Systems Modelling

A CASE Tool?

Cradle Systems Modelling together with Cradle Software Engineering could be considered by some to be merely a CASE tool. However, it is far more than that.

Cradle Systems Modelling consists of a rich set of fully integrated graphical modelling notations all using the same graphical editor.

A user or organisation may choose to use all or just some of the different modelling notations supported. Cradle understands the inter-relationships that may exist between the notations and allows the user to create (if appropriate) multiple hierarchies of different diagrams.

Systems Modelling is not however, just a set of drawing notations. It is far more than that:

• Any object on any diagram will have a Data Dictionary or Specification defining it. That object may be expandable into a different diagram in any appropriate notation.
• Cradle will ensure the consistency of Data Dictionary entries and Specifications within a diagram and between different diagrams.
• Animation tools and Consistency Checkers are provided to ensure systems behave in the way intended.

The philosophy with Cradle Systems Modelling is that the user will, in general, use the notation set most appropriate to the particular sub-system or sub-systems that he is currently defining. We will not impose a design methodology upon the user.

The following modelling notations are available:

• Architectural
• Structured
• Behavioural
• Object Oriented

Architectural

Architectural modelling is supported via Function Block Diagrams (FBDs).

Function Block Diagrams (FBDs) are used to show the organisation of, and flow of data between, pieces of system functionality. FBDs are intended to show the physical elements of a system and how they are interconnected.

FBDs are used typically for purely physical parts of the design (mechanical, electrical, and so on).

Structured

Structured Modelling is provided by enhanced support for the Yourdon Notation (Version 3.0 with Ward Mellor Real Time Extensions).

This notation set provides the following diagrams:

• Data Flow
• State Transition
• Entity Relationship
• Data Structure
• Structure Charts (Chen)

Data Flow Diagrams (DFDs) define the functionality of the system, or part of a system, and show the flow of control or data between data processes, control processes, the environment and information stores.

A State Transition Diagram (STD) defines the State Transitions of a Control Process shown on a parent Data Flow Diagram.

Entity Relationship Diagrams (ERDs) show graphically how different pieces of information are related.

Data Structure Diagrams (DSDs) are a graphical means of representing the composition of data.

Structure Charts (STCs) depict the interaction between software modules (procedures, functions, subroutines, processes or tasks. Cradle allows Structure Charts (STCs) to exist in a hierarchy, which is an extension to the traditional application of the Yourdon methodology.

Behaviour Diagrams

A Behaviour Diagram (BD) defines the functionality in a part of a system, and the flow of data between these functions.

Behaviour Diagrams use a notation that shows the passage of time.

The benefit of the BD notation is the way that sequence, iteration, and concurrency are shown on a single diagram by the arrangement of functions along a (possibly complex) time line.

Object Oriented

The latest addition to the Cradle Systems Modelling module is support for Object Oriented notations.

We now support the Unified Modelling Language

The diagram styles currently supported are:

• Use Case

• Object Interaction
• Event Trace
• Event Flow
• State
• Class
• Data Flow

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