Most of the time you use desktop virtualization, you simply add a virtual hard drive and install a guest operating system (like (K)Ubuntu Linux) in it. But some times – as in my case – you already have another operation system on a partition on your native hard drive. For a mac it’s either via Bootcamp or via something like rEfit enabling you to install a BIOS boot manager like Grub. Since it is kind of uncommon using such an existing partition for desktop virtualization, it is not supported (and documented) so good in the different virtualization solutions.
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Category: Tutorials
Exception Handling for Injection Interceptor
Remember my post “Circular Injection of Util Classes in EJB 3.0“? There I offered a some kind of ugly solution to the circular dependency problem for managed classes in Java EE 5. In a preceding post (Circular Dependencies of Session Beans) I grumbled about the exception handling in jBoss-5.1. It lets you alone with a meaningless error message and you have to guess what the problem is. Unfortunately my own code presented in the former post is even worse, since it logs problems but ignores them. It wasn’t mentioned for productive use, but it was annoying to me, so here is a little tune up adding exception handling and readable error messages.
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Inject CDI beans into Tapestry-5.x e.g. in Jboss-7.0.2-Final
As I explained in “Inject Java EE Beans into Tapestry-5.x“, the AppModule offers a way to configure Tapestry Web Applications directly in Java. In that post, we injected Java EE Beans into Tapestry applications. This time we do the same with Context and Dependency Injection (CDI) Beans. It follows the same procedure. The only difference is the way of looking up a bean. We still use JNDI for a lookup, but this time we retrieve the CDI BeanManager. In a second step we get the bean. For performance reasons we retrieve the bean only once per Thread (see annotation @Scope). It will be cached for subsequent lookups.
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CDI and Transactions e.g. in JBoss-7.0.2
In Java EE applications you are safe to consider that every method in a session bean has an associated transaction, since there is an implicit declaration of the transaction attribute required. If you like to change this behavior you have to configure this proactively by adding the annotation @TransactionAttribute with another value (see enum TransactionAttributeType). Context and Dependency Injection (CDI) does not have such an implicit declaration and no direct container managed support for transactions. But it has a very nice realization of the interceptor concept. This post shows, how to facilitate an interceptor in order to add a transaction to every (or a selection) method in a CDI bean, if it does not already exist. This is the default behavior of required.
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Transaction Handling for Ajax Components in Tapestry-5.x
In “Transaction Handling in Tapestry5” I described, how to configure transactions wrapping a complete page or component render request. The same is necessary (possible) for Ajax components. Besides having less transactions and sharing the first-level-cache for subsequent calls, this realizes the “Open Session in View Pattern” automatically. So you can access the database lazily via getter from an entity, for example, without running into lazy loading exceptions due to the fact that the transaction has been closed and the entities are detached already.
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Inject Java EE Beans into Tapestry-5.x
Tapestry uses it’s own Inversion Of Control (IOC) container. Tapestry pages are not Servlets or Servlet Filter (and not another managed class). Therefore they cannot be used for injection of Java EE Beans. But there is the AppModule, which is conceptual some kind of related to Spring Java Config. It allows to configure the Tapestry application directly in Java. Like everything in Tapestry it has an Adaptive API. Hence you have to follow a naming (signature) pattern for your methods and Tapestry finds them. You don’t have to implement an interface.
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Tapestry-5.3.1 and Jboss-7.0.2-Final
The Java web framework Tapestry 5 has a hot deployment/reload feature, that traverses the classpath, looking for new resources to load. Unfortunately, it is not capable to parse URLs of Jboss’ virtual file system and therefore does not find it’s own core libraries. This issue has been tracked in TAP5-576 and a solution for Jboss-5 and Jboss-6 can be found in the corresponding wiki articles. The same problem remains for Jboss-7. Accidentally the reflective calls to virtual file are restricted. But the solution for Jboss-6.1 does still work. Here is a little tutorial how to achieve this.
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Reversed Scrolling in Ubuntu
If you have installed ‘xmodmap’ you may add the following command in order to have reversed scrolling experience like in OS X Lion:
echo "pointer = 1 2 3 5 4 6 7 8 9 10 11 12" >> ~/.Xmodmap
The next time you start ubuntu gnome desktop it will ask you, whether it should load the xmodmap (you should add the .Xmodmap file). There you go.
Tally Clock
This blog entry shows, how to create a tally clock for your website. Below there is a nice one showing you the current time with tally packs (0-5):
div#tally2-clock {
text-align: center;
/* border: solid 1px #CCCCDD; */
min-width: 0px;
}
div#tally2-clock ul li {
display: inline-block;
}
div#tally2-clock ul li.clock0 {
background-image: url(“http://kingsware.kopv.de/wp-content/uploads/sites/3/2011/08/c0.png”);
width: 32px;
height: 32px;
}
div#tally2-clock ul li.clock1 {
background-image: url(“http://kingsware.kopv.de/wp-content/uploads/sites/3/2011/08/c1.png”);
width: 32px;
height: 32px;
}
div#tally2-clock ul li.clock2 {
background-image: url(“http://kingsware.kopv.de/wp-content/uploads/sites/3/2011/08/c2.png”);
width: 32px;
height: 32px;
}
div#tally2-clock ul li.clock3 {
background-image: url(“http://kingsware.kopv.de/wp-content/uploads/sites/3/2011/08/c3.png”);
width: 32px;
height: 32px;
}
div#tally2-clock ul li.clock4 {
background-image: url(“http://kingsware.kopv.de/wp-content/uploads/sites/3/2011/08/c4.png”);
width: 32px;
height: 32px;
}
div#tally2-clock ul li.clock5 {
background-image: url(“http://kingsware.kopv.de/wp-content/uploads/sites/3/2011/08/c5.png”);
width: 32px;
height: 32px;
}
function setClock2(val, idName) {
var tenthval = ((val – (val % 10)) / 10);
var tenval = (val % 10);
var prefix = “tally2-clock-“;
document.getElementById(prefix + idName + “1”).setAttribute(“class”, “clock” + tenthval);
if (tenval < 5) {
document.getElementById(prefix + idName + "2").setAttribute("class", "clock" + tenval);
document.getElementById(prefix + idName + "3").setAttribute("class", "clock0");
}
else {
tenval = tenval – 5;
document.getElementById(prefix + idName + "2").setAttribute("class", "clock5");
document.getElementById(prefix + idName + "3").setAttribute("class", "clock" + tenval);
}
}
function doTime2() {
var currDate = new Date();
var hour = currDate.getHours();
var minute = currDate.getMinutes();
var second = currDate.getSeconds();
setClock2(hour, 'hour');
setClock2(minute, 'minute');
setClock2(second, 'second');
}
function doInterval2() {
setInterval(doTime2, 1000);
}
function oldAndNew(oldfnc, newfnc) {
oldfnc();
newfnc();
}
if(window.onload != null) {
oldf = window.onload;
window.onload = oldAndNew(oldf, doInterval2);
}
else {
window.onload = doInterval2;
}
Standalone Tomcat with jBoss (2nd Edition)
This tutorial desribes, how to install and configure a standalone Tomcat, so that a deployed webapp can connect to a jBoss and use the authentication of the application server. This method is decoupled from the login module or authentication type (LDAP, Database, …), respectively. It differs from the approach described in Standalone Tomcat with jBoss plus authentication against LDAP, in that it allows for parallel logged in users and it does not need to authenticate to LDAP/Database on both sides, but on the jBoss only.