IDEF1X
IDEF1X is a modeling language in computer-aided manufacturing standard and belongs to the IDEF languages. The 1 stands for the modeling of information structures, with X the extension (English Extension) is characterized over the original standard.
IDEF1X is a data modeling technique and therefore focuses on the Entity- Relationship Model ( ERM).
History
As part of the ICAM Program of the U.S. Air Force IDEF1 1981 was published. With the same time rapidly advancing developments in the field of relational databases, the default had to be expanded relatively rapidly considerably. This extension has been published under the name IDEF1X first time in 1985. 1994 IDEF1X was adopted as the U.S. government standard (FIPS 184).
Importance
Due to the early disclosure and the intended independence of the modeling language of manufacturers of database software, many CASE- tool manufacturers have supported the notation. The requirement of U.S. military and government agencies made IDEF1X finally become a de facto standard (among others).
Scope
To IDEF1X in the original published context includes data modeling as a method of software development there too. Thus, data modeling concepts and modeling guidelines are listed with.
Since these topics are now merged into the general computer science, are syntax and semantics of the notation in the consideration of IDEF1X today in the foreground.
Notation
The standard defines notations for the ER diagram and the additional information in the ERM documentation. In the diagram are summarized the following conventions:
Entity syntax
Entities are represented as rounded rectangles when they are existence dependent on a relationship, otherwise in a normal rectangle.
The name ( or number ) is placed over it.
Attributes
The names of the attributes are written to the entity rectangle. Attributes that belong to the primary key are on, all the others. Below a dividing line
In addition to the names of other markings are included, such as " (O) " for optional.
Relations
Relationships know (such as in UML) a direction, manner of speaking: they go from the parent entity to the child entity. The child - end of the relationship is indicated by a small black circle. In addition, the cardinality of the relationship is represented by line type, end and commentary.
In addition to the circle at the child end of the relationship line is the cardinality of the child entities:
The cardinality of the parent side of the relationship can only be defined as optional or required. An optional relationship is provided at the end of the line the parents side with a diamond, a compelling relationship has a normal line end. This means that in no IDEF1X n: m relationships are allowed, which gives, among other things in the Chen notation. A n: m relationship must be considered when modeling consists of two one -to-many relationships have broken down. Another distinctive feature compared to other notations is the explicit representation of foreign key attributes, although these are redundant from modeling point of view.
Identifying relationships
An identifying relationship is a parent-child relationship in which the child entity is existence- dependent on the parent entity and the primary key of the parent entities in their own primary key takes. This Relationship is modeled with two display enhancements:
- The relationship line is drawn through ( a non- identifying relationship is dashed).
- The child entity is displayed in a rounded rectangle, see above.
Sub and super types
The concept of inheritance, referred to in data modeling as sub-and super-type is shown in IDEF1X on categorization.
The categorization is a lot of special relationships from the supertype to its subtypes, which are provided with a discriminator. A solid line goes from the supertype to the discriminator, a circle with a horizontal single or double line underneath. From each of the Diskriminatorlinie a solid line is for each subtype. The double line of the discriminator is the completeness of the subtypes listed in IDEF1X also called categories.