单项选择题 A developer is designing a web application which extensively uses EJBs and JMS. The developer finds thatthere is a lot of duplicated code to build the JNDI contexts to access the beans and queues. Further，because of the complexity， there are numerous errors in the code. Which J2EE design pattern provides asolution for this problem？（）

单项选择题 A developer is designing a web application that must support multiple interfaces，including： an XML web service for B2B HTML for web-based clients WML for wireless customers. Which designpattern provides a solution for this problem？（）

单项选择题 A developer is designing a multi-tier web application and discovers a need to hide the details of establishingand maintaining remote communications from the client. In addition， the application needs to find，in a transparent manner，the heterogeneous business components used to service the client’s requests. Which design patterns， working together， address these issues？（）