Entity Definition

Dragon1 Icon for Entity

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Dragon1 Definition for Entity:
An entity is something, like an object, that can be measured or identified in the real physical world.

What is the meaning of Entity?

Entity is one of the most important constructs within the Dragon1 open EA Method. Almost anything can be related to an entity.

Dragon1 distinguishes Entity Class (EntityClass), Entity Type, and Entity Instance.

Working with entities gives many advantages. Once an entity is defined, data, such as facts and events related to that entity, can be measured, collected, and processed. We can also model concepts and principles with entity classes and entity types.

Entity Class

Dragon1 defines an Entity Class as a group of entity instances that share certain characteristics (attribute values). For instance, 'Human' is an Entity Class, as many humans exist.

In Dragon1, we also define the term Concept. A concept is an idea, an abstraction of an implementation, or an approach. We can model a concept using one or more entity classes. For instance, 'Smartphone' is a concept. One could say that a concept is a conceptual entity, as it is an abstraction. So, a Smartphone can also be called an Entity Class, as in a group of entities.

Entity Classes have attributes, relationships with other entities, and functions.

Examples of attributes for the entity class Human are: Eyes, Arms, and Legs.

Examples of relationships with other entities are: Human is a specialization of Organism. 'Human' can have the role of Parent for another Human.

Examples of functions are: Walking, Sleeping, and Thinking.

The 'Hotel Services' concept is modeled in the diagram below. A hotel, as a base concept, has many concepts (sub-concepts) that can deliver services. All services can be listed on a menu (on the left) so that customers have an easy overview of all the services available to them. Every hotel concept is visualized here as an entity class. You see classes visualized with an oval containing a name.

The diagram was taken from the 'Entity-Centric Visualization of Open Data' paper. See the reference below.

Entity Type

Dragon1 defines the entity type as follows: a subgroup of relevant entity instances to be recognized. For instance, Child, Elderly, and Adult are entity types for the entity class "Human".

In designing entities, choices must be made when something is an entity class or entity type.

To visualize entity classes and entity types, specific formal models have been defined. Peter Chen defined ER models. Below, you see an example of such an ER model. The entity types here are visualized as boxes containing a name. The attributes are visualized using ovals that contain a name. You see immediately, without knowing the modeling rules, that a diagram of a model is hard to read and understand.

This diagram shows an ER model saying the following: Chemical and Supplier are entity types. In this diagram, the Entity Classes are not shown. The entity types have attributes like Name and Formula, as well as Name and Contact. The entity types Chemical and Supplier have a relationship of type Order. 'Order' has three attributes: PurchaseDate, Amount, and TotalCost.

Now that we have a formal model, we can collect data on orders, chemicals, and suppliers in the same structured way. For instance, put them in a database. With that data, we can, for instance, create an invoice or check payments.

Entity Instance

An entity instance (or entity for short) is an identifiable or measurable object in the real/physical world. For instance, you are an entity instance of the human entity class.

Entity Centric Visualization of Open Data

Dragon1, as a SaaS platform, is focused on visualizing data. Entity-centric visualization of data.

The Viewer is a Dragon1 application that allows you to visualize any data file (csv, xml, or other types of files) using 250+ icons for default entity classes.

Also, you can provide a definition file that extends the icons for entity classes that can be used.

Here is an example visualization of entity-centric open data, taken from the paper about it.

In this visualization, the images used to visualize a class are archetypes from the viewer's viewpoint. The better we select archetypes of the viewers, the better a picture is understood.

Read More

Here you can read more about entities:

• Visualization Peter Chen Entity Relationship Model
• Wikipedia > Entity Relationship Model
• Wikipedia > Entity meaning
• Entity-Centric Visualization of Open Data - Mladjan Jovanovic - Conference Paper · September 2015 - DOI 10.1007/978-3-319-22698-9_11 - ISSN 0302-9743
• https://wofford-ecs.org/DataAndVisualization/ermodel/material

If you have comments or remarks about this Dragon1 term or definition, please mail to specs@dragon1.com.