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

50 Concepts for Analysis, Specification and Design
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 3.12: Simplified Overview of Textual and Graphical Representations
Figure 3.13 shows the phases and milestones of the SHE method in a system specification
and design project. SHE has two phases, marked by a milestone in between. These
phases are the realisation of an Essential Specification and an Extended Specification. Before
starting the application of the method an Initial Requirements Description must be realised.
Milestone 3 indicates the start of the actual implementation and realisation of a system.
The goal of the Essential Specification phase is an analysis of essential system requirements
and the creation of both an abstract behaviour model and the highest level system
structure model (architecture). Both models are developed in a strong interaction. Behaviour
and structure are formalised into a Unified formal description in the language
POOSL. This description enables examination of various system properties via simulation
and formal verification. The result of these activities must be a correct abstract
system model. The goal of the Extended Specification phase is the incorporation of implementation
decisions in the essential system requirements. This leads to the creation
of both an extended behaviour model and the concrete system structure model (implementation
structure). Both models are developed in a strong interaction. Extended Behaviour
and Implementation Structure are formalised into an Extended Unified Model.
This is a formal description in the language POOSL. This description enables further detailed
examination of various system properties via simulation and formal verification.