WebSockets problem Re: NullPointerException in MapperListener; Tomcat#start() does not create a Container?

[Nick Williams <ni...@nicholaswilliams.net>]

On Mar 14, 2013, at 4:25 PM, Konstantin Kolinko wrote:

> 2013/3/15 Nick Williams <ni...@nicholaswilliams.net>:
>> 
>> On Mar 14, 2013, at 2:56 PM, Nick Williams wrote:
>> 
>>> Using a variety of tutorials I found online and the documentation for o.a.c.startup.Tomcat, I created the following main method to start up an embedded Tomcat. I'm using 7.0.37 Tomcat JARs.
>>> 
>>>   public static void main(String... arguments) throws Exception
>>>   {
>>>       Tomcat tomcat = new Tomcat();
>>>       tomcat.setBaseDir(".basedir");
>>>       tomcat.setPort(8973);
>>>       tomcat.enableNaming();
>>>       tomcat.init();
>>>       tomcat.start();
>>> 
>>>       System.out.println("X: " + tomcat.getConnector().getService().getContainer());
>>> 
>>>       tomcat.getServer().await();
>>>   }
>>> 
>>> The System.out.println is for debugging purposes, because I'm getting a NullPointerException. Obviously I'm doing something wrong, because about an hour of Googling turned up precisely zero results of anyone who's getting a NullPointerException in MapperListener#findDefaultHost. For some reason, it looks like a Container is never created. What gives? Here's the full output of running the JAR file:
> 
> 
> Why do you expect that default "Host" exist, if you have not created
> one, nor asked for one, nor deployed a web application,  all of them
> auto-create it if it is missing.
> 
> There may be different implementations of a Host. It needs
> configuration (name). Thus initially there is none created.
> 
> Calling tomcat.getHost() should be enough.
> 
> Note, that Tomcat needs a default web application (aka context with
> path "", aka ROOT) for certain features (error reporting) to work
> properly.

I understand what I was doing wrong, now. I was trying to take any web application errors out of the picture so that I could solve any other problems I was having first. I didn't realize that you couldn't start normally if you didn't have any applications to deploy, so I was actually causing more problems by removing the adding of my web application.

I don't need tomcat.getService().setContainer(tomcat.getEngine()) anymore now that I'm calling addWebapp on a proper web application.

Mark, my application successfully deploys to the ROOT context in the embedded Tomcat and a test servlet (/healthCheck) starts up properly and requests to it resolve properly. However, my WebSocket endpoints were not working. I was getting 404 errors for any requests to them. It tracked it down to missing service providers. The following files are missing from the org.apache.tomcat.embed:tomcat-embed-core artifact:

META-INF/services/javax.servlet.ServletContainerInitializer
META-INF/services/javax.websocket.ContainerProvider
META-INF/services/javax.websocket.server.ServerContainerProvider
META-INF/services/javax.websocket.server.ServerEndpointConfig.Configurator

When I added those to my uber-jar embedded JAR file, WebSockets started working properly. So, looks like something about the way that artifact is built is omitting those files accidentally. I can file a bug about this if you need me to.
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