Clarke, R.J. (2000) EDM-DSL 1 EDM

Clarke, R.J. (2000) EDM-DSL 2 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 3 ESD Related Definitions (2) n Evolutionary Prototyping (EP) is the general name for the activity developers undertake when they are involved in Evolutionary Systems Development n Evolutionary Development Methodology (EDM)- a methodology which supports ESD

Clarke, R.J. (2000) EDM-DSL 4 EDLC

Clarke, R.J. (2000) EDM-DSL 5 RPLC Investigation ConstructionAnalysisDesign Develop Prototype Test Prototype Amend Prototype Maintenance & Evaluation Operation & Acceptance

Clarke, R.J. (2000) EDM-DSL 6 EDLC Develop Prototype Test Prototype Amend Prototype

Clarke, R.J. (2000) EDM-DSL 7 Evolutionary Development (1) Test Prototype Amend Prototype Develop Prototype Test Prototype Amend Prototype Test Prototype Amend Prototype Candidate Prototypes Develop Prototype Develop Prototype

Clarke, R.J. (2000) EDM-DSL 8 Evolutionary Development (2) Develop Prototype Test Prototype Amend Prototype Develop Prototype Test Prototype Amend Prototype Develop Prototype Amend Prototype Spawn Test Prototype

Clarke, R.J. (2000) EDM-DSL 9 Evolutionary Development (3) Test Prototype Amend Prototype Develop Prototype Amend Prototype Develop Prototype Test Prototype Amend Prototype Develop Prototype Test Prototype Spawn Test Prototype Develop Prototype Amend Prototype

Clarke, R.J. (2000) EDM-DSL 10 Evolutionary Development (4) Test Prototype Amend Prototype Develop Prototype Develop Prototype Test Prototype Amend Prototype Develop Prototype Test Prototype Develop Prototype Test Prototype Amend Prototype Test Prototype Develop Prototype Amend Prototype Amend Prototype

Clarke, R.J. (2000) EDM-DSL 11 Evolutionary Development (6) Test Prototype Amend Prototype Develop Prototype Test Prototype Develop Prototype Test Prototype Test Prototype Amend Prototype Test Prototype Amend Prototype Develop Prototype Merge Develop Prototype Develop Prototype Amend Prototype Amend Prototype

Clarke, R.J. (2000) EDM-DSL 12 Evolutionary Development (7) Test Prototype Amend Prototype Develop Prototype Test Prototype Amend Prototype Develop Prototype Test Prototype Amend Prototype Develop Prototype Test Prototype Amend Prototype Develop Prototype

Clarke, R.J. (2000) EDM-DSL 13 Prototype Classification

Clarke, R.J. (2000) EDM-DSL 14 Prototype Classifications n Several classifications exist for distinguish the function or purpose of a prototype Floyd (1984) Floyd (1984) Law (1985) Law (1985) Mayhew & Dearnley (1987) Mayhew & Dearnley (1987)

Clarke, R.J. (2000) EDM-DSL 15 Prototype Classifications Floyd’s Classification n distinguishes three broad approaches to prototyping exploratory exploratory experimental experimental evolutionary evolutionary n structured the debate surrounding prototyping in general

Clarke, R.J. (2000) EDM-DSL 16 Prototype Classifications Floyd’s Classification: Exploratory n useful: early stages of systems development n focus: communications problems between prospective users and developers n prototype: catalyst to participation and ideas generation n aim: assist in requirements gathering

Clarke, R.J. (2000) EDM-DSL 17 Prototype Classifications Floyd’s Classification: Experimental n useful: testing all or some functions n focus: building a proposed solution to a particular problem n prototype: evaluated by experimental use prior to eventual implementation n aim: reduce implementation costs

Clarke, R.J. (2000) EDM-DSL 18 Prototype Classifications Floyd’s Classification: Evolutionary (1) n most controversial category n emphasis on gradual adaptation of the system in order to cope with changing organisational circumstances n system can be looked at as a sequence of versions

Clarke, R.J. (2000) EDM-DSL 19 Prototype Classifications Floyd’s Classification: Evolutionary (2) n each version once constructed, used and evaluated is treated as a prototype to its successor it has been argued that it should be called ‘versioning’ 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! but the use of a prototype means that it should not be thought of as versioning!

