ch14 - 14 Networking Issues CERTIFICATION OBJECTIVE...

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14 Networking Issues CERTIFICATION OBJECTIVE Understand Networking Issues
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2 Chapter 14: Networking Issues CERTIFICATION OBJECTIVE Understand Networking Issues It is better to know some of the questions than all of the answers. –James Thurber Good questions outrank easy answers. –Paul A Samuelson If you don’t ask the right questions, you don’t get the right answers. A question asked in the right way often points to its own answer. Asking questions is the ABC of diagnosis. Only the inquiring mind solves problems. –Edward Hodnett Clever as you are, I bet you’ve figured out where this is heading…the Developer exam is about you figuring out solutions to the problem/specification you’re given as your assignment. So, any attempt on our part to offer suggested potential solutions would, in our humble opinion, be defeating the whole point of the certification. However, given that this is a book about preparing for the exam, we can offer you questions. Things to think about. But we will start with a briefing on the core technologies involved: Serialization, Sockets, and RMI. There’s far more to learn about these than we could possibly say here, so we’re not even going to attempt to give you a crash-course. We’re assuming that you’re familiar with the technologies, and that you’ll do whatever research and experimentation you need to learn to use them correctly. We will, however, do a simple review and then look at issues you’ll need to consider when you build your project. RMI and Sockets As of this writing, the Developer exam expects you to know about networking. Well, not just know but actually develop a network server that allows remote clients to get information from a database (which you will also write). Normally, building a simple network server presents you with two choices: RMI or Sockets. If your assignment asks you to make a choice, rest assured that there is not one right answer . You will need to think through the tradeoffs, make a choice, and document your decision.
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One simple way to look at the difference is this: Sockets are low-level, RMI is high-level. In other words, RMI is a higher-level system that uses Sockets underneath. Whichever you choose, you’ll need to be very comfortable with it, and you’ll need to justify your choice. Serialization Somehow you’re going to have to move a client request —made on one machine— across a wire to another machine. For your assignment, that “machine” might be only a virtual machine running on the same physical computer, but the Big Issues are the same whether the two machines (the client and the server) are on the same physical box or not. Two JVM’s might as well be on two different boxes, with one key exception—the classpath. If two instances of a JVM are started on the same computer, they may well have access to the same stuff , and sometimes that masks a problem with your application. So, whatever you do, test test test on two different physical machines if you can. What form is the client request? Well, remember from Chapter 10 when we
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This note was uploaded on 09/17/2009 for the course CMPE 126 taught by Professor Gpour during the Fall '07 term at San Jose State.

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ch14 - 14 Networking Issues CERTIFICATION OBJECTIVE...

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