1. Component-based Authoring of Complex, Petri net-based Digital Library Infrastructure Yung Ah Park, Unmil P. Karadkar, and Richard Furuta Department of Computer Science and Center for the Study of Digital Libraries Texas A&M University Yung Ah Park, Unmil P. Karadkar, and Richard Furuta Department of Computer Science and Center for the Study of Digital Libraries Texas A&M University

2. Petri Net-based Hypertexts Directed, bipartite graph Separation of ‣ content from actions (links) ‣ content from structure ‣ content from presentation Support ‣ simulation of scenarios ‣ analysis of reachability (security) ‣ presentation changes in response to real-world conditions

3. Motivation Authors often create networks from scratch ‣ graphical authoring tool, xTed Draw places, transitions, arcs ‣ bottom-up process ‣ focus on placement of individual components and their connections ‣ prior support for hierarchical nets Hierarchical nets ‣ management of visual complexity ‣ abstraction for repeating structures ‣ lack of support for thinking in terms of high-level structures Hypertexts consist only of tens of nodes

4. Approach Support top-down, function-oriented authoring Component nets ‣ reusable building blocks (places, transitions, arcs) ‣ function-specific templates ‣ store characteristic and identifying metadata ‣ pre-defined templates for commonly used structures (help) Net composition ‣ operations for combining nets ‣ sequencing, parallel, choice, iteration, refinement Net Transformation ‣ reduce net complexity while preserving their function ‣ transformation: union, fusion

5. Composition Operations Construct hypertexts from existing fragments ‣ combine art collections for a virtual museum ➡ Vincent van Gogh collection (VG) ➡ Claude Monet collection (CM) Append CM to VG Provide option of browsing either collection To present two collections concurrently To present two collections concurrently sequenceparallel choice

6. off-campus on-campus input output input output On-campusOff-campusUnion(On-campus, Off-campus) input output t1t1 t2t2 t1t1 t2t2 Net Transformation Union transformation ‣ Unite nets with similar function

7. Net Template Flexible reuse of component net fragments ‣ place net fragments into repository ‣ locate fragments ➡ Functional similarity ➡ Structural similarity ‣ modify found fragments ‣ substitute with isomorphic nets ‣ compose nets using found fragments

8. 8 Flexible Reuse of Component Nets

9. Template-based caT Authoring Tool Templates Tree View Content Layout Textual Editor ‣ UI => Java 2D and swing components ‣ Each element of net is implemented by Jcomponents

10. Textual Authoring Language ConstructN 3 { Net N 1 ; Net N 2 ; Net N 3 ; N 3 =sequence(N 1,choice(N 1,N 2 )); } choice(N 1,N 2 ) Eliminates point-and-click interaction overhead TcAT synchronizes graphical and textual views

11. Evaluation Test the effectiveness of TcAT features ‣ improvement metrics relative to xTed and Web authoring ‣ experts also authored using the TcAT textual interface Test subjects ‣ 15, none had experience with xTed or TcAT ‣ no compensation, immediate, or direct benefits ‣ 5 novice (Use of computers and Web) ‣ 6 intermediate (Computer Science or Engineering) ‣ 4 expert (Graph theory or Petri nets) Task ‣ to create a digital art museum using van Gogh and Monet’s art ‣ subjects received image, summary, and descriptive text

12. Time taken to create collection

13. Performance Improvement

14. Conclusion Highlights of the user study ‣ test subjects’ performance improved using either TcAT modality ‣ Authoring was faster using the textual language than with FrontPage TcAT ‣ enables net authors to create named, function-specific templates ‣ compose large networks top-down, by combining fragments ‣ reduces complexity by automating visual positioning of net elements ‣ maintains synchronized textual and visual specification of the net ‣ 4 expert (Graph theory or Petri nets) Future Work ‣ continuing studies to explore cognitive processes in net uthoring ‣ Evaluation of specific features to improve TcAT’s utility

15. Questions