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Difference between revisions of "RT Shared Editing"
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Figure 1 shows a somewhat ''idealistic'' scenario where communication lag between several editing sites remains without undesired consequences because operations are generated and executed at all sites in an orderly fashion. | Figure 1 shows a somewhat ''idealistic'' scenario where communication lag between several editing sites remains without undesired consequences because operations are generated and executed at all sites in an orderly fashion. | ||
====Divergence==== | ====Divergence==== | ||
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| − | In a ''realistic'' distributed editing scenario, as depicted in Figure 2, the need for consistency maintenance becomes apparent. | + | In a ''realistic'' distributed editing scenario, as depicted in [[Media:cola_shared_editing_nontrivial_scenario.jpg|Figure 2]], the need for consistency maintenance becomes apparent. |
Due to dependencies between operations originating from different editors on a shared document and suffering from propagation lag in a distributed environment, shared data state at different sites can divert from each other. | Due to dependencies between operations originating from different editors on a shared document and suffering from propagation lag in a distributed environment, shared data state at different sites can divert from each other. | ||
Revision as of 15:36, 4 June 2006
Project Lead: Mustafa Isik
Mentor(s): Scott Lewis, Ken Gilmer
Contents
Motivation
The RT Shared Editor, which I'll dub Cola (collaborate) for now, is supposed to be a tool enabling developers to reap the benefits of pair programming within the Eclipse IDE.
The term pair programming describes an activity in which two developers simultaneously work on a single development machine.
Even though not new to the development community, pair programming has witnessed a significant rise in adoption over the last years. One of the main reasons being the inclusion to the set of eXtreme programming (aka XP) practices. Thus pair programming is especially, but certainly not only, popular among developers utilizing the values, principles and practices propagated by the XP methodology.
The reasoning behind pair programming, as articulated by software developer, author and XP figurehead Kent Beck (2005 p.42) is manifold and pair programmer's acivities are described as
- keep each other focused and on task
- brainstorm refinements to the system
- clarify ideas
- take initiative when their partner is stuck, lowering frustration
- hold each other accountable to the team's practices
From my own experience I can add, that programming in pairs has proved to beneficial in
- widening developers' horizon and perspectives on perceiving and tackling problems
- increasing trust in one's own skills and generating awareness for areas requiring improvement
- learning from more advanced developers
- improving through working with less experienced devs, motivating to reflect on the essence of one's own practices
- refining one's own communication skills
Current Situation
Tool-support for pair programming in Eclipse is pretty much non-existent. Pair programming sessions, as spontaneous as they might be arranged in some teams, usually are set up for longer periods of time, ranging anywhere from an hour to some four or five. Pairs consist of locally available developers.
Limitations & Problems
Geographical limitations do not permit for simple pair programming. Since individuals are required to sit in front of the same machine, they apparently have to be located at offices close to each other. Thus software development, not being a regionally bound activity, as proven by the sustained success and advances of open-source software and the nature of many open-source teams, has to be carried out without utilizing effective pair programming in many cases.
Even when developers are located at the same work site, the effort to get two people set up together in front of a computer (drinks, resources, etc.) proves not to be worth for short programming or reviewing tasks, which sometimes are all that is required. This does not mean that coders do not occasionally sit down for such quick tasks, but from personal experience not as often as it might be beneficial for oneself and/or the code.
Traditional instant messaging software does not lend itself for code communication among developers. Such software generally proves to be fairly feature-limited and catering to different target audiences. Theoretically it would lend itself for sending back and forth short code snippets at best, practically large-scale adoption of such behaviour has yet to be seen.
Open-plan offices or group cube farm layouts do not support developers in utilizing pair programming benefits either, quickly degrading the workspace noise-level to that of an airport lobby (by the way, the true problem here would be of course the office layout, but the scope of changing that is unfortunately usually beyond the individual developer).
Furthermore developers, who usually keep book resources in their personal work environment, end up being stripped of those for half of the time they are pair programming.
Resolution
Cola is supposed to support collaborative work on code from disparate locations, minimizing organizational impact and improving on flexibility issues concerning pair programming.
Developers are intended to be able to work simultaneously on a single source file, viewing changes made by other contributors in real-time and editing the most up-to-date version of the file at all times.
The initial incarnation of Cola is to materialize in the form of an Eclipse IDE plug-in.
Tasks
Concerning the development of the shared editor ...
Consistency Maintenance
Maintaining consistency among shared data in a distributed real-time editing environment is of prime importance.
Over the last decade a lot of thought has been dedicated to the research of domain-specific issues in real-time collaborative groupware systems. Chengzheng Sun and Clarence Ellis have authored a paper (Sun, C et al 1998) providing a thorough overview of such. The subsequent discussion of challenges specific to real-time collaborative editing is based on the referenced paper and intended to be self-sustaining in that you will not have to dig into academic research material to understand the challenges at hand.
Figure 1 shows a somewhat idealistic scenario where communication lag between several editing sites remains without undesired consequences because operations are generated and executed at all sites in an orderly fashion.
Divergence
In a realistic distributed editing scenario, as depicted in Figure 2, the need for consistency maintenance becomes apparent. Due to dependencies between operations originating from different editors on a shared document and suffering from propagation lag in a distributed environment, shared data state at different sites can divert from each other.
Operations XYZ....
Causality-violation
Intention-violation
Protocol Review
Integration into Eclipse Communication Framework
Resources
Meeting Notes
Papers & Books
- Beck, K 2005, Extreme Programming Explained - Embrace Change, 2nd Ed., Addison-Wesley, Boston MA (USA), p. 42
- Sun, C & Ellis, C 1998, Operational Transformation in Real-Time Group Editors: Issues, Algorithms, and Achievements, Proceedings of the ACM Conference on Computer-Supported Cooperative Work, Seattle WA (USA), pp. 59-68
- Nichols, D, Curtis, P, Dixon, M & Lamping, J 1995, High-Latency, low-bandwidth windowing in the Jupiter collaboration system, Proceedings of the 8th annual ACM symposium on User interface and software technology, Pittsburgh PA (USA), pp. 111-120