zookeeper_client
    by Phillip Pearson
    http://github.com/myelin/zookeeper_client

== DESCRIPTION:

zookeeper_client is a Ruby library to interface with the ZooKeeper
replicated object store / lock server.

Project maturity: early alpha.  Working, although very chatty and
there may be bugs to do with threading.  Expect to get your hands
dirty.

== REQUIREMENTS:

* ZooKeeper C client library (http://zookeeper.sourceforge.net/)

  See installation instructions in c/README, in the ZooKeeper source
  distribution.  zookeeper_client expects the headers to live in
  /usr/include/c-client-src/, which doesn't feel right but is where
  they go on my system when I run 'make install'.

== INSTALL:

  $ gem sources -a http://gems.github.com/
  $ gem install myelin-zookeeper_client

== USAGE:

= Connect to a server

  require 'rubygems'
  require 'myelin-zookeeper_client'
  z = ZooKeeper.new("localhost:2181")

= Create, set and read nodes

  z.create("/bacon", "text to be stored in the new node", 0)
  # => "/bacon"

  data, stat = z.get("/bacon")
  # => ["text to be stored in the new node", #<ZkStat:0xb771be54 @ephemeralOwner=0, @ctime=1216196667669, @aversion=0, @mzxid=1008, @cversion=0, @version=0, @czxid=1008, @mtime=1216196667669>]

  z.set("/bacon", "an entirely different line of text", stat.version)
  # => nil

  z.set("/bacon", "this won't work", stat.version)
  # CZooKeeper::BadVersionError: expected version does not match actual version

  data, stat = z.get("/bacon")
  # => ["an entirely different line of text", #<ZkStat:0xb77125d4 @ephemeralOwner=0, @ctime=1216196667669, @aversion=0, @mzxid=1009, @cversion=0, @version=1, @czxid=1008, @mtime=1216196704709>]

  z.delete("/bacon", stat.version)
  # => nil

= Create ephemeral and sequence nodes

  z.create("/parent", "parent node", 0)
  # => "/parent"

  z.create("/parent/test-", "an ordered node that will disappear when the connection goes down", ZooKeeper::EPHEMERAL | ZooKeeper::SEQUENCE)
  # => "/parent/test-0"

  z.create("/parent/test-", "an ordered node that will disappear when the connection goes down", ZooKeeper::EPHEMERAL | ZooKeeper::SEQUENCE)
  # => "/parent/test-1"

= Acquire locks

  z.try_acquire "/parent/lock-", "content for the lock file" do |have_lock|
    puts have_lock ? "we have the lock" : "we don't have the lock"
  end
  # we have the lock
  # => nil

== LICENSE:

(The MIT License)

Copyright (C) 2008 Phillip Pearson

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.