RWH's (simplistic) guide to ADAMO terminology

.ddl file

The .ddl file rigorously defines the structure of the data in a computer readable format (Data Definition Language). As well as describing the data model it also specifies types, validity ranges, relationships and provides additional documentation in the form of comments associated with the attributes.

ESet

An entity set (ESet) is a set of "things" or "objects" with identical structures. The entity is expressed by a group of attributes each carrying a value. In ADAMO, an ESet is mapped into a table format where each attribute constitutes a column and a complete entity is the collection values in a single row.

(attribute,value) pairs

An attribute might otherwise be called a "tag"; in FORTRAN it would be the variable name. Each attribute takes on some range of values. ADAMO pre-defines a number of types for attributes, such as REAL (all standard floating point values), INTE (legal integers), CHA4 (four character strings). In setting up a list of attributes the user picks an appropriate type. These can be further constrained, eg. INTE [1,100] would restrict the attribute to integers between one and one hundred, inclusive.

RSet

A relationship set connects entries in one ESet to those of another. This link can be partial (on either or both ends), in that not all members of one or both ESets have such a link connecting them to the other ESet. In ADAMO the relationship can at most be 1:1 or n:1, never n:m. In the first case, any relationship connects, at most, one entity from the first ESet to any given member of the second ESet. The n:1 case allows any number of members of the first set to point at the same entity in the second. What isn't allowed is for members of the first ESet to point to multiple members of the second ESet. This restriction can be overcome by setting up an intermediate ESet if necessary.

Dataflow

A dataflow groups together logically related ESets. Typically this would be a group of tables that would be collectively written to a file simultaneously.

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