Sunday, October 11, 2009

Combining TemporaryFolder @Rule with Spring 3

I like TDD, I like Springs @ContextConfiguration framework and I like JUnit 4.7's new Temporary folder. Getting the latter two to play nice isn't as easy as I hoped, so here's an attempt at a way to make them work.

Let's say you need to configure an incoming directory on a component using external configuration. For example in Spring Integration: <file:inbound-channel-adapter directory=#{} ... />.

I'm using expression language to load a property from a config object, which I wire in turn as a Spring bean. In my main application this config object can just be a for example, and in my test I can override that bean with an inner class from my test.

public static class Config {
public static final Map directories = new HashMap();

If you then use the containing context in a JUnit test it will be loaded up once the context is created, so you need to make sure to put the store value in the map @BeforeClass. Now I'd like to use a TemporaryFolder, to store files in the input directory of the channel adapter, but you can't refresh the property of a singleton bean each test. The @Rule will be applied before each test, resulting in the second test using a different directory from the context. A shame.

A working solution is to just remove the @Rule annotation from the TemporaryFolder and manually invoke create() and delete(). I'd like to know if there is a better solution.

Maven sample project can be found on GitHub.

If you give it a go, let me know if you find a neater option!

Friday, September 4, 2009

Spring Milestones and Snapshots with maven

It took me way longer than I wanted to set up a simple maven project using the Spring M4 and the latest snapshot of Spring Integration. For some reason this is not documented prominently on I commit on Spring Integration, so maybe I should do something about this, on the other hand, blogging is easier... I'll hand you the fix that still worked for me in 2009.

I'm a bit of a maven rookie. I've been using it for years now, but I still feel uncomfortable using it and I have given up on ever having a complete grasp of how it works. The general idea and functionality I understand and sympathize with, but other than that it's too painful to recommend. On the other hand, I just want my build to work and learning Gradle isn't on the top of my list if I need to get started now. Maven itself is tolerable but the plugin and repository landscape isn't.

I'm just going to save you 45 (if not more) minutes of searching and cursing before you find hints on the project pages.

Don't use the search tools for maven central (I like mvnrepository) for Spring dependencies.
Don't use SpringSources enterprise repository for milestones and snapshots. They might be there, but they end up there later than on S3.

There is a milestone and snapshot repository in S3, as described by Ben Hale in a blog. Use the repository snippets from that blog (also included here). Look carefully at the url of the s3browser.

Do use

The repositories are in s3, and while that is very cool, it's also a pain for you because you can't explore them with the url copied from the repository element. Keep a comment on that in your pom if you have colleagues.
<name>Spring Portfolio Milestone Repository</name>
<!-- browse via -->

<name>Spring Portfolio Snapshot Repository</name>
<!-- browse via -->

If you need artifacts from S2's enterprise repository too you can end up with a whopping 6 repository snippets just for your spring artifacts. Keeping track of which artifact comes from which can be daunting. If you're in the position to do so, using Nexus (or similar) can be used to mitigate that.

There are a lot more details to all this (related to OSGi and maven versioning schemes), but if you're just interested in making it work, you should be grand now.

Hope this helps.

Saturday, January 10, 2009

Push vs. Pull or Why company mailing lists are evil

Everybody that works for a large organization knows the semi Observer anti-pattern. In some form or another at least. It works like this: The Big Boss thinks that you need to know, so he pushes information to you through email. He is too lazy to push this corporate spam to all personnel individually so you get added to a list automatically. At least some of your bosses don't know that there is such a thing as BCC so soon all personnel knows all the lists they are on.

The next step is that people start holding discussions using the email addresses for those lists. I've seen these types of discussions spiral out of control in different firms I've worked for. This causes unreasonable load and distraction for the employees and can even cause the whole email system to collapse under the strain. I can tell you this is not the first time something like this has happened.

What makes this behavior unforgivable, is that there is such a simple solution.

Use RSS or newsgroups to let people subscribe to replacements for these lists and clearly separate directed communications (to a few people) from news and open discussions. By using this simple solution (and working for a company that actually does this right), I've managed to reduce my incoming email by 80%. It is still some work to go through all the mails after a few days of inactivity, but the thing is it is not absolutely impossible anymore. The other immensely satisfying improvement is that most mail I get I actually want to read.

I do have thousands of unread items piling up in my RSS reader and nntp client, but those I know I can safely discard when they get stale. They don't eat up disk space and I can always search them.

There are reasons to keep lists in the company anyway. For example some employees are too lazy or stupid to subscribe to RSS lists and newsgroups, if you are legally required to send out a communique an email push might come in handy. In those cases: use BCC. If something should not be done, make it impossible. Guidelines for Reply-All and the pleas and threats to follow them are just more unneccesary noise.

So bosses all over the world, if you read this: be smart and stop spamming your employees, they hate you for it and they're right.

I saw another complaint about many emails in general. I bet that this guy is subscribed to his own blog using email. He ends his post with:
If you are the person with the idea to save us all, send me an email and tell me all about it. Actually, strike that. Drop by my house and tell me all about it. I don’t want your message to get lost in my inbox
I'm not a venture capitalist, but still the difference is striking: my mailbox is completely read, and I spend less than an hour a day to keep it that way.