The com.oreilly.servlet package contains a set of useful utility classes
for servlet developers. Included are classes to help servlets parse
parameters, handle multipart requests (file uploads), generate multipart
responses (server push), negotiate locales for internationalization,
return files, manage socket connections, and act as RMI servers, among
other things. There's even a class to help applets communicate with
servlets. The package was developed by Jason Hunter for his book "Java
Servlet Programming" published by O'Reilly.  See:

WWW: http://www.servlets.com/cos/index.html

For more details.