Einträge von Martin Schaefer

Did you ever run into the problem of too many open files on Mac OS X? This is not very surprising, because when you open a new shell, you can see that the limit of open files for this process is set to a not very high value:

andromeda:~ martin$ ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) 6144
file size               (blocks, -f) unlimited
max locked memory       (kbytes, -l) unlimited
max memory size         (kbytes, -m) unlimited
open files                      (-n) 256
pipe size            (512 bytes, -p) 1
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 266
virtual memory          (kbytes, -v) unlimited

After installing "Java for Mac OS X 10.5 Update 4" I experienced a lot of trouble with NetBeans, e.g. I could neither create a new project, nor a new Java class in an existing project.

What helped, was using JDK 1.6 instead of JDK 1.5. To do this edit the file netbeans.conf and change apply this change:

#netbeans_jdkhome=/System/Library/Frameworks/JavaVM.framework/Versions/1.5/Home
netbeans_jdkhome=/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home

Recently, in a customer project, we needed some Ajax functionality in an otherwise Struts-based application. For ease of communication we wanted JSON as the protocol between GUI and backend. Due to project constraints however, we were restricted to a Java 1.4 code-base and could not introduce new third-party libraries, otherwise we would have probably considered Json-lib, which we had used successfully in the past, or possibly Jersey's ability for JAXB-based JSON serialization. Being trapped in this emergency situation, we did what we usually try to avoid: We re-invented the wheel and wrote SOS, which very conveniently also translates to Simple Object Serialization. The outcome was a low-footprint, easy-to-use but very flexible framework for Java object serialization for JSON, XML and other data bindings. This article explains the usage of the SOS library, but more importantly it offers an insight in object serialization in general.

The Weblogic application server encrypts passwords, e.g. in JDBC URLs, in it's configuration files, when the files are first read. If you want to use the same security mechanism in your application, or if you forgot a password: Here is how the encryption / decryption is done.

Wer Feiertage im Mac iCal oder auf dem iPhone vermisst, der kann im iCal z.B. den Kalender von icalx.com abonnieren. Schulferien für alle Bundesländer findet man bei schulferien.org.

Die neuen Kalender lassen sich dann über iTunes mit dem iPhone synchronisieren.

If you are working in the Java / J2EE environment, you should not miss the great new Java news feed aggregator by Oliver. It gives you a neat overview of the latest Java gossip and development aggregated from over 30 RSS feeds of your choice on one single page.

Having some trouble with Google's indexing of our blog, I took a look at their robots.txt yesterday (Halloween by any chance).

Vor kurzem hat mich ein Kollege auf das Initialization On Demand Holder Idiom aufmerksam gemacht, eine interessante Variante für thread-sichere Singletons bei Lazy Initialization, die ich natürlich nicht für mich behalten will. Hier also eine kurze Betrachtung des alt-bekannten Singleton-Patterns.