JMS with proper transactional properties

The main reason I am interested in JMS (inside the application) is for the transactional properties. JMS allows you to start an asynchronous task and make sure that the task is only scheduled if the transaction in which the JMS message was sent succeeds.

Similarly, JMS is smart enough to retry receiving the message until it was processed successfully (potentially with a backout scenario to assure that retries don’t hog the system).

This sounds great, but configuring JMS to work like this is hard.

The generic solution is to use XA transactions. In that case the transactions of your data sources (like your database) and your JMS provider are synchronized.

If you are only using one database, then using that database for persistence of your JMS messages avoids the need for XA transactions. There is only one data source, so no transactions to synchronize.

Using Spring and ActiveMQ this can be done using a configuration like the following. This only uses the JMS inside the application, connection from the outside is not possible. This example persists in a PostgreSQL database.

<!--  Embedded ActiveMQ Broker -->
<amq:broker id="broker" useJmx="false" persistent="true">
        <amq:transportConnector uri="tcp://localhost:0" />
        <amq:jdbcPersistenceAdapter changeAutoCommitAllowed="false" createTablesOnStartup="false" useDatabaseLock="false">
            <amq:dataSource><ref bean="dataSource" /></amq:dataSource>
<!--  ActiveMQ Destinations  -->
<amq:queue id="zzzz" physicalName="" />
<!-- JMS ConnectionFactory to use, configuring the embedded broker using XML -->
<amq:connectionFactory id="jmsFactory" brokerURL="vm://localhost" />
<bean id="jmsTransactionManager" class="org.springframework.jms.connection.JmsTransactionManager">
    <property name="connectionFactory" ref="jmsFactory" />
<bean id="jmsConnectionFactory" class="org.springframework.jms.connection.CachingConnectionFactory"
      p:targetConnectionFactory-ref="jmsFactory" />
<bean id="jmsListenerContainerFactory" class="org.springframework.jms.config.DefaultJmsListenerContainerFactory">
    <property name="connectionFactory" ref="jmsConnectionFactory" />
    <property name="sessionTransacted" value="true" />
    <property name="concurrency" value="3-10" />
<bean id="jmsProducerTemplate" class="org.springframework.jms.core.JmsTemplate"
      p:sessionTransacted="true" />

Your messages are now only delivered when your transaction in which the message was sent succeeds.
When the transaction in which the message is received rolls back, the message will be redelivered.

If needed, you can control how many times the message should be attempted to be processed. This can be done using code like the following:

@JmsListener(destination = "")
private static final int MAX_DELIVERY_ATTEMPTS = 3;
public void onMessage(Message message) {
    try {
        int count = message.getIntProperty("JMSXDeliveryCount");
        if (count > MAX_DELIVERY_ATTEMPTS) {
            LOG.warn("Processing JMS message {} failed {} times. It will not be retried.", message, MAX_DELIVERY_ATTEMPTS);
        // ..... normal handling of message
    } catch (JMSException e) {
        // ..... handle exception

Building an executable jar with embedded web server

To make using and deploying our application easier, I want it to be easy to run the application. Instead of requiring the installation of a servlet server like Tomcat, Jetty or a full blown application server, I aim to use an embedded server.

The end result is the ability to run our application using the following command:

java -jar application.jar

Possibly using some additional parameters like

java -DserverPort=8080 -DshutdownPort=8089 -jar application.jar

As web server I chose Undertow, a relatively new server which is also used in WildFly.

I want the result jar to still show the included libraries, so I do not want to make an uber-jar using something like the maven shade plugin. I rather want to build a jar which includes jars with all the dependencies.

Building this jar can be done using the maven assembly plugin, using a configuration like the following:

<assembly xmlns=""

I use a separate module to build the jar. In this module the main pom mainly contains all the application dependencies and the following configuration:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="" xmlns:xsi=""
    <name>Build executable jar</name>
        <!-- module dependencies which build the application -->
                        <id>make-assembly</id> <!-- this is used for inheritance merges -->
                        <phase>package</phase> <!-- bind to the packaging phase -->

This module will now build two jars, a normal jar (very small) and one with the dependencies which has the “with-deps” suffix. The latter can be used to start the application.

In the module itself we need only two classes.

We need a main class to start the application (the “mainClass” which is referenced in the manifest). This should start the application. To assure that the embedded jars are used, we need a special classloader. Apart from that, the main method refers to a different class which runs the application.

public final class WarRunner {
    private WarRunner() {
        // hide constructor
     * Run de "real" runner from the application.
     * @param args command line parameters
    public static void main(String[] args) {
        try {
            JarClassLoader.invokeMain("myapp.AppRunner", args);
        } catch (Throwable e) {
            System.err.println("Cannot run myapp.AppRunner: " + e.getMessage());

The second class is the JarClassLoader. This is based on the code from embedded jar classloader, but with some fixes.

