Glassfish v3 Servlet Container

Question

I'm wondering what a servlet container is in Glassfish. In some sources, I saw Glassfish using something like Grizzly, but Grizzly is a web framework:

Grizzly NIO and the web environment were designed to help developers use the Java ™ NIO API. Grizzly's goal is to help developers create scalable and reliable servers using NIO, as well as offer advanced infrastructure components: Web Framework (HTTP / S), Bayeux protocol, Servlet, HttpService OSGi and Comet.

What does it mean? Does Glassfish use grizzly as a web container. Or maybe Tomcat and Grizzly as an extension?

Answer 1

Grizzly is an HTTP connector. Glassfish uses the Tomcat engine plug (Catalina) as a servlet container. A simple proof is to check for stacktrace when an exception occurs in your business code. You will see org.apache.catalina.* In the back of the track, between the lines of com.sun.grizzly.* And the lines of your own business code. Usually it looks 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 one that uses Catalina, by the way, JBoss AS and IBM WebSphere also use it.