Static Extraction of Hierarchical Runtime Object Graphs...

Static Extraction of Hierarchical Runtime Object Graphs –Tool Demonstration

Marwan Abi-Antoun Jonathan Aldrich

School of Computer Science

Carnegie Mellon University

2

Object-Oriented Code vs. Runtime Structure

“An object-oriented program's runtime structureoften bears little resemblance to its code structure.

The code structure [...] consists of classes in fixed inheritance relationships.

A program's runtime structure consists of [...]

networks of communicating objects [...]

Trying to understand one from the other is like trying

to understand the dynamism of living ecosystems from the static taxonomy of plants and animals, and

vice versa.” (Gamma et al., 1994)

3

Object Diagram: a diagram of object structures which shows object instances exclusively.

Source: E. Gamma, R. Helm, R. Johnson, and J. Vlissides. Design Patterns: Elements of Reusable Object-Oriented Software. Addison-Wesley, 1994. (CD-ROM edition)

[…]

[…]

4

ToolButton

ToolButton

SelectionTool

fTool

JavaDrawApp

fListener

PaletteIcon

fIcon

ToolButton

SelectionTool

fTool

JavaDrawApp

fListener

fIcon

ToolButton

SelectionTool

fTool

JavaDrawApp

fListener

fIcon

ToolButton

ToolButton

Main

app

Undoable

SelectionTool

SelectionTool

myUndoActivity

JavaDrawApp

myDrawingEditor

Tool

fChild

AbstractTool$EventDispatchermyEventDispatcher

Object

SelectionTool

myUndoActivity

myDrawingEditorfChild


SelectionTool

SelectionTool

myUndoActivity

JavaDrawApp

myDrawingEditor

Tool

fChild

AbstractTool$EventDispatcher

myEventDispatcher

SelectionTool

myUndoActivity

myDrawingEditor

ToolfChild


myUndoActivitymyDrawingEditor

fChild


myEventDispatcher

myUndoActivity

JavaDrawApp

myDrawingEditor

fChild

myEventDispatcher

JavaDrawApp

JavaDrawApp

fSelectedToolButton

fDefaultToolButton

fTool

Animator

fAnimator

DrawingView

fView

Vector

mdiListeners

JComponent

desktop

JTextField

fStatusLine

EventListenerListlistenerList

fView

AnimatablefAnimatable

fDefaultToolButton

fSelectedToolButton

fTool

fAnimator

fView

Vector

mdiListeners

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

fAnimator

fView

Vector

mdiListeners

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

mdiListeners::elts

fAnimator

fView

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

mdiListeners::elts

fAnimator

fView

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

fAnimator

fView

mdiListeners

desktop

fStatusLine

listenerList

Rectangle

UndoableHandle

Image

DrawingEditor

Tool

fSelectGroup

fAnchorHandle

myDrawingEditor


myEventDispatcher

DragTrackermyWrappedTool

fSelectGroup

fAnchorHandle

myDrawingEditor


myWrappedTool

fSelectGroup

fAnchorHandle

myDrawingEditor


myEventDispatcher DragTracker

myWrappedTool

fSelected

fNormal

fPressed

DimensionfSize

Vector

Object[]elementData


myRegisteredListeners

myObservedTool

myObservedTool


myObservedTool


myObservedTool


myObservedTool

ToolListener

myRegisteredListeners::elts

myObservedTool


myUndoActivity

myDrawingEditor

myEventDispatcher

Figure

fAnchorFigure

listenerList[]

NULL_ARRAY[]

Tool support to extract runtime structure less mature

• Low-level objects

• No architectural abstraction

• Some analyses incorrectlyhandle aliasing

JavaDrawApp,

DrawingEditor,

represent one

runtime object.

Output of Womble on JHotDraw (15 KLOC)

Key Insight

Ownership domain annotations enable the extraction of sound hierarchical object graphs using static analysis.

