A Company.com 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 have become very large. There is also common processing code in many servlets because these use cases are very similar. 
Which two design patterns can be used together to refactor and simplify this web application？ （）

Company.com has decided to use the FUBAR Application Server to host their web application. Unfortunately， the FUBAR Application Server uses the server machine’s file system for its JNDI namespace. Every JNDI lookup performed in the web application is translated into a file 1/0 operation， which results in very poor performance. 
Which J2EE pattern can help with this performance issue？（）

A Company.com developer is designing a multi-tier web application and discovers a need to hide the details of establishing and maintaining remote communications from the client. In addition， because the business and resource tiers are distributed， the application needs to minimize the inter-tier network traffic related to servicing client requests. 
Which design patterns， working together， address these issues？（）

A Company.com 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 are NOT finalized. Any changes to the session bean API directly impacts the development of the presentation tier. 
Which design pattern provides a means to manage the uncertainty in the API？（）

A Company.com developer chooses to avoid using SingleThreadModel but wants to ensure that data is updated in a thread-safe manner. 
Which two can support this design goal？（）