Clarke, R.J. (2000) EDM-DSL 20 Prototype Classifications Floyd’s Classification: Evolutionary (3) ‘Version’ 1 ? ? ‘Version’ 2

Clarke, R.J. (2000) EDM-DSL 21 Prototype Classifications Floyd’s Classification: Evolutionary (4) ‘Version’ 2 ? ? ? ‘Version’ 3

Clarke, R.J. (2000) EDM-DSL 22 Prototype Classifications Floyd’s Classification: Evolutionary (5) ? ? ? ‘Version’ 3 Final ‘Version’ A B C

Clarke, R.J. (2000) EDM-DSL 23 Prototype Classifications Importance of Floyd (1984) provoked developers into thinking about the uses of prototypes provoked developers into thinking about the uses of prototypes typical questions included: typical questions included: aim of building the prototype? aim of building the prototype? which category? which category? appropriateness of particular types of prototypes at certain stages in the systems development? appropriateness of particular types of prototypes at certain stages in the systems development? improving the development by using a different series of prototypes? improving the development by using a different series of prototypes?

Clarke, R.J. (2000) EDM-DSL 24 Prototype Classification Law’s Types (1) n developed an extended (5) classification of prototypes n distinction between types is not absolute n 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 25 Prototype Classification Law’s Types (2) Exploratory Exploratory assist in the clarification of requirements assist in the clarification of requirements prototyping the logical specification prototyping the logical specification as per Floyd as per Floyd Experimental Experimental to find the solution to a particular problem to find the solution to a particular problem prototyping the design prototyping the design as per Floyd as per Floyd

Clarke, R.J. (2000) EDM-DSL 26 Prototype Classification Law’s Types (3) Performance Performance check whether solution handles workload check whether solution handles workload synthetic prototyping- prototype is run through a simulated workload synthetic prototyping- prototype is run through a simulated workload necessary simplification of the prototype makes this difficult necessary simplification of the prototype makes this difficult nevertheless, useful for identifying incompatible combinations of problem, hardware, software, people nevertheless, useful for identifying incompatible combinations of problem, hardware, software, people

Clarke, R.J. (2000) EDM-DSL 27 Prototype Classification Law’s Types (4) n Organisational a special case of experimental prototyping used to test a solution in proposed user environment a special case of experimental prototyping used to test a solution in proposed user environment ascertain that a users requirements are met ascertain that a users requirements are met clarify the needs of the surrounding organisation clarify the needs of the surrounding organisation needs may be met by changing manual procedures, staff, equipment, job descriptions, training needs may be met by changing manual procedures, staff, equipment, job descriptions, training

Clarke, R.J. (2000) EDM-DSL 28 Prototype Classification Law’s Types (5) Evolutionary Evolutionary refers to the situation that exists when the prototype is in operation refers to the situation that exists when the prototype is in operation through its use necessary alterations become apparent 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 when the need for change is recognised the operational system (‘version’) becomes the prototype for the development of an enhanced system as per Floyd as per Floyd

Clarke, R.J. (2000) EDM-DSL 29 Prototype Classification Importance of Law’s Types n like Floyd tries to provide a functional description of different types of prototypes n unlike Floyd, tries to describe most possibilities n provides an appreciation of the scope of prototyping

Clarke, R.J. (2000) EDM-DSL 30 Prototype Classification PUSH Model: Mayhew & Dearnley (1) n provide an alternative way of classifying prototyping n based on the central ‘participants’ found in any prototyping situation Prototyper (P) Prototyper (P) User (U) User (U) Software (S) Software (S) Hardware (H) Hardware (H)

Clarke, R.J. (2000) EDM-DSL 31 Prototype Classification PUSH Model: Mayhew & Dearnley (2) n each ‘participant’ (corner) interacts with all the others n can draw the interactions using a pyramid (edges) n can recognise each of Law’s types of prototypes accordingly- with some interesting results!

