An Exploratory Study of the Design Impact of Language Features for Aspect-oriented Interfaces

Transcription

1 An Exploratory Study of the Design Impact of Language Features for Aspect-oriented Interfaces Robert Dyer Hridesh Rajan Yuanfang Cai Iowa State University Drexel University This work was supported in part by NSF grant CCF

2 Motivation: What issues affect AO interfaces? Approach: Case study... AO Interfaces: pattern-based pointcuts (PCD), annotation-based pointcuts open modules (OM), and event types (EVT) Systems: MobileMedia (MM) and Health Watcher (HW) Measure: SE metrics (coupling, cohesion, size) and change propagation analysis Interesting Results Quantification problems - all interfaces Fragile pointcuts - only PCD Non-uniform context access - all but EVT Robert Dyer, Hridesh Rajan and Yuanfang Cai 1 Exploratory Study of Language Features for AO Interfaces

3 Aspect-Oriented Interfaces Who controls quantification? Aspects Base code Intermediary Robert Dyer, Hridesh Rajan and Yuanfang Cai 2 Exploratory Study of Language Features for AO Interfaces

4 Aspect-Oriented Interfaces Who controls quantification? Aspects AspectJ Hyper/J Eos CaesarJ Base code Aspect-aware Interfaces Open Modules Intermediary AspectJ with Annotations IIIA XPIs Ptolemy Robert Dyer, Hridesh Rajan and Yuanfang Cai 2 Exploratory Study of Language Features for AO Interfaces

5 Aspect-Oriented Interfaces Who controls quantification? Aspects AspectJ Hyper/J Eos CaesarJ Base code Aspect-aware Interfaces Open Modules Intermediary AspectJ with Annotations IIIA XPIs Ptolemy Robert Dyer, Hridesh Rajan and Yuanfang Cai 2 Exploratory Study of Language Features for AO Interfaces

6 Running Example class FileScreen - Display display Aspect-Oriented Interfaces + void save() Robert Dyer, Hridesh Rajan and Yuanfang Cai 3 Exploratory Study of Language Features for AO Interfaces

7 Pattern-based pointcuts (PCD) Aspect-Oriented Interfaces class FileScreen - Display display + void save() aspect ExceptionHandler around(scr): execution(* FileScreen.save()) && this(scr); try { proceed (); } catch (FileNotFoundException e) { scr.display.showfileerror (e); } Robert Dyer, Hridesh Rajan and Yuanfang Cai 4 Exploratory Study of Language Features for AO Interfaces

8 Open Modules (OM) Aspect-Oriented Interfaces class FileScreen - Display display + void save() aspect ExceptionHandler around(scr): execution(* FileScreen.save()) && this(scr); expose : execution(* save()); try { proceed (); } catch (FileNotFoundException e) { scr.display.showfileerror (e); } Robert Dyer, Hridesh Rajan and Yuanfang Cai 5 Exploratory Study of Language Features for AO Interfaces

9 Aspect-Oriented Interfaces Annotation-based pointcuts class FileScreen - Display display void save() aspect ExceptionHandler around(scr): execution(@filesaveevent * *()) && try { proceed (); } catch (FileNotFoundException e) { scr.display.showfileerror (e); } Robert Dyer, Hridesh Rajan and Yuanfang Cai 6 Exploratory Study of Language Features for AO Interfaces

10 Quantified, Typed Events (EVT) Aspect-Oriented Interfaces class FileScreen - Display display class ExceptionHandler + void m(filesaveevent next) + void save() when FileSaveEvent do m; announce FileSaveEvent(display) {.. } event FileSaveEvent + Display display try { next.invoke(); } catch (FileNotFoundException e) { next.display().showfileerror (e); } Robert Dyer, Hridesh Rajan and Yuanfang Cai 7 Exploratory Study of Language Features for AO Interfaces

