The document presents a framework for near real-time (NRT) collaborative conceptual modeling on the web, designed for synchronous editing to enhance user interaction across different locations. It discusses various foundational aspects of the framework, including functional and non-functional objectives, technical realization with XMPP for communication, and highlights the evaluation of usability and usefulness through user feedback sessions. Future work includes improvements to collaboration features and recommendations to enhance the modeling experience.

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1 This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
Near Real-Time Collaborative
Conceptual Modeling on the Web
Michael Derntl, Petru Nicolaescu, Stephan Erdtmann
Ralf Klamma, Matthias Jarke
RWTH Aachen University
Lehrstuhl Informatik 5 – Information Systems
lastname@dbis.rwth-aachen.de
ER 2015 | 21 Oct 2015
This work has been funded with support from the European Commission. This presentation reflects
the views only of the authors, and the Commission cannot be held responsible for any use which
may be made of the information contained therein.

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Motivation
 Conceptual modeling
– Key activity in many areas
– Social, creative process [FK98] – collaborative work [RKV08]
 Typical collaboration: asynchronous
 Availability of near real-time (NRT)
collaborative modeling tools
– On desktop and on the Web
– From highly domain-specific tools like Kanban Tool1…
– … to very generic ones like draw.io2
1 http://kanbantool.com
2 http://www.draw.io

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Near Real-Time Collaborative Editing
 Synchronous editing independent of the location of the
users
– Propagation of user actions to collaborators
– Responsiveness similar to single-user applications
– Consistency maintenance
 Inconsistencies caused by divergence or causality-
violation [SE98]
 Two approaches for consistency preservation
– Conflict prevention [XZS00]
– Conflict resolution [SE98]
 Architectures
– Centralized architecture (client/server)
– Decentralized architecture (peer-to-peer)

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Objectives
Functional
• Framework for NRT
collaborative modelling
(domain-independent)
• Meta model based
• Visual modeling
• Awareness
• Structure editing support
Non-Functional
• Open source code
• Building on open
protocols
• Runs in Web browsers
Research the shift towards Web-based collaborative modeling

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Related Tools & Frameworks
Platform Domain-
Indepen-
dent
Meta-
Modeling
NRT
Collab
oration
Awareness Web-
based
Open
Source
MetaEdit+ [TPK07] Smalltalk ✓ ✓ (✓)
ADOxx [FK13] Gecko/C++ ✓ ✓
DiaMeta [Mi07] Java / EMF ✓ ✓ ✓
Gallardo et al.
[GBR12]
Java / EMF ✓ ✓ ✓ ✓
Tiger [Eh05] Java / EMF ✓ ✓
AToM3 [LVA04] Python ✓ ✓ ✓
GenGED [BEW04] Java ✓ ✓
TWICE [SLHi14] Java/JS/
GWT
✓ ✓ ✓ ✓ ✓
SyncMeta JS/ ROLE SDK ✓ ✓ ✓ ✓ ✓ ✓

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Meta-Modeling Hierarchy

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 Real-time collaboration on both modeling layers
Meta-Modeling Framework:
Modeling Process & User Roles

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Example Languages
 Petri Net
 i*
 IMS LD
 …

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Metamodel (partial)

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 Model Editor is special instance of Meta-Model Editor
 Uses special Export Widget for Model Editor Generation
GUI Architecture

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Technical Realization
 Communication protocol: XMPP
– Suitable protocol for NRT communication
– Multiple extensions available (publish subscribe, multi-user chat)
– Client and server support
 Open source ROLE SDK based on Apache Shindig
– User management
– Personal and collaborative widget space management
– XMPP based multi-user chat
 Inter-widget communication (IWC) [GVD+11]
– Local IWC based on HTML5 Web Messaging API
– Remote IWC based on XMPP Publish Subscribe XEP
– Strophe.js (XMPP over BOSH and WebSockets)
 Conflict Resolution
– Opencoweb OT Javascript framework

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Model Editor - Functionality
 Near real-time synchronization
 Awareness
- Activity Pane
- Highlighting of nodes
 User interaction to add nodes / edges
- Palette
- Context menu
 Export of Model as JSON, PNG File
- Custom export widgets

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End-User Evaluation
 Goal
- Evaluation of usability and usefulness of Model Editor
- Obtain feedback for improvement
 Methodology
- Editor instance for i* modeling language [Yu95]
- Evaluation session in groups of two
- Participants could see and talk to each other, but were not
able to see each other‘s screen (Skype-like setting)
- Task: Jointly recreate a given i* model using the editor
- Rating using surveys with seven-point Likert scale items

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End-User Evaluation (cont.)
 Participants
- Ten group sessions with 20 participants in total
- Diverse expertise of conceptual modeling and the i*
modeling language (novices as well as experts)
- Regular to frequent usage of graphical editors

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Evaluation:
Quantitative Results
 Overall
– Very positive overall rating (M = 5.7; SD = 1.2)
– User interface and usability also good (M = 5.9 and 5.7,
respectively)
– Ratings independent of user experience (r = .32; p = .17)
 User interaction
– For adding nodes resp. edges participants prefer the context
menu (M = 5.9 and 5.7, resp.) over palette (M = 5.3 each)
 Awareness
– Node highlighting (M = 5.7; SD = 1.2) slightly higher than
activity pane (M = 5.5; SD = 1.4)

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Evaluation:
Suggested Improvements
 Increase overview for large models
 Highlighting of remote changes
 Keyboard shortcuts
 Multiselection of nodes
 Automatic node arrangement
 Drag & drop from palette

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Conclusion and Future Work
 Key points
- Browser-based Meta-Modeling Framework
- Generation of RTC Editors for Visual Modeling Languages
 Different types of user interaction
 Awareness
- Pilot case: i* editor; generally positive evaluation
 Future work
- Views for NRT modeling
- Recommendations during modeling
- Improvement of collaboration using the Yjs OSS library

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THANK YOU FOR LISTENING
nicolaescu@dbis.rwth-aachen.de
Nicolaescu Petru
SyncMeta Project Description
GitHub: https://github.com/rwth-acis/syncmeta

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