipo field has been defined with ontology1.
6. Press the create ontology button in the inspector. This action will create the new ontology a it will be ready to be used.

Creating the nodes

Nodes in local ontology are extensions of the common/shared ontology and it needs to be linked to any existing node to be represented into the ontology tree. For example if you want to extend the Objects section tch1 you need specify in your node that tch1 is his parent. Or if you want to create a whole new definition for Intangible Heritage you can set the parent of your node to point to the area Intangible dd323, this will allow you to create new areas or sections within your node. If you do not link your root nodes to existing nodes, your definition will work but it will not accessible in menu or in the place that you want act.

Mandatory TLD's

Dédalo use four main TLD's as core definition and is not possible remove them: dd, ontology, lg, hierarchy Why? Because the main functionalities as login, profiles, tables, tools, ontology definition, or multi-language features are defined by this TLD's. A small comment about rsc TLD, it is not core but is a important definition, because it manage all media (image, audiovisual, pdf, svg, 3d, ...), people, entities, etc. and although it is not mandatory, it is almost essential (you can create your own media management by your own, but is hard to do it).

Creating fist node

When you create a new TLD, you will have defined a Typology for your TLD, this typology helps to organise the ontology definitions and allows you to access it through the menu.

Therefore, to create the first node access your ontology section in the menu by navigating to Ontology->Instances-><typology>-><Your_ontology_name> where <typology> is the typology defined in Ontology main and <Your_ontology_name> is your own name in Ontology main.

And create the new node.