different perspectives SOA:

the bottom-up approach, which is primarily IT driven.也即把现有的Java bean包装重用成Web Service等。    And BPM,

the top-down approach, which is business driven，一切从头开始设计，包括WSDL等。   

我喜欢这么一句话： 从技术(technique)的角度来说，用bottom up approach; 从业务(business)的角度来说，用Top down approach