Specification of Reactive Hardware/Software Systems - Electronic ...

344 SHE Framework
Object Models
Object Class
Model
Object
Class
Diagrams
Message
Flow
Diagrams
Listed Requirements
System Dictionary
Object Instance Model
Instance
Structure
Diagrams
Unified Model:
POOSL Description
Requirements catalogue
Graphical models
Structure models
Architecture Structure
Diagrams
Implementation
Structure Diagrams
Architecture Decisions Statement
Textual models
Implementation Decisions Statement
Figure 11.8: Simplified Overview of Textual and Graphical Representations
that visualises relations between classes and the Object Instance Model that visualises
instances which are objects and/or clusters. Message Flow Diagrams show message
flows and Instance Structure Diagrams show channels. Notice that Instance Structure
Diagrams are both part of the Object Model as well as part of the Structure model.
Instance Structure Diagrams serve to formalise the informal architecture structure (or
implementation structure) as a structure of clusters, processes and channels.
11.4.2.2 Unified Model
The block ’Textual models’ in Figure 11.8 shows the Unified Model and the Requirements
Catalogue. A Unified Model is a formal description of a system in the language POOSL.
This model is called unified because it encompasses both behaviour and structure of the
system to be designed.
11.4.2.3 Requirements Catalogue
A Requirements Catalogue contains all items that must be specified but cannot be
formalised in the Unified Model. A minimum catalogue contains four items:
Listed Requirements. This is an extension of the Requirements List in the Initial
Requirements Description.