Reading Usenet News Messages (PHP Cookbook)

17.6.3. Discussion

Reading news from a news server requires you to connect to the server and specify a group you're interested in reading:

// open a connection to the nntp server
$server = "{news.php.net/nntp:119}";
$group = "php.general";
$nntp = imap_open("$server$group",'','',OP_ANONYMOUS);

The function imap_open( ) takes four parameters. The first specifies the news server to use and the newsgroup to read. The server here is news.php.net, the news server that mirrors all the PHP mailing lists. Add /nntp to let the IMAP extension know you're reading news instead of mail, and specify 119 as a port; that's typically the port reserved for NNTP. NNTP stands for Network News Transport Protocol; it's used to communicate with news servers, just as HTTP communicates with web servers. The group is php.general, the main mailing list of the PHP community.

The middle two arguments to imap_open( ) are a username and password, in case you need to provide verification of your identity. Because news.php.net is open to all readers, leave them blank. Finally, pass the flag OP_ANONYMOUS, which tells IMAP you're an anonymous reader; it will not then keep a record of you in a special .newsrc file.

Once you're connected, you usually want to either get a general listing of recent messages or all the details about one specific message. Here's some code that displays recent messages:

// read and display posting index
$last = imap_num_msg($nntp);
$n = 10; // display last 10 messages

// table header
print <<<EOH
<table>
<tr>
    <th align="left">Subject</th>
    <th align="left">Sender</th>
    <th align="left">Date</th>
</tr>
EOH;

// the messages
for ($i = $last-$n+1; $i <= $last; $i++) {
    $header = imap_header($nntp, $i);

    if (! $header->Size) { continue; }
           
    $subj  = $header->subject;
    $from  = $header->from;
    $email = $from[0]->mailbox."@".$from[0]->host;
    $name  = $from[0]->personal ? $from[0]->personal : $email;
    $date  = date('m/d/Y h:i A', $header->udate);

print <<<EOM
<tr>
    <td><a href="$_SERVER[PHP_SELF]"?msg=$i\">$subj</a></td>
    <td><a href="mailto:$email">$name</a></td>
    <td>$date</td>
</tr>
EOM;
     }

// table footer
echo "</table>\n";

To browse a listing of posts, you need to specify what you want by number. The first post ever to a group gets number 1, and the most recent post is the number returned from imap_num_msg( ). So, to get the last $n messages, loop from $last-$n+1 to $last.

Inside the loop, call imap_header( ) to pull out the header information about a post. The header contains all the metainformation but not the actual text of the message; that's stored in the body. Because the header is usually much smaller than the body, this allows you to quickly retrieve data for many posts without taking too much time.

Now pass imap_header( ) two parameters: the server connection handle and the message number. It returns an object with many properties, which are listed in Table 17-2.

Table 17-2. imap_header( ) fields from a NNTP server

Name	Description	Type	Example
`date` or `Date`	RFC 822 formatted date: `date('r')`	String	Fri, 16 Aug 2002 01:52:24 -0400
`subject` or `Subject`	Message subject	String	Re: PHP Cookbook Revisions
`message_id`	A unique ID identifying the message	String	<20030410020818. 33915.php@news.example.com>
`newsgroups`	The name of the group the message was posted to	String	php.general
`toaddress`	The address the message was sent to	String	php-general@lists.php.net
`to`	Parsed version of `toaddress` field	Object	mailbox: "php-general", host: "lists-php.net"
`fromaddress`	The address that sent the message	String	Ralph Josephs <ralph@example.net>
`from`	Parsed version of `fromaddress` field	Object	personal: "Ralph Josephs", mailbox: "ralph", host: "example.net"
`reply_toaddress`	The address you should reply to, if you're trying to contact the author	String	rjosephs@example.net
`reply_to`	Parsed version of `reply_toaddress` field	Object	Mailbox: "rjosephs", host: "example.net"
`senderaddress`	The person who sent the message; almost always identical to the `from` field, but if the `from` field doesn't uniquely identify who sent the message, this field does	String	Ralph Josephs <ralph@example.net>
`sender`	Parsed version of `senderaddress` field	Object	Personal: "Ralph Josephs", mailbox: "ralph", host: "example.net"
`Recent`	If the message is recent, or new since the last time the user checked for mail	String	Y or N
`Unseen`	If the message is unseen	String	Y or " "
`Flagged`	If the message is marked	String	Y or " "
`Answered`	If a reply has been sent to this message	String	Y or " "
`Deleted`	If the message is deleted	String	Y or " "
`Draft`	If the message is a draft	String	Y or " "
`Size`	Size of the message in bytes	String	1345
`udate`	Unix timestamp of message date	Int	1013480645
`Mesgno`	The number of the message in the group	String	34943

Some of the more useful fields are: size, subject, the from list, and udate. The size property is the size of the message in bytes; if it's 0, the message was either deleted or otherwise removed. The subject field is the subject of the post. The from list is more complicated. It's an array of objects; each element in the array holds an object with three properties: personal, mailbox and host. The personal field is the name of the poster: Homer Simpson. The mailbox field is the part of the email address before the @ sign: homer. The host is the part of the email address after the @ sign: thesimpsons.com. Usually, there's just one element in the from list array, because a message usually has just one sender.

Pull the $header->from object into $from because PHP can't directly access $header->from[0]->personal due to the array in the middle. Then combine $from[0]->mailbox and $from[0]->host to form the poster's email address. Use the ternary operator to assign the personal field as the poster's name, if one is supplied; otherwise, make it the email address.

The udate field is the posting time as an Unix timestamp. Use date( ) to convert it from seconds to a more human-friendly format.

You can also view a specific posting as follows:

// read and display a single message
$header = imap_header($nntp, $msg);
        
$subj  = $header->subject;
$from  = $header->from;
$email = $from[0]->mailbox."@".$from[0]->host;
$name  = $from[0]->personal;
$date  = date('m/d/Y h:i A', $header->udate);
$body  = nl2br(htmlspecialchars(imap_fetchbody($nntp,$msg,1)));

print <<<EOM
<table>
<tr>
    <th align=left>From:</th>
    <td>$name &lt;<a href="mailto:$email">$email</a>&gt;</td>
</tr>
<tr>
    <th align=left>Subject:</th>
    <td>$subj</td>
</tr>
<tr>
    <th align=left>Date:</th>
    <td>$date</td>
</tr>
<tr>
    <td colspan="2">$body</td>
</tr>
</table>
EOM;

The code to grab a single message is similar to one that grabs a sequence of message headers. The main difference is that you define a $body variable that's the result of three chained functions. Innermost, you call imap_fetchbody( ) to return the message body; it takes the same parameters as imap_header( ). You pass that to htmlspecialchars( ) to escape any HTML that may interfere with yours. That result then is passed to nl2br( ) , which converts all the carriage returns to XHTML <br /> tags; the message should now look correct on a web page.

To disconnect from the IMAP server and close the stream, pass the IMAP connection handle to imap_close( ):

// close connection when finished
imap_close($nntp);

Table 17-2. imap_header( ) fields from a NNTP server

17.6. Reading Usenet News Messages

17.6.1. Problem

17.6.2. Solution

17.6.3. Discussion

17.6.4. See Also