到底什么是MiddleWare（中间件），请用plain English描述
中间件这个词我们听的太多了，可是到底什么是中间件？为什么我们说像JBoss这样的东西是中间件？请看本文。本文用四点来概括了中间件是什么，很深刻。而且讲到了现在的SOA/ESB，其实就是中间件的体现。
中间件的关键四点：
1. First, it’s mostly invisible.
2. Second, it provides a standard way of doing things.
3. Third, it ties together parts of complex systems.
4. Fourth and finally, it lets you worry about other things.
中间件的关键四点：
1. First, it’s mostly invisible.
2. Second, it provides a standard way of doing things.
3. Third, it ties together parts of complex systems.
4. Fourth and finally, it lets you worry about other things.
