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4.28 Elementary Method "Object Design Technique" (ODT)  

  4.28 Elementarmethode "Objektentwurfstechnik" (OBJE)

Contents  
  • 1 Identification/Definition of the Method
  • 2 Brief Characteristic of the Method
  • 3 Limits of the Methods Application
  • 4 Specification of the Methods Allocation
  • 5 Interfaces
  • 6 Further Literature
  • 7 Functional Tool Requirements
  • 1 Identification/Definition of the Method

    /ESA, 1989/ pp. 1-12

    The notation forms the way they are represented in /ESA, 1989/ have to be taken as examples.

    2 Brief Characteristic of the Method

    Objective and Purpose

    The objective of method "Object Design Technique" (ODT) is to describe the architecture of a SW system with the help of objects and its configuration and communication structure. In this connection, the "objects" are items of the SW Architecture, i. e. they represent components, modules, and databases.

    Means of Representation

    Object diagrams are the means to represent the ODT.

    An object is described by a unique name, by the object-specific data and the operations, possible on the basis of these data references to other objects ("required operations") as well as by a list of the operations and data made available for other objects. In this connection it is necessary to differentiate between "active" objects (i. e. these objects comprise an independent control flow) and "passive" objects (i. e. these objects are only active if an operation is initiated by other objects). Any objects that have not been further decomposed are referred to as "terminal objects" and the uppermost object in the hierarchy is referred to as "root object".

    Object diagrams graphically represent the root object, its characteristics and refinement to further objects, down to the terminal objects. The calling structure of the objects ("used" relation) is made particularly clear.

    Section 6 of the literature contains a list of examples of possible notation forms for objects and object diagrams.

    Operational Sequence

    The objects of the first and second design level (including all active objects) are identified and the corresponding object diagram is generated. The external stimuli (synchronous and asynchronous events) are linked with the corresponding stimulated objects. The object hierarchy is refined down to the level of terminal objects.

    3 Limits of the Methods Application

    Method ODT is applied for realtime-oriented systems with concurrent processes for the design and representation of the SW Architecture. In a function-oriented traditional design, STRD - Structured Design might be the better method.

    4 Specification of the Methods Allocation

    No. Activity Description
    4.1 SD4.1 - SW Architecture Design The static program structure of the software is specified by means of the ODT. All active and passive objects and its calling and communication structure are identified. In this connection, the active objects are designed on the basis of the processes identified in SD4.1 - SW Architecture Design.

    Starting with the evaluation level E5 the design concepts hierarchical decomposition, abstraction, and information hiding have to be strictly applied.

    The method completely covers the subproduct SW Architecture.Overview of SW Components, SW Modules,Processes and Databases.

    5 Interfaces

    - not applicable -

    6 Further Literature

    /Booch, 1987/ Software Engineering with Ada
    /Buhr, 1984/ System Design with Ada
    /ESA, 1989/ HOOD Reference Manual. Issue 3.0
    /Shumate, 1992/ Software Specification and Design - A Disciplined Approach for Real-Time Systems

    7 Functional Tool Requirements

    SSD03 - Supporting Architectural Design

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