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？（）

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？（）

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？（）

A developer has created a web application that includes a servlet for each use case in the application.These servlets have become rather difficult to maintain because the request processing methods havebecome very large. There is also common processing code in many servlets because these use cases arevery similar.
Which two design patterns can be used together to refactor and simplify this web application？（）