Here is a solution to use Restlet (http://www.restlet.org/) with Grizzly (https://grizzly.dev.java.net/) and a Comet async Servlet.
The App.java is starting a standalone Grizzly Web Server. It is hosting an async Servlet and the Restlet Engine. The Restlet Engine is used as a servlet.
Download Code: AsyncRestlet
App.java
package asyncrestlet;
import com.sun.grizzly.comet.CometAsyncFilter;
import com.sun.grizzly.http.embed.GrizzlyWebServer;
import com.sun.grizzly.http.servlet.ServletAdapter;
import org.restlet.ext.servlet.ServerServlet;
/**
* The App
*
* Demonstration to use the Restlet framework and an async servlet.
* The async servlet uses the comet package.
*
* Starts grizzly standalone servlet container with restlet and comet servlet.
*
*
* Run server:
*
* mvn -Dexec.classpathScope=runtime -Dexec.args="-classpath %classpath asyncrestlet.App" -Dexec.executable=java exec:exec
*
* To test:
*
* (wget -O - -q "http://localhost:8181/async" &); echo "async GET started"; sleep 2; wget -O - -q "http://localhost:8181/async"
*
* wget -O - -q "http://localhost:8181/restlet/therestlet"
*
*/
public class App {
public static void main(String[] args) throws Exception {
// static content is linked from here
GrizzlyWebServer gws = new GrizzlyWebServer(8181, "no static content");
// add the async filter for comet functionality
gws.addAsyncFilter(new CometAsyncFilter());
// Adding async servlet
ServletAdapter simpleServletAdapter = new ServletAdapter();
simpleServletAdapter.setContextPath("/async");
simpleServletAdapter.setServletInstance(new AsyncServlet());
// register above defined adapters
gws.addGrizzlyAdapter(simpleServletAdapter, new String[]{"/async"});
// Adding restlet servlet
ServletAdapter restletServletAdapter = new ServletAdapter();
restletServletAdapter.setContextPath("/restlet");
// this is the magic restlet servlet
restletServletAdapter.setServletInstance(new ServerServlet());
// let the restlet servlet know which appplication to start
restletServletAdapter.addContextParameter("org.restlet.application", "asyncrestlet.RestletApplication");
// register above defined adapters
gws.addGrizzlyAdapter(restletServletAdapter, new String[]{"/restlet"});
// let Grizzly run
gws.start();
System.out.println("to test async:\n\n (wget -O - -q \"http://localhost:8181/async\" &); echo \"async GET started\"; sleep 2; wget -O - -q \"http://localhost:8181/async\"\n\n");
System.out.println("to test restlet:\n\n wget -O - -q \"http://localhost:8181/restlet/therestlet\"\n\n");
}
}
AsyncServlet.java
package asyncrestlet;
import com.sun.grizzly.comet.CometContext;
import com.sun.grizzly.comet.CometEngine;
import com.sun.grizzly.comet.CometEvent;
import com.sun.grizzly.comet.CometHandler;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* AsyncServlet
*
* uses comet for async http
*
* every GET waits 5 seconds. With another GET the wait can be interrupted
*
*/
public class AsyncServlet extends HttpServlet {
private class CounterHandler
implements CometHandler<HttpServletResponse> {
private HttpServletResponse response;
@Override
public void onInitialize(CometEvent event)
throws IOException {
}
@Override
public void onInterrupt(CometEvent event)
throws IOException {
PrintWriter writer = response.getWriter();
writer.write("timeout from async\n");
writer.flush();
removeThisFromContext();
}
@Override
public void onTerminate(CometEvent event)
throws IOException {
removeThisFromContext();
}
@Override
public void attach(HttpServletResponse attachment) {
this.response = attachment;
}
private void removeThisFromContext() throws IOException {
response.getWriter().close();
CometContext context =
CometEngine.getEngine().getCometContext(contextPath);
context.removeCometHandler(this);
}
@Override
public void onEvent(CometEvent event) throws IOException {
if (CometEvent.NOTIFY == event.getType()) {
PrintWriter writer = response.getWriter();
writer.write("hello from async\n");
writer.flush();
event.getCometContext().resumeCometHandler(this);
}
}
}
private static final long serialVersionUID = 1L;
private String contextPath;
@Override
public void init(ServletConfig config) throws ServletException {
super.init(config);
contextPath = config.getServletContext().getContextPath() + "/async";
CometEngine cometEngine = CometEngine.getEngine();
CometContext context = cometEngine.register(contextPath);
context.setExpirationDelay(5 * 1000);
}
@Override
protected void doGet(HttpServletRequest req,
HttpServletResponse res)
throws ServletException, IOException {
CounterHandler handler = new CounterHandler();
handler.attach(res);
CometEngine engine = CometEngine.getEngine();
CometContext context = engine.getCometContext(contextPath);
context.notify(null);
context.addCometHandler(handler);
}
}
RestletApplication.java
package asyncrestlet;
import org.restlet.Application;
import org.restlet.Restlet;
import org.restlet.resource.Get;
import org.restlet.resource.ServerResource;
import org.restlet.routing.Router;
/*
* RestletApplication
*
* The restlet application
*/
public class RestletApplication extends Application {
/**
* Creates a root Restlet that will receive all incoming calls.
*/
@Override
public synchronized Restlet createInboundRoot() {
// Create a router Restlet that routes each call to a
// new instance of HelloWorldResource.
Router router = new Router(getContext());
// Defines only one route
router.attach("/therestlet", RestletResource.class);
return router;
}
}
RestletResource.java
package asyncrestlet;
import org.restlet.resource.Get;
import org.restlet.resource.ServerResource;
public class RestletResource extends ServerResource {
@Get
public String represent() {
return "hello from restlet\n";
}
}
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>AsyncRestlet</groupId>
<artifactId>AsyncRestlet</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>AsyncRestlet</name>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.6</source>
<target>1.6</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<configuration>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>maven-restlet</id>
<name>Maven Restlet Repository</name>
<url>http://maven.restlet.org</url>
</repository>
<repository>
<id>JavaNet</id>
<name>Maven JavaNet Repository</name>
<url>http://download.java.net/maven/2/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.7</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>com.sun.grizzly</groupId>
<artifactId>grizzly-comet</artifactId>
<version>1.9.18b</version>
</dependency>
<dependency>
<groupId>com.sun.grizzly</groupId>
<artifactId>grizzly-servlet-webserver</artifactId>
<version>1.9.18b</version>
</dependency>
<dependency>
<groupId>org.restlet.jee</groupId>
<artifactId>org.restlet</artifactId>
<version>2.0-M7</version>
<exclusions>
<exclusion>
<artifactId>org.osgi.core</artifactId>
<groupId>org.osgi</groupId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.restlet.jee</groupId>
<artifactId>org.restlet.ext.servlet</artifactId>
<version>2.0-M7</version>
<type>jar</type>
</dependency>
</dependencies>
</project>
Resources:
http://blogs.sun.com/msreddy/entry/how_to_make_grizzly_comet
http://www.javaworld.com/javaworld/jw-03-2008/jw-03-asynchhttp.html?page=6
http://blogs.sun.com/japod/entry/jersey_aplication_sharing_grizzly_with
Servlet Communication:
http://docstore.mik.ua/orelly/java-ent/servlet/ch11_03.htm
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