Post on 05-Dec-2014
description
Operational Transformation
The Secret behind Google Docs, Google Wave and Zoho Suite:
Who I am
Matteo Collina
Twitter: @matteocollina
Website: matteocollina.com
What do I do?
I study a lot..
CCAC North Library http://www.flickr.com/photos/ccacnorthlib/3554627894/in/photostream/ CC by 2.0
...and today I'll speak about whatI've studied!
CCAC North Library http://www.flickr.com/photos/ccacnorthlib/3554627894/in/photostream/ CC by 2.0
We will see...
We will see...
1. Why Real Time is cool
2. Why we are solving the wrong problem
3. An algorithm to rule them all
is all about interaction..
..between people,
that acts through Browsers,
that communicate through a server!
We can create new forms of collaboration!
There are LOTS of frameworks
There are LOTS of frameworks...
...and companies!
...and companies!Thanks!
The frameworks are solving
1. How we present the data to the user
2. How to transfer the data on the wire
Where is the interaction between
people?
What happens when they change the same
document?
Really?
Johannes Gilger http://www.flickr.com/photos/heipei/3236351860/
How can we handle
conflicts?Johannes Gilger http://www.flickr.com/photos/heipei/3236351860/
Can users understand
this?Johannes Gilger http://www.flickr.com/photos/heipei/3236351860/
We usually lock our documents to protect them!
Only the user that locked the document can edit it!
Some people are doing it correctly..
Some people are doing it correctly..
..how?
What happens when we edit a document?
Insert(0,"hello ")
Delete(6, 5)
Insert(6,"world")
s = "jsday"
s = "hello jsday"
Insert(0,"hello ")
s = "hello jsday"
s = "hello "
Delete(6, 5)
s = "hello "
s = "hello world"
Insert(6,"world")
The operations are processedas they arrive: what happens if there are more users sending them?
What happens if the operations come from
two users?
sA = "hello world" sB = "hello world"
sA = "hello world" sB = "hello world"
What happens if operations get
delayed?
sA = "hello jsday" sB = "hello world"
Operational Transformation
➡ has been a research topic for more than 20 years
➡ is a family of algorithms
❖ Jupiter has lead to Google Docs / Wave
Operational Transformation
Operational Transformation
1.reorders the operations
2.handles the conflicts between operations
3.garantees the same result on all nodes
Reorder Problem
How can we reorder the operations?
What is the intention behind
the delete?
s = "hello jsday"
s = "hello "
Delete(6, 5)
The intention behind the delete is to remove the "jsday" string
Delete(6, 5) Delete'(12, 5)
Insert(6,"world")
Delete(6, 5) Delete'(12, 5)
Insert(6,"world")
OT transposes the Delete through the Insert
s = "hello worldjsday"
s = "hello world"
Delete'(12, 5)
s = "hello worldjsday"
s = "hello world"
Delete'(12, 5)
OT is about changing where and how the ops
are executed
What happens if two users delete the same string?
Delete(6, 5) NoOperation
Delete(6, 5)
What happens if two users delete the same string?
Operational Transformation
reorders the operations
handles the conflicts between operations
garantees the same result on all nodes
Unfortunately, there is some nasty
math involved!
http://www.flickr.com/photos/oneaustin/1261907803
DEMO!!!
TL;DR
http://www.flickr.com/photos/evilaugust/3307382858
TL;DR
http://www.flickr.com/photos/evilaugust/3307382858
Operational transformation:• allows to build true real time
applications;• is really hard;• garantee the same results for
every users!
..but we started with a question!
What do I do?
• Ph.D. Student
• Software Engineer @ Mavigex
• Conference Speaker (?)
What do I do?
Choose your tools wisely!
http://www.flickr.com/photos/chuffy/186676221
Thank You!
Any Questions?