Draft list of changes in Servlet 4.0

The proposed final draft (PDF) of the Servlet 4.0 spec has just been made available at GitHub.

The major new feature is HTTP/2 support and specifically the push support that comes with it. Java EE already has support for push via WebSockets (including WebSocket support in JSF 2.3), but there are other interesting changes as well, such as for instance the Mapping Discovery API.

The following contains a terse list of changes, taken from section A.1 of the above linked Servlet 4.0 PFD document. All mentioned references to sections are to that document.

1. Requirement to support HTTP/2, see Section 1.2, “What is a Servlet Container?” on page 1-1 and “What is a Servlet?” on page 1 1. This includes HTTP/2 server push, see “HTTP/2 Server Push” on page 3 29.
2. Modify javadoc for ServletContext getAttribute() and getInitParameter(), specify that NullPointerException must be thrown if the argument “name” is null.
3. Modify javadoc for ServletContext.setAttribute() and setInitParameter() to specify that NullPointerException must be thrown if the “name” argument is null.
4. DeprecateHttpServletRequestWrapper.isRequestedSessionIdFromUrl().
5. Add @Deprecated to classes and methods with @deprecated in javadoc: ServletContext, ServletRequestWrapper, SingleThreadModel, UnavailableException, HttpServletRequest, HttpServletResponse, HttpServletResponseWrapper, HttpSession, HttpSessionContext, HttpUtils.
6. Add default-context-path in the schema of web.xml and the description in Section 30., “default-context-path Element” on page 14-180 and the figure, Section FIGURE 14-1, “web-app Element Structure”.
7. Modify Section 7.7.1, “Threading Issues” to clarify non-thread safety of objects vended from requests and responses.
8. Clarify metadata-complete in Section 8.1, “Annotations and pluggability”.
9. Add default to methods in ServletContextAttributeListener, ServletContextListener, ServletRequestAttributeListener, ServletRequestListener, HttpSessionActivationListener, HttpSessionAttributeListener, HttpSessionBindingListener, HttpSessionListener.
10. Add javax.servlet.GenericFilter and javax.servlet.http.HttpFilter
11. Clarify the merging of in web.xml and web-fragment.xml in Section 8.2.3, “Assembling the descriptor from web.xml, web-fragment.xml and annotations”.
12. Modify javadoc for ServletContext.getEffectiveSessionTrackingModes() without specifying the default value.
13. Remove DTDs and Schemas from binary artifact for Servlet API.
14. Add getSessionTimeout and setSessionTimeout in ServletContext. See javadoc, Section 4.4.4 and Section 7.5.
15. Add addJspFile() in ServletContext. See javadoc, Section 4.4.1.4 and Section 4.4.1.7.
16. Add request-character-encoding and response-character-encoding in the schema of web.xml. See the corresponding descriptions of the elements in Section 31. and Section 32.
17. Add getRequestCharacterEncoding, setRequestCharacterEncoding, getResponseCharacterEncoding and setResponseCharacterEncoding in ServletContext. Update the corresponding javadoc of ServletContext, ServletRequest and ServletResponse. See Section 4.4.5, Section 3.12 and Section 5.6.
18. Describe mapping discovery API. See Section 12.3, “Runtime Discovery of Mappings”.
19. Update the javadoc of Registration, ServletContext, ServletRegistration for the behaviors of returned sets.
20. Clarify the behaviors of complete and dispatch in AsyncContext before the container-initiated dispatch that called startAsync has returned to the container. See Section , “AsyncContext” on page 2-13.
21. Clarify interpretation of fileName parameter for method Part.write(). See the javadoc for details.
22. Clarify encoding used for reading the request URL. See Section 12.1, “Use of URL Paths” on page 12-125 for details.
23. Specified support for HTTP trailer. See Section 5.3, “HTTP Trailer” for details. Add getTrailerFields(), isTrailerFieldsReady() in HttpServletRequest and setTrailerFields in HttpServletResponse. See the corresponding javadoc.