This paper presents the eDOBS tool. eDOBS is the little brother of the Fujaba environment. While Fujaba is used to create graph grammar based specifications and programs, eDOBS is used to browse graphs, to edit graphs, and to execute graph transformations

Geiger, Leif

Zündorf, Albert

English

Electronic Communications of the EASST (European Association of Software Science and Technology)

Electronic Communications of the EASSTVolume 1 (2006)Proceedings of theThird International Workshop on Graph Based Tools(GraBaTs 2006)eDOBS - Graphical Debugging for EclipseLeif Geiger and Albert Z̈undorf4 pagesGuest Editors: Albert Zündorf, Daniel VarróManaging Editors: Tiziana Margaria, Julia Padberg, Gabriele TaentzerECEASST Home Page: http://www.easst.org/eceasst/ ISSN 1863-2122ECEASSTeDOBS - Graphical Debugging for EclipseLeif Geiger 1 and Albert Z ündorf 11 University of Kassel,Software Engineering Research Group,Wilhelmsḧoher Allee 73, 34121 Kassel, Germanyleif.geiger@uni-kassel.dealbert.zuendorf@uni-kassel.dehttp://www.se.eecs.uni-kassel.de/se/Abstract: This paper presents the eDOBS tool. eDOBS is the little brother of theFujaba environment. While Fujaba is used to create graph grammar based specifica-tions and programs, eDOBS is used to browse graphs, to edit graphs, and to executegraph transformations.Keywords: graph browser, graph editor, graph grammar execution1 IntroductionA graph based environment usually provides a component to visualize the current host graph andto allow the application of rewrite rules. In the Fujaba Tool Suite this functionality is provided bythe Dynamic Object Browser, Dobs. Fujaba is a CASE tool which uses UML class diagrams forthe specification of graph schemata and so called story diagrams to model graph transformations.Note that Fujaba generates conventional Java source code from those graph rewrite rules and weemploy a usual Java compiler and runtime environment to execute this code. Accordingly thecode for graph rewrite rules works on usual Java heap objects and Java references between suchobjects. So, the object browser Dobs also works on usual Java heap objects. Since Fujaba iscurrently being ported to Eclipse [FE04], we also ported Dobs. The new tool is called eDOBS1.The tight integration into Eclipse makes eDOBS even more helpful for the developer. This willbe shown in the following chapters.2 eDOBS - The graph BrowsereDOBS is an Eclipse plugin, which visualizes the current heap of a Java program at runtime asa UML object diagram. eDOBS may typically be used within a debugging session. Instead ofthe variable view, the eDOBS panel may show the content of variables and how the referencedobjects are related to each other. If e.g. the developer is just debugging his application and hashit a breakpoint in classShuttle as shown in the editor (1) in figure1, he is now able to call the”Browse in eDOBS” command on all variables known by the debugging environment. This canbe done directly in the source code, in the Variables view (2) or in one of the other views providedby the Eclipse debug plugin. After triggering this command, the content of the selected variablewill be displayed as object in the eDOBS diagram view (3). In the example the developer has1 The eDOBS project was founded by an IBM Eclipse innovation grant in 2005.1 / 4 Volume 1 (2006)eDOBSchoosen the local variablethis to be displayed in eDOBS from the Variables view. The localvariable is then shown as the object labeleds0 in the eDOBS diagram. Note that to facilitaterecognition, eDOBS may be configured to use certain icons for certain kinds of objects, as wasdone in figure1. If the developer selects the so displayed object, all attributes of this object willbe displayed in the eDOBS attribute view (4) and all methods in the method view (5). In figure1 the objectr5 has been selected and its attributes and methods are shown.At any time, the depicted object structure may be extended by including neighbors of alreadyshown objects. This allows to explore complex object structures step by step. Here, one wouldcall the ”Expand object” action on the objects0 . This will then display the objectt8 and thelink between those two objects. Note that eDOBS, like Dobs, hides the internal structures ofusual container classes and eDOBS does not show array objects. Thus, to-many relationships arejust shown as many links but not e.g. as a complex binary tree structure. This raises the level ofabstraction from plain programming