entity
- Incomputer science, an entity is described as an abstract, individual object that can be tangible or intangible. In object-oriented programming, an entity is comparable to an object or instance. Entity is often applied in the context of modeling the data-oriented view using entity-relationship modeling ( ER). Entities can exist in relation to themselves and also to other entities. Entities are assigned a specific entity type. The properties of entities are characterized by attributes. This allows entities of the same entity type to be distinguished from each other. Entity sets denote the summary of individual entities of an entity type. Entity types can in turn be assigned to entity classes. This corresponds to the view in object-oriented programming.
- In the layer view, an instance represents an active element within a layer. The instance is a single concrete application within a layer. It can receive and send information and is thus a device capable of communication. A layer of an end system can have several instances. Corresponding instances of the same layer in different end or transit systems are called partner instances( peer-to-peer entities). Through the user element, an application process has access to one or more application instances. The International Telecommunication Union( ITU) refers to an entity as a concrete or abstract unit in a paper. In the OSI reference model, entity refers to the conceptual object that provides the necessary functions in one of the two layers.