For anyone who has subscribed to this blog or follows it regularly, please come on over to my new self-hosted blog, where I’ll continure the thread and maybe add some more.  I haven’t found a way to redirect my WordPress.com RSS readers automatically to the new site.

Here it is: dobesland.com

As an old Objective-C fan, I was surprised and amused to read about Objective-J, an object-oriented enhancement to javascript including the old OpenStep (well, GNUstep) API’s.  It’s for a similar purpose as GWT, I suppose.

Cappuccino is built on top of standard web technologies like JavaScript, and it implements most of the familiar APIs from GNUstep and Apple’s Cocoa frameworks.

http://www.webappers.com/2008/09/06/cappuccino-web-framework-in-objective-j/

Not sure what to think of this, but hey, Objective-C was cool so why not Objective-J?

When I first heard about Google Chrome my reaction was “Huh?  Another browser to support?”  However, now that the browser has been released I’ve realized why they bothered.  It’s simply the fastest and best looking browser for Windows right now.  I love the look of it, but even more so I love the speed of it!

I am the developer and user of online accounting software for small businesses written using the Google Web Toolkit (GWT).  When I tried our software in Chrome out of curiousity I was astounded to see how fast it was – first, it loads regular web pages as fast or faster than Opera, my old favorite browser.  Second, it loads and runs my accounting application much faster than I’ve ever seen before!

I was quite intrigued by this so I went and actually read the comic Google released about Chrome to find out more.  Apparently they contracted a company to write a new javascript JIT engine to run javascript, which they’ve apparently done a great job of!  And, it’s open source.

Hopefully Safari, Firefox, Opera, and (if we’re really lucky) Internet Explorer will take advantage of their Javascript engine so we can all enjoy faster Web 2.0 DHTML applications.

I’ve recently switched my hosting from single self-managed dedicated server at 1and1 to a managed virtual private data center on “the cloud” with ENKI consulting.  The benefits of the grid computing technology they are using are numerous, including improved security, automatic redundant failover, and great mangement and monitoring tools.

As part the improved security, each component of the system (webserver, database) runs in its own virtual machine, and only has the bare minimum access to files and other services that it needs.  When setting these up, I have to ssh to each component individually.  Access is provided to the seperate components by having a different ssh port on one externally available IP address.

Typing in “ssh -p 7543 dobes@543.32.54.32″ with varying port numbers, usernames, and IP addresses can be a pain.  Today I found out that you can specify aliases in your ssh configuration that set up connection options, hostnames, and IP addresses.

Simply edit ~/.ssh/config and put sections like:

Host glassfish-live

HostName 543.32.54.32

Port 7543

User dobes

Compression on

IndentityFile  ~/.ssh/id_rsa_live

Each time ssh finds “Host” it treats the settings that follow as specific to that host, and “HostName” tells it the “real” host to connect to.  These aliases are a great shortcut and I was so pleased to discover them I couldn’t wait to share them.

Hope you make good use of this one …

I’ve been dealing with this for a while now trying to figure out why, when using my online accounting software, users sporadically get a StatusCodeException when sending requests to the server.  I finally this week figured out what was going on; glassfish was dropping the connection or sending bad responses occasionally because it doesn’t behave in the was that the mod_proxy modules of these webservers expect it to.

Originally I was running lighttpd and I was thinking this might be a bug in lighttpd, so I eventually switched to apache.  Once I was running apache I got a much more verbose error – instead of just a plan 500 or 502 status code I got a message.  I googled that error message plus glassfish and found the solution.

I thought I’d share it here so that future searchers who are using lighttpd or apache will have more places to find the answer.

To fix the issue, add:

SetEnv force-proxy-request-1.0 1

SetEnv proxy-nokeepalive 1

To your apache httpd.conf.  I don’t know what the equivalent fix for lighttpd is, if there is any.

From this fix, it appears that glassfish is misbehaving in some way in relation to being behind a proxy, but I don’t what way that is and I’m just glad I fixed this mysterious problem!

If any of you readers have more information about this issue, please comment!

I recently ran into an issue where a class I share between GWT and server-side java code would really, really benefit from being able to accept or return a Calendar object.  However, GWT doesn’t come with a Calendar class, so the appeared to be impossible.  Or, is it?

After some digging around in the documentation I discovered that GWT provides a directive in their module XML called “super-path”.  By adding something like:

<super-path path=”gwtonly”/>

To my *.gwt.xml file, I can tell GWT to load my own emulation classes when compiling javascript; when running in hosted mode, it will use the Java implementation of these classes.

Here’s an example source tree structure for this:

• myapp/

• myapp/MyApp.gwt.xml
• myapp/client/*.java
• myapp/gwtonly/java/lang/Calendar.java
• myapp/gwtonly/java/lang/GregorianCalendar.java

In my Calendar and GregorianCalendar I just define exactly the methods and constants that I need for the code to *compile*.  Note that I’m not planning to actually use these classes;  I could, but the implementation is so minimal it would cause confusion for future programmers who wouldn’t understand why the calendar class behaved so weirdly in client-side code.

However, now I discovered that I have errors in my code when I compile.  Huh?  In eclipse it’s happy but in GWT it says something like “package declaration should be java.lang, but it should be myapp.gwtonly.java.lang”.  Oh, I see, it’s really using that package as a source folder, not as a package.  So, I fix it by changing the “package” declaration at the top to “java.lang”.  Guess who is unhappy now?  eclipse!  The two compilers can’t see eye-to-eye any more.

