Last week Javablogs.com top 10

Web Services No Better Than CORBA?

Is your UML Composition French or American?

Si l'agrégat est détruit (ou copié), ses composants le sont aussi.

Composition [...] is exactly like Aggregation except that the lifetime of the 'part' is controlled by the 'whole'. This control may be direct or transitive. That is, the 'whole' may take direct responsibility for creating or destroying the 'part', or it may accept an already created part, and later pass it on to some other whole that assumes responsibility for it.

Are UML Aggregation and Composition Good Concepts?

• Aggregation is strictly meaningless ; as a result, I recommend that you ignore it in your own diagrams .If you see it in other people's diagrams, you'll need to dig deeper to find out what they mean by it . Different authors and teams use it for very different purposes.
• Composition is a good way of showing properties that own by value, properties to value objects (page 73), or properties that have a strong and somewhat exclusive ownership of particular other components.

• B is a client of A if every object of type B may contain information about one or more objects of type A.
• B is an heir of A if B denotes a specialized version of A.

SOA and B. Meyer

While rereading parts of Object Oriented Software Construction from B. Meyer, I still find valuable information I overlooked. In the part about functional decomposition where he argues pro and cons of top-down / bottom-up approaches, he has the intuition of the current SOA hype. By showing that

Real systems have no top.

He suggests that the only way to build complex software is through a service oriented architecture. Of course SOA is a very old concept. Meyer example of Operating Systems is a fine one.

Another interesting remark is his object motto to design an object oriented system:

Ask not first what the system does Ask what it does it to!

Tired Of 'My 10 Best XXX' Blog Posts

Bilinear Gaussian Lanczos? Downsampling!

• mplayer: advises bilinear for quality and describes artifacts for each algo
• a blogger: advises lanczos. This links shows pictures produced by each algo.
  
• digital image interpolation: seems to have a preference for bicubic, what photoshop uses.
• videohelp: tested various algorithms and think Bicubic spline is the best.

• wikipedia lanczos
  
• wikipedia bilinear

Getting Started With DOM, XOM, DOM4J by Parsing an RSS Feed - An Experience Review

SAXReader reader = new SAXReader();
Document doc = reader.read(response);
Collection posts = new ArrayList();
List entries = doc.getRootElement().elements("entry");
if (LOG.isDebugEnabled()) 
{
        LOG.debug("found "+entries.size()+" entries");
}
for (int i = 0; i <entries.size();i++)
{
        Element entry = (Element) entries.get(i); 
        Map m = new HashMap();
        for (Iterator it = entry.elementIterator();it.hasNext();)
        {
                Element detail = (Element) it.next();
                String name = detail.getName();
                if (name.equals("link"))
                {
                        m.put("link",detail.attribute("href").getValue());
                }
                else if (name.equals("content"))
                {
                        m.put("content",detail.asXML());
                }
                else
                {
                        m.put(name,detail.getTextTrim());
                }
        }
        
        posts.add(m);                   
        if (LOG.isDebugEnabled())
        {
                LOG.debug("found="+m.get("title")+", url="+m.get("link"));
        }
}

Bad JDK Design Example

Have you ever used the Authenticator class? It is standard since JDK 1.2. This allows you to establish authenticated HTTP requests. OnJava has an in-depth article presenting it. Now here is my story about it.

The other day I just wanted to do that a simple authenticated HTTP request. You would expect it to be very simple to do in the modern internet world.

It is actually not very difficult to do, by hand, a JavaWorld article presents this way. Unfortunately it uses internal JDK sun classes for Digest and I am uncomfortable to use that since it is not guaranteed to work on any JVM. So I have to download jakarta commons-codec to just do a simple authenticated HTTP request. I really wonder why some of those codecs are not in the JDK (not as sun.* classes but as java.* classes).

When I read that it was possible to do it a standard way in JDK 1.2, I was excited. I was wrong. Not only you have to extend a class (ok, implementation is faily simple) that adds in my mind unnecessary clutter, but you are forced to have only 1 Authenticator at a given time (and this Authenticator scope seems much wider than just securing HTTP connection). What about server programs dealing with different credentials?

So I am left downloading jarkata httpclient library that is more powerful and easier to use than hand coded digest authentication (that anyway needs common codecs) just to have HTTP authentication the way it should be done.

Current Popular Subjects In Java Blogs

Based on my blogs entries and success of other blog entries, I present the current trendy subjects and the not trendy ones:

In:

• Design Patterns
• Ruby on Rails
• EJB (bashing)
• RSS
• Spring
• Hibernate
• Javascript and AJAX
• Java Virtual Machine

Out:

• RMI
• Portal
• Jini

Neutral

• JDK 5 features

As you can see most of the popular stuff is fairly common, not that new. I will do a finer, less common, analysis later if I have time.