# Data Model and Concepts ## Entity - A physical or logical object with associated information. - Has zero or more attributes. - May or may not have sensors and controllers (from device integrations). - May or may not have (hidden) EntityState variables. - May or may not define other entities as delegates of its state. ## EntityState - The hidden state of the entity/device that is sensed and/or controlled - A single entity may have zero or more states. ## EntityStateDelegation - An EntityState of an entity may just be a proxy for another entity's state. e.g., A thermometer entity with a temperature state is a proxy for an area that is a room. - We use the terms 'delegate' and 'principal' for the entities involved in the relation. - Main use is to have the delegate's visual representation reflect the status of the principal's state. - May be one-to-one, one-to-many or many-to-one relationship. ## Location - Has an SVG image that defines the visual and coordinate space. - Has zero or more entities. - Entities optionally associated with a position. - Has zero or more collections. - Collections optionally associated with a position. - Can dfined one or more locations. ## LocationView - Associated with a Location. - Can define one or more Location Views for a Location. - Defines the view a bounding box area and rotation of the location SVG. - Defines what entities are and are not visible in this views. - Defines the view context for sensors and controllers (info, control) - ViewContext = { information, control } ## LocationItem - Used as an abstraction/interface for items that can be associated with a Location. - Helps define a consistent visual represenation for LocationView. - Initially, Entity and Collection are the two concrete examples fof an LocationItem ## EntityPosition / CollectionPosition - For entities/collections positioned in a Location an visually appearing as an icon. - Defines the position, scale and rotation of the icon. ## EntityPath / CollectionPath - For entities/collections positioned in a Location an visually appearing as an open or closed path. ## Device (runtime concept, not a DB model) - An entity with at least one sensor or controller ## Sensor - Provides an observation value of a single entity's state variable. - Sensors and their states can only be created through integrations (not user editable). ## Controller - Provides an action to affect a single entity state variable. - Controllers and their states can only be created through integrations (not user editable). ## Collection - Defines a logical connection for a group of one or more entities. - Some entities in a collection may be unpositioned e.g., tools, appliances and devices are potential examples of unpositioned collections - Collections may or may not be shown in a Location View (as a path).