There is a solution – eclipse has a feature called “exclusion filters”.  I open the “Java Build Path” panel for the project, find the source folder that has all of this in it, and add an “exclude” filter for myapp/gwtonly/.  Now eclipse just ignores those files; I’ve lost a lot of eclipse java features as a result, but at least it works.

All this is part of my work on simple online accounting software, if you’re a consultant, entrepreneur, virtual assistant, bookkeeper, or freelancer go check it out.

After much frustration I finally figured out how to get my existing private key and certificate into glassfish’ keystore so that it worked.  You see, I did something that the makers of java keytool never thought of – I didn’t use keytool to generate my private key!  Unfortunately, keytool doesn’t allow you to import an existing private key, you can only import the certificates (e.g. the public keys).  It took me a few hours to figure out this bit of idiocy, and kudos to this blog post for enlightening me:

Import private key and certificate into Java Key Store (JKS)

I followed his steps to convert the keys into DER format and generate a keystore file from that.  Then I used keytool’s -importkeystore command to merge that new keystore into glassfish’ keystore, and used keytool to change the key’s password to match the keystore’s password.  Fixed!

I’ve been working for almost a year now on my own Web 2.0 SaaS Accounting Software startup.  As I’m getting closer to a real market launch I’m learning a lot about the business and marketing side of things (yeah, it takes more than technology).  In that vein I’ve decided to try and gather some data about the market I’m thinking about that I can use to develop a revenue model and marketing strategy.

I hope that many of the readers passing through this blog will be willing to take a survey about their accounting needs and practices so I can figure out if I’m going in the right direction.

Here’s the link: You And Accounting Survey

I know you would do it out of kindness to help my fledgling startup, but there’s another perk – you’re also entered into a draw for a $200 gift certificate at Amazon!

Thanks in advance!

Let’s say that power means “the amount of work done per unit of time.”

It could be said that development is made up of these types of work (and much more):

• Design
• Prototyping
• Learning the Language
• Writing New Code
• Understanding Old Code
• Refactoring
• Debugging New Code
• Debugging Old Code
• Reading Other People’s Code
• Debugging Other People’s Code
• Making Use of Libraries
• Making Libraries
• Refactoring Libraries
• Updating to Refactored Libraries

JavaScript, Python, and dynamic languages in general do well in some of these areas but not others

For example, “Writing New Code” seems to be the area of focus for advocates of dynamic languages, who see a big power gain there, and possibly in “Learning the Language”.

It seems to me, however, that Java is just as powerful as dynamic languages in the other categories, and much more powerful if you use an IDE with support for completion and refactoring.

That is to say, I can get a hell of a lot more refactoring done per unit of time in Java using Eclipse than I’ve seen in any other language.

This post was inspired this other blog post that compares using GWT to Javascript: http://blogs.pathf.com/agileajax/2007/05/angry_at_gwt.html

Lately the “Don’t Repeat Yourself”, or DRY, principle is quite popular. I like it quite a bit myself. However, when using ejb3unit, I found that I had to maintain two lists of persistence classes – one for ejb3unit, and one for the java persistence system. Today I finally decided to address this problem, and I haven’t regretted it!

I wrote a method which finds and parses my META-INF/persistence.xml and returns an array of classes from it. I can pass this to the constructor of the BaseSessionBeanFixture when I create the test case object.

Here it is:

 public static Class[] getDbClasses() {

        URL[] persistenceUnits;

 	try {

 		persistenceUnits = Classpath.search("META-INF/", "persistence.xml");

 	} catch (IOException e) {

 		throw new Error(e);

 	}

        Set> classes = new HashSet>();

        for (int i = 0; i < persistenceUnits.length; i++) {

            URL url = persistenceUnits[i];

    		try {

             nu.xom.Builder b = new nu.xom.Builder(false);

             Document d = b.build(url.openStream());

             Nodes unitNodes = d.getRootElement().query("//p:persistence-unit",  			new XPathContext("p", "http://java.sun.com/xml/ns/persistence"));

             for(int j=0; j < unitNodes.size(); j++) {

             	Node unitNode = unitNodes.get(j);

            	Element unitElt = ((Element)unitNode);

 		String unitName = unitElt.getAttributeValue("name");
		if(!unitName.equals("my-persistence-context"))
          		continue;

 	        Nodes classNodes = unitElt.query("//p:class",  			new XPathContext("p", "http://java.sun.com/xml/ns/persistence"));

 	        for(int k=0; k < classNodes.size(); k++) {

            		Node classNode = classNodes.get(k);

             		if(!(classNode instanceof Element))

             			continue;

         			Element classElt = (Element)classNode;

         			if(!(classElt.getLocalName().equals("class")))

         				continue;

 	            	String className = classNode.getValue();

 	                System.out.println("   class: "+className);

 	            	Class classInstance = Class.forName(className);

 	            	classes.add(classInstance);

 	            }

             }

    		} catch(Exception x) {

    			x.printStackTrace();

    			throw new Error(x);

    		}

        }

        return classes.toArray(new Class[classes.size()]);

 }

This is making use of the “Classpath” utility class from facelets, available here. Also note that you’ll have to replace “my-persistence-context” with your own persistence context name.

This also serves as an example of how to find things in the classpath and configure yourself; I’ve used for my own GWT templating system based on facelets. I used the facelets code to find my own tag libraries, just the way that facelets does. It’s quite a nice model for auto-discovery!