So you have a RESTful Java webapp built using Jersey, some POJO/JAXB models that you’d like to serialize using Jackson, and think it’d be sweet to validate models using annotations (JSR 303 – Bean Validation)? And you like your objects to be immutable (Effective Java Item #15). You’ve come to the right place. Hibernate Validator is the reference implementation for JSR 303 and arguably the best currently available, so we’ll use it along with Jersey and Jackson to form the backbone of this recipe.

The general idea behind the ValidatingJacksonJsonProvider is that we can annotate any of the parameters used in our resource classes with @Valid to have the object automatically validated during the Jackson JSON serialization process.

So, first, annotate your POJO/JAXB object with some constraints, like @Min(0) and @NotEmpty. Continued…

We have a class that needs to limit the number of logged messages to avoid DDOSes. But this particular piece of software is still using JULI (yes, I know, not my decision though). Since JULI doesn’t support NDC or MDC, we needed to get creative to test this logging limit.

You probably create a static logger for your class, something like

public class LoggingClass {
    private static Logger logger = Logger.getLogger(LoggingClass.class.getName());
    ...
}

or the equivalent with SLF4J’s LoggerFactory.

PowerMock can help you mock this logger. Yes, its that powerful. First, Continued…

A week ago, I posted a quick fix to a bug in the Sharebox tutorial. The next day, it appears that the site hosting this tutorial expired, and its content could be lost. Never fear! Google’s cached version is here. To make it easier for you, I’ve posted the source code developed through the tutorial to my Github and you can see Sharebox in action on heroku. Lastly, I’m also hosting a cached copy of the tutorial for safekeeping, in the event its lost overwritten in Google’s cache.

• Sharebox source code on Github
• Sharebox demo on Heroku
• Sharebox tutorial (hosted cached copy)

Hope this helps!

While going through the (quite good) ShareBox Tutorial that teaches you to build a Dropbox-like sharing app, I stumbled on a nasty bug. The tutorial wisely uses the paperclip gem for file attachments, but after moving from local hosting to Amazon’s S3, I started getting an exception in the AssetsController create action.

  ActiveRecord::UnknownAttributeError in AssetsController#create
  unknown attribute: uploaded_file
  app/controllers/assets_controller:17:in `create'

At the time, Googling the error didn’t help (gasp!), so here are all the pieces together to help any wary travelers who may stumble here looking for the same answer. Continued…

Tried to install pyyaml today but got a couple nasty errors.

$ sudo easy_install  pyyaml
Searching for pyyaml
Reading http://pypi.python.org/simple/pyyaml/
Reading http://pyyaml.org/wiki/PyYAML
Best match: PyYAML 3.10
Downloading http://pyyaml.org/download/pyyaml/PyYAML-3.10.zip
Processing PyYAML-3.10.zip
Running PyYAML-3.10/setup.py -q bdist_egg --dist-dir /tmp/easy_install-8Co0C6/PyYAML-3.10/egg-dist-tmp-FYdiLy
build/temp.macosx-10.7-intel-2.7/check_libyaml.c:2:18: error: yaml.h: No such file or directory
build/temp.macosx-10.7-intel-2.7/check_libyaml.c: In function ‘main’:
build/temp.macosx-10.7-intel-2.7/check_libyaml.c:5: error: ‘yaml_parser_t’ undeclared (first use in this function)
...
lipo: can't open input file: /var/tmp//ccxDQipT.out (No such file or directory)

and

libyaml is not found or a compiler error: forcing --without-libyaml
(if libyaml is installed correctly, you may need to
 specify the option --include-dirs or uncomment and
 modify the parameter include_dirs in setup.cfg)

Fortunately, after piecing together a couple posts, the fix is easy. Use the following command to install PyYAML.

sudo python -m easy_install pyyaml

We must install this way because the problem is a bug in an Python’s setuptools. Its been fixed in later versions, but for now this did the trick for me.

Resources

• http://pyyaml.org/ticket/186
• http://pyyaml.org/ticket/94
• http://andreasjacobsen.com/2008/10/10/using-python-setuptools-on-the-mac/

Today, I was working from my parent’s home in Arkansas where we don’t have broadband, so my Mac was offline. I tried to start Eclipse and it just popped a dialog mentioning a log file with no other message.

After a bit of searching the errors in the log, Stack Overflow came to the rescue.

just add an alias for localhost to the network interface:

sudo ifconfig en0 alias 127.0.0.1

That’s all you have to do, really.

About a week ago, I lost my Kindle. This makes me sad. After tracking it on security cameras until it left the film of vision (left in cart at grocery store), I’ve devised a last ditch effort. Remember that convenience method of emailing documents to your kindle? Well, I’ve just created a PDF pleading for its return, including my contact info. Will it work? Maybe not, but it can’t hurt either. You can do this yourself.

1. Write a “please return my Kindle” note in MS Word. I used size 20 font, all caps, and short sentences. Continued…

I’m learning so many new things at BrightTag! Among them, I’m helping develop a new service in node.js. After piecing together a few articles online about using node for asynchronous testing of REST services, I thought I’d share the testing setup I’d settled on, in case it can help you. The setup is written for vowsjs and can easily be tailored to your situation. I’ve tried to make heavy use of asynchronization, macros, and contextualized requests. In the case below, I was integration-testing an oauth security middleware (simplified here for, well, simplicity). Continued…