At this point, we are not going to detail Equinox configuration in Eclipse, which would be beyond scope of this example. We assume that it is already configured.\n<\/p>\n
2. Adding Jetty dependencies to OSGi Target<\/h2>\n2.1 Jetty libraries<\/h3>\n
Jetty JAR files, which happen to exist under the lib<\/i> folder of the Jetty installation contain appropriate manifest entries(MANIFEST.MF) for OSGi deployment. All we have to do is, to copy the necessary JARs under our OSGi target.<\/p>\n
The necessary libraries are as follows:<\/p>\n
- \n
- jetty-util<\/li>\n
- jetty-http<\/li>\n
- jetty-io<\/li>\n
- jetty-security<\/li>\n
- jetty-server<\/li>\n
- jetty-servlet<\/li>\n
- jetty-webapp<\/li>\n
- jetty-deploy<\/li>\n
- jetty-xml<\/li>\n
- jetty-osgi-servlet-api<\/li>\n<\/ul>\n
We have to place these libraries in a location that our OSGi container is aware of. We can wither copy to an existing location, or create a new location. In this example, we have copied to an existing OSGi target location.<\/p>\n
2.2 jetty-osgi-boot Bundle<\/h3>\n
After copying Jetty dependencies, we have to add the jetty-osgi-boot bundle to the OSGi target. jetty-osgi-boot is the bundle that performs the initialization of the Jetty server. This bundle is not included in the Jetty installation, but can be easily obtained from Maven Central Repository<\/a>.<\/p>\n
Once we have downloaded the bundle, we should copy it to the OSGi target location.<\/p>\n
2.3 Reloading OSGi Target<\/h3>\n
After we have copied the Jetty libs and boot bundle, we have to refresh our container in Eclipse. This can be performed following the steps below:<\/p>\n
- \n
- Open Eclipse “Preferences<\/em>” from the Menu<\/li>\n
- Search for \u201cTarget<\/em>\u201d from the search box on the top left.<\/li>\n
- Select your OSGi target<\/li>\n
- Press \u201cReload<\/em>\u201d.<\/li>\n<\/ol>\n
3. Running the Jetty Server on the OSGi container<\/h2>\n
jetty-osgi-boot bundle provides two options for the server initialization one of which must be configured:<\/p>\n
- \n
- Setting jetty.home.bundle<\/li>\n
- Setting jetty home<\/li>\n<\/ul>\n
The first option stipulates that Jetty runs with the predefined XML files coming with the bundle JAR. The second option requires setting a Jetty home with the necessary configuration files. In this example, we will take the second option.<\/p>\n
This can be accomplished as follows:<\/p>\n
- \n
- Create a folder named \u201cosgi-jetty-home<\/em>\u201d (You can name is as you wish.)<\/li>\n
- Create the folder \u201cosgi-jetty-home\/etc<\/em>\u201d<\/li>\n
- Include jetty.xml, jetty-selector.xml and jetty-deploy.xml<\/em> files under \u201cosgi-jetty-home\/etc<\/em>\u201d. (Alternatively, you can copy from jetty-osgi-boot<\/i> JAR or jetty installation)<\/li>\n
- Add the following JVM parameter to run configuration of your OSGi container: -Djetty.home=\/path\/to\/your\/osgi-jetty-home<\/em><\/li>\n<\/ol>\n
When you run the OSGi container, you will see that Jetty has started on port 8080. You can check via your browser navigating to http:\/\/localhost:8080<\/a>.
