Instantiation

FOREST Overview Product Model Document Types

Document Types
(Instantiation of the Reference Model)

Applied Languages and Concepts

Within the FOREST approach, the general reference model of problem specifications is instantiated using a real-time temporal logic as basic formal description technique. This allows the creation of precise problem specifications with an unambiguous semantics. To enhance the intelligibility of a problem specification, we provide explanations in natural language for each elementary phenomenon, object, and formalized property. Moreover, to be able to handle problem specifications of large systems, we have combined structuring concepts such as modularization, aggregation, inheritance, and parameterization with the temporal logic.

General Structure

To manage problem specifications of large systems, we structure a problem specification into several so-called description classes. Relations among description classes are established by aggregation and inheritance. Description classes specifying common aspects are further organized in so-called groups.

Structure of a Description Class

A description class consists of seven parts:

INTENTION: The INTENTION part is mandatory. All other parts are optional. In the INTENTION part, a developer informally describes which part of a system is considered in a description class.
FORMAL PARAMETERS: In the FORMAL PARAMETERS part, two kinds of parameters of a description class can be specified: sort parameters and number parameters. A parameter of a parameterized description class always has to be instantiated if this class is aggregated or if another description class inherits from this parameterized description class.
BASE CLASSES: In the BASE CLASSES part, all description classes from which this description class inherits are listed. The BASE CLASSES parts of all description classes thus defines the inheritance relation among the description classes. Note that inheritance between two classes also implies a specialization between both classes, in the sense that the derived class is an extension of the base class.
SIGNATURE: The SIGNATURE part contains all entities that are necessary to talk about the part of the system considered in this description class. Following the guidelines of the reference model, there has to be an intention explaining which phenomenon is represented to support the one-to-one relationship between phenomena and terms. Moreover, the scope of each entity representing an elementary phenomenon has to be specified.
DOMAIN KNOWLEDGE,
REQUIREMENT SPECIFICATION,
MACHINE SPECIFICATION:
In the DOMAIN KNOWLEDGE, REQUIREMENT SPECIFICATION, and MACHINE SPECIFICATION parts, the properties of the objects belonging to a description class are specified. The properties are assigned to these three parts according to the classification of statements given by the reference model. The name of each property is chosen to reflect the description class and the part to which this property is assigned. Each property usually consists of a formula in real-time temporal logic and of a translation of this formula into natural language.





 

 
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