Glassfish v3 servlet container
glassfish
Solution
Grizzly is the HTTP connector. Glassfish uses a fork of Tomcat's engine (Catalina) as servlet container. An easy evidence is checking the stacktrace when some exception occurs in your business code. You'll see `org.apache.catalina.*` deep down in the trace, between the `com.sun.grizzly.*` lines and the lines of your own business code. It typically look like this:
...
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:680)
Glassfish is not the only which uses Catalina by the way, JBoss AS and IBM WebSphere also use it.
Problem
I'm wondering what is the servlet container in Glassfish. In some sources I saw that Glassfish uses something like Grizzly, but Grizzly is a web framework: The Grizzly NIO and Web framework has been designed to help developers to take advantage of the Java™ NIO API. Grizzly's goal is to help developers to build scalable and robust servers using NIO and we are also offering extended framework components: Web Framework (HTTP/S), Bayeux Protocol, Servlet, HttpService OSGi and Comet. What does it mean? Does Glassfish use Grizzly as web container. Or maybe Tomcat, and Grizzly as an extension?