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Evolutionary Development Methodologies Nomenclature_ Overview

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Evolutionary Development Methodologies Nomenclature_ Overview Powered By Docstoc
					EDM




      Clarke, R.J. (2000) EDM-DSL   1
   ESD Related Definitions (1)
 Evolutionary Systems Development (ESD)- is the
  formal name for Evolutionary Prototyping
 An approach whereby the initial design proposals are
  put forward in the form of a physical working model
 Analysts, working in partnership with users,
  gradually improve the prototype of the system...
 ...until it meets a level of acceptability decided by the
  user.
 When this happens the prototype becomes the new
  system
                                       Clarke, R.J. (2000) EDM-DSL   2
 ESD Related Definitions (2)
 Evolutionary Prototyping (EP) is the
  general name for the activity developers
  undertake when they are involved in
  Evolutionary Systems Development
 Evolutionary Development Methodology
  (EDM)- a methodology which supports
  ESD


                           Clarke, R.J. (2000) EDM-DSL   3
EDLC




       Clarke, R.J. (2000) EDM-DSL   4
                                RPLC
                Investigation
                                                  Develop
                                                 Prototype
 Maintenance &                  Analysis
  Evaluation
                                                               Test
                                                             Prototype
  Operation &
  Acceptance                    Design            Amend
                                                 Prototype

                Construction


40-40                                      Clarke, R.J. (2000) EDM-DSL   5
EDLC
 Develop
Prototype


              Test
            Prototype


 Amend
Prototype


                Clarke, R.J. (2000) EDM-DSL   6
Evolutionary Development (1)
                                        Develop
                                       Prototype

                                                  Test
                                                Prototype

                    Candidate
                                       Amend
                    Prototypes        Prototype


 Develop                                    Develop
Prototype                                  Prototype

          Test                                        Test
        Prototype                                   Prototype


 Amend                                         Amend
Prototype
                                 Clarke, R.J.Prototype
                                              (2000) EDM-DSL 7
Evolutionary Development (2)
                                      Develop
                                     Prototype


                                                 Test
                                               Prototype


                                      Amend
                                     Prototype
                        Spawn
 Develop                                   Develop
Prototype                                 Prototype

              Test                                      Test
            Prototype                                 Prototype

 Amend                                        Amend
Prototype
                                Clarke, R.J.Prototype
                                             (2000) EDM-DSL 8
Evolutionary Development (3)
                                               Develop
                                              Prototype

        Spawn
                                                            Test
                                                          Prototype
                     Develop
                    Prototype                  Amend
                                              Prototype
                              Test
                            Prototype
 Develop                                           Develop
Prototype                                         Prototype
                     Amend
                    Prototype
          Test                                                 Test
        Prototype                                            Prototype


 Amend                                             Amend
Prototype                                         Prototype
                                        Clarke, R.J. (2000) EDM-DSL   9
Evolutionary Development (4)
    Develop                                              Develop
   Prototype                                            Prototype


                 Test                                               Test
               Prototype                                          Prototype
                            Develop
                           Prototype
    Amend                                                Amend
   Prototype                                            Prototype
                                         Test
                                       Prototype
 Develop                                                      Develop
Prototype                                                    Prototype
                            Amend
                           Prototype
           Test                                                         Test
         Prototype                                                    Prototype


  Amend                                                          Amend
 Prototype
                                                   Clarke, R.J.Prototype
                                                                (2000) EDM-DSL 10
Evolutionary Development (6)
    Develop                                          Develop
   Prototype                                        Prototype


                 Test                                             Test
               Prototype                                        Prototype
                            Develop
                           Prototype                 Amend
    Amend
   Prototype                                        Prototype
                                     Test
                                   Prototype
 Develop                                                  Develop
Prototype                                                Prototype
                            Amend
                           Prototype
          Test                                                        Test
        Prototype                                                   Prototype


 Amend                     Merge                             Amend
Prototype
                                               Clarke, R.J.Prototype
                                                            (2000) EDM-DSL 11
Evolutionary Development (7)
                                      Develop
   Develop                           Prototype
  Prototype

                                                   Test
                Test                             Prototype
              Prototype

                                      Amend
   Amend                             Prototype
  Prototype

          Develop                           Develop
         Prototype                         Prototype

                       Test                              Test
                     Prototype                         Prototype

          Amend                             Amend
         Prototype                         Prototype
                                 Clarke, R.J. (2000) EDM-DSL   12
Prototype Classification




                 Clarke, R.J. (2000) EDM-DSL   13
Prototype Classifications
 Severalclassifications exist for
 distinguish the function or
 purpose of a prototype
  Floyd (1984)
  Law (1985)
  Mayhew & Dearnley (1987)




