    <sect1 id="using">
      <title>How to use neon from your application</title>

      <para>This section describes how to add &neon; support to an
      application.  If you just want to quickly try out &neon;, use
      the <xref linkend="refconfig"/> script.</para>

      <para>The &neon; source code is designed to be easily embedded
      into an application source tree.  &neon; has no dependencies on
      libraries other than an SSL toolkit and XML parser, though the
      source tree can be configured to have no support for SSL or XML
      if desired.  To configure the &neon; source code some <ulink
      url="http://www.gnu.org/software/autoconf/">GNU autoconf</ulink>
      macros are supplied, which can be used in a number of ways, as
      follows:</para>
      
      <itemizedlist>
	<listitem>
	  
	  <para>autoconf macros are distributed in the 'macros'
	  subdirectory of the neon distribution.  Use the NEON_LIBRARY
	  macro from your configure.in to check for the presence of
	  the neon library installed on the system.  The macro adds an
	  '--with-neon=...'  argument to configure, which allows the
	  user to specify a location for the library (the standard
	  /usr and /usr/local directories are checked automatically
	  without having to be specified).</para></listitem>
	  
	  <listitem><para>The 'src' directory of the neon package can be
	  imported directly into your application, if you do not wish
	  to add an external dependency.  If you wish to bundle, use
	  the NEON_BUNDLED macro to configure neon in your application:
	  here, the neon sources are bundled in a directory called
	  'libneon':</para>
	  
	  <programlisting>NEON_BUNDLED(libneon, ...)</programlisting>
	  
	  <para>If your application supports builds where srcdir != builddir,
	  you should use the NEON_VPATH_BUNDLED macro like this:</para>
	  
	  <programlisting>NEON_VPATH_BUNDLED(${srcdir}/libneon, libneon, ...)</programlisting>
	  
	  <para>If you use this macro, a '--with-included-neon' option
	  will be added to the generated configure script.  This
	  allows the user to force the bundled neon to be used in the
	  application, rather than any neon library found on the
	  system. If you allow neon to be configured this way, you
	  must also configure an XML parser. Use the NEON_XML_PARSER
	  macro to do this.</para></listitem>
	  
	  <listitem><para>The final argument to the _BUNDLED macros is a
	  set of actions which are executed if the bundled build *is*
	  chosen (rather than an external neon which might have been
	  found on the user's system).  In here, use either the
	  NEON_LIBTOOL_BUILD or NEON_NORMAL_BUILD macro to set up the
	  neon Makefile appropriately: including adding the neon source
	  directory to the recursive make.</para></listitem>
	  
	</itemizedlist>
	
	<para>A full fragment might be:</para>
	
<programlisting>NEON_BUNDLED(libneon, [
  NEON_NORMAL_BUILD
  NEON_XML_PARSER
  SUBDIRS="libneon $SUBDIRS"
])</programlisting>
	
	<para>This means the bundled neon source directory (called 'libneon')
	is used if no neon is found on the system, and the standard XML
	parser search is used.</para>
	
      </sect1>

      <sect1 id="example">
        <title>Example application</title>

	<para>The code below is a simple example which sends a
	<literal>PUT</literal> request, using the API from
	<literal>&lt;ne_basic.h&gt;</literal>:

<programlisting><![CDATA[
#include <stdio.h>
#include <stdlib.h>

#include <ne_basic.h>

static const char data[] = "Example data.\n";

int main(int argc, char **argv)
{
    ne_session *sess;
    int ec = EXIT_SUCCESS;

    ne_sock_init(); /* Global library initialization. */

    sess = ne_session_create("http", "localhost", 80);

    if (ne_putbuf(sess, "/dav/data.txt", data, sizeof data)) {
        fprintf(stderr, "PUT Request failed: %s\n", ne_get_error(sess));
        ec = EXIT_FAILURE;
    }

    ne_session_destroy(sess);

    return ec;
}
]]></programlisting></para></sect1>
      
      <sect1 id="compliance">
	<title>Standards compliance</title>
	
	<para>&neon; is intended to be compliant with the IETF and W3C
	standards which it implements, with a few exceptions due to
	practical necessity or interoperability issues.  These
	exceptions are documented in this section.</para>

