	CS 580 Client-Server Programming Fall Semester, 2000 Assignment 2 Comments
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Contents of Doc 22, Assignment 2 Comments

References
Student papers


Doc 22, Assignment 2 Comments Slide # 2

Assignment 2 Comments

Names

Use Java Standard name

ClassName
methodName

this_is_not_java_standard

Some Bad habits

file1
file2
flag = getFile( blah)
if (flag) then
   more blah
else
   even more blah
Doc 22, Assignment 2 Comments Slide # 3

Line Wrap

Just say no to line wrap in source code

If you have problem with line wrap in hard copy:

Place the following comment in a file:

//234567890123456789012345678901234567890etc

Make the comment long enough to insure line wrap

Print the file using the commands/printer you use to print your assignments

Determine how many columns you have before you get line wrap

Use a few columns less than that

In your source code files you can place a comment of the max length for a guide

Test out your tabs


Doc 22, Assignment 2 Comments Slide # 4

Threads

This does not start a thread:

Thread test = new Thread();
Test.run()

This does start a thread:

Thread test = new Thread();
Test.start()

But in a server this will do more harm than good:

All threads at same priority
No concurrency
Main thread with accept may have to wait on other threads before it can accept new call

Java threads perform differently on different platforms

Unless you are careful with threads, Java programs do not port well


Doc 22, Assignment 2 Comments Slide # 5

Positional Data

public void main(String[] args ) {
   String port = args[1];
   String file = args[2];
   etc.

Say no to positional data

Error prone
Very hard to modify

For command line arguments use flags:

java Server -p 5555 -f myFile

SDSU Java library makes it easy to do this

Most languages/systems have library code to parse command line arguments!

Learn it and use it!


Doc 22, Assignment 2 Comments Slide # 6

Very Bad Coupling!

File cs325 = new File("cs325");
File cs419 = new File("cs419");
blah
if (value.equals( "Exam1") ) 
   blah
else if (value.equals( "Project 2" ))
   blahs

If the instructor adds a new assignment the program has to be rewritten

The program must be rewritten for every course that uses it

Before the program could be used in a course, the instructor must know the name of every assignment, quiz, project and test


Doc 22, Assignment 2 Comments Slide # 7

Testing

Manual verses Automatic Tests
Manual

Must be run by a person
A person must check the results of a test to determine if the test passed or failed

Automated

Tests can be run by a program
Test results are tabulated by a program

In most cases automated unit tests are preferred over manual unit tests

JUnit test with no asserts are really manual tests

Most people know the mechanics of JUnit

Need to work on test coverage & better tests


Doc 22, Assignment 2 Comments Slide # 8

Logging

Recall that servers

Run for a long time
Are not constantly monitored by humans

Must log

All transactions
All problems

try
   {
   blah
   }
catch (FileException readProblem)
   {
   // no code here
   }

What happens when the exception occurs?

Server does not operate correctly
You have not record of what caused the problem


Doc 22, Assignment 2 Comments Slide # 9

Logging & Debug Statements

try
   {
   blah
   Logger.log("a message");
   System.out.println( "aMessage");
   Blah
   System.out.println( "I made it here");
   }
catch (FileException readProblem)
   {
   System.out.println( "file exception occured");
   }

Sort of works in development, but what happens when you deploy?


Doc 22, Assignment 2 Comments Slide # 10

Use the Logging Debug Statements
When debugging:

SelectiveLogger activeLog = (SelectiveLogger ) ScreenLogger.register();
activeLog.debugOn();

In production:

SelectiveLogger activeLog =
   (SelectiveLogger ) FileLogger.register("fileName");
activeLog.debugOff();

Server Code:

try
   {
   blah
   Logger.log("a message");
   Blah
   Logger.debug( "I made it here");
   }
catch (FileException readProblem)
   {
   Logger.log( "file exception occured");
   }

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