How To Write A Program In Ptolemy

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1 A Preliminary Study of Quantified, Typed Events Robert Dyer 1, Mehdi Bagherzadeh 1, Hridesh Rajan 1 and Yuanfang Cai 2 1 Iowa State University 2 Drexel University {rdyer,mbagherz,hridesh}@cs.iastate.edu yfcai@cs.drexel.edu March 16, 2010

2 Ptolemy: What, Why? Background An Example in AspectJ An Example in Ptolemy Ptolemy 1 adds quantified, typed events to OO languages 1 Well-defined interfaces between base & crosscutting code 2 Separate type-checking, modular reasoning Combines aspect-oriented (AO) and implicit invocation (II) Solves problems with AO and II: AO: quantification failure, fragile pointcuts, limited context information II: coupling of observers, no replacement of event code, no quantification 1 Rajan and Leavens - ECOOP 08 Dyer, Bagherzadeh, Rajan and Cai 2 Preliminary Study of Quantified, Typed Events

3 Background An Example in AspectJ An Example in Ptolemy This Paper: Why, How, and What? Motivation: Why use Quantified, Typed Events 2? Approach: MobileMedia case study 3 : Change impact and Design value analysis Software engineering metrics: makes implicit coupling in AO explicit and decreases change impact NOV analysis: Ptolemy needs ITDs (so we added it) 2 Rajan and Leavens - ECOOP 08 3 Figueiredo et al - ICSE 08 Dyer, Bagherzadeh, Rajan and Cai 3 Preliminary Study of Quantified, Typed Events

4 Running Example : Figure Editor Background An Example in AspectJ An Example in Ptolemy Elements of drawing Points, Lines, etc All such elements are of type FElement Challenge: Modularize display update policy Whenever an element of drawing changes Update the display Dyer, Bagherzadeh, Rajan and Cai 4 Preliminary Study of Quantified, Typed Events

5 Point and its two Events Background An Example in AspectJ An Example in Ptolemy class Point implements FElement { int x; int y; void setx(int x) { this.x = x; }.. void makeequal(point other) { if(!other.equals(this)) { other.x = this.x; other.y = this.y; }}} Changing FElement is different for two cases. Actual abstract event inside makeequal is the true branch. Dyer, Bagherzadeh, Rajan and Cai 5 Preliminary Study of Quantified, Typed Events

6 Background An Example in AspectJ An Example in Ptolemy Aspect Modularizing Display Updating aspect Update { around(felement fe) : execution(point.set*(..)) && this(fe) (execution(point.make*(..)) && args(fe) if(!fe.equals(this(fe)))) { proceed(fe); Display.update(); }} Enumeration required of two different joinpoints. Had to use if pointcut to get to the real event. Alternative is to refactor makeequal (refactoring doesn t always creates meaningful abstractions). Dyer, Bagherzadeh, Rajan and Cai 6 Preliminary Study of Quantified, Typed Events

7 Ptolemy: Declaring Event Types Background An Example in AspectJ An Example in Ptolemy void event FEChanged { FElement changedfe; } Event type is an abstraction (design this first). Declares context available at the concrete events. Interface, so allows design by contract (DBC) methodology. Dyer, Bagherzadeh, Rajan and Cai 7 Preliminary Study of Quantified, Typed Events

8 Ptolemy: Announcing Events Background An Example in AspectJ An Example in Ptolemy class Point implements FElement { int x; int y; void setx(int x) { announce FEChanged(this) { this.x = x; }} void makeequal(point other) { if(!other.equals(this)) { announce FEChanged(other) { other.x = this.x; other.y = this.y; }}}} Explicit, declarative, typed event announcement. Provides flexibility, e.g. see makeequal. Dyer, Bagherzadeh, Rajan and Cai 8 Preliminary Study of Quantified, Typed Events

9 Ptolemy: Binding to Events Background An Example in AspectJ An Example in Ptolemy class Update { when FEChanged do update; void update (FEChanged next) { invoke(next); //Like AspectJ proceed Display.update(); } public Update() { register(this); //Allows dynamic deployment }} Dyer, Bagherzadeh, Rajan and Cai 9 Preliminary Study of Quantified, Typed Events

10 Research Questions Motivation Background An Example in AspectJ An Example in Ptolemy How do these two designs compare? When do we see benefits of AO? When do we see benefits of Ptolemy? Dyer, Bagherzadeh, Rajan and Cai 10 Preliminary Study of Quantified, Typed Events