<\/div> <\/div><\/p>\n![\"OSGi](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/07\/osgi1_2.jpg\")
<\/a>OSGi powered Jetty<\/figcaption><\/figure><\/p>\n 4. Deploying a Servlet on the OSGi Jetty<\/h2>\n
In this part, we will show how to deploy a simple servlet on the Jetty which runs in our OSGi container. The example can be extended to include web apps, resource handlers or other configuration.<\/p>\n
In this example we are going to create a simple OSGi bundle, in the activator of which, we will configure a Servlet and register its handler as an OSGi component.<\/p>\n
4.1 Creating the Eclipse Project<\/h3>\n
We start with creating the Eclipse project. The steps needed are as follows:<\/p>\n
- \n
- Click on \u201cFile–>New->Plug-in Project\u201d.<\/i><\/li>\n
- Type project name as \u201cjetty-osgi-example<\/i>\u201d.<\/li>\n
- Select \u201can OSGi framework\u201d<\/em> as the target platform.<\/li>\n
- Press \u201cNext”<\/em>.<\/li>\n
- Check the option:\u201dGenerate an Activator\u2026.\u201d.<\/li>\n
- Press \u201cFinish\u201d<\/em>.<\/li>\n
- \n
![\"Creating](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/07\/osgi2_11.jpg\")
<\/a>Creating the Eclipse project<\/figcaption><\/figure><\/li>\n<\/ol>\n 4.2 Adding Required Plugins<\/h3>\n
After we have created our project, we have to add Jetty dependencies as Required Plugins in the MANIFEST.MF<\/i> file. We can do it through Eclipse as follows:<\/p>\n
- \n
- Open \u201cMETA-INF\/MANIFEST.MF<\/i>\u201d file with Eclipse Editor<\/li>\n
- On the \u201cDependencies<\/em>\u201d, click on \u201cAdd\u201d button on the \u201cRequired Plug-ins<\/em>” section.<\/li>\n
- Type \u201cJetty<\/em>\u201d in the search box and add all the Jetty plugins that are available in the OSGi container.<\/li>\n
- Press \u201cOK<\/em>\u201d.<\/li>\n<\/ol>\n
Now, the Jetty dependencies are ready. Our MANIFEST.MF<\/i> file looks like:<\/p>\n
MANIFEST.MF<\/em><\/span><\/p>\n
Manifest-Version: 1.0\nBundle-ManifestVersion: 2\nBundle-Name: Jetty-osgi-example\nBundle-SymbolicName: jetty-osgi-example\nBundle-Version: 1.0.0.qualifier\nBundle-Activator: jetty_osgi_example.Activator\nBundle-RequiredExecutionEnvironment: JavaSE-1.8\nImport-Package: org.osgi.framework;version=\"1.3.0\"\nBundle-ActivationPolicy: lazy\nRequire-Bundle: org.eclipse.jetty.server;bundle-version=\"9.2.11\",\n org.eclipse.jetty.osgi-servlet-api;bundle-version=\"3.1.0\",\n org.eclipse.jetty.servlet;bundle-version=\"9.2.11\",\n org.eclipse.jetty.deploy;bundle-version=\"9.2.11\",\n org.eclipse.jetty.http;bundle-version=\"9.2.11\",\n org.eclipse.jetty.io;bundle-version=\"9.2.11\",\n org.eclipse.jetty.osgi.boot;bundle-version=\"9.2.11\",\n org.eclipse.jetty.security;bundle-version=\"9.2.11\",\n org.eclipse.jetty.util;bundle-version=\"9.2.11\",\n org.eclipse.jetty.webapp;bundle-version=\"9.2.11\",\n org.eclipse.jetty.xml;bundle-version=\"9.2.11\"\n\n<\/pre>\n
4.3 Wiring our Servlet to OSGI and Jetty<\/h3>\n
After setting the dependencies, we are going deploy a simple Servlet on our OSGi powered Jetty. Our Servlet is named as JcgServlet<\/i> and very simple as follows:[ulp id=’xFHGZUmgemwCMrAR’]<\/p>\n
JcgServlet.java<\/em><\/span><\/p>\n
