1 Software Reuse in Eclipse Kellie-Ann Smith Norgye Yuanyuan Song Xiang Yin Jia Xu

2 Outline Motivation Software Reuse Eclipse Plug-in Architecture A Case Study Demo Conclusion Discussion

3 Motivation Reuse is important in current software development Eclipse provides an open architecture for IDE development [Gamma & Beck 2003] Is the reuse model of Eclipse different from previous models?

4 Reuse Snapshot Software reuse is using existing software artifacts to create a new software system [Freeman 1983]  Source code fragments  Module-level implementation  Design structures  Specification  Test suite  Documentation  etc. Reuse failed to become a standard software engineering practice [Kruger 1992] Reuse can reduce complexity of software [Brooks]

5 Basic Issues in Reuse Model Abstraction  how to describe the essential characteristic of a reusable software artifacts Selection  how to locate, compare and select reusable software artifacts Specialization  how to specialize a generalized software artifact Integration  how to combine a collection of selected and specialized artifacts into a complete software system [Kruger 1992]

6 How to Evaluate a Reuse Model Ease of Use Cost-Effectiveness [Frakes & Terry 1992] Scalability Reliability Evolvability

7 Eclipse Plug-in Introduction – Plug-in Model Plug-in: a component that provides service within the context of the Eclipse workbench.  Manifest file  Jar files and other resources  Plug-in runtime class  Plug-ins are activated only as needed Eclipse runtime: plug-in management kernel. All functionality of the platform is provided by plug-ins

8 Eclipse Plug-in Introduction -- Extension Relationship among plug-ins  Dependency  Extension Host plug-in provides the extension point Extender plug-in defines the extension Host often “calls” extender when specified events are recognized

9 Extension

10 A Case Study: A Compare/Merge Tool --- Requirements Functions  Comparison and merge of files/folders from the whole file system  2-way and 3-way  Filters  Select-Merge & Auto merge  … GUI  Multiple compare/merge windows, Tree structure view, Difference highlighting, Navigation, Dialog interface  …

11 What can we reuse in Eclipse – Compare Plug-In Supports:  structural and textual compare operations  displaying results of comparison Extension Points:  Structure Creators  Structure Merge Viewers  Content Merge Viewers  Content Viewers

12 How the Compare Plug-In works General Idea of How It Works:  Choose Files/folders in the workspace and start the compare operation  Differencing engine finds the differences between the selected resources  Differences returned and presented in the Viewer(s)  Specific structures, differencers and viewers can be registered as extensions

13 What’s missing per our requirements Open files in the file system to compare Compare/Merge dialog A side-by-side structure merge view Filters, Line numbers, …

14 Improvement #1 New Structure Merge Viewer  Goal: Enhance GUI to support side-by-side structure merge view  Proposed Approach: write a new viewer for the extension point “ Structure Merger Viewer”.  Experience: It is very hard to just “plug” a new GUI while keep all other things untouched.  Implementation: see demo.

15 Improvement #2 Open external files & compare/merge dialog  Goal: provide a new entry point, support external file Compare/Merge.  Approach: utilize ActionSet extension point to develop menu item and toolbar item. Using a new dialog as entry interface Import external files into eclipse workspace in the form of link files.  Implementation see demo.

16 Conclusion --- Issues in Eclipse Plug-in Reuse Model Abstraction  the name of a plug-in Selection  No systematic way like WDSL for web service Specialization  extendable plug-ins Integration  eclipse run-time

17 Discussion Ease of Use  Extension is good for new features under Eclipse framework  Lack of selection mechanism Cost-Effectiveness  Not well-organized documentation, much time on learning Scalability  Lack of plug-in resources and selection mechanism Reliability  The HelloWorld example doesn’t even work at every time Evolvability Other issues  Ease of debugging? Separation of view and model is good/bad?

18 Reference Brooks, F. “No silver bullet”, “No silver bullet refired” Frakes, W., Terry, C., Software reuse: metrics and models, ACM Computing Surveys, Volume 28 Issue 2 June 1996 Freeman, P. “Reusable software engineering: Concepts and Research directions”, 1983 Gamma., Erich, Beck., Kent, Contributing to Eclipse, 2003 Krueger, Charles W. “Software reuse”, ACM Computing Surveys, Volume 24, Issue 2 (June 1992)