Concept of data and data structure
Introduction
A finite elements project contains a great quantity of information, i.e. a significant volume of data. These data are saved in a database, managed by specific tools.
Data and data structure
The Flux database makes a logical distinction between data structure (or data type) and data themselves (see blocks below).
Definitions
The principal terms, used in this document to make a distinction between data and data structure, are presented in the table below.
| Term | Definition |
|---|---|
| Entity-type | an entity-type is a logical data structure defined by a name and a certain number of fields (attributes, relations, cases) |
| Entity | an entity is an object corresponding to an entity-type characterized by an identifier (number/name) and fields (attributes, relations, case) |
Caution on the vocabulary: the terms “entity” and “occurrence of entity” can be also used instead of “entity-type” and “entity”.
Example
For points:
- the entity-type Point is a data structure of the database, that contains:
- an identifier (a number)
- cases: parameterized or propagated point
- attributes: color, visibility
- the entities (Point[1], Point[2], …) are the objects ( data ) of Flux project
In practice
From a practical point of view:
- during the creation of a new project the file (F3D_STR.SBD), which describes the data structure, is read by the program
- during the project saving the data structures and the data of the project are stored in the project directory (*.FLU).
Software version / compatibility
A new software version often corresponds to a development of the data structures.
The logical distinction between data structure and data makes it possible to ensure compatibility between an old Flux project and the more recent Flux version: during the old project opening, with a new software version the database is automatically updated .