Welcome to Ninth Avenue. Here you will find articles, howtos and bug fixes for server-side webapp development with Java EE, JSF, Unix and CSS.

How To Catch A ClassNotFoundException

By , 13 April 2014

HTTP request from spammers trying to exploit our commenting system is causing a ClassNotFoundException deep in the JSF / Java code. Specifically, spammers are sending serialized objects in the javax.jsf.ViewState parameter for classes that no longer exist in our system. The resulting exception is this:

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Comparison Of Cloud Storage / Backup Services

By , 17 January 2014

The company that was storing our backups online was always a little flakey and recently the scripts just started failing altogether. Time to find a new backup service methinks.

Since I first looked at backup online the market has changed a lot. It's now called "cloud storage" for starters, and the number of companies providing competing services has ballooned.

Here is a quick comparison a few key players on the market, and the monthly cost of storing 100GB of backups. The server being backed up is running Ubuntu, so the last column shows how the backups are run. Rsync is our preferred method.

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Embed Code Plugin For FCKEditor

By , 17 November 2013

Here's a plugin I just whipped up for FCKEditor which makes it easy to add embedded HTML code such as YouTube and Vimeo videos.

FCKEditor Embed Plugin Dialog

To install, download the plugin below and unzip it in your plugin folder. Then add the following line to your fck_config.js:

FCKConfig.Plugins.Add('embed');

You will also need to add an 'Embed' entry to your toolbar array in fck_config.js.

Download the FCKEditor Embed Plugin Now.

One problem you should be aware of is that browsers now try to protect users from XSS (Cross-Site Scripting) injection, so if you send iframe tags in the embed code, they might get stripped out. To fix this problem, you need to ensure your server adds the following header:

X-XSS-Protection: 0

 

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How To Export Google Reader Feeds Into Opera

By , 19 March 2013

Everyone is up in a storm since Google announced they were killing Google Reader. Although I liked Google Reader, I believe change creates opportunities and unsurprisingly a better solution for feed reading presented itself almost immediately. In fact it was already installed on my system.

It's called Opera.

I installed Opera to read email when Mozilla killed Thunderbird and after some heavy customisation I'd say it works pretty well. It's much faster than Thunderbird for a start.

Now it looks like Opera is not only going to save my RSS feeds, but make my news reading more organised thanks to it's flexible user interface.

So here is a quick howto with screenshots for people who need to get off Google Reader and want to try out Opera.

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Preserving JSF Request Parameters and REST URLs

By , 13 February 2013

Have you ever used a URL pattern something like this?

http://localhost/app/widgets/WidgetEditor.xhtml?id=300 

or perhaps this?

http://localhost/app/widgets/300/edit 

Well, as a JSF developer you've probably already realized a little problem. How do you remember the id from request to request? There are a few simple solutions.

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How To Get The HTTP Status Code In Selenium WebDriver

By , 16 November 2012

One of the first things you'll notice when you start testing your web application with Selenium WebDriver is that there is no API to get the HTTP status code for a page. If you want to know why, you can go and read WebDriver issue #141. Personally I don't care why - I just want to test my HTTP reponse codes (especially 403 Permission Denied).

There is a fairly simple workaround you can use for WebDriver, but firstly lets look at how to do it without WebDriver. Nobody said you HAVE to use Selenium right?

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JSF Error Pages That Actually Work

By , 27 October 2012

Here is an annoying problem using JSF error pages for JSF requests. Everything looks just fine, HttpServletResponse.sendError() sends the error page, but JSF continues processing and starts throwing exceptions after the response is complete. This happens even if you call FacesContext.responseComplete(), and also when the error page is sent at different stages of the JSF lifecycle.

It seems like invoking the FacesServlet for sendError() breaks the state of the original FacesContext.

When sending an error during view build I get this exception:

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Why Is Maven So Slow? [Solved]

By , 24 October 2012

I couldn't figure out why the heck my maven builds where taking so long. I thought Java was supposed to be fast these days and here I am waiting 30 seconds to run a unit test. So I did some digging and eventually found the problem.

On Linux, the default JVM is the Server JVM which does all sorts of useful optimisations for long running server process but is absolutely dog slow for building source code (this could also be a reason why the Linux community thinks Java sucks so much).

To find out what JVM you are running simply type:

$ java -version
java version "1.6.0_26"
Java(TM) SE Runtime Environment (build 1.6.0_26-b03)
Java HotSpot(TM) Server VM (build 20.1-b02, mixed mode)

If you see "Server VM" like the example above do me a favor and time your maven compile (mvn clean compile) then switch to the Client VM, time it again and post your results in the comments below.

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How To Sort Your Unit Tests By Layer In TestNG

By , 11 October 2012

Each of my unit tests extends from a different base class depending on what layer of my application they are testing. i.e.

BaseTest
 `- BaseDBTest
     `- BaseOpsTest
         `- BaseUITest

These superclasses are very convenient places to put shared test code like starting a server, opening the database, doing a HTTP get or even just checking that assert is enabled.

When testing the whole application, it doesn't make much sense to me to run tests from all layers in random order. There are clear dependencies between the layers and if a lower layer fails I want to know about it before it blows up into the upper layers (if you believe its better to mock unit test dependencies then you might as well stop reading now).

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How To Create Email From JSF Templates

By , 1 October 2012

Hi everybody. In this blog I'm going to share a little trick for creating emails using JSF Facelets templates. The concept is actually independent of JSF and could be used for any servlet-based technology.

Right, so the basic idea is to temporarily trick the ServletResponse object into writing all the content to an in-memory buffer, rather than streaming it to the client's browser. We then manually invoke the JSF render phase for the particular view using the special ServletResponse and voila!, the captured output can be put into an email.

Let's have a look at some of the code.

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