Ignore zoomst10

[yaz-moved-to-github.git] / doc / odr.xml

diff --git a/doc/odr.xml b/doc/odr.xml
index 2824d6c..6a135e9 100644 (file)
--- a/doc/odr.xml
+++ b/doc/odr.xml
@@ -1,4 +1,4 @@
-<!-- $Id: odr.xml,v 1.12 2004-03-19 21:12:13 adam Exp $ -->
+<!-- $Id: odr.xml,v 1.18 2006-04-25 11:25:08 marc Exp $ -->
  <chapter id="odr"><title>The ODR Module</title>
   
   <sect1 id="odr.introduction"><title>Introduction</title>
@@ -355,6 +355,57 @@ void do_nothing_useful(int value)
     
    </sect2>
 
+   <sect2><title>Printing</title>
+    <para>
+     When an ODR stream is created of type <literal>ODR_PRINT</literal>
+     the ODR module will print the contents of a PDU in a readable format.
+     By default output is written to the <literal>stderr</literal> stream.
+     This behavior can be changed, however, by calling the function
+     <synopsis>
+      odr_setprint(ODR o, FILE *file);
+     </synopsis>
+     before encoders or decoders are being invoked.
+     It is also possible to direct the output to a buffer (of indeed
+     another file), by using the more generic mechanism:
+     <synopsis>
+      void odr_set_stream(ODR o, void *handle,
+                         void (*stream_write)(ODR o, void *handle, int type,
+                                              const char *buf, int len),
+                         void (*stream_close)(void *handle));
+     </synopsis>
+     Here the user provides an opaque handle and two handlers,
+     <replaceable>stream_write</replaceable> for writing,
+     and <replaceable>stream_close</replaceable> which is supposed
+     to close/free resources associated with handle. 
+     The <replaceable>stream_close</replaceable> handler is optional and
+     if NULL for the function is provided, it will not be invoked.
+     The <replaceable>stream_write</replaceable> takes the ODR handle
+     as parameter, the user defined handle, a type 
+     <literal>ODR_OCTETSTRING</literal>, <literal>ODR_VISIBLESTRING</literal>
+     which indicates the type of contents is being written.
+    </para>
+    <para>
+     Another utility useful for diagnostics (error handling) or as
+     part of the printing facilities is:
+     <synopsis>
+      const char **odr_get_element_path(ODR o);
+     </synopsis>
+     which returns a list of current elements that ODR deals with at the 
+     moment. For the returned array, say <literal>ar</literal>, 
+     <literal>ar[0]</literal> is the top level element,
+     <literal>ar[n]</literal> is the last. The last element has the
+     property that <literal>ar[n+1] == NULL</literal>.
+    </para>
+    <example>
+     <title>Element Path for record</title>
+     <para>
+      For a database record part of a PresentResponse the
+      array returned by <function>odr_get_element</function>
+      is <literal>presentResponse</literal>, <literal>databaseOrSurDiagnostics</literal>, <literal>?</literal>, <literal>record</literal>, <literal>?</literal>, <literal>databaseRecord</literal> . The question mark appears due to 
+      unnamed constructions.
+     </para>
+     </example>
+   </sect2>
    <sect2><title>Diagnostics</title>
 
     <para>
@@ -489,9 +540,9 @@ void do_nothing_useful(int value)
    <tip>
     <para>
      There is an ASN.1 tutorial available at
-     <ulink url="http://asn1.elibel.tm.fr/en/introduction/">this site</ulink>.
+     <ulink url="&url.asn.1.tutorial;">this site</ulink>.
      This site also has standards for ASN.1 (X.680) and BER (X.690) 
-     <ulink url="http://asn1.elibel.tm.fr/en/standards/">online</ulink>.
+     <ulink url="&url.asn.1.standards;">online</ulink>.
     </para>
    </tip>