Jetty webapp osgi way

I will show how to expose simple Jetty OSGi service and use it to register hello world webapp. This app will serve static content from OSGi bundle and implement sample request handler under ServiceMix 4.Code is available here: http://github.com/rafalrusin/jetty-service
Alternative solutions are: using standard OSGi HTTP service http://www.osgi.org/javadoc/r4v42/org/osgi/service/http/HttpService.htmlto register servlet; and wrap existing WAR application using PAX WEB http://wiki.ops4j.org/display/paxweb/Pax+Web.I won’t consider those two, since Jetty itself provides flexible way to handle webapps (including registering servlets). So those two are unnecessary overhead and are less flexible. Anyway those two are usually implemented on top of Jetty.
So the first thing to do is to create Jetty OSGi service. Basicly it will be a Spring Bean exposed to OSGi. Following snippet does the job:

<bean id="jetty-service" class="org.apache.jetty.service.JettyServiceImpl" init-method="init" destroy-method="destroy"/>
<osgi:service id="jetty-service-osgi" ref="jetty-service" interface="org.apache.jetty.service.api.JettyService" />

This will expose jetty-service to OSGi. All other components, which connect to it will wait automaticly until it’s registered.Exposed interface has following methods:

public Handler registerApp(String name, Handler handler) throws Exception;
public void unregisterApp(Handler handler) throws Exception;

Those will be invoked to register Hello World application. JettyServiceImpl on the other hand, starts embedded Jetty Server and handles apps registration.
package org.apache.jetty.service;

import org.apache.jetty.service.api.JettyService;
import org.mortbay.jetty.Handler;
import org.mortbay.jetty.Server;
import org.mortbay.jetty.handler.ContextHandler;
import org.mortbay.jetty.handler.ContextHandlerCollection;

public class JettyServiceImpl implements JettyService {
    private Server server;
    private ContextHandlerCollection rootContext;

    public void init() throws Exception {
        server = new Server(8080);
        rootContext = new ContextHandlerCollection();
        server.setHandler(rootContext);
        server.start();
    }

    public void destroy() throws Exception {
        server.stop();
    }

    public Handler registerApp(String name, Handler handler) throws Exception {
        server.stop();
        ContextHandler h = rootContext.addContext("/" + name, name);
        h.setHandler(handler);
        server.start();
        return h;
    }

    public void unregisterApp(Handler handler) throws Exception {
        server.stop();
        rootContext.removeHandler(handler);
        server.start();
    }
}

Next step is to implement sample web app. First, we need to connect jetty-service bean to make it visible in our app.

  <osgi:reference id="jetty-service" interface="org.apache.jetty.service.api.JettyService" bean-name="jetty-service"/>

<bean class=“org.apache.jetty.service.example.HelloWorld” init-method=“init” destroy-method=“destroy”>
<property name=“jettyService” ref=“jetty-service”/>
Then, we need to implement sample app.

package org.apache.jetty.service.example;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.jetty.service.api.JettyService;
import org.apache.jetty.service.util.BundleResource;
import org.mortbay.jetty.Handler;
import org.mortbay.jetty.HttpConnection;
import org.mortbay.jetty.Request;
import org.mortbay.jetty.handler.AbstractHandler;
import org.mortbay.jetty.handler.ContextHandler;
import org.mortbay.jetty.handler.ContextHandlerCollection;
import org.mortbay.jetty.handler.ResourceHandler;

public class HelloWorld {
    private JettyService jettyService;
    private Handler registered;

    public void setJettyService(JettyService jettyService) {
        this.jettyService = jettyService;
    }

    public void init() throws Exception {
        ContextHandlerCollection handler = new ContextHandlerCollection();

        handler.addContext("/app", "app").setHandler(new AbstractHandler() {
            public void handle(String target, HttpServletRequest request,
                               HttpServletResponse response, int arg3) throws IOException,
                    ServletException {
                response.setContentType("text/html");
                response.setStatus(HttpServletResponse.SC_OK);
                response.getWriter().println(
                    "Hello World from Java"
                    + request.getParameterMap()
                );

                Request base_request = (request instanceof Request) ? (Request) request : HttpConnection.getCurrentConnection().getRequest();
                base_request.setHandled(true);
            }
        });

        ResourceHandler resourceHandler = new ResourceHandler();
        resourceHandler.setBaseResource(new BundleResource(getClass().getResource("/static")));
        ContextHandler contextHandler = handler.addContext("", "");
        contextHandler.setHandler(resourceHandler);

        registered = jettyService.registerApp("helloWorld", handler);
    }

    public void destroy() throws Exception {
        jettyService.unregisterApp(registered);
    }
}

Here, we register sample request handler at ‘app’ sub path and serve static content from jar using BundleResource. Last thing is registering app using jettyService under ‘helloWorld’ context. So our application will be exposed under http://localhost:8080/helloWorld/ address.
ServiceMix has also so called features. This is the way to collect multiple dependencies under a single name. So we have to create features.xml file, like this:

<features>
    <feature name="jetty-service" version="${project.version}">
        <bundle>mvn:org.apache.jetty.service/service/${project.version}bundle> feature>

<feature name=“example-jetty-service-helloworld” version=“${project.version}”>
<feature version=“${project.version}”>jettyservicefeature>
<bundle>mvn:org.apache.jetty.service/examplehelloworld/${project.version}bundle>
feature>
features>

Basicly, we can provide particular dependencies for our project.
Next, we do ‘mvn install’ on our project and run apache-servicemix-4.2.0-fuse-01-00/bin/servicemix karaf console. On the console, we need to type following commands:

features:addUrl mvn:org.apache.jetty.service/service-karaf/0.1.0-SNAPSHOT/xml/features
features:install example-jetty-service-helloworld
osgi:list
[ 230] [Active ] [ ] [Started] [ 60] Unnamed – org.apache.jetty.service:service:bundle:0.1.0-SNAPSHOT (0.1.0.SNAPSHOT)
[ 231] [Active ] [ ] [Started] [ 60] Unnamed – org.apache.jetty.service:example-helloworld:bundle:0.1.0-SNAPSHOT (0.1.0.SNAPSHOT)
Now, we can enter http://localhost:8080/helloWorld/ to test our app.
And that’s it. OSGi and ServiceMix 4 features enable easy way to use dynamic modules in web apps. For example, it’s veryeasy to build simple web framework with loadable components on page (something like mini implementation of Portlets).