6

Extracting sound hierarchical object graphs using static analysis

• Why static analysis?• Dynamic analysis shows object graphs for

a few program runs, not all

• Why sound?• To be most useful, show all objects and

relations that could exist at runtime

7

Model

View

Controller

figureChangeEvent(+):DrawingChangeEvent

fPoly(+):Shape

textFigure1(+):Drawing

myBorderOffset(+):Point2D

polyLineConnector(+):Connector

fStartDecoration(+):AbstractLineDecoration

fLocator(+):Locator

undoableHandle(+):Handle

myDrawingView(+):DrawingView

myUndoableActivity(+):UndoableAdapter

myAlignment(+):Alignment

myUndoManager(+):UndoManager

fStorageFormatManager(+):StorageFormatManager

myDefaultStorageFormat(+):StorageFormat

fAnimator(+):Thread

autoscrollInsets(+):Insets

app(+):DrawingEditor

fDefaultToolButton(+):ToolListener

textTool(+):Tool

bufferedUpdateStrategy(+):Painter

constrainer(+):PointConstrainer

menu(+):CommandListener

cmd(+):Command

system:Main

Extracting sound hierarchical object graphs using static analysis

• Hierarchical graphs• Flat graphs do not

provide architectural abstraction or scale

ToolButton

ToolButton

SelectionTool

fTool

JavaDrawApp

fListener

PaletteIcon

fIcon

ToolButton

SelectionTool

fTool

JavaDrawApp

fListener

fIcon

ToolButton

SelectionTool

fTool

JavaDrawApp

fListener

fIcon

ToolButton

ToolButton

Main

app

Undoable

SelectionTool

SelectionTool

myUndoActivity

JavaDrawApp

myDrawingEditor

Tool

fChild


Object

SelectionTool

myUndoActivity



SelectionTool

SelectionTool

myUndoActivity

JavaDrawApp

myDrawingEditor

Tool

fChild


myEventDispatcher

SelectionTool

myUndoActivity

myDrawingEditor

ToolfChild



fChild


myEventDispatcher

myUndoActivity

JavaDrawApp

myDrawingEditor

fChild

myEventDispatcher

JavaDrawApp

JavaDrawApp

fSelectedToolButton

fDefaultToolButton

fTool

Animator

fAnimator

DrawingView

fView

Vector

mdiListeners

JComponent

desktop

JTextField

fStatusLine


fView


fDefaultToolButton

fSelectedToolButton

fTool

fAnimator

fView

Vector

mdiListeners

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

fAnimator

fView

Vector

mdiListeners

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

mdiListeners::elts

fAnimator

fView

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

mdiListeners::elts

fAnimator

fView

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

fAnimator

fView

mdiListeners

desktop

fStatusLine

listenerList

Rectangle

UndoableHandle

Image

DrawingEditor

Tool

fSelectGroup

fAnchorHandle

myDrawingEditor


myEventDispatcher


fSelectGroup

fAnchorHandle

myDrawingEditor


myWrappedTool

fSelectGroup

fAnchorHandle

myDrawingEditor



myWrappedTool

fSelected

fNormal

fPressed

DimensionfSize

Vector

Object[]elementData



myObservedTool

myObservedTool


myObservedTool


myObservedTool


myObservedTool

ToolListener


myObservedTool


myUndoActivity

myDrawingEditor

myEventDispatcher

Figure

fAnchorFigure

listenerList[]

NULL_ARRAY[]

8

Demonstration Outline

• Ownership annotations• Adding annotations

• Typechecking annotations

• Runtime structure• Extraction tool

• Real-World Example• JHotDraw

• Additional material• Static analysis

Ownership Domains

10

Ownership domains[Aldrich and Chambers, ECOOP’04]

• Each object defines conceptual groups (ownership domains) to hold its state

• Separate object’s internals from object’s boundary (accessible to outside)

