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Domain Modeling (Incomplete)

XIDDL and XML Schema

IDEA uses the XIDDL (acronym TBD) language to represent declarative system models. Historically, XIDDL was designed as a language to which other domain definition languages could be easily translated, and not necessarily a language that could be easily read by people. Hence, it is based on XML, which is easily parsed and constructed, and which favors explicit representation over implicit representation through structure, etc. Unfortunately, XML is not a particularly human-friendly representation, and the IDEA team, to date, has not developed an alternate, more human-readable language to be used on the "front end" of model development.

As with other XML-based languages, the rules for XIDDL syntax are represented in an XML schema, encapsulated in a file (link TBD).

IDEA models systems in terms of time-variant state variables. The state variables are represented as timelines that are populated over all time with discrete (non-continuously varying) states that persist over variable time intervals. Each state potentially has parameters that govern its semantics. IDEA allows constraints to be imposed between different states, either on the same timeline or on different timelines. Constraints can define temporal relationships or relationships between state paramters. State variables (timelines) are grouped within objects that represent different entities, real or virtual, within the system.

To enable the above, IDEA models comprise an extensive list of mandatory and optional components, which are described in the following sections. They include:


• Duration Constants: Numeric constants defining time durations.
• Object Classes: Definitions of collections of state variables (timelines), the instances of which are IDEA objects.
• Procedures: States, known informally as tokens.
• Attributes: State variables, known informally as timelines.
• Compatibilities: Constraints.
• Agent: An IDEA controller.

CameraControl Sample Model

The CameraControl application model will serve as a guide for the following descriptions. It appears in the following path:


{PROJ_DIR}/IDEA-ALL/CameraControl/Model/cameracontrol.xiddl


Please refer to the CameraControl Domain (Incomplete) section for a description of the domain.

Object Partition

The object partition of an XIDDL model defines constants, label sets, procedures, and attributes of the model.


Duration Constants

Duration constants are lowest-level structures of XIDDL. They define integer durations whose default time unit is determined in a constant of the agent definition (see Agents Partition). The CameraControl model defines two duration constants

Classes

Predicates

Compatibilities Partition

Agents Partition

Communications Channels

Model File Aggregation

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IDEA Tutorial Table of Contents Previous: CameraControl Domain (Incomplete) Next: Domain Initial State (TBD)

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