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No matter why, no matter is it a good idea. Sometimes one just wants to check or it's necessary to be done. Mock a static method, woot? Impossibru!

In pure Java world it is still a struggle. But Groovy allows you to do that really simple. Well, not groovy alone, but with a great support of Spock.

Lets move on straight to the example. To catch some context we have an abstract for the example needs. A marketing project with a set of offers. One to many.

import spock.lang.Specification

class OfferFacadeSpec extends Specification {

    OfferFacade facade = new OfferFacade()

    def setup() {
        GroovyMock(Project, global: true)
    }

    def 'delegates an add offer call to the domain with proper params'() {
        given:
            Map params = [projId: projectId, name: offerName]

        when:
            Offer returnedOffer = facade.add(params)

        then:
            1 * Project.addOffer(projectId, _) >> { projId, offer -> offer }
            returnedOffer.name == params.name

        where:
            projectId | offerName
            1         | 'an Offer'
            15        | 'whasup!?'
            123       | 'doskonała oferta - kup teraz!'
    }
}
So we test a facade responsible for handling "add offer to the project" call triggered  somewhere in a GUI.
We want to ensure that static method Project.addOffer(long, Offer) will receive correct params when java.util.Map with user form input comes to the facade.add(params).
This is unit test, so how Project.addOffer() works is out of scope. Thus we want to stub it.

The most important is a GroovyMock(Project, global: true) statement.
What it does is modifing Project class to behave like a Spock's mock. 
GroovyMock() itself is a method inherited from SpecificationThe global flag is necessary to enable mocking static methods.
However when one comes to the need of mocking static method, author of Spock Framework advice to consider redesigning of implementation. It's not a bad advice, I must say.

Another important thing are assertions at then: block. First one checks an interaction, if the Project.addOffer() method was called exactly once, with a 1st argument equal to the projectId and some other param (we don't have an object instance yet to assert anything about it).
Right shit operator leads us to the stub which replaces original method implementation by such statement.
As a good stub it does nothing. The original method definition has return type Offer. The stub needs to do the same. So an offer passed as the 2nd argument is just returned.
Thanks to this we can assert about name property if it's equal with the value from params. If no return was designed the name could be checked inside the stub Closure, prefixed with an assert keyword.

Worth of  mentioning is that if you want to track interactions of original static method implementation without replacing it, then you should try using GroovySpy instead of GroovyMock.

Unfortunately static methods declared at Java object can't be treated in such ways. Though regular mocks and whole goodness of Spock can be used to test pure Java code, which is awesome anyway :)No matter why, no matter is it a good idea. Sometimes one just wants to check or it's necessary to be done. Mock a static method, woot? Impossibru!

In pure Java world it is still a struggle. But Groovy allows you to do that really simple. Well, not groovy alone, but with a great support of Spock.

Lets move on straight to the example. To catch some context we have an abstract for the example needs. A marketing project with a set of offers. One to many.

import spock.lang.Specification

class OfferFacadeSpec extends Specification {

    OfferFacade facade = new OfferFacade()

    def setup() {
        GroovyMock(Project, global: true)
    }

    def 'delegates an add offer call to the domain with proper params'() {
        given:
            Map params = [projId: projectId, name: offerName]

        when:
            Offer returnedOffer = facade.add(params)

        then:
            1 * Project.addOffer(projectId, _) >> { projId, offer -> offer }
            returnedOffer.name == params.name

        where:
            projectId | offerName
            1         | 'an Offer'
            15        | 'whasup!?'
            123       | 'doskonała oferta - kup teraz!'
    }
}
So we test a facade responsible for handling "add offer to the project" call triggered  somewhere in a GUI.
We want to ensure that static method Project.addOffer(long, Offer) will receive correct params when java.util.Map with user form input comes to the facade.add(params).
This is unit test, so how Project.addOffer() works is out of scope. Thus we want to stub it.

The most important is a GroovyMock(Project, global: true) statement.
What it does is modifing Project class to behave like a Spock's mock. 
GroovyMock() itself is a method inherited from SpecificationThe global flag is necessary to enable mocking static methods.
However when one comes to the need of mocking static method, author of Spock Framework advice to consider redesigning of implementation. It's not a bad advice, I must say.

Another important thing are assertions at then: block. First one checks an interaction, if the Project.addOffer() method was called exactly once, with a 1st argument equal to the projectId and some other param (we don't have an object instance yet to assert anything about it).
Right shit operator leads us to the stub which replaces original method implementation by such statement.
As a good stub it does nothing. The original method definition has return type Offer. The stub needs to do the same. So an offer passed as the 2nd argument is just returned.
Thanks to this we can assert about name property if it's equal with the value from params. If no return was designed the name could be checked inside the stub Closure, prefixed with an assert keyword.

Worth of  mentioning is that if you want to track interactions of original static method implementation without replacing it, then you should try using GroovySpy instead of GroovyMock.

Unfortunately static methods declared at Java object can't be treated in such ways. Though regular mocks and whole goodness of Spock can be used to test pure Java code, which is awesome anyway :)