11 Aspect-Oriented Interfaces Pattern-based pointcuts (PCD) execution (* save()) Annotation-based pointcuts execution * *()) Open Modules (OM) expose: execution(* save()) Quantified, Typed Events (EVT) when FileSaveEvent do handler; Robert Dyer, Hridesh Rajan and Yuanfang Cai 8 Exploratory Study of Language Features for AO Interfaces

12 Aspect-Oriented Interfaces How do these AO interfaces compare to each other? What problems occur, and for which interface(s)? Need: explore via case studies! Robert Dyer, Hridesh Rajan and Yuanfang Cai 9 Exploratory Study of Language Features for AO Interfaces

13 Earlier Studies Experimental Setup Key Results Kiczales and Mezini [ECOOP 2005] Studied 7 AO interfaces Only compared with a very simple example Figueiredo et al [ICSE 2008] Studied MobileMedia, OO vs PCD Hoffman and Eugster [ICSE 2008] Exception handling with AO Studied only 2 AO interfaces Only 1 type of crosscutting behavior Robert Dyer, Hridesh Rajan and Yuanfang Cai 10 Exploratory Study of Language Features for AO Interfaces

14 Our Study Experimental Setup Key Results MobileMedia [FIGUEIREDO 2008] Software to manipulate photos, music, video on mobile devices Health Watcher [SOARES 2002] [KULESZA 2006] Web application for users to file health complaints OO OM EVT MM Existing Existing New 1 New 2 New HW Existing Existing New 1 New 2 New Total size of study: 400k LOC 1 Based on recommendations of Kiczales and Mezini, ECOOP Based on recommendations of Ongkingco et al., AOSD 2006 Robert Dyer, Hridesh Rajan and Yuanfang Cai 11 Exploratory Study of Language Features for AO Interfaces

15 Software Engineering Metrics Experimental Setup Key Results Coupling method call or field access naming an event type naming an annotation Cohesion Number of: lines, components, attributes, and operations Robert Dyer, Hridesh Rajan and Yuanfang Cai 12 Exploratory Study of Language Features for AO Interfaces

16 Change Propagation Experimental Setup Key Results Detects: Adds, Removes, and Changes in Classes, Aspects, Pointcuts, Event Types, and Annotations Robert Dyer, Hridesh Rajan and Yuanfang Cai 13 Exploratory Study of Language Features for AO Interfaces

17 Experimental Setup Key Results What were some interesting results? OM EVT Quantificaton Failure???? Less Expressive Quantificaton???? Fragile Pointcuts???? Non-uniform Context???? Robert Dyer, Hridesh Rajan and Yuanfang Cai 14 Exploratory Study of Language Features for AO Interfaces

18 Quantification Failure Experimental Setup Key Results What if we want to advise the for loop? void m() {.. for ( int i = 0..) {.. }.. } Not possible in or OM. Must extract as method. Robert Dyer, Hridesh Rajan and Yuanfang Cai 15 Exploratory Study of Language Features for AO Interfaces

19 Quantification Failure Experimental Setup Key Results OM EVT Quantificaton Failure yes yes yes no Less Expressive Quantificaton???? Fragile Pointcuts???? Non-uniform Context???? In MobileMedia, 5% of advised points Robert Dyer, Hridesh Rajan and Yuanfang Cai 16 Exploratory Study of Language Features for AO Interfaces

20 Less Expressive Quantification Experimental Setup Key Results private interface SynchronizedClasses {}; declare parents : ComplaintRepositoryArray implements SynchronizedClasses ; Object around ( Object o): this (o) && execution (* SynchronizedClasses +.*(..) ) { synchronized (o) { return proceed (o); } } What if a method is added to ComplaintRepositoryArray? Robert Dyer, Hridesh Rajan and Yuanfang Cai 17 Exploratory Study of Language Features for AO Interfaces

21 Less Expressive Quantification Experimental Setup Key Results OM EVT Quantificaton Failure yes yes yes no Less Expressive Quantificaton no no no yes Fragile Pointcuts???? Non-uniform Context???? and OM releases automatically advise new methods and sub-types EVT releases must manually maintain this design rule Robert Dyer, Hridesh Rajan and Yuanfang Cai 18 Exploratory Study of Language Features for AO Interfaces

