Page Life Cycle
Request (HTML/JS/JSON/Text/XML)---------> Callback------------->Init
Request 相当于URL跳转，
Callback相当于page onload()
init 相当于执行<script>
Business Flow
Cycle1---->Cycle2---->Cycle3---->Cycle4--- ---->CycleN
Request (HTML/JS/JSON/Text/XML)---------> Callback------------->Init
Request 相当于URL跳转，
Callback相当于page onload()
init 相当于执行<script>
Cycle1---->Cycle2---->Cycle3---->Cycle4--- ---->CycleN