[jdom-interest] Re: can jdom be used inside a servlet?

[Joseph Bowbeer]

> Can jdom be used inside a servlet?

This is an infrequent but recurring question.

You might be encountering the problem I describe below:

Many XML parsers *close* the input stream when they read eof (-1).

This is true of Xerces, which is JDOM's default parser.  It is also true
of Crimson.

  org.apache.xerces.readers.UTF8Reader
  org.apache.crimson.parser.InputEntity

Unfortunately, closing a SocketInputStream closes the underlying
SocketImpl, setting its file descriptor to null.  Since your servlet
cannot write to a socket with a null file descriptor, your servlet will
not be able to respond.

One workaround is to read everything into a buffer before handing-off to
the JDOM builder.

  byte[] buf = new byte[length];
  new DataInputStream(inputStream).readFully(buf);
  InputStream in = new ByteArrayInputStream(buf);

Another workaround is to protect your socket's input stream with an
InputStream wrapper that doesn't close the underlying stream (override
the 'close' method).  Or you can switch to a servlet container that
doesn't give your servlet direct access to the socket input stream (what
servlet container are you using?).


----- original message -----
From: "Yibing Li" <yli at mgfairfax.rr.com>
To: <jdom-interest at jdom.org>
Date: Wed, 6 Dec 2000 18:43:01 -0500
Subject: [jdom-interest] can jdom be used inside a servlet?

We are trying to use jdom in our xml API project to
receive a xml document and send back the response as
a xml document. This can be easily done by using a simple
servlet. But our developer find once jdom builder is instantiated, the
program stops there. Is this  related to  something special in the
threading model of xml parser?

Please advise.