	<sect2><title>RFC 2518, HTTP Extensions for Distributed Authoring&mdash;WebDAV</title>
	
	<para>&neon; is deliberately not compliant with section
	23.4.2, and treats property names as a (namespace-URI, name)
	pair.  This is <ulink
	url="http://lists.w3.org/Archives/Public/w3c-dist-auth/1999OctDec/0343.html">generally
	considered</ulink> to be correct behaviour by the WebDAV
	working group, and is likely to formally adopted in a future
	revision of the specification.</para></sect2>
	
        <sect2><title>RFC 2616, Hypertext Transfer Protocol&mdash;HTTP/1.1</title>
        
        <para>There is some confusion in this specification about the
        use of the <quote>identity</quote>
        <firstterm>transfer-coding</firstterm>.  &neon; ignores the
        <literal>Transfer-Encoding</literal> response header if it
        contains only the (now deprecated) <quote>identity</quote>
        token, and will determine the response message length as if
        the header was not present.  &neon; will give an error if a
        response includes a <literal>Transfer-Encoding</literal>
        header with a value other than <quote>identity</quote> or
        <quote>chunked</quote>.</para></sect2>

        <sect2>
        <title><ulink url="https://datatracker.ietf.org/doc/html/rfc3986">RFC 3986</ulink> Uniform Resource Identifier (URI): Generic Syntax and <ulink url="https://datatracker.ietf.org/doc/html/rfc6874">RFC 6874</ulink>, Representing IPv6 Zone Identifiers in Address Literals and Uniform Resource Identifiers</title>

        <para>&neon; parses and handles scoped IPv6 link-local literal
        addresses passed to <xref linkend="refsess"/> since version
        <literal>0.34</literal>, following the syntax in RFC 6874. An
        example <literal>host</literal> argument would be
        <literal>"[fe80::cafe%25eth0]"</literal> where
        <literal>"eth0"</literal> is the scope ID. Since <ulink
        url="https://datatracker.ietf.org/doc/html/rfc9110">RFC
        9110</ulink> does not reference the extended syntax of scoped
        IPv6 literals, and a scope ID has no meaningful interpretation
        outside of the client host, it is omitted from the
        <literal>Host</literal> header sent over the wire. So the
        example argument here translates to an HTTP/1.1 header field
        of <literal>Host: [fe80::cafe]</literal>.</para>
        </sect2>

        <sect2>
        <title>RFC 7616, HTTP Digest Access Authentication</title>

        <para>&neon; is not strictly compliant with the quoting rules
        given in the grammar for the <literal>Authorization</literal>
        header.  The grammar requires that the <literal>qop</literal>
        and <literal>algorithm</literal> parameters are not quoted,
        however one widely deployed server implementation
        (Microsoft&reg; IIS 5) rejects the request if these parameters
        are not quoted.  &neon; sends these parameters with
        quotes&mdash;this is not known to cause any problems with
        other server implementations.</para>

        <para>RFC 7616 predates RFC 9112 and uses conflicting language
        around URIs. &neon; uses the RFC 9112
        <literal>request-target</literal> in both the
        <literal>A2</literal> grammar and the <literal>uri=</literal>
        parameter of the <literal>Authorization</literal>
        header. &neon; will accept (and resolve) any URI-reference in
        the <literal>domain=</literal> parameter for
        <literal>WWW-Authenticate</literal> response header
        field.</para>

        </sect2>

	<sect2>
        <title>Namespaces in XML</title>

        <para>The &neon; XML parser interface will accept and parse
        without error some XML documents which are well-formed
        according to the XML specification but do not conform to the
        "Namespaces in XML" specification <xref
        linkend="bib.xmlnames"/>.  Specifically: the restrictions on
        the first character of the <literal>NCName</literal> rule are
        not all implemented; &neon; will allow any
        <literal>CombiningChar</literal>, <literal>Extender</literal>
        and some characters from the <literal>Digit</literal> class in
        this position.</para> </sect2>
 
        <!-- a few RFC2818/3280 issues: rules about when to cache
        sessions in the face of unclean shutdown are strict, neon is
        probably not compliant: document or fix.  Likewise SSL
        shutdown issues in general.  Cert hostname checks allow
        wildcard "*." syntax which is less than 2818 but more than
        3280 requires. -->

    </sect1>
