Incremental Change of Software Taxonomy of Evolution Changes - - PowerPoint PPT Presentation

▶
incremental change of software taxonomy of evolution
SMART_READER_LITE
LIVE PREVIEW

Incremental Change of Software Taxonomy of Evolution Changes - - PowerPoint PPT Presentation

Jun 01, 2023 175 likes •734 views

Incremental Change of Software Taxonomy of Evolution Changes Incremental change (IC) adds substantial new functionality Refactoring (restructuring) preserves the functionality Replacement substitute one functionality

slide-1
SLIDE 1

Incremental Change of Software

slide-2
SLIDE 2

Taxonomy of Evolution Changes

  • Incremental change (IC)

– adds substantial new functionality

  • Refactoring (restructuring)

– preserves the functionality

  • Replacement

– substitute one functionality by another – example: replacing buggy code

  • Retracting

– deletes a functionality

slide-3
SLIDE 3

Strategies for IC

  • Anticipated change

– information hiding, parametrization – localize change within one class

  • Many changes cannot be anticipated

– process of learning during development

  • Microsoft: 70% of requirements predicted
  • Ford project: 30% predicted

– examples of unexpected changes

  • company mergers, introduction of Euro
slide-4
SLIDE 4

Unanticipated IC

  • The Software was not prepared/designed for it
  • Very common situation in practice
  • A substantial part of software engineering
slide-5
SLIDE 5

The Mini-process of IC

  • Initiation
  • IC design
  • IC implementation & Tests
  • Release
slide-6
SLIDE 6

IC Initiation

  • Problem Report

– May require logs, traces

  • Preventive Maintenance

– enhance reliability, comprehensibility, extensibility, etc.

  • New Feature Request

– additional functionality of the product – usually initiated by the customers, marketing, management

  • All change requests

– assigned a priority and placed on the queue – hot problems cause instant reprioritization

slide-7
SLIDE 7

IC Design

  • Concept Location

– Find where in the code the change will be done

  • Study Code and Documentation
  • Identify/Weigh Alternative Solutions
  • Implementation strategy

– Divide large changes into several smaller ones – Each has its own implementation and testing activity

  • Impact analysis

– Find all components that will be affected by the change

slide-8
SLIDE 8

IC Implementation

  • Refactoring 1 (pre-factoring)

– Restructure the software to localize change

  • Actualization

– Implements the new code

  • Incorporation

– Replaces the new code by the old

  • Change propagation

– Changes all other components that must be changed

  • Refactoring 2 (post-factoring)

– Improves clarity, readability

slide-9
SLIDE 9

Testing

  • Unit tests of the components

– Guarantee that units (classes) work

  • Regression test

– Guarantee that things that did not change still work

  • Integration test

– Guarantee that the whole system works again

  • Tests are done both during and after

implementation

slide-10
SLIDE 10

IC Release

  • Release build
  • Write Release Notes
  • Make release available to customer
slide-11
SLIDE 11

Concept location

  • plays key role in IC
  • concepts are present in the code
  • primitive concepts have to be enriched

– Point-of-Sale: introduce credit card payment – old code: payment represented as just one number

  • latent concepts have to be implemented

– Student Registration: introduce prerequisite check – old code assumption: prerequisites are satisfied

slide-12
SLIDE 12

Concept location

  • finds code that implements concept
  • part of program comprehension
  • concept location methodologies

– human knowledge – "grep" (pattern matching) – dynamic search (execution traces) – static search through dependency graph – traceability tools

slide-13
SLIDE 13

Top-down search

  • Depth first search done by programmer:

Start with the top class (main in C++) while (concept is not implemented here)

if (the concept is a part of the composite functionality) move to subclass which leads to the concept else backtrack

concept located

slide-14
SLIDE 14

Change propagation

  • Refactoring 1 (pre-factoring)

– Restructure the software to localize change

  • Actualization

– Implements the new code

  • Incorporation

– Replaces the new code by the old

  • Change propagation

– Changes all other components that must be changed

  • Refactoring 2 (post-factoring)

– Improves clarity, readability

slide-15
SLIDE 15

Change propagation

– if the visited class is modified, it may no longer fit

  • secondary changes must be made in interacting

(“neighboring”) classes

  • secondary changes may trigger additional changes

– “ripple effect”

– Process

  • Mark neighboring classes of a class that changed
  • visit the marked classes one-by-one
slide-16
SLIDE 16

Three possibilities for marked class visit

  • Change class

– Mark all neighbors

  • Do not change class but propagate

– Mark all neighbors

  • Do not change class and do not propagate

– Erase the mark

slide-17
SLIDE 17

Three options (class diagram)

Change class mark Do not change class but propagate

slide-18
SLIDE 18

Three options (class diagram)

Do not change class and do not propagate

slide-19
SLIDE 19

Example change propagation

  • Point-Of-Sale application
  • Old program
  • keeps an inventory, receives delivery, sells

products, and supports a cash register.