                              Clarke, R.J. (2000) EDM-DSL   14
Prototype Classifications
       Floyd’s Classification
              three broad
 distinguishes
 approaches to prototyping
  exploratory
  experimental
  evolutionary
           the debate surrounding
 structured
 prototyping in general


                         Clarke, R.J. (2000) EDM-DSL   15
 Prototype Classifications
 Floyd’s Classification: Exploratory

 useful:early stages of systems
  development
 focus: communications problems
  between prospective users and
  developers
 prototype: catalyst to participation
  and ideas generation
 aim: assist in requirements gathering

                          Clarke, R.J. (2000) EDM-DSL   16
  Prototype Classifications
 Floyd’s Classification: Experimental

 useful: testing all or some functions
 focus: building a proposed solution
  to a particular problem
 prototype: evaluated by
  experimental use prior to eventual
  implementation
 aim: reduce implementation costs


                           Clarke, R.J. (2000) EDM-DSL   17
  Prototype Classifications
Floyd’s Classification: Evolutionary (1)
 most  controversial category
 emphasis on gradual adaptation of
  the system in order to cope with
  changing organisational
  circumstances
 system can be looked at as a
  sequence of versions


                           Clarke, R.J. (2000) EDM-DSL   18
  Prototype Classifications
Floyd’s Classification: Evolutionary (2)

 eachversion once constructed, used
 and evaluated is treated as a
 prototype to its successor
  it has been argued that it should be called
   ‘versioning’
  but the use of a prototype means that it should
   not be thought of as versioning!




                                  Clarke, R.J. (2000) EDM-DSL   19
  Prototype Classifications
Floyd’s Classification: Evolutionary (3)




                                ?


                                          ?



    ‘Version’ 1            ‘Version’ 2
                           Clarke, R.J. (2000) EDM-DSL   20
  Prototype Classifications
Floyd’s Classification: Evolutionary (4)




                           ?



                           ?                 ?


    ‘Version’ 2            ‘Version’ 3
                           Clarke, R.J. (2000) EDM-DSL   21
  Prototype Classifications
Floyd’s Classification: Evolutionary (5)



                                        A
   ?

                      B
   ?             ?

                                          C
   ‘Version’ 3             Final ‘Version’
                           Clarke, R.J. (2000) EDM-DSL   22
    Prototype Classifications
         Importance of Floyd (1984)
 provoked  developers into thinking about
  the uses of prototypes
 typical questions included:
  aim of building the prototype?
  which category?
  appropriateness of particular types of prototypes at
   certain stages in the systems development?
  improving the development by using a different
   series of prototypes?


                                    Clarke, R.J. (2000) EDM-DSL   23
    Prototype Classification
              Law’s Types (1)

 developed   an extended (5)
  classification of prototypes
 distinction between types is not
  absolute
 relates to the chief purpose of a
  prototype in relation to its typical
  occurence (timing) during the
  development process

                              Clarke, R.J. (2000) EDM-DSL   24
    Prototype Classification
                Law’s Types (2)
 Exploratory
  assist in the clarification of requirements
  prototyping the logical specification
  as per Floyd
 Experimental
  to find the solution to a particular problem
  prototyping the design
  as per Floyd


                                    Clarke, R.J. (2000) EDM-DSL   25
 Prototype Classification
            Law’s Types (3)
 Performance
  check whether solution handles workload
  synthetic prototyping- prototype is run
   through a simulated workload
  necessary simplification of the prototype
   makes this difficult
  nevertheless, useful for identifying
   incompatible combinations of problem,
   hardware, software, people



                               Clarke, R.J. (2000) EDM-DSL   26
    Prototype Classification
                Law’s Types (4)
 Organisational
  a special case of experimental prototyping used to
   test a solution in proposed user environment
  ascertain that a users requirements are met
  clarify the needs of the surrounding organisation
  needs may be met by changing manual procedures,
   staff, equipment, job descriptions, training




                                   Clarke, R.J. (2000) EDM-DSL   27
    Prototype Classification
                  Law’s Types (5)

 Evolutionary
  refers to the situation that exists when the
   prototype is in operation
  through its use necessary alterations become
   apparent
  when the need for change is recognised the
   operational system (‘version’) becomes the
   prototype for the development of an enhanced
   system
  as per Floyd

                                 Clarke, R.J. (2000) EDM-DSL   28
 Prototype Classification
     Importance of Law’s Types
 likeFloyd tries to provide a
  functional description of different
  types of prototypes
 unlike Floyd, tries to describe
  most possibilities
 provides an appreciation of the
  scope of prototyping


                          Clarke, R.J. (2000) EDM-DSL   29
 Prototype Classification
PUSH Model: Mayhew & Dearnley (1)
 provide  an alternative way of
  classifying prototyping
 based on the central ‘participants’
  found in any prototyping situation
  Prototyper (P)
  User (U)
  Software (S)
  Hardware (H)


                          Clarke, R.J. (2000) EDM-DSL   30
   Prototype Classification
 PUSH Model: Mayhew & Dearnley (2)
 each  ‘participant’ (corner) interacts
  with all the others
 can draw the interactions using a
  pyramid (edges)
 can recognise each of Law’s types of
  prototypes accordingly- with some
  interesting results!


