January 23, 2012

How to get to TouK

This Tuesday, architect-wannabe group has it's meeting at TouK at 18:00. Since TouK is not an easy company to find, here's the video tutorial Piotr Przybylak asked for. It starts at Rondo Zesłańców Syberyjskich (driving from north). Hope it helps.

Thanks to Maciej Próchniak for participation :)

And here is a map:

Show larger map

January 12, 2012

Bash'ing your git deployment

Chuck Norris deploys after every commit. Smart men deploy after every successful build on their Continuous Integration server. Educated men, deploy code directly from their distributed version control systems. I, being neither, had to write my deployment script in bash.

We're using git and while doing so I wanted us to:
  • deploy from working copy, but...
  • make sure that you can deploy only if you committed everything
  • make sure that you can deploy only if you pushed everything upstream
  • tag the deployed hash
  • display changelog (all the commits between two last tags)

Here are some BASH procedures I wrote on the way, if you need them:

make sure that you can deploy only if you committed everything
verifyEverythingIsCommited() {
    gitCommitStatus=$(git status --porcelain)
    if [ "$gitCommitStatus" != "" ]; then
        echo "You have uncommited files."
        echo "Your git status:"
        echo $gitCommitStatus
        echo "Sorry. Rules are rules. Aborting!"
        exit 1

make sure that you can deploy only if you pushed everything upstream
verifyEverythingIsPushedToOrigin() {
    gitPushStatus=$(git cherry -v)
    if [ "$gitPushStatus" != "" ]; then
        echo "You have local commits that were NOT pushed."
        echo "Your 'git cherry -v' status:"
        echo $gitPushStatus
        echo "Sorry. Rules are rules. Aborting!"
        exit 1

tag the deployed hash

Notice: my script takes first parameter as the name of the server to deploy to (this is $1 passed to this procedure). Also notice, that 'git push' without the '--tags' does not push your tags.
tagLastCommit() {
    d=$(date '+%y-%m-%d_%H-%M-%S')
    git tag "$1_$d"
    git push --tags

This creates nice looking tags like these:

display changelog (all the commits between two last tags)
printChangelog() {
    echo "This is changelog since last deploy. Send it to the client."
    twoLastHashesInOneLine=$(git show-ref --tags -s | tail -n 2 | tr "\\n" "-");
    twoLastHashesInOneLineWithThreeDotsNoMinusAtTheEnd=$(echo $twoLastHashesInOneLineWithThreeDots | sed 's/-$//');
    git log --pretty=oneline --no-merges --abbrev-commit  $twoLastHashesInOneLineWithThreeDotsNoMinusAtTheEnd

The last command gives you a nice log like this:
e755c63 deploy: fix for showing changelog from two first tags instead of two last ones
926eb02 pringing changelog between last two tags on deployment
34478b2 added git tagging to deploy

Atom Feeds with Spring MVC

How to add feeds (Atom) to your web application with just two classes?
How about Spring MVC?

Here are my assumptions:
  • you are using Spring framework
  • you have some entity, say “News”, that you want to publish in your feeds
  • your "News" entity has creationDate, title, and shortDescription
  • you have some repository/dao, say "NewsRepository", that will return the news from your database
  • you want to write as little as possible
  • you don't want to format Atom (xml) by hand
You actually do NOT need to use Spring MVC in your application already. If you do, skip to step 3.

Step 1: add Spring MVC dependency to your application
With maven that will be:

Step 2: add Spring MVC DispatcherServlet
With web.xml that would be:
Notice, I set the url-pattern to “/feed” which means I don't want Spring MVC to handle any other urls in my app (I'm using a different web framework for the rest of the app). I also give it a brand new contextConfigLocation, where only the mvc configuration is kept.

Remember that, when you add a DispatcherServlet to an app that already has Spring (from ContextLoaderListener for example), your context is inherited from the global one, so you should not create beans that exist there again, or include xml that defines them. Watch out for Spring context getting up twice, and refer to spring or servlet documentation to understand what's happaning.

