多项选择题 A developer is designing a multi-tier web application and discovers a need to log each incoming clientrequest. Which two patterns， taken independently， provide a solution for this problem？（）

单项选择题 A developer is designing the presentation tier for a web application that relies on a complex session bean.The session bean is still being developed and the APIs for it are NOT finalized. Any changes to the sessionbean API directly impacts the development of the presentation tier.  Which design pattern provides a meansto manage the uncertainty in the API？（）

多项选择题 WhichtwoarecharacteristicsoftheFrontControllerpattern？（）