Network programming in Java (DCU specific)

In DCU, HTTP requests to remote sites (outside DCU) are meant to go through one of the DCU proxy servers.

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How to make your Java programs use the DCU proxy

You may need this on Windows in DCU.
You may or may not need this on Linux in DCU.

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Possible solution - Insert in code

You can put something like this in your code before you make HTTP requests:

 
System.setProperty( "proxySet", "true" );
System.setProperty( "proxyHost", "proxy.dcu.ie" );
System.setProperty( "proxyPort", "8080" );

The problem is then your code won't work outside DCU (e.g. if you run the program at home).

• System class

• Networking
  • Networking Properties
• Networking tutorial
  • Setting the Proxy Host

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Better solution - Use Java command-line arguments

A better solution is to leave your code alone and set the proxy via the $ java -D command-line option:

$ java -DproxySet=true -DproxyHost=proxy.dcu.ie -DproxyPort=8080 prog

• How to Connect through a Proxy
• $ java command-line options.

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How to automate the command-line arguments (Windows)

To avoid typing these command-line arguments every time, write a short BAT file to call java with the correct command-line options.
Write the program dcujava.bat:

@echo off java -DproxySet=true -DproxyHost=proxy.dcu.ie -DproxyPort=8080 %*

And then, when outside DCU:

$ java prog (args)

When inside DCU:

$ dcujava prog (args)

And you don't have to change your code.

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How to automate the command-line arguments (Linux)

Write the shell script dcujava:

java -DproxySet=true -DproxyHost=proxy.dcu.ie -DproxyPort=8080 $*

And then, when outside DCU:

$ java prog (args)

When inside DCU:

$ dcujava prog (args)

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Detect IP address

Could figure out automatically (by looking at your IP address) if you are in DCU and if so automatically switch to using the DCU proxy.

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ISP proxy

On some ISPs you may need to change this to go through their proxy.