• Ensure private state not leaked

• Distinguish different “subsystems” within object

11

Example: Sequence

head iterator

@Domains@Domains@Domains@Domains({“ownedownedownedowned”, “itersitersitersiters”})

classclassclassclass Sequence {

@Domain@Domain@Domain@Domain(“ownedownedownedowned”) Cons head;

public public public public @Domain@Domain@Domain@Domain(“itersitersitersiters”)

Iterator iterator() {return new return new return new return new Iterator(head);

}

}

Object

LEGEND

• Sequence has private state (head)• Should not be accessible to outside

• Sequence has iterators that are accessible to outside• Can also access private state

seq: Sequence

12

Sequence Code Structure

13

Sequence: Private Domain

• Each object has one or more domains• E.g., Sequence declares domains owned and iters

• Each object is in exactly one domain• E.g., head in domain owned; iterator in domain iters

head

owned






}

}

seq: Sequence

Object

LEGEND

Domain

14

Sequence: Public Domain

• Each object has one or more domains• E.g., Sequence declares domains owned and iters

• Each object is in exactly one domain• E.g., head in domain owned; iterator in domain iters

head iterator

owned iters






}

}

seq: Sequence

Object

Domain

LEGEND

15

Sequence Runtime Structure

state

list

iters

owned

object:Object

it:Iterator

cons:Cons

seq:Sequence

system:SequenceClient

16

Sequence Runtime Structure

• Collapse Sequence’s sub-structure

statelist

object:

Object

seq(+):

Sequencesystem:

SequenceClient

17

Encapsulation and Containment

(1) Strict encapsulation(private domain)

(2) Logical containment(public domain)

OWNED

seq:Sequence

head:ConsX

seq:Sequence

it:Iterator

ITERS

18

Annotation Tool Support

• Use Java 1.5 annotations

• Typechecker uses Eclipse JDT

• Warnings in Eclipse’s problem window

19

Demo: Checking Sequence

• Cannot return head of list• Head of list in private domain

• Stronger than making field private

• Cannot nullify head of list• Stronger than Java visibility (e.g., private)

• Iterate over list• Iterator in public domain

20

Ownership Domain Parameters

@DomainParams@DomainParams@DomainParams@DomainParams({“elemselemselemselems”})classclassclassclass Sequence {@Domain@Domain@Domain@Domain(“ownedownedownedowned<elemselemselemselems>”)Cons head;

…………}

@DomainParams@DomainParams@DomainParams@DomainParams({“elemselemselemselems”})classclassclassclass Cons {

@@@@DomainDomainDomainDomain(“elemselemselemselems”) Object obj; @@@@DomainDomainDomainDomain(“ownerownerownerowner<elemselemselemselems>”) Cons next;

}

• To share objects across domains• Add domain parameter to hold elements in list• Implicit domain parameter “owner”

(Same as me, a.k.a. “peer” or “same”)

ownedclientobjects

elems

seq : Sequence

:Cons

owner

Demo: Annotating Listeners

(Iteration 1)

22

Listeners Example

• Listeners tricky in object-oriented code

• Reuse annotated Sequence• Disguised as ArrayList

23

Listeners Code Structure

interfaceinterfaceinterfaceinterface Listener { }

classclassclassclass BaseChart implementsimplementsimplementsimplements Listener {

List< Listener> listeners;}classclassclassclass BarChart extendsextendsextendsextends BaseChart { }

classclassclassclass PieChart extendsextendsextendsextends BaseChart { }

classclassclassclass Model implementsimplementsimplementsimplements Listener {List<Listener> listeners;}

classclassclassclass Main {Model model;BarChart barChart;PieChart pieChart;

}

Class diagram by Eclipse UML.

24

Demo: Listeners example

• Tool to add default annotations• Declare owned private domain• Private field à place in domain owned

• owned: object fully encapsulated

• String à mark shared• shared: shared persistently or globally

• Method parameter à mark lent• lent: temporary alias within method

• Not a smart inference tool!