  • Classes designed and implemented at a minimal

level of functionality

slide-20
SLIDE 20

UML class diagram

slide-21
SLIDE 21

Incremental change

  • complexities of sale taxes
  • different products may have different sales tax,

depending on state law

  • location

– “tax” in class “item”

  • actualization

– new class taxCategory

slide-22
SLIDE 22

Incorporation

sale register saleLineItem store item taxCategory

slide-23
SLIDE 23

Change propagation

sale register saleLineItem store item taxCategory

slide-24
SLIDE 24

Change propagation

sale register saleLineItem store item taxCategory

slide-25
SLIDE 25

Change propagation

sale register saleLineItem store item taxCategory

slide-26
SLIDE 26

Change propagation

sale register saleLineItem store item taxCategory

slide-27
SLIDE 27

Change propagation

sale register saleLineItem store item taxCategory

slide-28
SLIDE 28

Summary adding tax

  • 1 new class was implemented
  • All 5 old classes had to be visited (!)
  • 3 old classes had to be changed
slide-29
SLIDE 29

Example Drawlets

  • Application framework Drawlets

– adds graphical display to a host application

  • Drawing canvas

– lines, free-hand lines, rectangles, rounded rectangles, triangles, pentagons, polygons, ellipses, text boxes, images

slide-30
SLIDE 30

Drawlets

  • more than 100 classes, 35 interfaces and 40,000

lines of code – originally implemented by Kent Beck, Ward Cunningham

  • later ported into Java
  • “perfect API”

– http://www.rolemodelsoft.com/aboutUs/ drawlets.htm

slide-31
SLIDE 31

The host application

  • responsible for providing an instance of the

drawing canvas, toolbars, and tool buttons

  • Class SimpleApplet is a host application

– is a part of the Drawlet library – SimpleApplet runs in any browser

slide-32
SLIDE 32

SimpleApplet window

slide-33
SLIDE 33

Top classes

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette LabelTool Figure

slide-34
SLIDE 34

Concept Location :: Example

  • Locating figure properties in Drawlets
slide-35
SLIDE 35

Example Drawlets: Top class

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette LabelTool Figure

slide-36
SLIDE 36

Wrong way

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette LabelTool Figure

slide-37
SLIDE 37

Backtrack

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette LabelTool Figure

slide-38
SLIDE 38

Right way

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette LabelTool Figure

slide-39
SLIDE 39

Wrong way

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette LabelTool Figure

slide-40
SLIDE 40

Backtrack

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette LabelTool Figure

slide-41
SLIDE 41

Concept Location :: Summary

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette LabelTool Figure

slide-42
SLIDE 42

Change Request

  • implement an "owner" for each figure

– owner put that figure onto the canvas – only owner is allowed to move that figure – each session declares a session owner

  • this session owner will own all new figures created
  • no other owner will be allowed to manipulate them
  • This change will make SimpleApplet more

versatile and useful

– support for cooperative work

slide-43
SLIDE 43

Extraction

  • The concepts relevant to the change

– figure owner and session owner – both are implicit

  • old code assumes that there is just one owner who
  • wns both sessions and figures
slide-44
SLIDE 44

Location

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette LabelTool Figure

slide-45
SLIDE 45

Actualization

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette OwnerIdentity SimpleListener LabelTool Figure

slide-46
SLIDE 46

Incorporation

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette OwnerIdentity SimpleListener LabelTool Figure

slide-47
SLIDE 47

Propagation

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette OwnerIdentity SimpleListener LabelTool Figure

slide-48
SLIDE 48

Propagation

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette OwnerIdentity SimpleListener LabelTool Figure

slide-49
SLIDE 49

Propagation

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette OwnerIdentity SimpleListener LabelTool Figure

slide-50
SLIDE 50

Propagation

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette OwnerIdentity SimpleListener LabelTool Figure

slide-51
SLIDE 51

Propagation

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette OwnerIdentity SimpleListener LabelTool Figure

slide-52
SLIDE 52

Propagation

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette OwnerIdentity SimpleListener LabelTool Figure

slide-53
SLIDE 53

Propagation

SequenceOfFigures ShapeTool EllipseTool RectangleTool RectangularCreationTool PG_RectImageTool Locator CanvasTool AbstractFigure SimpleDrawingCanvas DrawingCanvas ToolPalette SimpleApplet ToolBar LocatorConnectionHandle PrototypeConstructionTool SelectionTool ConstructionTool StylePalette OwnerIdentity SimpleListener LabelTool Figure

slide-54
SLIDE 54

Shorter change propagation

  • Long change propagation is a problem

– it would be advantageous to shorten it

  • opportunistic refactoring

– moves code affected by change into fewer classes

  • splitting the roles
slide-55
SLIDE 55

More info on the case study

  • Václav Rajlich, Prashant Gosavi: Incremental

Change in Object-Oriented Programming. IEEE Software 21(4): 62-69 (2004)