structures to the level of UML object diagrams. This higherlevel of abstraction considerably facilitates the exploration of complex object structures.Figure 1: eDOBSAfter exploration of the current situation in eDOBS, the developer may decide to continue hisdebugging session. He may resume the debuggee VM and stop at another breakpoint or stepthrough the code. During such step-wise execution, eDOBS immediately reflects changes to theobject structure.When exploring object structures in eDOBS, the way back to the Eclipse or Fujaba4Eclipseartifact is offered for all elements. That means that you can jump from an object / attribute /method in eDOBS directly to the source code or to the corresponding Fujaba4Eclipse diagram.Proc. GraBaTs 2006 2 / 4ECEASST3 eDOBS - The graph editorFurthermore, eDOBS enables the developer to make instant changes to the object structure. If thedeveloper recognizes a misconfiguration in the object structure while debugging, he can instantlychange that. eDOBS enables the user to create or remove objects and links and to change attributevalues. Furthermore, methods can be called in eDOBS. Here again, changes done to the objectstructure while these method calls are instantly displayed. Figure2 shows the editing operations”Create new object”, ”Edit Attribute” and ”Call method”.Figure 2: Editing operation in eDOBSNote that one does not necessarily need to start working with eDOBS while debugging. Thedeveloper can also create an empty diagram, where he can start from scratch setting up an objectstructure using eDOBS editing functionality. And on this structure one can then again call meth-ods and explore the results, etc. This is especially useful in freshmen courses for Java, becauseone does not need one ”public static void main (String[] args)” but can start right in eDOBScreating Java objects. If the Java code is generated by Fujaba and marked as persistent there, onemay easily save the so created object structure and load it in eDOBS afterwards.If one uses Fujaba4Eclipse to specify an application, the structure of the application is mod-eled using a type graph and the behavior is modeled using graph transformation rules. Since Fu-jaba4Eclipse generates pure Java code from the type graph and the transformation rules, eDOBScan be easily used to create instance graphs of the type graph and to perform the graph transfor-mation rules on those graphs. Thus, eDOBS is the graph editor and transformation rule debuggerof Fujaba4Eclipse.3 / 4 Volume 1 (2006)eDOBS4 ConclusioneDOBS is a browser, editor and transformation rule application tool for object structures / typedinstance graphs. It uses an abstraction layer to get access to the graph. Currently, there existsaccess layers for objects in Java debuggers, Java objects in the same VM as eDOBS (using reflec-tion), and for objects in JMI repositories, like NetBeans MDR [MM03]. eDOBS is an Eclipseplugin and integrates well with the Eclipse JDT and also with the Fujaba4Eclipse plugin. In ad-dition, there exists a standalone version of eDOBS (a so called Rich Client Platform application)which is e.g. integrated into the latest non-eclipse version of Fujaba, Fujaba 5. This RCP appli-cation can be easily integrated into every Java tool, to allow quick access to the internal objectstructure for visualization or debugging purposes.Bibliography[Fu02] Fujaba Homepage, University of Paderborn, http://www.fujaba.de/.[FE04] Fujaba4Eclipse Homepage, University of Paderborn,http://wwwcs.upb.de/cs/fujaba/projects/eclipse/.[ddd95] Andreas Zeller: DataDisplayDebugger Homepage, 1995,http://www.gnu.org/software/ddd/[G02] L. Geiger: Design Level Debugging mit Fujaba; Informatiktage 2002 der Gesellschaft frInformatik (GI), Bad Schussenried, Germany, November 8 - 9 (2002).[GZ02] L. Geiger, A. Zndorf: Graph Based Debugging with Fujaba; Workshop on Graph BasedTools, International Conference on Graph Transformations, Barcelona, Spain, October 6 -12 (2002) .[Blu98] Michael Klling: BlueJ − The Interactive Java Environment, Homepage, 1998,http://www.bluej.org/[G04] Leif Geiger: The eDOBS Project, 2004, http://www.se.eecs.uni-kassel.de/se/index.php?edobs[MM03] Martin Matula: NetBeans Metadata Repository, Whitepaper, 2003,http://mdr.netbeans.org/Proc. GraBaTs 2006 4 / 4

eDOBS - Graphical Debugging for Eclipse

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eDOBS - Graphical Debugging for Eclipse

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