public class JarClassLoader extends URLClassLoader {
    private static boolean isJar(String fileName) {
        return fileName != null && fileName.toLowerCase().endsWith(".jar");
    private static File jarEntryAsFile(JarFile jarFile, JarEntry jarEntry) throws IOException {
        String name = jarEntry.getName().replace('/', '_');
        int i = name.lastIndexOf(".");
        String extension = i > -1 ? name.substring(i) : "";
        File file = File.createTempFile(name.substring(0, name.length() - extension.length()) + ".", extension);
        try (InputStream input = jarFile.getInputStream(jarEntry)) {
            try (OutputStream output = new FileOutputStream(file)) {
                int readCount;
                byte[] buffer = new byte[4096];
                while ((readCount = != -1) {
                    output.write(buffer, 0, readCount);
                return file;
     * Build classpath with extra jars in it.
     * @param urls urls
     * @param parent parent class loader
    public JarClassLoader(URL[] urls, ClassLoader parent) {
        super(urls, parent);
        try {
            ProtectionDomain protectionDomain = getClass().getProtectionDomain();
            CodeSource codeSource = protectionDomain.getCodeSource();
            URL rootJarUrl = codeSource.getLocation();
            String rootJarName = rootJarUrl.getFile();
            if (isJar(rootJarName)) {
                addJarResource(new File(rootJarUrl.getPath()));
        } catch (IOException e) {
    private void addJarResource(File file) throws IOException {
        JarFile jarFile = new JarFile(file);
        Enumeration<JarEntry> jarEntries = jarFile.entries();
        while (jarEntries.hasMoreElements()) {
            JarEntry jarEntry = jarEntries.nextElement();
            if (!jarEntry.isDirectory() && isJar(jarEntry.getName())) {
                addJarResource(jarEntryAsFile(jarFile, jarEntry));
    public synchronized Class<?> loadClass(String name) throws ClassNotFoundException {
        try {
            Class<?> clazz = findLoadedClass(name);
            if (clazz == null) {
                clazz = findClass(name);
            return clazz;
        } catch (ClassNotFoundException e) {
            return super.loadClass(name);
     * Invoke main method in given class using this classloader.
     * @param name class to invoke
     * @param args command line arguments
     * @throws ClassNotFoundException oops
     * @throws NoSuchMethodException oops
     * @throws InvocationTargetException oops
    public static void invokeMain(String name, String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException {
        ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
        try {
            final String mainMethodName = "main";
            JarClassLoader loader = new JarClassLoader(((URLClassLoader) ClassLoader.getSystemClassLoader()).getURLs(), contextClassLoader);
            Thread.currentThread().setContextClassLoader(loader); // replace contextClassloader
            Class<?> clazz = loader.loadClass(name);
            Method method = clazz.getMethod(mainMethodName, String[].class);
            int mods = method.getModifiers();
            if (method.getReturnType() != void.class || !Modifier.isStatic(mods) || !Modifier.isPublic(mods)) {
                throw new NoSuchMethodException(mainMethodName);
            try {
                method.invoke(null, (Object) args); // Crazy cast "(Object)args" because param is: "Object... args"
            } catch (IllegalAccessException e) {
                // This should not happen, as we have disabled access checks
                System.err.println("Probleem during JarClassLoader.invokeMain: " + e.getMessage());
        } finally {

What remains to be done is write the AppRunner class (which should be in the module with the application code):

public final class AppRunner {
    private static final Logger LOG = LoggerFactory.getLogger(AppRunner.class);
    private static final String CONTEXT_PATH = "/app";
    private static final int SERVER_PORT = 8080;
    private static final int SHUTDOWN_PORT = 8089;
    private static final int SHUTDOWN_WAIT = 5;
    private static GracefulShutdownHandler shutdownHandler;
    private static Undertow server;
    private AppRunner() {
        // hide constructor
     * Main method to start the application
     * @param args command line parameters - not used at the moment - configuration through properties
    public static void main(final String[] args) {
        int serverPort = getProperty("km.server.port").orElse(SERVER_PORT);
        int shutdownPort = getProperty("km.shutdown.port").orElse(SHUTDOWN_PORT);
        int shutdownWaitSeconds = getProperty("km.shutdown.wait").orElse(SHUTDOWN_WAIT);
        try {
            ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
            DeploymentInfo servletBuilder = Servlets.deployment()
                    .addInitParameter("contextConfigLocation", "classpath:app-web-applicationContext.xml")
                    .addInitParameter("resteasy.logger.type", "SLF4J")
                    .addInitParameter("resteasy.wider.request.matching", "true")
                    .addListener(new ListenerInfo(RequestContextListener.class))
                    .addListener(new ListenerInfo(ResteasyBootstrap.class))
                    .addListener(new ListenerInfo(SpringContextLoaderListener.class))
                    .addServlets(Servlets.servlet("RESTEasy", HttpServletDispatcher.class)
                    .setResourceManager(new ClassPathResourceManager(classLoader, "web"));
            DeploymentManager manager = Servlets.defaultContainer().addDeployment(servletBuilder);
            HttpHandler servletHandler = manager.start();
            PathHandler path = Handlers.path(Handlers.redirect(CONTEXT_PATH))
                    .addPrefixPath(CONTEXT_PATH, servletHandler);
            shutdownHandler = Handlers.gracefulShutdown(path);
            server = Undertow.builder()
                    .addHttpListener(serverPort, "localhost")
                    .addHttpListener(shutdownPort, "localhost", exchange -> {
                        exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, "text/plain");
                                String.format("Going to shutdown when all requests have ended or %s seconds, whichever occurs first.", shutdownWaitSeconds));
                        new Thread(() -> {
                            try {
                                shutdownHandler.awaitShutdown(shutdownWaitSeconds * 1000);
                            } catch (InterruptedException ie) {
                                LOG.warn("Wait for undertow requests to end was interrupted.", ie);
                  "Gracefully shut down.");
        }  catch (ServletException e) {
            LOG.error("Kan servlet niet starten.", e);
    private static Optional<Integer> getProperty(String propertyName) {
        String propertyValue = System.getProperty("km.server.port");
        if (StringUtils.isNotBlank(propertyValue)) {
            try {
                return Optional.of(Integer.parseInt(propertyValue));
            } catch (NumberFormatException nfe) {
                LOG.error(String.format("Cannot parse property %s with value %s to a number, ignoring value.", propertyName, propertyValue));
        return Optional.empty();

