php MessagePack介绍
1，今天在hacknews上看到很多人对messagepack的争论。首先了解什么是MessagePack：MessagePack is a binary-based efficient object serialization library. It enables to exchange structured objects between many languages like JSON. But unlike JSON, it is very fast and small.
2，MessagePack的主要用途，作者解释说有两大用途：一是Space-efficient storage for Memcache entries (Pinterest)，节省空间类型的mamcache应用；另一个是用于RPC传输， This use case is fairly close to my original intent. When one is designing an RPC system, one of the first tasks is to specify and implement a communication protocol. This process can get pretty hairy as you need to worry about a lot of low-level issues like Endian-ness. By using MessagePack, one can skip designing and implementing a communication protocol entirely and accelerate development.
3,争议的地方是MessagePack的benchmark说，他比protocolBuffer，Json快很多倍。但是有人不相信，做个javasript下的测试（json与messagePack）。发现MessagePack仅是压缩后的数据比json少10%左右，而压缩和解压时间则和json的解析器比起来要费时很多。
4，“MsgPack vs. JSON: Cut your client-server exchange traffic by 50% with one line of code”这篇文章使用了messagePack做服务器的优化，降低服务器的数据量，更加合理的利用带宽。作者强调了他们宁愿浪费客户端的0.5ms—1ms，但是服务器使用ruby的MessagePack解析器，效率能够比JSON快5倍。
The difference to JSON is, that MsgPack is binary-based - this gives the possibility to make the exchanged data a) smaller and use less bytes, I guess we all know the advantages of that, however there is an even bigger advantage: b) It is faster to parse and encode, having a parser parse 40 bytes takes about twice as long as parsing 20 bytes.
myJSONString = JSON.stringify(myObject);
myObject = JSON.parse(myJSONString);
var myByteArray = msgpack.pack(myObject);
myObject = msgpack.unpack(myByteArray);
MessagePack作者也认为MessagePack may not be the best choice for client-side serialization as described by the blog author.引用2的作者有点小悲剧。
5，BSon是Json的二进制形式，但是与JSon有语法不兼容的地方。但是MessagePack保证语义上能够做到一致。
6，场景需求不同，导致技术的应用有所差异。
PHP试用MessagePack
It's like JSON. but fast and small.
这句吸引了我，去瞧了下。
官网：http://msgpack.org
官方的安装方法忽悠人，msgpack目录下根本没php目录...只看到csharp,erlang,go,java,ruby等目录。
git clone https://github.com/msgpack/msgpack.git
cd msgpack/php
phpize
./configure && make && make install
还是在PHP官网扩展找到了：http://pecl.php.net/package/msgpack
最后更新时间：2012-09-14，昨天的版本。
附安装过程：
wget http://pecl.php.net/get/msgpack-0.5.2.tgz
tar zxf msgpack-0.5.2.tgz
cd msgpack-0.5.2
/usr/local/hx/php/bin/phpize
./configure --with-php-config=/usr/local/hx/php/bin/php-config
make && make install
然后把msgpack.so加到php.ini里，重启php，完成安装。
开始测试：
$data = array(0=>'abcdefghijklmnopqrstuvwxyz',1=>'厦门','abc'=>'1234567890');
分别对其msgpack_pack，json_encode，serialize，长度为：50,62,87
然后分别执行10000次，耗时：9.95 毫秒，17.45 毫秒，8.85 毫秒
解开执行10000次，耗时：14.76 毫秒，23.93 毫秒，14.61 毫秒
msgpack的性能至少超过json50%，虽然和serialize其实速度差不多，但serialize占用空间明显比较多。
另外，GBK的程序方便了，中文也可以msgpack_pack，用json的话还要批量转换成utf-8之后才能json_encode。
引用：
1，MessagePack官方网站
2，MsgPack vs. JSON: Cut your client-server exchange traffic by 50% with one line of code
HN评论地址：http://news.ycombinator.com/item?id=4090831
