deploy web app to jetty: service_unavailable

i have a gwt app deployed to Jetty, i use maven, maven-jetty-plugin, following the instruction provided here: http://docs.codehaus.org/display/JETTY/Maven+Jetty+Plugin, my project follows the maven structure so no configuration needed, all i need is to run : mvn jetty:run, then i can see jetty server started, back to browser, i typed 127.0.0.1:8080 i saw a page with Error 404 -Not Found, saying:

No context on this server matched or handled this request.
Context known to this server are:
 /console --> org.mortbay.jetty.plugin.Jetty6PluginWebAppC开发者_如何学Pythonontext@1c093b3c{/console./Users/Hj/Documents/workspace/samples/console/src/main/webapp}

and that's my webapp '/console', so i click that link, it went to 127.0.0.1:8080/console url and here is the message on that page:

HTTP ERROR: 503
Problem accessing /console. Reason: SERVICE_UNAVAILABLE

does anyone know what's wrong here? i think the web app was deployed to Jetty, how come it says service unavailable? thanks.