                           Clarke, R.J. (2000) EDM-DSL   31
 Prototype Classification
PUSH Model: Mayhew & Dearnley (3)
            Software




 Users                 Hardware


          Prototype
                       Clarke, R.J. (2000) EDM-DSL   32
     Prototype Classification
PUSH Model: Exploratory Prototyping (4)

 prototyping the specification
 centres on communication
 involves P, U, S            Software




                      Users                         Hardware


                              Prototype
                               Clarke, R.J. (2000) EDM-DSL   33
    Prototype Classification
PUSH Model: Experimental Prototyping (5)

 adequacy  of proposed solution
 involves P, S, H
 3 subtypes:               Software
  experimental prototyping
  PS



                        Users                        Hardware


                                Prototype
                                Clarke, R.J. (2000) EDM-DSL   34
    Prototype Classification
PUSH Model: Experimental Prototyping (6)

 adequacy  of proposed solution
 involves P, S, H
 3 subtypes:               Software
  performance prototyping
  SH



                       Users                        Hardware


                               Prototype
                               Clarke, R.J. (2000) EDM-DSL   35
    Prototype Classification
PUSH Model: Experimental Prototyping (7)

 adequacy  of proposed solution
 involves P, S, H
 3 subtypes:               Software
  hardware prototyping
  PH



                          Users                        Hardware


                                  Prototype
                                  Clarke, R.J. (2000) EDM-DSL   36
     Prototype Classification
PUSH Model: Organisational Prototyping (8)

  clarifywider system requirements
  involves U, S, H
  3 subtypes:                Software
   ergonomic prototyping
   UH



                        Users                        Hardware


                                Prototype
                                Clarke, R.J. (2000) EDM-DSL   37
     Prototype Classification
PUSH Model: Organisational Prototyping (9)

  clarifywider system requirements
  involves U, S, H
  3 subtypes:                Software
   functional prototyping
   US



                             Users                        Hardware


                                     Prototype
                                     Clarke, R.J. (2000) EDM-DSL   38
    Prototype Classification
PUSH Model: Evolutionary Prototyping (10)

  but, cannot fit evolutionary
   prototyping onto the picture
  Mayhew and Dearnley argue that
   evolutionary prototyping has h/w and
   s/w implications, therefore
   evolutionary prototyping is simply an extension
    of organisational prototyping
   evolutionary prototyping simply has a longer
    time lapse between enhancements

                                   Clarke, R.J. (2000) EDM-DSL   39
   Prototype Classification
 PUSH Model: Mayhew & Dearnley (3)

                     S

   Functional            Experimental



Ergonomic                            Performance

        U
                              H

   Exploratory   P        Hardware

                              Clarke, R.J. (2000) EDM-DSL   40
Characteristics of ESD




                Clarke, R.J. (2000) EDM-DSL   41
   Characteristics of ESD (1)
 Overlap   of Analysis, Design and
  Construction Stages
 Limited Modelling of the Existing System
 emphasis on early identification of the
  'logical' requirements, so that quick
  prototypes can be produced



                           Clarke, R.J. (2000) EDM-DSL   42
  Characteristics of ESD (2)
 Partnership and User Responsibility
 both analysts and users bring
  unique expertise
 Formalisation of Prototype
  Boundaries
 system development can consist of
  many small prototypes, need to
  delineate each prototype

                          Clarke, R.J. (2000) EDM-DSL   43
Characteristics of ESD (4)
 Early Implementation
 Flexibility & Scalability- tailor the
  methodology to the needs of
  organisation




                            Clarke, R.J. (2000) EDM-DSL   44
 Characteristics of ESD (4)
 in RP, the purpose of the prototype
  was only to gather requirements
  during analysis and design
 in ESD, the main purpose of the
  prototype is to promote
  communication
 the prototype serves many
  purposes often simultaneously

