Created by Jerry Wang on Jun 26, 2014
用于测试的xml：
<catalog>
<cd>
<title>Empire Burlesque</title>
<artist>Bob Dylan</artist>
<country>USA</country>
<company>Columbia</company>
<price>10.90</price>
<year>1985</year>
</cd>
<cd>
<title>Hide your heart</title>
<artist>Bonnie Tyler</artist>
<country>UK</country>
<company>CBS Records</company>
<price>9.90</price>
<year>1988</year>
</cd>
</catalog>
step1: 整个document 被匹配，输出<html><body，当前执行到<h2>My CD Collection</h2> ( 被蓝色标识出来)
step2: <h2>My CD Collection</h2>添加到输出，开始执行 < xsl:apply-templates/>:
step3: 从debugger callstack观察到line 7的apply-templates 会trigger /catalog/cd/title node的匹配，进入line 14 p node:
step4: 输出p node的内容(line 16 )
callstack:
step5: title node的匹配完成，继续剩下的document 输出:
callstack从line 16 返回到line 0: