利用Yahoo! Search API开发自已的搜索引擎-php版

    美国东部时间3月1日，雅虎公司联合创始人之一的杨致远将宣布公司的搜索网络将进入Web服务。雅虎公司在www.developer.yahoo.com网站建立了Yahoo Search Developer Network，公司计划在此纽约举行的搜索引擎战略大会(Search Engine Strategies Conference)上推出这一计划。该网络将允许开发者在雅虎搜索之上建立新的应用程序，其中包括图像、视频、新闻以及地区搜索等内容。想要使用这项服务的会员必须先去http://api.search.yahoo.com/webservices/register_application  申请一个自已的ID号，注：每个ID号每天只能搜索5000次。

    下面我们看一下，如何用PHP脚本调用Yahoo! Search API实现搜索的效果，全部脚本如下：
  

// Yahoo Web Services PHP Example Code
// Rasmus Lerdorf
// www.knowsky.com

$appid = 'YahooDemo';
// 在这输入你申请的ID号

$service = array('image'=>'http://api.search.yahoo.com/ImageSearchService/V1/imageSearch',
                 'local'=>'http://api.local.yahoo.com/LocalSearchService/V1/localSearch',
                 'news'=>'http://api.search.yahoo.com/NewsSearchService/V1/newsSearch',
                 'video'=>'http://api.search.yahoo.com/VideoSearchService/V1/videoSearch',
                 'web'=>'http://api.search.yahoo.com/WebSearchService/V1/webSearch');
?>

if(empty($_REQUEST['query']) || !in_array($_REQUEST['type'],array_keys($service))) done();

// Ok, here we go, we have the query and the type of search is valid
// First build the query
$q = '?query='.rawurlencode($_REQUEST['query']);
if(!empty($_REQUEST['zip'])) $q.="&zip=".$_REQUEST['zip'];
if(!empty($_REQUEST['start'])) $q.="&start=".$_REQUEST['start'];
$q .= "&appid=$appid";

// Then send it to the appropriate service
$xml = file_get_contents($service[$_REQUEST['type']].$q);

// Parse the XML and check it for errors
if (!$dom = domxml_open_mem($xml,DOMXML_LOAD_PARSING,$error)) {
  echo "XML parse error\n";
  foreach ($error as $errorline) {
  /* For production use this should obviously be logged to a file instead */
    echo $errorline['errormessage']."
\n";
    echo " Node  : " . $errorline['nodename'] . "
\n";
    echo " Line  : " . $errorline['line'] . "
\n";
    echo " Column : " . $errorline['col'] . "
\n";
  }
  done();
}

// Now traverse the DOM with this function
// It is basically a generic parser that turns limited XML into a PHP array
// with only a couple of hardcoded tags which are common across all the
// result xml from the web services
function xml_to_result($dom) {
  $root = $dom->document_element();
  $res['totalResultsAvailable'] = $root->get_attribute('totalResultsAvailable');
  $res['totalResultsReturned'] = $root->get_attribute('totalResultsReturned');
  $res['firstResultPosition'] = $root->get_attribute('firstResultPosition');

  $node = $root->first_child();
  $i = 0;
  while($node) {
    switch($node->tagname) {
      case 'Result':
        $subnode = $node->first_child();
        while($subnode) {
          $subnodes = $subnode->child_nodes();
          if(!empty($subnodes)) foreach($subnodes as $k=>$n) {
            if(empty($n->tagname)) $res[$i][$subnode->tagname] = trim($n->get_content());
            else $res[$i][$subnode->tagname][$n->tagname]=trim($n->get_content());
          }
          $subnode = $subnode->next_sibling();
        }
        break;
      default:
        $res[$node->tagname] = trim($node->get_content());
        $i--;
        break;
    }
    $i++;
    $node = $node->next_sibling();
  } 
  return $res;
}

$res = xml_to_result($dom);

// Ok, now that we have the results in an easy to use format,
// display them.  It's quite ugly because I am using a single
// display loop to display every type and I don't really understand HTML
$first = $res['firstResultPosition'];
$last = $first + $res['totalResultsReturned']-1;
echo "

matched ${res[totalresultsavailable]}, showing $first to $last

Result Set Map: ${res[ResultSetMapUrl]}

// Create Previous/Next Page links
if($start > 1)
  echo '   ';
if($last   echo 'Next Page->';
done();
?>

有兴趣的朋友还可以看一下由[动态网站制作指南]所制作的ASP版本：http://www.knowsky.com/yahoo/