I am very fond of logging as a complement to debugging, since I can “trace” actions in my programs even if the classes is in production. “But hey, logging makes the application go slower!” you might think. Well, it’s up to you to decide, a small performance hit is likely to occur, a big hit if you don’t read the documentation of for instance the PatternLayout.
I use Log4j a lot in the Java code I design and write, and haven’t noticed any big difference between logging and not logging.
So, you might have used Log4j a bit and used Chainsaw to look at Log4j logging files. Why not look at the logging in realtime? Here is how to do it.

Setting up Log4j

To see the logging in real time, I use an appender called SocketHubAppender that acts as a server. Create the log4j.xml in the root of your Java application’s directory, or add the vital bits to your own:

< ?xml version=\"1.0\" encoding=\"UTF-8\" ?>
< !DOCTYPE log4j:configuration SYSTEM \"log4j.dtd\">
debug=\"true\">
class=\"org.apache.log4j.net.SocketHubAppender\">

When starting your application and outputs some logging messages with the usual logger.debug(“Hello world!”); it will be sent to the appender’s socket, defined above as 1020. The output can’t be read using a telnet session, because the things you will see is the logging events serialized… You need something to look at those serialized logging events with – Chainsaw!

Configure Chainsaw

Create a file (or add the vital bits below to your own…) called chainsaw-config.xml somewhere on your local disk, for instance c:\temp\chainsaw-config.xml, and change the host from my.remote.host.net to the host where you set up the logging with the SocketHubAppender and that the port matches the one you used:

< ?xml version=\"1.0\" encoding=\"UTF-8\" ?>
< !DOCTYPE log4j:configuration >








Start Chainsaw via Java Web Start by launching the jnlp-file at the homepage. Open the menu “View”, “Show Application-wide Preferences”, go to the “General” tab and enter “file://c:/temp/chainsaw-config.xml” (leave out the quotation marks) in the “Automatic Configuration URL” field, or whatever you named your config file. Click “OK” and restart Chainsaw. You should now see your receiver to the right named “MyRemoteLogging”.
Try starting up your Java application and output some logging, and you will see them pop up directly in Chainsaw!

So why not use a simple file or database to log to? You can do that too, you are not limited to one appender per application. You can set up as many as you want, for instance a ConsoleAppender, a SocketHubAppender and a JDBCAppender that logs the events to all those targets.
Log4j is powerful, but it doesn’t makes miracles if you don’t use some structured logging. Events like “Hello world!” is not going to help you, but some well designed NDC.push()’s and other will do good. And don’t forget to add the NotesExceptionRenderer to your class path, so that you get more info from those badly-designed exceptions :-)

Joachim Dagerot introduced us into ext.js, a client-side framework with lot’s of goodies like menus, trees, tabbed tables, layouts etc. The framework looked really impressive, and applications based on it was more of a Windows experience. When developing applications with ext.js, almost everything is done in JavaScript, including the templates of the pages. You don’t have to download the complete framework, you can take bits and pieces, if you want only a part of the gadgets.

After more beverages, snacks and more chatting, connections were made, business cards and email addresses exchanged hands. I left rather early though, I hope my fellow bloggers to give the full story ;-) Photos were taking during the meeting, and I would really love to see them, since I didn’t use my own camera.

I hope that this event wasn’t the last of it’s kind in Sweden, it was great fun to see fellow bloggers and geeks!
Thanks for a great event everyone, especially Ekakan who arranged the g33k date!!

Btw, the picture at the top is NOT from the g33k date, it was just a picture I used in the presentation as an illustration of the thin red line between being a geek and a nerd. :-D

• g33k date presentation
• g33kdate.nsf zipped
• EclipseMe, J2ME plug in for Eclipse
• Sun Java Wireless Toolkit
• nbot

[tags]g33k, geek, J2ME, AJAX, Webservice, Ekakan[/tags]

try {
String xml = "Hello World";
PrintWriter writer = getAgentOutput();
writer.println("Content-type: text/xml");
XMLEchoer echoer = new XMLEchoer(writer);
echoer.start(xml);
} catch(Exception e) {
e.printStackTrace();
}
}
}


To get it working, you need a SAX implementation, like Apache Xerces 2. Just drop the JAR files from Xerces 2 into the jvm/lib/ext directory in your Notes or Domino installation. Restart the http task if you are testing with Domino.

• XMLEchoer.java

[tags]Java, XML, SAX[/tags]

1. Microsoft XML Parser: 0.2 seconds
2. NotesSAXParser: 2.2 seconds
3. NotesDOMParser: 2.5 seconds

When executed on a Domino server, the result was a bit different, since the server is a bit old:

1. Microsoft XML Parser: 1.0 seconds
2. NotesSAXParser: 5.0 seconds
3. NotesDOMParser: 7.7 seconds


Public Sub serializeNode(node As NotesDOMNode_
, outStream As NotesStream)
On Error Goto catch

If node.NodeType = DOMNODETYPE_ELEMENT_NODE _
And Not endWritten Then
Call outStream.writeText("")
End If
Exit Sub
catch:
Error Err, Err & Lsi_Info(2) & ":" & Erl & "|" & Error
End Sub


• pass both the NotesDOMDocumentNode AND the original NotesDOMParser at all times
• write my own Serialize method
• pass the XML string only, and do the parsing at each method. I think this would be really slow…

To further illustrate what I want, here is an example:

Public Sub testDOMParser()
Dim parser As NotesDOMParser
Dim inStream As NotesStream
Dim node As NotesDOMDocumentNode
Set inStream = session.createStream()
Call inStream.open("c:\temp\test.xml")
Set parser = session.createDOMParser(inStream)
Call parser.process()
Set node = parser.document
Call serializeDocument(node)
End Sub
Public Sub serializeDocument(node As NotesDOMDocumentNode)
' Here, I want to do something like this:
Dim outStream As NotesStream
Dim parser As NotesDOMParser
Set outStream = session.createStream()
Set parser = session.createDOMParser(node, outStream)
parser.exitOnFirstFatalError = True
Call parser.serialize()
Print "Serialized tree: " + outStream.readText()
End Sub


Anyone who have had any experience with this and are willing to share their thoughts? We are talking R6 here…