Learn About Sun Certified Associate for the Java Platform

  By Certification Magazine —

References:
Controlling program flow: The Java for loop construct
Java Programming with J2SE 5
Operators and Flow Control in Java

Controlling program flow: Selection statements in Java
Java Programming with J2SE 5
Operators and Flow Control in Java

Objective: Java Platforms and Integration Technologies.
SubObjective: Describe at a high level the benefits and basic characteristics of RMI.

Single answer, multiple choice.

Which statement is true regarding Remote Method Invocation (RMI)?

A.    RMI uses the same port to communicate between client and server.
B.    RMI uses low-level sockets to invoke remote machines.
C.    RMI is an example of the client/server model.
D.    RMI isolates clients from servers by a well-defined encapsulating interface.

Answer:
D

Tutorial:
RMI isolates clients from the server by a well-defined encapsulating interface. RMI provides a distributed object system to develop distributed Java applications. You can easily develop distributed applications by using RMI instead of using sockets for the same purpose. RMI does not design a protocol to communicate between client and server. RMI defines and implements the remote interface, develops client/server applications, generates stubs and skeletons, compiles the server and client, and starts the RMI registry.

RMI does not use any port to communicate between client and server. In RMI, a client sends a message to an object that interprets the message to decide what to do and which service to perform. A client/server model uses ports to communicate between client and server.

RMI does not use low-level sockets to invoke remote machines. RMI isolates the client from the server by a well-defined encapsulating remote interface. A client/server model uses low-level sockets to establish communication between client and server.

RMI is not an example of the client/server model. RMI is an example of a distributed object-based system. In the client/server model, a client interacts with the server by using low-level sockets and the same set of protocols. RMI uses a distributed object-based system to establish communication between client and server.

References:
Distributed Java Programming with RMI and CORBA
Java.sun.com
http://java.sun.com/developer/technicalArticles/RMI/rmi_corba/

Objective: Client Technologies.
SubObjective: Describe at a high level the basic characteristics of servlet and JSP support for HTML thin-clients.

Multiple answers, multiple choice.

Which statements are true regarding servlets and Java Server Pages (JSP)? (Choose two.)

A.    During the translation phase, JSP pages are converted to a servlet source.
B.    During the translation phase, servlets are converted to JSP pages.
C.    Servlets and JSP pages are compiled into class files.
D.    Servlets, not JSP pages, are compiled into class files.
E.    The translation phase is carried out each time a Web server receives an incoming request for the JSP page.
F.    The translation phase is carried out each time a Web server receives an incoming request for the servlet page.

Answers:
A, D

Tutorial:
The following statements are correct regarding servlets and JSP:

* During the translation phase, JSP pages are converted to a servlet source.
* Servlets, not JSP pages, are compiled into class files.

During the translation phase, JSP pages are converted to a servlet source, and then the converted servlet code is compiled into a class file. The translation phase is carried out by the JSP engine.

The translation phase does not convert the servlets to JSP pages. The translation phase is carried out by the JSP engine, which converts JSP pages to a servlet source.

Servlets and JSP pages are not compiled into class files. The JSP engine converts JSP pages to servlets, and the converted servlet code is compiled into a class file.

The option stating that the translation phase is carried out each time a Web server receives an incoming request for the JSP page is incorrect. The translation phase is carried out for the first time when it receives an incoming request for the JSP page.

The option stating that the translation phase is carried out each time a Web server receives an incoming request for the servlet page is incorrect. The JSP engine translates JSP pages to servlets. Additionally, the translation phase is carried out for the first time when it receives an incoming request for the JSP page.

References:
Servlets and JSP Pages Best Practices
Java.sun.com
http://java.sun.com/developer/technicalArticles/javaserverpages/servlets_jsp/