How to find out the implementation of Spring Integration's XML Namespace?

When I was reading the documents or books about Spring Integration, I always wanted to find out the underlying implementation, which is the easiest way for me to understand how it works and how it doesn't.

For example,

<int:channel id="queueChannel">
    <queue capacity="25"/>
</int:channel>

<int:poller fixed-rate="5000"/>

What is the underlying support Java class?

First of all, I need to know how to define namespace in Spring.

• http://mozhenghua.iteye.com/blog/1830842 (Chinese link: spring自定义标签实现)

From this article, I learnt that there are two properties files that are very important to me. And one of them is the entry for me to locate the class I want to know:

* spring.handlers

For Spring Integration (core), this is the content of the file:

http\://www.springframework.org/schema/integration=org.springframework.integration.config.xml.IntegrationNamespaceHandler

In turn, I found out this:

registerBeanDefinitionParser("channel", new PointToPointChannelParser());

registerBeanDefinitionParser("poller", new PollerParser());