question with sockets and XML

Hi all, I have to do the following: open a socket to an external server authenticate on that server begin retrieving articles and write to local files I am able to connect the server via Net/Sockets.php and authenticate. Now the tricky part...the data is fed via an XML format... I would like to say "start reading lines starting with <tag> until line containing </tag>" then, take that information and write it to a file. The problem is that the articles are not fixed length. Any help appreciated. --- Michael