package jetty_osgi_example;\n\nimport java.io.IOException;\n\nimport javax.servlet.ServletException;\nimport javax.servlet.http.HttpServlet;\nimport javax.servlet.http.HttpServletRequest;\nimport javax.servlet.http.HttpServletResponse;\n\npublic class JcgServlet extends HttpServlet{\n\n\t@Override\n\tprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {\n\t\tresp.getWriter().println(\"Hello JCG, Hello OSGi\");\n\t}\n\t\n\tpublic JcgServlet() {\n\t\tsuper();\n\t}\n}\n\n<\/pre>\nNow we are going to wire this Servlet to our Jetty. As you remember, while creating the Eclipse Project, we had checked the option \u201cGenerate an Activator..<\/i>.\u201d. This selection creates a class jetty_osgi_example.Activator<\/em>. In this class, we can register our components to OSGi once the bundle is activated. Now we are going to register our Servlet Handler, so that it will be available to the Jetty.<\/p>\n
We are going to implement the activate()<\/em> method of the Activator. Below you can see the Activator<\/em> class decorated with source code comments.<\/p>\n
Activator.java<\/em><\/span><\/p>\n
package jetty_osgi_example;\n\nimport java.util.Hashtable;\n\nimport org.eclipse.jetty.server.handler.ContextHandler;\nimport org.eclipse.jetty.servlet.ServletContextHandler;\nimport org.eclipse.jetty.servlet.ServletHandler;\nimport org.osgi.framework.BundleActivator;\nimport org.osgi.framework.BundleContext;\n\npublic class Activator implements BundleActivator {\n\n\tprivate static BundleContext context;\n\n\tstatic BundleContext getContext() {\n\t\treturn context;\n\t}\n\n\t\n\tpublic void start(BundleContext bundleContext) throws Exception {\n\t\tActivator.context = bundleContext;\n\t\t\n\t\t\/\/1. We create a Servlet Handler\n\t\tServletHandler handler = new ServletHandler();\n\n\t\t\/\/2. We register our Servlet and its URL mapping\n\t\thandler.addServletWithMapping(JcgServlet.class, \"\/*\");\n\n\t\t\/\/3. We are creating a Servlet Context handler\n\t\tServletContextHandler ch= new ServletContextHandler();\n\t\t\n\t\t\/\/4. We are defining the context path\n\t\tch.setContextPath(\"\/jcgservletpath\");\n\t\t\n\t\t\/\/5. We are attaching our servlet handler\n\t\tch.setServletHandler(handler);\n\t\t\n\t\t\/\/6. We are creating an empty Hashtable as the properties\n\t\tHashtable props = new Hashtable();\n\t\t\n\t\t\/\/ 7. Here we register the ServletContextHandler as the OSGi service\n\t\tbundleContext.registerService(ContextHandler.class.getName(), ch, props);\n\n\t\tSystem.out.println(\"Registration Complete\");\n\t}\n\n\t\n\tpublic void stop(BundleContext bundleContext) throws Exception {\n\t\tActivator.context = null;\n\t}\n\n}\n\n<\/pre>\nIn the activator, we have first created a ServletHandler<\/i> and registered our Servlet<\/i> along with a mapping. Thereafter we appended it to a ServletContextHandler<\/i> with a context path. Lastly we have registered our ServletContextHandler<\/i> as an OSGi component. Now our Jetty Server will find our ServletContextHandler <\/i>as its context handler.<\/p>\n
Please note that, the the components are resolved by name, therefore the component name ContextHandler.class.getName()<\/i> shouldn\u2019t be replaced with an arbitrary name.<\/p>\n
After we implemented our bundle, we can run our OSGi container. when we try to access http:\/\/localhost:8080\/jcgservletpath\/<\/a>, we will see that our request is handled by our Servlet with the following response:<\/p>\n
- On the \u201cDependencies<\/em>\u201d, click on \u201cAdd\u201d button on the \u201cRequired Plug-ins<\/em>” section.<\/li>\n
- Type project name as \u201cjetty-osgi-example<\/i>\u201d.<\/li>\n
- Create the folder \u201cosgi-jetty-home\/etc<\/em>\u201d<\/li>\n
- Create a folder named \u201cosgi-jetty-home<\/em>\u201d (You can name is as you wish.)<\/li>\n
- Search for \u201cTarget<\/em>\u201d from the search box on the top left.<\/li>\n
- Open Eclipse “Preferences<\/em>” from the Menu<\/li>\n
![\"Servlet](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2015\/07\/osgi3_1.jpg\")
<\/a>