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From Wendall Cada <>
Subject Re: Google Summer of Code topics
Date Sat, 23 Mar 2013 00:13:02 GMT
The webpage for this github project isn't liked from their web pages. 
Can be found


On 03/22/2013 05:07 PM, Wendall Cada wrote:
> On 03/22/2013 12:48 PM, Dave Cottlehuber wrote:
>> On 22 March 2013 19:14, Mark Hahn <> wrote:
>>>>   Implement partial reads and updates of documents,
>>> In case anyone didn't know, you can do partial updates right now 
>>> with an
>>> update handler.  I have been using one for some time that allows the 
>>> app to
>>> modify any part of a doc with a single http request.  It even allows 
>>> one to
>>> modify an attribute nested inside objects.  I've ended up using only 
>>> this
>>> for all updates.
>> Hi Mark,
>> Completely true. Maybe you would like to contribute that back perhaps?
>> Even as a wiki entry that would be useful for folk, and I'm happy to
>> help clean up / document if required.
>> I was thinking at the time of the JSON PATCH draft RFC, aka
>> Did you use this approach, or tackle it differently?
>> Another idea that I had on the back burner was implementing
>> cryptographic support for doc signing, e.g. pgp-like signing and
>> validation, or even encryption. I think Jim Klo has done this or
>> something similar already.
>> A+
>> Dave
> I think this idea is really a great one. Every time I bring this up, 
> the response is "Why don't you just send the entire doc?". We'll, I 
> could give a zillion reasons at least, but here are the main ones:
> 1. I want to be able to limit what I send over the wire without 
> resorting to the latest fad in over the wire json compression 
> techniques. Just simply being able to send my actual changes will beat 
> every one of these methods 100% of the time.
> 2. I want to only share a subset of the actual doc with the 
> client-side app.
> 3. Have the ability to store a history of doc changes easily.
> Imagine a scenario where all changes are stored as attachments and I 
> can easily replay events over the lifetime of a doc, or a truncated 
> history, depending on how long you want to store this for. Full 
> replicatable (sp?) history for an entire db!
> I've implemented quite a few solutions in some test code over the last 
> several months. What I've found is that diff is the slowest possible 
> way to do this. Maybe some of these solutions are faster now, but was 
> crazy slow when I looked at it about six months ago.
> I saw some very clever OT (Operation Transformation) techniques in 
> use. There is currently a really neat github project that has been 
> maintaining some very good implementations. Of particular interest is 
> the javascript implementation 
> On that same site, there is quite a bit of information about OT. I 
> really think it would be awesome for a SoC project to have this 
> implemented in Erlang. There is some long-term potential of possibly 
> speeding up replication utilizing OT/diffs.
> Wendall

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