Solving the 8 Queens puzzle with bit operations

The 8 queens puzzle is a classic (and quite fun to solve) toy problem: place eight queens on a chess board in such a way that all queens could fully move without being obstructed by any other queen. While without practical applications, it illustrates a number of aspects of designing algorithms and implementing programmes: - … Continue reading Solving the 8 Queens puzzle with bit operations →

Connecting with Eclipse to a remote SVN repository via SSH on non-standard ports

Having been bitten by this for the n-th time (with n being subjectively a large integer), I'm noting this down for the following generations to benefit; and hopefully to save myself some fiddling next time it happens. Without further ado: How to connect with SVN to a remote repository that is running on a non-standard … Continue reading Connecting with Eclipse to a remote SVN repository via SSH on non-standard ports →

Ubuntu 12.10 64bit on the HP ProBook 4720s

With the trusty HP ProBook 4720s refusing to give up it's time to give the new Ubuntu 12.10 a spin. After having tried out the 11 and the 12 series with mixed feelings [1], [2]. Installation Installation of the live CD image on a USB stick was easy and without any problems. The system booted … Continue reading Ubuntu 12.10 64bit on the HP ProBook 4720s →

ORA-12519 connection errors and JUnit tests

In my current project we are running hundreds of JUnit tests which load a Spring application context, a Hibernate session factory and a c3p0 pool. The entire suite runs fine everywhere except a single machine where some tests will occasionally fail with a "ORA-12519, TNS:no appropriate service handler found" on an Oracle XE. The cause[1,2] … Continue reading ORA-12519 connection errors and JUnit tests →

The jsp-file directive

The jsp-file directive in web.xml allows mapping of JSPs to concrete URLs: <servlet> <servlet-name>My Hidden Page</servlet-name> <jsp-file>/mydir/foo.jsp</jsp-file> </servlet> <servlet-mapping> <servlet-name>My Hidden Page</servlet-name> <url-pattern>/hidden</url-pattern> </servlet-mapping> Shame on me, I didn't know about this. As seen here: http://mail-archives.apache.org/mod_mbox/tomcat-users/200107.mbox/%3CPine.BSF.4.21.0107271807540.7976-100000@localhost%3E