Clarke, R.J. (2000) EDM-DSL 32 Prototype Classification PUSH Model: Mayhew & Dearnley (3) Software Users Hardware Prototype

Clarke, R.J. (2000) EDM-DSL 33 Prototype Classification PUSH Model: Exploratory Prototyping (4) n prototyping the specification n centres on communication n involves P, U, S Software Users Hardware Prototype

Clarke, R.J. (2000) EDM-DSL 34 Prototype Classification PUSH Model: Experimental Prototyping (5) adequacy of proposed solution adequacy of proposed solution involves P, S, H involves P, S, H 3 subtypes: 3 subtypes: experimental prototyping experimental prototyping PS PS Software Users Hardware Prototype

Clarke, R.J. (2000) EDM-DSL 35 Prototype Classification PUSH Model: Experimental Prototyping (6) adequacy of proposed solution adequacy of proposed solution involves P, S, H involves P, S, H 3 subtypes: 3 subtypes: performance prototyping performance prototyping SH SH Software Users Hardware Prototype

Clarke, R.J. (2000) EDM-DSL 36 Prototype Classification PUSH Model: Experimental Prototyping (7) adequacy of proposed solution adequacy of proposed solution involves P, S, H involves P, S, H 3 subtypes: 3 subtypes: hardware prototyping hardware prototyping PH PH Software Users Hardware Prototype

Clarke, R.J. (2000) EDM-DSL 37 Prototype Classification PUSH Model: Organisational Prototyping (8) clarify wider system requirements clarify wider system requirements involves U, S, H involves U, S, H 3 subtypes: 3 subtypes: ergonomic prototyping ergonomic prototyping UH UH Software Users Hardware Prototype

Clarke, R.J. (2000) EDM-DSL 38 Prototype Classification PUSH Model: Organisational Prototyping (9) clarify wider system requirements clarify wider system requirements involves U, S, H involves U, S, H 3 subtypes: 3 subtypes: functional prototyping functional prototyping US US Software Users Hardware Prototype

Clarke, R.J. (2000) EDM-DSL 39 Prototype Classification PUSH Model: Evolutionary Prototyping (10) but, cannot fit evolutionary prototyping onto the picture but, cannot fit evolutionary prototyping onto the picture Mayhew and Dearnley argue that evolutionary prototyping has h/w and s/w implications, therefore 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 is simply an extension of organisational prototyping evolutionary prototyping simply has a longer time lapse between enhancements evolutionary prototyping simply has a longer time lapse between enhancements

Clarke, R.J. (2000) EDM-DSL 40 Prototype Classification PUSH Model: Mayhew & Dearnley (3) S U H P Hardware Exploratory Experimental Performance Ergonomic Functional

Clarke, R.J. (2000) EDM-DSL 41 Characteristics of ESD

Clarke, R.J. (2000) EDM-DSL 42 Characteristics of ESD (1) n Overlap of Analysis, Design and Construction Stages n Limited Modelling of the Existing System n emphasis on early identification of the 'logical' requirements, so that quick prototypes can be produced

Clarke, R.J. (2000) EDM-DSL 43 Characteristics of ESD (2) n Partnership and User Responsibility n both analysts and users bring unique expertise n Formalisation of Prototype Boundaries n system development can consist of many small prototypes, need to delineate each prototype

Clarke, R.J. (2000) EDM-DSL 44 Characteristics of ESD (4) n Early Implementation n Flexibility & Scalability- tailor the methodology to the needs of organisation

