Java News Brief (JNB): Monitoring and Management with J2SE 5.0
This month's Java News Brief (JNB) talks about Monitoring and Management with J2SE 5.0. It is written by yours truly, based on the OCI internal Java lunch I did 26 days ago.
The inspriation came a few days before J2SE 5.0 was released, when I was looking at the latest beta. What do I do when I inspect a JDK beta? Well, First of all, I did some thing like this:
[weiqi@gao] $ cd $JAVA_HOME/bin; ls appletviewer jarsigner javaws jstack native2ascii serialver apt java jconsole jstat orbd servertool ControlPanel javac jdb jstatd pack200 tnameserv extcheck javadoc jinfo keytool policytool unpack200 HtmlConverter javah jmap kinit rmic idlj javap jps klist rmid jar java-rmi.cgi jsadebugd ktab rmiregistry
I then did a ls in $JAVA_HOME/doc and saw a file named (something like, I don't recall exactly) blockdiagram.html. It contained an HTML table version of the Java Block Diagram. Somehow the word "Management" just jumped out of the HTML table at me. And I said, I have to learn what this is all about.
I can think of numerous situations in my past Java projects where something like this would be very useful, either in development or in production. I hope the article will be helpful for someone.
Like always, please do subscribe to the JNB list (the form is at the upper right corner of the JNB page). You will receive future JNB articles in email.
Oh, one more thing, have you ever read the file $JAVA_HOME/THIRDPARTYLICENSEREADME.txt?
Happy Chinese New Year
Today, Wednesday February 9, 2005, is Chinese New Year, Year 4702 the Year of the Rooster.
To my Chinese and Asian friends and colleagues, a Happy and Prosperous New Year. May all your wishes come true. May all your endeavers be successful.
To everyone else, I have some explaining to do.
The Chinese Calendar
The Chinese calendar is based on the movements of the moon and the sun. Here's how it works. A month starts with a new moon. Since the moon circles the earth in 29.5 days, the length of the month alternates between 29 and 30 days. It always goes 30, 29, 30, 29, 30, 29,... forever.
A year is 12 months. A mornal year has 354 days, 11 days short of a solar year. To catch up with the solar year, every so often (2 or 3 years) there will be a leap month. It's always a 29 day month, making a 383-day year.
Luckily there is a 19 year cycle in the movement of the moon and the sun. So the two calendars goes back in synch every 19 years. So February 9th was also the Chinese New Year in 1986 and will be again in 2024.
Solar Positions
Whereas in the Western world, we notice the four solar stations: Winter and Summer solstice, and the String and Autumn equinox, and call them the "start" of the seasons, in Chinese calendar, we observe 24 such stations: the four just mentioned, plus 20 more, roughly once every half a month. The four just mentioned are considered the "middle" of the season. 12 of the stations are major, the other 12 are minor. The four mentioned above are major ones. It always goes major, minor, major, minor,...
Every month contains a major and a minor. In Western calendar, these fall on roughly exact dates every month, the 6th and 21st from January to June, the 8th and 23rd from July to December. Since the length of the months are so arbitrary in and because of the leap day, the above estimates may be off by as much as 2 days.
In Chinese calendar the solar stations drifts later and later every month since a month is only 29 or 30 days. The month when one of them drifts off the end of the month will contain only one of the solar stations. In such a month, the only solar station in the month is on the 15th. If it is a minor station, the month is a leap month. This always happens on a 29 day month.
Start of the Year, The Animals
The start of the Chinese year is the second new moon after the Winter solstice. It's always between January 23rd and February 22nd.
This has important implications. If you ever went to a Chinese restaurant and read the placemat that has the "Chinese Zodiac" printed on them, you no doubt know your animal sign. Well, if your birthday is before January 23, you belong to the animal sign of the previous year. You don't want to get who's compatible with you wrong, do you?
What's Good About This
Regularity. Solar eclipses always happen on the first of the month. Lunar eclipses always happen on the 15th of the month.
No political influence. Explain why August has 31 days.
Good rough estimates. Raise your head and look for the moon. You can deduce the date of the month quite easily by the phase of the moon.