[jax-rs-spec users] content not available after calling ServletRequest.getParameter()

From: <>
Date: Wed, 5 Feb 2014 11:13:00 +0000 (UTC)

I ran in an issue where CDI and JAX-RS 2 are not working together. In
case a Resource class is also using CDI, parameters used in resource
methods won't work (they might be empty).

Checking the problem (with Jersey and Weld) showed this:
A CDI implementation needs to provide a CDI Conversation Filter. In the
Weld case, this filter calls ServletRequest.getParameter(). The servlet
javadoc mentions
"If the parameter data was sent in the request body, such as occurs
with an HTTP POST request, then reading the body directly via
getInputStream() or getReader() can interfere with the execution of
this method."

As a consequence, a single Filter implementation calling
ServletRequest.getParameter() may consume the request body, which
causes subsequent consumption of this request body to fail. Hence,
using a MessageBodyReader (prepackaged or custom) will fail.

Unless I am missing something, I don't think this is a flaw in CDI,
Servlet spec, or JAX-RS, but the combination is not working. The whole
JAX-RS spec implicitly assumes the method request body is available,
but the combination of the Servlet spec and the CDI spec makes this
impossible (there can only be 1 consumer of the method request body,
either CDI or Jersey).

More info on the issues:

- Johan