Step 3. add ROME – a library to handle Atom format
With maven that is:

Step 4. write your very simple controller
public class FeedController {
    static final String LAST_UPDATE_VIEW_KEY = "lastUpdate";
    static final String NEWS_VIEW_KEY = "news";
    private NewsRepository newsRepository;
    private String viewName;

    protected FeedController() {} //required by cglib

    public FeedController(NewsRepository newsRepository, String viewName) {
        notNull(newsRepository); hasText(viewName);
        this.newsRepository = newsRepository;
        this.viewName = viewName;

    @RequestMapping(value = "/feed", method = RequestMethod.GET)        
    public ModelAndView feed() {
        ModelAndView modelAndView = new ModelAndView();
        List<News> news = newsRepository.fetchPublished();
        modelAndView.addObject(NEWS_VIEW_KEY, news);
        modelAndView.addObject(LAST_UPDATE_VIEW_KEY, getCreationDateOfTheLast(news));
        return modelAndView;

    private Date getCreationDateOfTheLast(List<News> news) {
        if(news.size() > 0) {
            return news.get(0).getCreationDate();
        return new Date(0);
And here's a test for it, in case you want to copy&paste (who doesn't?):
public class FeedControllerShould {
    @Mock private NewsRepository newsRepository;
    private Date FORMER_ENTRY_CREATION_DATE = new Date(1);
    private Date LATTER_ENTRY_CREATION_DATE = new Date(2);
    private ArrayList<News> newsList;
    private FeedController feedController;

    public void prepareNewsList() {
        News news1 = new News().title("title1").creationDate(FORMER_ENTRY_CREATION_DATE);
        News news2 = new News().title("title2").creationDate(LATTER_ENTRY_CREATION_DATE);
        newsList = newArrayList(news2, news1);

    public void prepareFeedController() {
        feedController = new FeedController(newsRepository, "viewName");

    public void returnViewWithNews() {
        ModelAndView modelAndView = feedController.feed();
                .includes(entry(FeedController.NEWS_VIEW_KEY, newsList));

    public void returnViewWithLastUpdateTime() {

        ModelAndView modelAndView = feedController.feed();

                .includes(entry(FeedController.LAST_UPDATE_VIEW_KEY, LATTER_ENTRY_CREATION_DATE));

    public void returnTheBeginningOfTimeAsLastUpdateInViewWhenListIsEmpty() {
        given(newsRepository.fetchPublished()).willReturn(new ArrayList<News>());

        ModelAndView modelAndView = feedController.feed();

                .includes(entry(FeedController.LAST_UPDATE_VIEW_KEY, new Date(0)));
Notice: here, I'm using fest-assert and mockito. The dependencies are:

Step 5. write your very simple view
Here's where all the magic formatting happens. Be sure to take a look at all the methods of Entry class, as there is quite a lot you may want to use/fill.
import org.springframework.web.servlet.view.feed.AbstractAtomFeedView;

public class AtomFeedView extends AbstractAtomFeedView {
    private String feedId = "tag:yourFantastiSiteName";
    private String title = "yourFantastiSiteName: news";
    private String newsAbsoluteUrl = "http://yourfanstasticsiteUrl.com/news/"; 

    protected void buildFeedMetadata(Map<String, Object> model, Feed feed, HttpServletRequest request) {
        setUpdatedIfNeeded(model, feed);

    private void setUpdatedIfNeeded(Map<String, Object> model, Feed feed) {
        Date lastUpdate = (Date)model.get(FeedController.LAST_UPDATE_VIEW_KEY);
        if (feed.getUpdated() == null || lastUpdate != null || lastUpdate.compareTo(feed.getUpdated()) > 0) {

    protected List<Entry> buildFeedEntries(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
        List<News> newsList = (List<News>)model.get(FeedController.NEWS_VIEW_KEY);
        List<Entry> entries = new ArrayList<Entry>();
        for (News news : newsList) {
            addEntry(entries, news);
        return entries;

    private void addEntry(List<Entry> entries, News news) {
        Entry entry = new Entry();
        entry.setId(feedId + ", " + news.getId());
        entry = setSummary(news, entry);
        entry = setLink(news, entry);

    private Entry setSummary(News news, Entry entry) {
        Content summary = new Content();
        return entry;

    private Entry setLink(News news, Entry entry) {
        Link link = new Link();
        link.setHref(newsAbsoluteUrl + news.getId()); //because I have a different controller to show news at http://yourfanstasticsiteUrl.com/news/ID
        return entry;


Step 6. add your classes to your Spring context
I'm using xml approach. because I'm old and I love xml. No, seriously, I use xml because I may want to declare FeedController a few times with different views (RSS 1.0, RSS 2.0, etc.).

So this is the forementioned spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="mediaTypes">
                <entry key="atom" value="application/atom+xml"/>
                <entry key="html" value="text/html"/>
        <property name="viewResolvers">
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver"/>

    <bean class="eu.margiel.pages.confitura.feed.FeedController">
        <constructor-arg index="0" ref="newsRepository"/>
        <constructor-arg index="1" value="atomFeedView"/>

    <bean id="atomFeedView" class="eu.margiel.pages.confitura.feed.AtomFeedView"/>

And you are done.

I've been asked a few times before to put all the working code in some public repo, so this time it's the other way around. I've describe things that I had already published, and you can grab the commit from the bitbucket.

Hope that helps.