To validate that a JSF2 input text field contains a valid IPv4 IP address use the following code:
<h:inputText id="inputBoxId" value="#{backingBean.field}" validatorMessage="IP address is not valid">
<f:validateRegex pattern="^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$" for="inputBoxId" />
</h:inputText>
The regular expression can also be used outisde of JSF2 of course.
Having jumped in at the deepend with JSF2 recently I noticed that adding comments to my facelets pages using the standard HTML commenting syntax:
<!-- comment here -->
actually results in the comment being sent as part of the output stream to the browser.
This is very annoying because I’ve generally put the comments in the xhtml for maintenance purposes so I don’t want anyone who views the source to see them; also they can actually be interpreted by JSF component libraries and add rendered output which you didn’t expect (such as extra rows in auto generated tables).
Thankfully JSF2 has a handy setting to stop comments being sent in the output stream. In your project web.xml file simply add the following to your web-app section:
<context-param>
<param-name>javax.faces.FACELETS_SKIP_COMMENTS</param-name>
<param-value>true</param-value>
</context-param>
Comments should no longer make it to the output stream.
To enable remote debugging of a java application pass the following options to the JVM:
-Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9999
Where 9999 is the port than the remote debugger will connect to.
Setting “suspend” to “y” will suspend the VM until the remote debugger is attached – which can then resume the session.
I use Eclipse IDE for remote debugging; other IDEs are available.
I find myself creating and making use of increasingly complex JavaScript code as part of my day to day work.
JavaScript is now the standard mechanism for client side data manipulation in most web-based applications and as such has become increasingly important for all software developers to understand. There are plenty of tutorials and documentation on the web, but one of the most useful resources I have come across is JavaScript Garden which documents a lot of the quirks and performance issues within the language.
I’d be very interested in any other useful JavaScript resources covering the more complex areas of the language so please leave a comment if you know of any.
Facebook has added a new setting to it’s Security Options to allow users to connect using the secure and encrypted HTTPS protocol which encrypts the http traffic going over the wire. This is good news for Facebook users and will hopefully encourage more mainstream sites to enable HTTPS secure connections by default.
Using HTTPS ensures that snoopers can’t simply pick up plain text login credentials being transmitted over insecure connections (e.g. coffee shop wifi). The Firesheep firefox plugin demonstrates how easy it is to snoop on user credentials.
To enable HTTPS within facebook follow these steps:
Facebook will now attempt to serve your connections over HTTPS. Note that many applications will not support HTTPS and will push you back onto HTTP.
Facebook now uses the Jabber (XMPP) protocol for Facebook Chat – this means that any device/software which supports the Jabber protocol can connect to facebook chat.
The Nokia N900 supports the Jabber protocol out of the box as part of it’s instant messaging support, so the N900 can connect to Facebook chat seamlessly. Below are the steps I followed to enable Facebook Chat on my N900.
e.g. joebloggs@chat.facebook.com
That’s it, you should now be signed in to Facebook Chat.
You can see who’s online and start chats using the Conversations/IM widget.
On Ubuntu 9.10, using Gnome desktop:
System -> Preferences -> Main Menu
This will prevent the following tool, which allows you to choose which applications sit under which menus and also to add new applications to the menus.
ubuntu upgrade
I recently got around to upgrading my development machines from Ubuntu 9.04 to 9.10, mainly because 9.04 is now end of life.
The upgrade itself went very smoothly – just a case of agreeing to all the defaults and letting the upgrade software do it’s thing.
Everything was going well until the install completed and I got invited to restart the machine to complete the install… “no problem” I think, this has been the smoothest upgrade ever.
The computer restarts, I see a simple Ubuntu logo on both screens and then…. nothing. Both screens go blank and that’s how they stay. I can’t even Ctrl-Alt-F1 to a terminal. After some thought I recall that I put some proprietary ATI drivers on the 9.04 install to drive the ATI graphics card I use for dual monitors – I guess they don’t play nicely with X in Ubuntu 9.10. The problem then is probably in the xconfig
So here’s the solution that worked for me (I know there are probably more elegant solutions):
> sudo rm /etc/X11/xorg.conf
This got me back up and running, and there was need to download any extra drivers for 9.10; I simply used the System -> Preferences -> Display options to configure my monitors as I wanted them.
Calm has been restored to the Karmic Koala.
undocumentedtitle 