Interesting Things

I am migrating these to my wiki.

• FA decoding- here is a perfect example of one of the many errors encountered in the free-text entry of area forecasts:

  AIRMET -- mountain obscuration
For Washington, Oregon, California
Mountains occasional obscured by clouds / precipitation / mist / fog. Conditions ending Pilot Station AK [0AK] - 20 miles south of Fortuna CA [FOT] 12 noon PDT (19Z) to 2pm PDT (21Z)

  For some reason the forecaster used zero instead of capital oh for Oakland's abbreviation. The FAA ID zero-AK is indeed Pilot Station, Alaska. My first approach was to make a rule set of common errors like this, but there are too many!

• Postresql vs Mysql:
  • Mysql has roots as a fast, lightweight sql interface to data stored in simple files.
  • Mysql: due to pluggable datastore architecture, lots of FUD going around about de-facto performance: blindingly fast but generally only with non-transactional back end. Must compare apples to apples when looking at other dbs which cannot turn transactions off.
  • MySql was lacking (but may have by now) stored procedure support, sub-query support, view support
  • MySql transactional datastores behave like SqlServer and DB2: writes block reads. In Oracle and Postgres, reads can occur even though pending writes exist in a table.
  • Licensing terms and open source model of mysql: copyright is owned by MySql and they dual license the code, either freely via GPL or paid via a less-restricted, embeddable license. Because the company needs to hold copyright to the entire code in order to release it under different licenses, this limits who can contribue, basically to the handful of FT devs employed by MySql. Postgresql dev is much more open.
• Five-minute port of ssltelnet to Redhat and openssl
• sample EAR with no datasource
• When flying over Niagara Falls this year, I was unable to reconcile the "Niagara Falls Temporary Flight Restriction Area" map with what I was seeing on the ground. The trouble is the only "railroad yard" I saw was up near The Whirlpool. It was only until I looked with Google maps that I found that the "railroad yard" in the diagaram (NE AFD p 263ish) was abandoned and in fact no longer exists.
• In PostgreSQL, the user has to have CREATEDB (as opposed to NOCREATEDB) plus permission to create in the schema in order to create a db.
• On Fedora, in order for JDK 1.4.2 networking to work, we had to tell it not to use IPV6 with the system property java.net.preferIPv4Stack=true

• Servlet links

  • JSR 154 aka Servlet 2.4
  • J2EE 1.3 compat
  • J2EE 1.4 compat
  • Servlet 2.3 and JSP 1.2 are from J2EE 1.3
• IBM abuse of terminology:
  

• Use the {@link #getComponentAt(int, int) getComponentAt} method.
  

• public abstract interface Status {
  // 	Public Constants
  	public static final int STATUS_ACTIVE ;	=0
  	public static final int STATUS_COMMITTED ;	=3
  	public static final int STATUS_COMMITTING ;	=8
  	public static final int STATUS_MARKED_ROLLBACK ;	=1
  	public static final int STATUS_NO_TRANSACTION ;	=6
  	public static final int STATUS_PREPARED ;	=2
  	public static final int STATUS_PREPARING ;	=7
  	public static final int STATUS_ROLLEDBACK ;	=4
  	public static final int STATUS_ROLLING_BACK ;	=9
  	public static final int STATUS_UNKNOWN ;	=5
  }
  

• Explain dynamic sql in Oracle 8 with NVARCHAR2 variables requires TRANSLATE(:4 USING NCHAR_CS)
• Debug Xerces with -Djaxp.debug
• To enable IBM jvm debugging, you have to modify the bootclasspath:
  java -Xbootclasspath:/cvs/jvm/IBMJava2-131/lib/tools.jar:/cvs/jvm/IBMJava2-131/jre/lib/rt.jar
-Xdebug -Xrunjdwp:transport=dt_socket,address=8100,server=y,suspend=n
• iptables rules for filtering aim ads

  iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 205.188.165.185 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 205.188.165.57 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 205.188.165.121 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 205.188.165.249 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 152.163.208.121 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 152.163.208.185 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 152.163.208.249 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 152.163.208.57 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 64.12.174.57 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 64.12.174.121 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 64.12.174.185 -j REJECT iptables -A OUTPUT -o $EXTERNAL_INTERFACE -d 64.12.174.249 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 205.188.165.185 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 205.188.165.57 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 205.188.165.121 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 205.188.165.249 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 152.163.208.121 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 152.163.208.185 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 152.163.208.249 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 152.163.208.57 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 64.12.174.57 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 64.12.174.121 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 64.12.174.185 -j REJECT iptables -A FORWARD -o $EXTERNAL_INTERFACE -d 64.12.174.249 -j REJECT