Mailing-List: contact zookeeper-user-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: zookeeper-user@hadoop.apache.org
Received-SPF: neutral (athena.apache.org: local policy)
Message-ID: <4B4B6BD6.9040901@apache.org>
Date: Mon, 11 Jan 2010 10:20:06 -0800
From: Patrick Hunt <phunt@apache.org>
User-Agent: Thunderbird 2.0.0.23 (X11/20090817)
MIME-Version: 1.0
To: zookeeper-dev@hadoop.apache.org, adam@rosien.net
CC: zookeeper-user@hadoop.apache.org
Subject: Re: blog post about zk and group membership
References: <cf67d0ac1001091514m56291faeh2270fb626783f3ee@mail.gmail.com>
	 <4B4B64B3.4000102@apache.org>
 <cf67d0ac1001111008j1eb8d80dq312a2a46337c56de@mail.gmail.com>
In-Reply-To: <cf67d0ac1001111008j1eb8d80dq312a2a46337c56de@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Adam Rosien wrote:
> Re "off the shelf", my title of "Actually Implementing" was a *bit*
> snarky to try and gain some readers, but it wasn't intended to be
> sharp criticism; more documented recipes is a good thing for everyone.
> I'd be happy to submit a JIRA with a group membership recipe.
> 

Ya, I got that, no worries. It was a valid point and something I've been 
asked before. Figured I could get some (addl) free work out of the deal. ;-)

Disqus seems to be having troubles, I've tried like 3 times to comment 
on your blog post, did it finally make it through?

> Re zkclient, I agree that documentation is a big thing, which I hope
> to help out with as I use it more. I'm talking now with one of the
> developers about zkclient's implementation of data serialization since
> that is another big area; zk pushes all serialization semantics into
> the clients, which is ok but requires its own practical strategies.

Yea, that's an interesting point. I suspect that a wrapper around the 
data (zk contrib? subclass/proxy of ZooKeeper?) that put content-type 
type information into the "header" of the data portion might be useful. 
The wrapper could encode/decode based on the data type in ZK, vs the 
data type the user would like. The wrapper could support whichever 
encode/decode the user would like (say xml/json to start) etc... Donno 
how useful in general but in a larger system with a bunch of 
heterogeneous clients accessing it might be interesting.

Patrick

> 
> On Mon, Jan 11, 2010 at 9:49 AM, Patrick Hunt <phunt@apache.org> wrote:
>> Adam, this is awesome! I've retweeted it on my twitter account:
>> http://twitter.com/phunt/status/7637054275
>>
>> A few comments:
>>
>> 1) you are correct about the "off the shelf" part, but really alot of that
>> is our marketing blurb, we paint with a broad stroke. I think it would make
>> sense to include this sort of detail in the "recipes" page though, would you
>> be interested to create a JIRA and submit some content? (you could re
>> purpose alot of what you have in your post)
>>
>> 2) re zkclient - I have not been following that project closely of late,
>> however Mahadev and I did review their code a few months ago. At that time
>> we had some concerns about the semantic impact of some of the design choices
>> they made (which were fine, just not well documented and therefor easy for
>> users to miss). In particular (again, at the time, may be addressed by now)
>> watch notifications could be lost during disconnected/expired sessions, and
>> the user would not be made aware of this.
>>
>> 3) excellent point/suggestion on the "rogue" service
>>
>> Patrick
>>
>> Adam Rosien wrote:
>>> I've written a blog post about using ZooKeeper for group membership at
>>> KaChing:
>>>
>>> http://bit.ly/6yraP6
>>> http://eng.kaching.com/2010/01/actually-implementing-group-management.html
>>>
>>> Any comments or feedback is welcome.
>>>
>>> .. Adam