                         Clarke, R.J. (2000) EDM-DSL   45
Benefits of ESD




            Clarke, R.J. (2000) EDM-DSL   46
        Benefits of ESD (1)
 Involving, committing and satisfying users
 Decreasing communications problems
 Decreasing development costs
 Reducing operational costs
 Reducing time for development
 Producing the right system first time
 Cutting human resource requirements during
  development

                             Clarke, R.J. (2000) EDM-DSL   47
      Benefits of ESD (2)
 Stage  Overlap or more correctly
  Partial Stage Overlap
 Incremental Delivery
 Tailorability of EDMs
 User Participation
 we will concentrate on the first two
 benefits, in a following lecture we will
 discuss the last two

                              Clarke, R.J. (2000) EDM-DSL   48
Partial Stage Overlap
        EDM




               Clarke, R.J. (2000) EDM-DSL   49
      Partial Stage Overlap (1)
       Traditional Development (SDLC)

Feasibility      Define      Program   Acceptance      Train
              Requirements                             Users




         Study        Design       Test      Convert           Install
        Current     New System
        System



              Does not support Stage Overlap

                                            Clarke, R.J. (2000) EDM-DSL   50
      Partial Stage Overlap (2)
                             EDM

Feasibility    Define                   Test
              Prototype               Prototype




         Study             Develop            Convert Install
        Current           Prototype
        System




                                             Clarke, R.J. (2000) EDM-DSL   51
      Partial Stage Overlap (2)
                               EDM

Feasibility    Define
                                        Test
              Prototype
                                      Prototype




         Study
                           Develop            Convert Install
        Current
                          Prototype
        System




                                                  Clarke, R.J. (2000) EDM-DSL   52
      Partial Stage Overlap (2)
                           EDM

Feasibility    Define
              Prototype
                              Test
                            Prototype




         Study
        Current
        System       Develop
                                    Convert Install
                    Prototype




                                        Clarke, R.J. (2000) EDM-DSL   53
      Partial Stage Overlap (2)
                  EDM

Feasibility




         Study
        Current
        System

                   Convert Install



                             Clarke, R.J. (2000) EDM-DSL   54
      Partial Stage Overlap (2)
                     EDM

Feasibility




         Study
        Current
        System



                  Convert Install

                                    Clarke, R.J. (2000) EDM-DSL   55
      Partial Stage Overlap (2)
                         EDM

Feasibility




         Study
        Current
        System



                  Convert Install

                                    Clarke, R.J. (2000) EDM-DSL   56
      Partial Stage Overlap (2)
                              EDM
                  Supports Partial Overlap
Feasibility




                               Define Prototype

                                  Develop Prototype
         Study
        Current                        Test Prototype
        System




                     Convert Install
                                              Clarke, R.J. (2000) EDM-DSL   57
   Stage Overlap Comparison (4)
     SDLC and EDLC Based Methodologies

          Define
               Develop         Finish
                      Test   Prototyping




 Start
Project




                                                 Finish
                                                 Project
                                           Clarke, R.J. (2000) EDM-DSL   58
Incremental Delivery




               Clarke, R.J. (2000) EDM-DSL   59
    Incremental Delivery


       A



B


        C

                   Clarke, R.J. (2000) EDM-DSL   60
    Incremental Delivery
                    A             B            C
                  Sta Fin      Sta Fin      Sta Fin

       A
             t0 1:4                        1

             t1       1:4                          1

B            t2                 2          2,3

             t3                 1 2              2,3

        C    t4                     1

                            Clarke, R.J. (2000) EDM-DSL   61
    Incremental Delivery
                    A             B            C
                  Sta Fin      Sta Fin      Sta Fin

       A
             t0 1:4                        1

             t1       1:4                          1

B            t2                 2          2,3

             t3                 1 2              2,3

        C    t4                     1

                            Clarke, R.J. (2000) EDM-DSL   62
    Incremental Delivery
                    A             B            C
                  Sta Fin      Sta Fin      Sta Fin

       A
             t0 1:4                        1

             t1       1:4                          1

B            t2                 2          2,3

             t3                 1 2              2,3

        C    t4                     1

                            Clarke, R.J. (2000) EDM-DSL   63
    Incremental Delivery
                    A             B            C
                  Sta Fin      Sta Fin      Sta Fin

       A
             t0 1:4                        1

             t1       1:4                          1

B            t2                 2          2,3

             t3                 1 2              2,3

        C    t4                     1

                            Clarke, R.J. (2000) EDM-DSL   64
    Incremental Delivery
                    A             B            C
                  Sta Fin      Sta Fin      Sta Fin

       A
             t0 1:4                        1

             t1       1:4                          1

B            t2                 2          2,3

             t3                 1 2              2,3

        C    t4                     1

                            Clarke, R.J. (2000) EDM-DSL   65

				
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