Clarke, R.J. (2000) EDM-DSL 45 Characteristics of ESD (4) n in RP, the purpose of the prototype was only to gather requirements during analysis and design n in ESD, the main purpose of the prototype is to promote communication n the prototype serves many purposes often simultaneously

Clarke, R.J. (2000) EDM-DSL 46 Benefits of ESD

Clarke, R.J. (2000) EDM-DSL 47 Benefits of ESD (1) n Involving, committing and satisfying users n Decreasing communications problems n Decreasing development costs n Reducing operational costs n Reducing time for development n Producing the right system first time n Cutting human resource requirements during development

Clarke, R.J. (2000) EDM-DSL 48 Benefits of ESD (2) n Stage Overlap or more correctly Partial Stage Overlap n Incremental Delivery n Tailorability of EDMs n User Participation we will concentrate on the first two benefits, in a following lecture we will discuss the last two we will concentrate on the first two benefits, in a following lecture we will discuss the last two

Clarke, R.J. (2000) EDM-DSL 49 Partial Stage Overlap EDM

Clarke, R.J. (2000) EDM-DSL 50 Partial Stage Overlap (1) Traditional Development (SDLC) Feasibility Study Current System Define Requirements Design New System Program Test Acceptance Train Users Convert Install Does not support Stage Overlap

Clarke, R.J. (2000) EDM-DSL 51 Partial Stage Overlap (2) EDM Feasibility Study Current System Define Prototype Develop Prototype Test Prototype ConvertInstall

Clarke, R.J. (2000) EDM-DSL 52 Partial Stage Overlap (2) EDM Develop Prototype Test Prototype ConvertInstall Feasibility Study Current System Define Prototype

Clarke, R.J. (2000) EDM-DSL 53 Partial Stage Overlap (2) EDM Develop Prototype Feasibility Study Current System Define Prototype Test Prototype ConvertInstall

Clarke, R.J. (2000) EDM-DSL 54 Partial Stage Overlap (2) EDM Feasibility Study Current System ConvertInstall

Clarke, R.J. (2000) EDM-DSL 55 Partial Stage Overlap (2) EDM Feasibility Study Current System ConvertInstall

Clarke, R.J. (2000) EDM-DSL 56 Partial Stage Overlap (2) EDM ConvertInstall Feasibility Study Current System

Clarke, R.J. (2000) EDM-DSL 57 Partial Stage Overlap (2) EDM Supports Partial Overlap Feasibility Study Current System Define Prototype Develop Prototype Test Prototype ConvertInstall

Clarke, R.J. (2000) EDM-DSL 58 Stage Overlap Comparison (4) SDLC and EDLC Based Methodologies Define Develop Test Finish Prototyping Finish Project Start Project

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

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

Clarke, R.J. (2000) EDM-DSL 61 Incremental Delivery A B C A B C Sta Fin Sta Fin Sta Fin t 0 1:4 1 t 1 1:4 1 t 2 2 2,3 t ,3 t 4 1

Clarke, R.J. (2000) EDM-DSL 62 Incremental Delivery A B C A B C Sta Fin Sta Fin Sta Fin t 0 1:4 1 t 1 1:4 1 t 2 2 2,3 t ,3 t 4 1

Clarke, R.J. (2000) EDM-DSL 63 Incremental Delivery A B C A B C Sta Fin Sta Fin Sta Fin t 0 1:4 1 t 1 1:4 1 t 2 2 2,3 t ,3 t 4 1

Clarke, R.J. (2000) EDM-DSL 64 Incremental Delivery A B C A B C Sta Fin Sta Fin Sta Fin t 0 1:4 1 t 1 1:4 1 t 2 2 2,3 t ,3 t 4 1

Clarke, R.J. (2000) EDM-DSL 65 Incremental Delivery A B C A B C Sta Fin Sta Fin Sta Fin t 0 1:4 1 t 1 1:4 1 t 2 2 2,3 t ,3 t 4 1