11 Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events Observed Benefits of Aspect-oriented Designs Static crosscutting features are very useful Inter-type declarations (ITDs) Declare Parents Softened Exceptions Dyer, Bagherzadeh, Rajan and Cai 11 Preliminary Study of Quantified, Typed Events

12 Inter-type declarations (ITDs) Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events Had to be emulated in Ptolemy 4 AspectJ: public T C.field; Ptolemy emulation strategy: static Hashtable fieldmap; public static T getfield(c); public static void setfield(c, T); 4 Ptolemy now supports AspectJ-style ITDs Dyer, Bagherzadeh, Rajan and Cai 12 Preliminary Study of Quantified, Typed Events

13 Declare Parents Motivation Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events Affects the type hierarchy Only used in revision 8 Effects modeled similar to ITDs Dyer, Bagherzadeh, Rajan and Cai 13 Preliminary Study of Quantified, Typed Events

14 Softened Exceptions Motivation Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events Aspects handle certain exceptions Softened exceptions don t need declared thrown in the base code Con: Ptolemy version still must declare those exceptions are thrown Pro: Ptolemy s exception handling code is (un)pluggable Dyer, Bagherzadeh, Rajan and Cai 14 Preliminary Study of Quantified, Typed Events

15 Softened Exceptions Motivation Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events AspectJ version: declare soft: RecordStoreEx : execution(public void ImageAccessor.addImageData(..)); public void addimagedata(..) throws InvalidImageDataEx, PersistenceMechanismEx { Without the aspect, the base code won t compile! Dyer, Bagherzadeh, Rajan and Cai 15 Preliminary Study of Quantified, Typed Events

16 Softened Exceptions Motivation Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events Ptolemy version: public void addimagedata(..) throws InvalidImageDataEx, PersistenceMechanismEx, RecordStoreEx { Even though RecordStoreEx isn t thrown by the body, it still must be declared! Dyer, Bagherzadeh, Rajan and Cai 16 Preliminary Study of Quantified, Typed Events

17 Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events Observed Benefits of Quantified, Typed Events No Quantification Failure No Fragile Pointcuts Can easily advise other advice (due to symmetry) Dyer, Bagherzadeh, Rajan and Cai 17 Preliminary Study of Quantified, Typed Events

18 Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events Solves Quantification Failure Problem In revision 2, the AspectJ version had to expose a while loop (by refactoring of course) Similar problems in other revisions Ptolemy versions did not need to refactor those points to expose to the aspects Dyer, Bagherzadeh, Rajan and Cai 18 Preliminary Study of Quantified, Typed Events

19 Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events Example of Quantification Failure in AO OO version:.. while (is.read(b)) {.. }.. AspectJ version:.. internalreadimage(..);.. private void internalreadimage(..) { while (is.read(b)) {.. } } Dyer, Bagherzadeh, Rajan and Cai 19 Preliminary Study of Quantified, Typed Events

20 No Quantification Failure Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events OO version:.. while (is.read(b)) {.. }.. Ptolemy version:.. announce ReadInternalImageAsByteArrayEvent() { while (is.read(b)) {.. } }.. Dyer, Bagherzadeh, Rajan and Cai 20 Preliminary Study of Quantified, Typed Events

21 No Fragile Pointcuts Motivation Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events Aspects implicitly match the base code Quantified, typed events make this coupling explicit Changes to the base code (e.g., renaming a method) can propogate to the aspects AspectJ: execution(* DeletePhoto(..)) Ptolemy: when DeletePhotoEvent do Handler What if DeletePhoto is renamed to RemovePhoto? Dyer, Bagherzadeh, Rajan and Cai 21 Preliminary Study of Quantified, Typed Events

22 Can easily advise other advice Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events AspectJ allows you to advise all advice, not specific advice bodies Exception handling modularity was not maintained in later revisions for AspectJ versions Ex: revision 8, aspect lancs.midp.mobilephoto.alternative.music.musicaspect Dyer, Bagherzadeh, Rajan and Cai 22 Preliminary Study of Quantified, Typed Events

23 Benefits of Aspect-oriented Designs Benefits of Quantified, Typed Events after() : addnewmediatoalbum() { try { /* advice body */ } catch (InvalidImageDataException e) {.. } } public void handler(addmediatoalbumevent next){ announce AddNewMediaToAlbumHandlerEvent() { /* advice body */ } } Dyer, Bagherzadeh, Rajan and Cai 23 Preliminary Study of Quantified, Typed Events