This code starts creates a servlet. It says that the resources to be served can be found in the “web” package (as there is no webapp (folder) you have to give the explicit location.
It also registers a shutdown handler. Any request on the shutdown port will block incoming requests and wait for max 5s until pending requests are all handled. Then the server is shut down.

Ubuntu Phone, synchronizing your contacts and calendar with ownCloud

I love Ubuntu Touch and have been using it on a LG Nexus 4 for a couple of months.
Now that my real Ubuntu phone has arrived in the shape of a BQ Aquaris 4.5 Ubuntu Edition, it is time to properly connect it to my address book and calendars which I have on ownCloud (thanks to Eliwan).

Ubuntu phone

Ubuntu is a great operating system for the smartphone. One of the extra attractions is the ability to be avoid disclosing private information to one of big IT companies like Apple, Google or Microsoft.

Unfortunately though, there is no user interface (should I say ‘app’) yet to enter the necessary configuration. You have to do this using the shell at this moment.

  • From the configuration app select ‘About this phone’ and then (at the bottom) ‘Developer mode’. Switch it on.
  • From a Ubuntu PC, run “adb shell”. If adb is not available it will tell you how to install it. If you don’t have a Ubuntu PC you can run the commands below from the shell app.
  • Create your ownCloud connection:
    syncevolution --configure --template WebDAV username=yourUserName password=yourPassWord syncURL= keyring=no target-config@owncloud

    Replace ‘yourUserName’ with your username and ‘yourPassword’ with your password. The ‘’ should be replaced by your ownCloud root.

  • To sync your contacts:
    syncevolution --configure database= backend=carddav target-config@owncloud myaddressbook
    syncevolution --configure --template SyncEvolution_Client sync=none syncURL=local://@owncloud username= password= owncloud
    syncevolution --configure sync=two-way backend=addressbook database= owncloud myaddressbook
    syncevolution --sync slow owncloud myaddressbook

    Replace ‘yourUserName’ with your username. The ‘’ should be replaced by your ownCloud root.

  • To sync your personal calendar:
    syncevolution --configure \
    	database= \
    	backend=caldav \
    	target-config@owncloud calendar-calendarName
    syncevolution --configure sync=two-way backend=calendar database= owncloud calendar-calendarName
    syncevolution --sync slow owncloud calendar-calendarName

    You can verify the link using the chain icon (CalDAV link) in the user interface.
    Replace ‘calendarName’ with the name of your calendar and ‘yourUserName’ with your username. The ‘’ should be replaced by your ownCloud root.

  • To create and sync additional calendars, you have to make sure an extra calendar is created and linked:
    syncevolution --configure \
    	database= \
    	backend=caldav \
    	target-config@owncloud calendar-calendarName
    syncevolution --create-database backend=calendar database=LocalName
    syncevolution --configure backend=calendar database=LocalName @default LocalName
    syncevolution --configure sync=two-way backend=calendar database=LocalName owncloud calendar-calendarName
    syncevolution --sync slow owncloud calendar-calendarName

    ‘LocalName’ needs to be replaced with the name you want for the calendar in the calendar app.
    You can verify the link using the chain icon (CalDAV link) in the user interface.
    Replace ‘calendarName’ with the name of your calendar and ‘yourUserName’ with your username. The ‘’ should be replaced by your ownCloud root.

There is one minor glitch I see at this moment. The ‘all-day events’ are currently visible in the calendar in both the day itself and the following day.

If you want to add the calendar app to the launcher which is displayed when swiping from the left you should open the app, then swipe from the left (all across the screen) to make sure the launcher stays on screen. With the calendar open the calendar icon should be there. Now indicate and hold the calendar item. This should display a little menu with the item ‘pin shortcut’. Select that.