Enthuware

What you mean with default servlet?

Would it be sth like <url-pattern>* OR /</url-pattern>?

As per Section 12.2:

A string containing only the ’/’ character indicates the "default" servlet of the application. In this case the servlet path is the request URI minus the context path and the path info is null.

HTH,
Paul.

If you have the following mappings:
/foo/bar/*    mapped to servlet1
*.bop    mapped to servlet4

Why the requests to /foo/bar/index.bop  will go to servlet1 ?

This is because an extension mapping is considered ONLY if there is no path matching. Here, /foo/bar/index.bop does have a path matching with /foo/bar/*

In the explanation, /catalog/index.html will go to default servlet.
I think / will go to the default servlet.
But I think /catalog/index.html will be mapped to an index.html file under /catalog directory of the web application. But if this index.html file does not exist, it will return a 404 error.

Why do you think so?

Hi, I tried this with Tomcat 8.
When /catalog/index.html (where catalog is a folder under the root of the web application) does not exist , it returns resource not found.

Well, then probably tomcat 8 doesn't follow the specification because the text in the explanation is taken from Section 12.2.2 - "Example Mapping Set" of Servlet 3.0 specification.

HTH,
Paul.