Programming Jabber

State 3: Retrieve a vCard

If we receive a single argument in the request, we’ll take it to be a JID, passed from the link in the table build in the previous state, and immediately build an IQ-get to retrieve the vCard. The JID is to be found in the first element in the @a array—$a[0].

  else {

    my $iq = $nf->newNode('iq');
    $iq->attr('to', $a[0]);
    $iq->attr('type', IQ_GET);
    $iq->insertTag('vcard', NS_VCARD);

Notice how the name of the query tag in this query is not query, but vcard. See Section 6.5.1 in Chapter 6 for details.

The retrieval query is in the form of an IQ-get, rather than an IQ-set. As we needed to send information in our JUD query (the search criteria), an IQ-set was appropriate. Here, an IQ-get is appropriate as we’re not including any information to qualify our request; all we need to send is this:

<iq type='get' to='[e-mail]'>
  <vcard xmlns='vcard-temp'/>
</iq>

After sending the <iq/> element, waiting for the response, and checking for any errors, we extract the vCard detail and display it:

    my $result = $c->ask($iq);

    if ($result->attr('type') eq IQ_ERROR)  {
      $r->print("Sorry, cannot retrieve the vCard for $a[0]");
      $r->print("</body></html>");
      $c->disconnect;
      return;
    }

The structure of the vCard namespace is rather complicated and long-winded, and it’s common for many of the fields to remain unfilled. So to keep the script simple, we’re going to display all the top-level fields that aren’t empty:

 my $vcard = $result->getTag('', NS_VCARD); print ("<strong>$a[0]</strong>\n"); ...