I'm currently running my webapps on Tomcat 6 in production, and would like to evaluate running Tomcat in embedded mode.
Is there a good tutorial or other resource besides what's in the api documentation?
6 Answers
Code speaks for itself. See the pom.xml snippet and the class to run tomcat.
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>catalina</artifactId>
<version>6.0.18</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>coyote</artifactId>
<version>6.0.18</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.tomcat</groupId>
<artifactId>jasper</artifactId>
<version>6.0.18</version>
<scope>test</scope>
</dependency>
public class RunWebApplicationTomcat {
private String path = null;
private Embedded container = null;
private Log logger = LogFactory.getLog(getClass());
/**
* The directory to create the Tomcat server configuration under.
*/
private String catalinaHome = "tomcat";
/**
* The port to run the Tomcat server on.
*/
private int port = 8089;
/**
* The classes directory for the web application being run.
*/
private String classesDir = "target/classes";
/**
* The web resources directory for the web application being run.
*/
private String webappDir = "mywebapp";
/**
* Creates a single-webapp configuration to be run in Tomcat on port 8089. If module name does
* not conform to the 'contextname-webapp' convention, use the two-args constructor.
*
* @param contextName without leading slash, for example, "mywebapp"
* @throws IOException
*/
public RunWebApplicationTomcat(String contextName) {
Assert.isTrue(!contextName.startsWith("/"));
path = "/" + contextName;
}
/**
* Starts the embedded Tomcat server.
*
* @throws LifecycleException
* @throws MalformedURLException if the server could not be configured
* @throws LifecycleException if the server could not be started
* @throws MalformedURLException
*/
public void run(int port) throws LifecycleException, MalformedURLException {
this.port = port;
// create server
container = new Embedded();
container.setCatalinaHome(catalinaHome);
container.setRealm(new MemoryRealm());
// create webapp loader
WebappLoader loader = new WebappLoader(this.getClass().getClassLoader());
if (classesDir != null) {
loader.addRepository(new File(classesDir).toURI().toURL().toString());
}
// create context
// TODO: Context rootContext = container.createContext(path, webappDir);
Context rootContext = container.createContext(path, webappDir);
rootContext.setLoader(loader);
rootContext.setReloadable(true);
// create host
// String appBase = new File(catalinaHome, "webapps").getAbsolutePath();
Host localHost = container.createHost("localHost", new File("target").getAbsolutePath());
localHost.addChild(rootContext);
// create engine
Engine engine = container.createEngine();
engine.setName("localEngine");
engine.addChild(localHost);
engine.setDefaultHost(localHost.getName());
container.addEngine(engine);
// create http connector
Connector httpConnector = container.createConnector((InetAddress) null, port, false);
container.addConnector(httpConnector);
container.setAwait(true);
// start server
container.start();
// add shutdown hook to stop server
Runtime.getRuntime().addShutdownHook(new Thread() {
public void run() {
stopContainer();
}
});
}
/**
* Stops the embedded Tomcat server.
*/
public void stopContainer() {
try {
if (container != null) {
container.stop();
}
} catch (LifecycleException exception) {
logger.warn("Cannot Stop Tomcat" + exception.getMessage());
}
}
public String getPath() {
return path;
}
public void setPath(String path) {
this.path = path;
}
public static void main(String[] args) throws Exception {
RunWebApplicationTomcat inst = new RunWebApplicationTomcat("mywebapp");
inst.run(8089);
}
public int getPort() {
return port;
}
}
There are a number of reasons why one might use Tomcat over Jetty:
- One is already familiar with Tomcat
- One is developing web applications that need to be easily transported to a Tomcat installation
- The Jetty developer documentation is actually spottier than Tomcat's (amazing!)
- Getting questions answered in the Jetty community can sometimes take years, as in 2007. see Embedding Jetty
- Important: After Jetty 6.1.*, each web application opens into its own JVM, so if you're trying to gain programmatic access between your standalone access and your web app, your only hope is via a web API.
- If it's an issue for you, Tomcat is an open source project who intellectual property is owned by the Apache Foundation, Jetty is open source but owned by a small private company (Mortbay Consulting)
Point #5 has been important in my work. For example, I can gain direct access to a JSPWiki instance via Tomcat, but it's completely inaccessible when using Jetty. I asked for a solution to that in 2007 and haven't yet heard an answer. So I finally gave up and began using Tomcat 6. I've looked into Glassfish and Grizzly, but so far Tomcat is (amazingly) the most stable and well-documented web container (which isn't saying much really).
This might help.
If you download the source package for Tomcat6.x, you get this class:
Which is an example of how to use the Embedd class: its a shell to stop|start a specific Tomcat installation. (I mean you can set up CATALINA_BASE to point at an existing Tomcat installation).
If you compile this you can run like this:
java -D"catalina.base=%CATALINA_BASE%" -D"catalina.home=%CATALINA_HOME%" org.apache.catalina.startup.Catalina start
I'm not sure how to alter this code to shutdown the server yet though!
After reading this thread some months ago, I wrote this project: spring-embedded-tomcat. It can be used to embed tomcat6 into Spring-based applications.
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