25

Standard and third-party libraries

• Annotate external code• Ideally, library provider adds annotations• Annotations shared amongst authors

• Only annotate parts of library in use

• Wizard to generate skeleton XML file

26

Listeners Runtime Structure (version 1)

• Listeners at the top-level

DOCUMENT VIEW

model:

Model

listeners:

List<Listener>

barChart:

BarChart

pieChart:

PieChart

listeners:

List<Listener>

Runtime Structure

28

Code Structure – Take 1







}

Class diagram extracted by Eclipse UML.

29

Code Structure – Take 2







}Class diagram by AgileJ.

30

• Who points to who?

• Do not distinguish between conceptually different instances of same class

• Extra details: abstract classes, interfaces, etc.

• No hierarchy

Code vs. Runtime Structure

DOCUMENT

VIEW

Class diagram extracted by AgileJ.

Demo: Annotating Listeners

(Iteration 2)

32

Change annotations

• Instance encapsulation

• May require changing code to avoid representation exposure, e.g., • Return copy instead of alias to internal List• Pass object linearly

33

Listeners Runtime Structure (version 2)

DOCUMENT

OWNED

VIEW

OWNED

OWNED

listeners:List<Listener>

barChart:BarChart

pieChart:PieChart

model:Model



X

pieChart.OWNED != barChart.OWNED

34

Abstraction by Ownership Hierarchy

• Push secondary objects underprimary objects using

(1) Strict encapsulation(private domain)

(2) Logical containment(public domain)

OWNED

seq:Sequence

head:ConsX

seq:Sequence

it:Iterator

ITERS

35

Hierarchy Provides Abstraction

• Can collapse object sub-structure

• Summary edges account for hidden objects

DOCUMENT

VIEW

model(+):Model

barChart(+):BarChart

pieChart(+):PieChart

36

Tool Features

• Control projection depth

• Collapse/expand substructure• Selected domain or • Selected object

• Summary edges

• Elide private domains

• Control object labeling

Case Study: JHotDraw

38

Extract As-BuiltRuntime Graph

Extract As-BuiltRuntime Graph

AnnotationsAnnotations

1. Add

3. Refine and iterate

CodeCode

Annotation/Extraction Process

2. Control Display4. (Optional) Change

code and refine

39

Annotation/Extraction Process

1. Choose top-level domains

2. Achieve desired number of objects in top-level domainsa) Push secondary objects under primary objectsb) Use abstraction by types to merge objects

3. Achieve appropriate visual detaila) Collapse or expand substructure of objectsb) Change projection depth across all objects

40

ConnectionFigure

Connector

DecoratorFigure

Handle

NullHandle TrackHandle

Locator

0..*

0..*

0..*2

Painter

PointConstrainer

Tool

DrawingEditor

DrawingView

CreationTool SelectionToolHandleTracker

Figure

Drawing

0..*

CompositeFigure

JHotDraw: Code Structure

Manually generated UML Class Diagram for JHotDraw [Riehle, Thesis 2000].

41

View

Model

Controller

ConnectionFigure

Connector

DecoratorFigure

Handle

NullHandle TrackHandle

Locator

0..*

0..*

0..*2

Painter

PointConstrainer

Tool

DrawingEditor

DrawingView

CreationTool SelectionToolHandleTracker

Figure

Drawing

0..*

CompositeFigure

JHotDraw: Model-View-Controller (MVC)

42

JHotDraw: Adding Annotations to Code

File: Main.java

43

JHotDraw: “30-second Architecture”

• Hide contents of domains• Dotted edges summarize field references

• Interestingly: no callback from M to C

Model

View

Controller

Main

44

JHotDraw: “30-minute Architecture”