22 Fragile Pointcuts Experimental Setup Key Results aspect ExceptionHandler { after (): execution (* FileScreen. save (..) ).. } class FileScreen { void save () {.. } } What if we rename the method? void export () {.. } Robert Dyer, Hridesh Rajan and Yuanfang Cai 19 Exploratory Study of Language Features for AO Interfaces

23 Fragile Pointcuts Experimental Setup Key Results OM EVT Quantificaton Failure yes yes yes no Less Expressive Quantificaton no no no yes Fragile Pointcuts yes no no no Non-uniform Context???? Only PCD releases OM, and EVT releases throw compiler errors if the interface changes Observed in 3 releases of MobileMedia 18% of all pointcut changes in MM were fragile Robert Dyer, Hridesh Rajan and Yuanfang Cai 20 Exploratory Study of Language Features for AO Interfaces

24 Non-uniform Context Experimental Setup Key Results class FileScreen { Display display ; void save () {.. } } aspect ExceptionHandler { around ( FileScreen scr ): execution (* FileScreen. save ()) && this ( scr ) { try { proceed (); } catch ( FileNotFoundException e) { scr. display. showfileerror (e); } } } Pointcut can t directly access the display. Robert Dyer, Hridesh Rajan and Yuanfang Cai 21 Exploratory Study of Language Features for AO Interfaces

25 Non-uniform Context Experimental Setup Key Results OM EVT Quantificaton Failure yes yes yes no Less Expressive Quantificaton no no no yes Fragile Pointcuts yes no no no Non-uniform Context yes yes yes no Problem occurred frequently in MobileMedia Required making fields public, adding public getters, or marking aspect privileged (which breaks encapsulation) Aspects become coupled to the advised class Robert Dyer, Hridesh Rajan and Yuanfang Cai 22 Exploratory Study of Language Features for AO Interfaces

26 Results Experimental Setup Key Results OM EVT Quantificaton Failure yes yes yes no Less Expresive Quantificaton no no no yes Fragile Pointcuts yes no no no Non-uniform Context yes yes yes no All interfaces had problems with quantification Only PCD had fragile pointcuts Only EVT had uniform context access Robert Dyer, Hridesh Rajan and Yuanfang Cai 23 Exploratory Study of Language Features for AO Interfaces

27 Future Work Can we quantify the value of each design? Net-Options Value (NOV) analysis [BALDWIN 2000] 3 [SULLIVAN 2001] 4 Additional case study candidates Additional AO interfaces 3 Baldwin and Clark, Design Rules, Vol 1, Sullivan et al., The Structure and Value of Modularity in Software Design, ESEC/FSE 01 Robert Dyer, Hridesh Rajan and Yuanfang Cai 24 Exploratory Study of Language Features for AO Interfaces

28 Motivation: What issues affect AO interfaces? Approach: Case study... AO Interfaces: pattern-based pointcuts (PCD), annotation-based pointcuts open modules (OM), and event types (EVT) Interesting Results OM EVT Quantificaton Failure yes yes yes no Less Expresive Quantificaton no no no yes Fragile Pointcuts yes no no no Non-uniform Context yes yes yes no Robert Dyer, Hridesh Rajan and Yuanfang Cai 25 Exploratory Study of Language Features for AO Interfaces

29 Questions?

30

31 Inter-type Declarations Other Results Raw Data Add fields or methods to existing types or change the type hierarchy. aspect A { int C.f = 5; void C.m() {.. } declare parents : C implements Serializable ; } Available for OM, and EVT. Robert Dyer, Hridesh Rajan and Yuanfang Cai 26 Exploratory Study of Language Features for AO Interfaces

