Recently in Software Category

I'm going to the World tour: North America - Joel on Software. If anyone wants to tag along with me, just register and let me know. It is free!

I'm still waiting for someone to come up with a good use case for Twitter in the Enterprise. Monthly status reporting comes to mind. If I can Twitter everything I do throughout the day and then come back later with some tool to help build my monthly status report...I think that could be useful. But that is a stretch.

It was Twittervision that started this post. I'm not sure how much of my life I have wasted staring at this page but the time (measured in minutes) was still way too much!

Java has a robust and flexible security framework to control many aspects of a running application. Blocking System.exit() is one of those fined grain things that can be easily controlled with a SecurityManager. But why? If you don't have control over the entire code base (e.g. a third party library) then to make sure your app will keep on running it may just be something you have to do.

    final SecurityManager securityManager = new SecurityManager() 
        {
            public void checkPermission(Permission permission) 
            {
                if ("exitVM".equals(permission.getName())) 
                {
                    throw new SecurityException("System.exit attempted and blocked.");
                }
            }
        };
    System.setSecurityManager(securityManager);

From Mark comes a couple of useful sites listing common database connection strings

• ConnectionStrings.com
• SQLStrings.com

Charlie sent this to me earlier this year and I read it again tonight. Character Encoding when doing Java web development isn't easy and this article spells out what needs to be done when dealing with non-Western languages.

• UTF-8
• UTF-8
• UTF-8
• ...

There was an interesting piece in a recent Java Lobby Newsletter on Java IP Caching. The basic story goes something like this. Two servers each running a Java Process are communicating with each other. Server #1's IP Address changes and Server #2 will only reconnect after a JVM restart.

Digging into the javadoc for InetAddress makes it real easy to explain this behavior. And I'll be the first to admit that I had no idea this was the default behavior. Java's default is to cache IP addresses!

Java's IP caching behavior can be controlled by two system properties:

networkaddress.cache.ttl (default: -1) Indicates the caching policy for successful name lookups from the name service. The value is specified as as integer to indicate the number of seconds to cache the successful lookup. A value of -1 indicates "cache forever".

networkaddress.cache.negative.ttl (default: 10) Indicates the caching policy for un-successful name lookups from the name service. The value is specified as as integer to indicate the number of seconds to cache the failure for un-successful lookups. A value of 0 indicates "never cache". A value of -1 indicates "cache forever".

Remember this the next time you are playing Java Trivia, or if you want to be really devious, put this on a interview questionairre.

Every introductory programming book begins with a "Hello, World!" program, but this Louisana Tech site takes that concept to the extreme. Almost 200 different examples using 200 different languages.

Sites like this don't make me miss college. I can't believe I had a whole semester of Lisp and Prolog.

Lisp

(DEFUN HELLO-WORLD ()
                  (PRINT (LIST 'HELLO 'WORLD)))

Prolog

hello :-
printstring("HELLO WORLD!!!!").

printstring([]).

printstring([H|T]) :- put(H), printstring(T).