Model

View

Controller


fPoly(+):Shape

textFigure1(+):Drawing




fLocator(+):Locator








fAnimator(+):Thread




textTool(+):Tool




cmd(+):Command

system:Main

Showing top-

level domains

and objects

LEGEND

formal_domain

domain1

domain2

Object:DeclaredType

Object1_with_Substructure (+):DeclaredType1

Object2:DeclaredType2

domain link

RootObject:Type

field reference

45

Model

owned

owned

View

Controller


fPoly(+):Shape

fFigures:Vector<Figure>

textFigure1:Drawing

_theQuadTree(+):QuadTree

fMap:MapfAttributes:

FigureAttributes

fDisplayBox:Shape

fPoints:Vector<Point>


fListeners:Vector<DrawingChangeListener>


fDrawingLockHolder:Runnable



fLocator(+):Locator







fAnimator(+):Thread




textTool(+):Tool




cmd(+):Command

system:Main

JHotDraw: “30-minute Architecture”

Showing Drawing’s sub-

structure

ToolButton

ToolButton

SelectionTool

fTool

JavaDrawApp

fListener

PaletteIcon

fIcon

ToolButton

SelectionTool

fTool

JavaDrawApp

fListener

fIcon

ToolButton

SelectionTool

fTool

JavaDrawApp

fListener

fIcon

ToolButton

ToolButton

Main

app

Undoable

SelectionTool

SelectionTool

myUndoActivity

JavaDrawApp

myDrawingEditor

Tool

fChild


Object

SelectionTool

myUndoActivity



SelectionTool

SelectionTool

myUndoActivity

JavaDrawApp

myDrawingEditor

Tool

fChild


myEventDispatcher

SelectionTool

myUndoActivity

myDrawingEditor

ToolfChild



fChild


myEventDispatcher

myUndoActivity

JavaDrawApp

myDrawingEditor

fChild

myEventDispatcher

JavaDrawApp

JavaDrawApp

fSelectedToolButton

fDefaultToolButton

fTool

Animator

fAnimator

DrawingView

fView

Vector

mdiListeners

JComponent

desktop

JTextField

fStatusLine


fView


fDefaultToolButton

fSelectedToolButton

fTool

fAnimator

fView

Vector

mdiListeners

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

fAnimator

fView

Vector

mdiListeners

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

mdiListeners::elts

fAnimator

fView

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

mdiListeners::elts

fAnimator

fView

desktop

fStatusLine

listenerList

fSelectedToolButton

fDefaultToolButton

fTool

fAnimator

fView

mdiListeners

desktop

fStatusLine

listenerList

Rectangle

UndoableHandle

Image

DrawingEditor

Tool

fSelectGroup

fAnchorHandle

myDrawingEditor


myEventDispatcher


fSelectGroup

fAnchorHandle

myDrawingEditor


myWrappedTool

fSelectGroup

fAnchorHandle

myDrawingEditor



myWrappedTool

fSelected

fNormal

fPressed

DimensionfSize

Vector

Object[]elementData



myObservedTool

myObservedTool


myObservedTool


myObservedTool


myObservedTool

ToolListener


myObservedTool


myUndoActivity

myDrawingEditor

myEventDispatcher

Figure

fAnchorFigure

listenerList[]

NULL_ARRAY[]

Output of Womble

JHotDraw Runtime Object Graph

Static Analysis

47

Static analysis

• Build TypeGraph from program’s AST

• Convert to ObjectGraph that soundly approximates all runtime object graphs (ROG)

ROG: graph where nodes represent runtime objects, edges represent reference or usage relations