32 Inter-type Declarations Other Results Raw Data Extremely useful feature for AO languages MobileMedia R8 has ITDs in 50% of aspects Health Watcher uses declare parents in 25% of aspects Robert Dyer, Hridesh Rajan and Yuanfang Cai 27 Exploratory Study of Language Features for AO Interfaces

33 Other Results Raw Data MobileMedia - SE Metrics MobileMedia - Change Propagation Health Watcher - SE Metrics Health Watcher - Change Propagation CBC LCOO R2 R3 R4 R5 R6 R7 R8 OO OM PCD EVT OO OM PCD EVT Robert Dyer, Hridesh Rajan and Yuanfang Cai 28 Exploratory Study of Language Features for AO Interfaces

34 Other Results Raw Data MobileMedia - SE Metrics MobileMedia - Change Propagation Health Watcher - SE Metrics Health Watcher - Change Propagation NOO NOA NOC LOC R2 R3 R4 R5 R6 R7 R8 OO OM PCD EVT OO OM PCD EVT OO OM PCD EVT OO OM PCD EVT Robert Dyer, Hridesh Rajan and Yuanfang Cai 29 Exploratory Study of Language Features for AO Interfaces

35 Other Results Raw Data MobileMedia - SE Metrics MobileMedia - Change Propagation Health Watcher - SE Metrics Health Watcher - Change Propagation Components Added Removed R2 R3 R4 R5 R6 R7 R8 Total OO OM PCD EVT Differences to PCD marked in BOLD blue OO OM PCD EVT Changed OO OM PCD EVT Robert Dyer, Hridesh Rajan and Yuanfang Cai 30 Exploratory Study of Language Features for AO Interfaces

36 Other Results Raw Data MobileMedia - SE Metrics MobileMedia - Change Propagation Health Watcher - SE Metrics Health Watcher - Change Propagation Pointcuts R2 R3 R4 R5 R6 R7 R8 Total OM PCD Differences to PCD marked in BOLD blue OM PCD Add Remove Change OM PCD Events/Anns R2 R3 R4 R5 R6 R7 R EVT Differences to EVT marked in BOLD EVT Add Rem EVT Robert Dyer, Hridesh Rajan and Yuanfang Cai 31 Exploratory Study of Language Features for AO Interfaces

37 Other Results Raw Data MobileMedia - SE Metrics MobileMedia - Change Propagation Health Watcher - SE Metrics Health Watcher - Change Propagation CBC LCOO R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 OO OM PCD EVT OO OM PCD EVT Robert Dyer, Hridesh Rajan and Yuanfang Cai 32 Exploratory Study of Language Features for AO Interfaces

38 NOO NOA NOC LOC Other Results Raw Data MobileMedia - SE Metrics MobileMedia - Change Propagation Health Watcher - SE Metrics Health Watcher - Change Propagation R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 OO OM PCD EVT OO OM PCD EVT OO OM PCD EVT OO OM PCD EVT Robert Dyer, Hridesh Rajan and Yuanfang Cai 33 Exploratory Study of Language Features for AO Interfaces

39 Other Results Raw Data MobileMedia - SE Metrics MobileMedia - Change Propagation Health Watcher - SE Metrics Health Watcher - Change Propagation Components Added Removed R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 Total OO OM PCD EVT Differences to PCD marked in BOLD blue OO OM PCD EVT Changed OO OM PCD EVT Robert Dyer, Hridesh Rajan and Yuanfang Cai 34 Exploratory Study of Language Features for AO Interfaces

40 Other Results Raw Data MobileMedia - SE Metrics MobileMedia - Change Propagation Health Watcher - SE Metrics Health Watcher - Change Propagation Pointcuts R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 Total OM PCD Differences to PCD marked in BOLD blue OM PCD Add Remove Change OM PCD Events/Anns R1 R2 R3 R4 R5 R6 R7 R8 R9 R EVT Differences to EVT marked in BOLD EVT Add Rem EVT Robert Dyer, Hridesh Rajan and Yuanfang Cai 35 Exploratory Study of Language Features for AO Interfaces