24 Software Engineering Metrics Net Options Value Analysis Overview of Change Impact AO vs. Ptolemy Ptolemy design limited change propagation Only had to change 13 event types in revision 7 AO revisions required changing 50 pointcuts in revision 7 No other Ptolemy revision required changing event types 28 pointcuts changed across 4 other AO revisions Dyer, Bagherzadeh, Rajan and Cai 24 Preliminary Study of Quantified, Typed Events

25 Software Engineering Metrics Net Options Value Analysis Net Options Value Analysis AO vs. Ptolemy 5 4 OO AO PTL R1 R2 R3 R4 R5 R6 R7 R8 Dyer, Bagherzadeh, Rajan and Cai 25 Preliminary Study of Quantified, Typed Events

26 Software Engineering Metrics Net Options Value Analysis Net Options Value Analysis AO vs. Ptolemy 5 4 OO AO PTL R1 R2 R3 R4 R5 R6 R7 R8 Ptolemy: higher NOV values for R2-R6 AO: higher value in R6 (Ptolemy doesn t have ITDs) Revisions adding ITDs: R3-R8 Dyer, Bagherzadeh, Rajan and Cai 26 Preliminary Study of Quantified, Typed Events

27 of Study and Future Work Explicit Coupling increases from OO AO Ptolemy Despite more coupling in Ptolemy, lower change impact Net options value increases from OO AO Ptolemy Future Work: Repeat the study with Ptolemy + ITDs Compare to other AO interface features Dyer, Bagherzadeh, Rajan and Cai 27 Preliminary Study of Quantified, Typed Events

28 Questions? ptolemy/ Dyer, Bagherzadeh, Rajan and Cai 28 Preliminary Study of Quantified, Typed Events

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30 Mobile Media Metrics Tables Citations Releases Table Release Description Type of Change R1 MobilePhoto core R2 Exception handling included Non-functional concern R3 Added photo sorting Optional feature Added editing photo labels Mandatory feature R4 Added favorites Optional feature R5 Allow users to keep multiple copies of photos Optional feature R6 Added send photo to other users by SMS Optional feature R7 Photo management made into two alternatives: photo or music One mandatory feature into two alternatives R8 Add video management Alternative feature Dyer, Bagherzadeh, Rajan and Cai 30 Preliminary Study of Quantified, Typed Events

31 Mobile Media Metrics Tables Citations Change Propagation Coupling and Cohesion Size Metrics Components PCs Event Types R2 R3 R4 R5 R6 R7 R8 OO Added AO PTL OO Removed AO PTL OO Changed AO PTL Added AO Removed AO Changed AO Added PTL Removed PTL Changed PTL Dyer, Bagherzadeh, Rajan and Cai 31 Preliminary Study of Quantified, Typed Events

32 Mobile Media Metrics Tables Citations Change Propagation Coupling and Cohesion Size Metrics LCOO CBC Average Max Average Max R2 R3 R4 R5 R6 R7 R8 OO AO PTL OO AO PTL OO AO PTL OO AO PTL Dyer, Bagherzadeh, Rajan and Cai 32 Preliminary Study of Quantified, Typed Events

33 Mobile Media Metrics Tables Citations Change Propagation Coupling and Cohesion Size Metrics NOO NOA NOC LOC R2 R3 R4 R5 R6 R7 R8 OO AO PTL OO AO PTL OO AO PTL OO AO PTL Dyer, Bagherzadeh, Rajan and Cai 33 Preliminary Study of Quantified, Typed Events

34 Mobile Media Metrics Tables Citations 1 Eduardo Figueiredo, Nelio Cacho, Claudio Sant Anna, Mario Monteiro, Uira Kulesza, Alessandro Garcia, Sergio Soares, Fabiano Ferrari, Safoora Khan, Fernando Castor Filho and Francisco Dantas. Evolving software product lines with aspects: an empirical study on design stability. In ICSE Hridesh Rajan and Gary T. Leavens. Ptolemy: a language with quantified, typed events. In ECOOP Kevin J. Sullivan, William G. Griswold, Yuanfang Cai, and Ben Hallen. The structure and value of modularity in software design. In ESEC/FSE 01. Dyer, Bagherzadeh, Rajan and Cai 34 Preliminary Study of Quantified, Typed Events