Operational Transformation is a technique for synchronizing changes to a document among different clients. It is widely used in different technologies both open and closed source (e.g., ShareJS, Apache Wave and Google Drive Realtime API) OTLY is a framework based on Operational Transformation that is being developed by XWiki SAS as a refactoring of its realtime editor. OTLY aims at providing a common foundation for contributing collaborative document models and binding to widely used editors. OTLY is targeting both Java and Javascript for the client side, and Java on the server side.

1. OTLY
A framework for realtime collaboration
Fabio Mancinelli
fabio.mancinelli@xwiki.com
Operational Transformation is a technique for synchronizing changes to a document
among different clients. It is widely used in different technologies both open and closed
source (e.g., ShareJS, Apache Wave and Google Drive Realtime API) OTLY is a framework
based on Operational Transformation that is being developed by XWiki SAS as a
refactoring of its realtime editor. OTLY aims at providing a common foundation for
contributing collaborative document models and binding to widely used editors. OTLY is
targeting both Java and Javascript for the client side, and Java on the server side.
www.ow2.org
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2. OT Everywhere !
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NodeJS based – Open Source
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TogetherJS
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Etherpad
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ShareJS
...a lot more !
Java based – Open Source
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Apache Wave
OpenCoWeb
Proprietary
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Google Drive Realtime API
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3. OTLY
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Framework targeting the Java world
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Based on Operational Transformation (OT)
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Embeddable in Java programs
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Extensible
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Simple API
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4. What is OT ?
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Optimistic concurrency control mechanism
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Used in high-latency, low bandwidth systems
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Basic blocks : operations + transformations
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5. What is OT ?
xform(c, s) = (c', s') | c ∘ s' = s ∘ c'
C
S'
S
C'
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6. What is OT ?
xform(c, s) = (c', s') | c ∘ s' = s ∘ c'
C
S'
S
C'
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7. What is OT ?
...
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8. OTLY Architecture
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Document models
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Bindings
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For supporting different types of operations :
text, rich text, spreadsheets, etc.
For supporting different types of editors :
HTML text area, WYSIWYG editors, etc.
GWT for simplifying code sharing on Javascript
clients and Java server
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9. OTLY API
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Simple API (inspired by ShareJS)
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Client side (JS)
–
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otly = new otly.Otly() ;
pad = document.getElementById("pad")
otly.open("simpletext", "foo", function(doc) {
doc.bind(pad, "textarea") ;
}) ;
Client side (Java)
–
JFrame frame = ...
otly = new Otly() ;
DocumentModel documentModel = otly.open("simpletext", "foo") ;
documentModel.bind(frame) ;
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10. Conclusion
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Extensible architecture
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Helps to build a community that provides new
document models and bindings
We are working on a reference implementation that will
work with the XWiki WYSIWYG + other popular simple
text editors and will be integrated in XWiki
Issues
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OT is complex to get it right
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GWT is very heavyweight
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11. Acknowledgements
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Some of the work has been done in the context
of the RESILIENCE Project
OTLY is based on the initial work done in the
context of the Wiki3.0 project by the INRIA
Score Team and XWiki SAS
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