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Real time-collaborative-editor-presentation
- 3. Motivation
- 4. Approach
- 5. R & D
- 6. Results
- 7. Future work
- 8. Demo / Questions / Discusion
- 10. Comet
- 11. WebSockets
- 16. send e-mail
- 17. modify documents
- 18. manually merge
- 21. Network lag
- 23. Data divergence among participants
- 24. UI problems
- 33. executed on the local copy
- 38. Convergence
- 43. Convergence
- 44. OT – Causality
- 46. ins(a<X<b)
- 47. ins(a<X)
- 48. ins(X>b)
- 50. The effect of executing O does not change the effects of independent operations * Chengzheng Sun, Xiaohua Jia, Yanchun Zhang, Yun Yang, and David Chen. Achieving convergence, causality preservation, and intention preservation in real-time cooperative editing systems. ACM Transactions on Computer-Human Interaction , 5(1):63−108, March 1998.
- 51. OT – Intention violation
- 52. OT – Intention violation + Divergence
- 53. OT – Intention preservation
- 54. OT – Convergence
- 55. OT – Convergence
- 59. Repetitive and error prone
- 60. Iterative
- 62. Used in Google Wave, Google Docs, ACE
- 63. Requires a central server
- 64. Eliminates TP2, but requires TP1
- 73. XHR
- 75. Flash
- 77. productive collaborative document editing environment
- 78. don't have to worry about stepping on each others toes
- 80. Cut/ copy/ paste
- 81. Basic keyboard shortcuts (Ctrl + Home/End etc.)
- 84. Aloha – need API
- 85. Some slides of this presentation belong to Claudia Ignat [email_address] INRIA researcher in the SCORE Team http://score.loria.fr Remark
Editor's Notes
- Hello, my name is B. F. I'm a software engineer in the SCORE Team at INRIA. and I will talk about a Web based real-time collaborative editor. To capture your interest, it's something similar mostly with GoogleWave and Etherpad.
- Here's the agenda... Short intro: introduce you in the context of real-time web. Motivation: why there is a need for this kind of tool Approach: I will explain the theoretical framework used to solve concurrency conflicts R&D – where I have studied the state of the art, what problems I've encountered and their solutions, the technologies used etc., technical details Results – highlight main features of the editor Future work – what I will be doing in the near future DEMO
- As we all know HTTP is a request/response based protocol, not designed to support real-time functionalities. Please raise your hand who has'nt heard buzzwords like: HTML5, Server-sent events, XHR multipart, Pushlet, Server push, Reverse Ajax, Forever frame, Streaming? Shame on you! These are all under the umbrella of Comet term, which is a technique that uses some kind of long-lived HTTP connection to reduce the latency with which messages are passed from the server to browser.
- If in the past the common way of collaboratively work consisted in a error prone & time consuming loop, where you had to attach documents to e-mails, send it, receive a modified copy, manually merge. It might be shocking but nowadays too, this is the main M.O. Real-time hah! But we've got real problems! To name just a few: 1) HTTP was not designed/intended with ”push” in mind, limited speed of comunication due to network lag 2) text colision and divergent data among participants The challenge of real-time collaborative editing is to figure out exactly how to apply edits from remote users, which were originally created in versions of the document that never existed locally, and which may conflict with the user's own local edits. And for this we need a smart merging algo 3)Client-side UI problems – were handled via a turn-taking approach (one user at a time obtains a lock, edits happilly, while the others got upset …) you know, a frustrating experience. The algo used in the prototype, does not use locking (all users can freely edit any parts of a document at the same time) To achieve n-way synch protocol, a 2 way synch protocol is used..., each client optimistically executes it's operation, and the server serializes incoming messages.
- With the advent of web 2.0 technologies and to adress this kind of problems the Wiki3.0 project arose. It aims at developing a next generation collaboration platform that integrates real-time editing and interactions, social-networking feature. The final outcome is to deliver a solution that will greatly ehnance the productivity in terms of knowledge exchange and creation.
- OT – what is it and how can it suit my needs? ”Is a technology for supporting a range of collaboration functionalities in advanced groupware systems”. Has been continuously researched in the context of group editing for more than 20 years And that's right, it's the heart and soul of RT collaborative editing. (Other approaches as well: CRDT) Optimisitic approach for document replication: Local editing operations are executed without being delayed or blocked, sent to remote sites Received by a remote site, AND transformed before execution according to CONCURRENT operations that might happen, then executed on the local copy The lock-free, non-blocking property of OT makes the local response time insensitive to networking latencies. These properties of OT play a big part in providing a smooth user experience.
- In OT the textual documents are seen as a sequence of characters. The caracters are obviously generated by operations. Operations: ins(p, c) & del(p) Even with just 2 basic operations, there are some problems! Main issues: Causality preservation Intention preservation Convergence
- In OT the textual documents are seen as a sequence of characters. The caracters are obviously generated by operations. Operations: ins(p, c) & del(p) Even with just 2 basic operations, there are some problems! Main issues: Causality preservation Intention preservation Convergence I'll briefly cover these aspects further!
- Realtime collaboration means to change the content the user is actually editing. This change due to the HTML standard technically can only be done by moving the cursor (= collapsed selection) to the position where the remote changes occur and restore to previews cursor position (or selection, if it was a selection before). This sounds simple but looking in detail a lot of problems come out. If the cursor or selection is not restored the cursor will jump to the top of the editable DOM element whenever a remote change occurs. This would result in an unusable behavior.
- Realtime collaboration means to change the content the user is actually editing. This change due to the HTML standard technically can only be done by moving the cursor (= collapsed selection) to the position where the remote changes occur and restore to previews cursor position (or selection, if it was a selection before). This sounds simple but looking in detail a lot of problems come out. If the cursor or selection is not restored the cursor will jump to the top of the editable DOM element whenever a remote change occurs. This would result in an unusable behavior.
- Now we'll proceed with the DEMO!
- Ok, so before pointing your browser to: … And start typing .... Please note that currently it;s a prototype, please report any bugs encountered! Enjoy!