When you deploy a web application in a JavaEE application server, it usually consist of a .war archive. Sometimes, the web application needs some configuration parameters. The most common way to do this is to have <context-param> in web.xml. That is simple and works fine except that the web.xml file needs to be inside the .war archive. This makes it inconvenient to change a configuration parameter since you have to repack the .

When you install Ubuntu 8.04 (hardy) desktop, you get a lot of packages installed by default. Most users will never use many of these packages, so you end up with a lot of unnecessary packages. Most of these packages are harmless and only waste disk space when not used. However, some packages can actually affect the system in a negative way, such as draining resources (other then disk space), and you should consider removing them if you not actively use them.

(This post has been edited since it was first published.) I wondered why you usually mount / (the root file system) read-write in Linux and decided to do some experiments to find out if it is possible to have it mounted read-only. So why do you want to do that? Perhaps you have the root file system on a read-only media, such as CD-ROM. Or on a writable media which can only handle a limited number of writes, such as a CD-RW or flash disk.

(This article has been edited since it’s first publication.) In Linux, and other UNIX-like systems, you have to be root (have superuser privileges) in order to listen to TCP or UDP ports below 1024 (the well-known ports). This port 1024 limit is a security measure. But it is based on an obsolete security model and today it only gives a false sense of security and contributes to security holes. The port 1024 limit forces you to run all network daemons with

Unintentional catching of runtime exceptions Unfortunately, checked exceptions in Java are defined as all Exceptions which are not RuntimeExceptions. This makes it a bit tricky to catch all checked exceptions (but not any runtime exceptions). It would have been better if checked exceptions were defined by a specific class, CheckedException, but that’s too late to change now. Too often Java programmers catch all exceptions when they really only should catch checked exceptions.

When the built-in HDD controller in my computer broke down, I decided to try running my computer diskless with LAN booting. I use Ubuntu Linux 6.10 and I have another computer with a large HDD acting as server. I followed the instructions in this HOWTO. I changed MODULES to “netboot” in initramfs.conf and I had to add a driver for my network adapter to the modules file in the initramfs configuration.

I’m currently developing my first AJAX based web application. The goal is to have a pure AJAX application, i.e. never reload the entire page, use only background XMLHTTPRequest to contact the server. My observations so far is that it is possible to do most of the application logic I need. But the performance of Javascript execution in the browser is a big obstacle. The application is centered around a list of data items in a scrollable area.

Java Remote Method Invocation (RMI) contains a tool rmiregistry to run a stand-alone remote object registry. According to the RMI tutorial, rmiregistry is normally used in an RMI application. I wonder why. It’s actually almost as simple to run the remote object registry within the RMI server. You only have to use java.rmi.registry.LocateRegistry#createRegistry(int port) method like this: Registry registry = LocateRegistry.createRegistry(port); registry.bind("Foo", stub); Here is a complete example. This is also more efficient since you don’t have to start a separate JVM for the registry.