private void validate(Node node) throws ActivationException, ValidationException, NoSuchServiceException, ContributionReadException {
node.startComposite("sample-helloworld", "helloworld.composite");
Helloworld helloworldService = node.getService(Helloworld.class, "HelloworldComponent");
Assert.assertEquals("Hello petra", helloworldService.sayHello("petra"));
node.stopComposite("sample-helloworld", "helloworld.composite");
try {
node.getService(Helloworld.class, "HelloworldComponent");
Assert.fail();