● Problem ● Approach ● Analysis ● Evaluation ● Conclusion

48

…

TypeGraph: show types, domains inside types, and objects in domains

BarChart

OWNED

listeners: List<Listener>

…

Main

DOCUMENT

VIEW

pieChart: PieChart

barChart:BarChart

model:Model List<Listener>

OWNED

head

ELTS

obj: Listener

M

Is-Aobj: Type

Object

Type Type

F

A

Formal Domain

Actual Domain


49

…

ObjectGraph: instantiate types, starting with root

BarChart

OWNED


…

Main

DOCUMENT

VIEW

pieChart: PieChart

barChart:BarChart


OWNED

head

ELTS

obj: Listener

M

Is-Aobj: Type

Object

Type Type

F

A

Formal Domain

Actual Domain


50

…

ObjectGraph: instantiate types, starting with root

BarChart

OWNED


…

main: Main

DOCUMENT

VIEW

pieChart: PieChart

barChart:BarChart


OWNED

head

ELTS

obj: Listener

M

Is-Aobj: Type

Object

Type Type

F

A

Formal Domain

Actual Domain


51

BarChart

OWNED


…

ObjectGraph: instantiate types, show domains and objects inside domains

…

main: Main

DOCUMENT

VIEW

pieChart: PieChart

barChart:BarChart


OWNED

head

ELTS

obj: Listener

M

Is-Aobj: Type

Object

Type Type

F

A

Formal Domain

Actual Domain


52

…


…

main: Main

DOCUMENT

VIEW

pieChart: PieChart

barChart:BarChart


OWNED

head

ELTS

obj: Listener

BarChart

OWNED


M

Is-Aobj: Type

Object

Type Type

F

A

Formal Domain

Actual Domain


53

main: Main

VIEW

pieChart: PieChart…


barChart: BarChart

OWNED


List<Listener>

OWNED

head

ELTS

obj: Listener

MIs-A

obj: Type

Object

Type Type

F

A

Formal Domain

Actual Domain

DOCUMENT

model: Model…


54

main: Main

VIEW



barChart: BarChart

OWNED


List<Listener>

OWNED

head

ELTS

obj: Listener

MIs-A

obj: Type

Object

Type Type

F

A

Formal Domain

Actual Domain

DOCUMENT

model: Model…


55

main: Main

VIEW



barChart: BarChart

OWNED


List<Listener>

OWNED

head

ELTS

obj: Listener

MIs-A

obj: Type

Object

Type Type

F

A

Formal Domain

Actual Domain

DOCUMENT

model: Model…


56

main: Main

VIEW


DOCUMENT


model: Model…

barChart: BarChart

OWNED

M


OWNED

head

ELTS

obj: Listener obj:

TypeObject

F

A

Formal Domain

Actual Domain


57

main: Main

VIEW


DOCUMENT

ObjectGraph: pull objects from formal domains to actual domains

model: Model…

barChart: BarChart

OWNED

M


OWNED

head

ELTS

obj: Listener obj:

TypeObject

F

A

Formal Domain

Actual Domain


58

main: Main

VIEW


DOCUMENT


model: Model…

barChart: BarChart

OWNED

M


OWNED

head

ELTS

obj: Listener obj:

TypeObject

F

A

Formal Domain

Actual Domain

obj: Listener


59

main: Main

VIEW


DOCUMENT


model: Model…

barChart: BarChart

OWNED

M


OWNED

head

ELTS

obj: Listener obj:

TypeObject

F

A

Formal Domain

Actual Domain

obj: Listener

obj: Listener


60

main: Main

VIEW


DOCUMENT

ObjectGraph: merge objects, in one domain, that may alias, based on types

{model: Model, obj:Listener}…

barChart: BarChart

OWNED

M


OWNED

head

ELTS

obj: Listener obj:

TypeObject

F

A

Formal Domain

Actual Domain

obj: Listener

class Model implements Listener {…}


61

main: Main

VIEW


DOCUMENT

ObjectGraph: add edges to represent field references

{model: Model, obj:Listener}…

barChart: BarChart

OWNED

M


OWNED

head

ELTS

obj: Listener obj:

TypeObject

F

A

Formal Domain

Actual Domain

obj: Listener


62

Conclusion

• Ownership domain annotationsenable extraction of hierarchicalruntime object graphs using static analysis

• Provide architectural abstraction by ownership hierarchy and by types

Static Extraction of Hierarchical Runtime Object Graphs...

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