<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.yaz-scan" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>yaz_scan</refname>
  <refpurpose>Prepares for a scan</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>void</type><methodname>yaz_scan</methodname>
   <methodparam><type>resource</type><parameter>id</parameter></methodparam>
   <methodparam><type>string</type><parameter>type</parameter></methodparam>
   <methodparam><type>string</type><parameter>startterm</parameter></methodparam>
   <methodparam choice="opt"><type>array</type><parameter>flags</parameter></methodparam>
  </methodsynopsis>
  <para>
   This function prepares for a Z39.50 Scan Request on the specified 
   connection.
  </para>
  <para>
   To actually transfer the Scan Request to the server and receive the
   Scan Response, <function>yaz_wait</function> must be called. Upon
   completion of <function>yaz_wait</function> call
   <function>yaz_error</function> and <function>yaz_scan_result</function> to
   handle the response.
  </para>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>id</parameter></term>
     <listitem>
      <para>
       The connection resource returned by <function>yaz_connect</function>.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>type</parameter></term>
     <listitem>
      <para>
       Currently only type <literal>rpn</literal> is supported.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>startterm</parameter></term>
     <listitem>
      <para>
       Starting term point for the scan.
      </para>
      <para>
       The form in which the starting term is specified is given by parameter
       <parameter>type</parameter>.
      </para>
      <para>
       The syntax this parameter is similar to the RPN query as described in
       <function>yaz_search</function>. It consists of zero or more 
       <literal>@attr</literal>-operator specifications, then followed by 
       exactly one token.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>flags</parameter></term>
     <listitem>
      <para>
       This optional parameter specifies additional information to control 
       the behaviour of the scan request. Three indexes are currently read 
       from the flags array:
       <literal>number</literal> (number of terms requested),
       <literal>position</literal> (preferred position of term) and
       <literal>stepSize</literal> (preferred step size).
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.void;
  </para>
 </refsect1>
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>PHP function that scans titles</title>
    <programlisting role="php">
<![CDATA[
<?php
function scan_titles($id, $startterm) 
{
  yaz_scan($id, "rpn", "@attr 1=4 " . $startterm);
  yaz_wait();
  $errno = yaz_errno($id);
  if ($errno == 0) {
    $ar = yaz_scan_result($id, $options);
    echo 'Scan ok; ';
    foreach ($options as $key => $val) {
      echo "$key = $val &nbsp;";
    }
    echo '<br /><table>';
    while (list($key, list($k, $term, $tcount)) = each($ar)) {
      if (empty($k)) continue;
      echo "<tr><td>$term</td><td>$tcount</td></tr>";
    }
    echo '</table>';
  } else {
    echo "Scan failed. Error: " . yaz_error($id) . "<br />";
  }
}
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
</refentry>

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