Out With The Old... - PHP

The first thing you should know is that PHP allows file transfer across both HTTP and FTP connections. The ability to upload files over HTTP has been available since PHP3, while the newer FTP functions have made an appearance only in later versions of PHP3 and in PHP4.

Before we begin, you need to make sure that your version of PHP includes FTP support. You can check this by creating a PHP file containing the code

<?
phpinfo();
?>

and checking the resulting output through your Web browser. There's a section named "Additional Modules" which lists the modules supported by your build; in case you don't find the FTP module listed, you'll need to recompile your build with FTP support.

To start with, let's refresh your memory of what a typical FTP session looks like:

$ ftp ftp.server.com
Connected to ftp.server.com
220 server.com FTP server ready.
Name (server:john): john
331 Password required for john.
Password:
230 User john logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
200 PORT command successful.
150 Opening ASCII mode data connection for /bin/ls.
drwxr-xr-x  5 john   users        3072 Nov  2 11:03 .
drwxr-xr-x  88 root     root         2048 Nov  1 23:26 ..
drwxr--r--   2 john   users        1024 Oct  5 13:26 bin
drwx--x--x   8 john   users        1024 Nov  2 10:59 public_html
drwxr--r--   4 john   users        1024 Nov  2 11:26 tmp
-rw-r--r--   1 john   users     2941465 Oct  9 17:21 data.zip
226 Transfer complete.
ftp> bin
200 Type set to I.
ftp> get data.zip
local: data.zip remote: data.zip
200 PORT command successful.
150 Opening BINARY mode data connection for data.zip(2941465 bytes).
226 Transfer complete.
ftp> bye
221 Goodbye.

As you can see, the process can be broken down into clearly-identifiable segments. There's the connection phase (which opens a connection to the FTP server); the authentication phase (where the user identifies himself or herself and is permitted access to the FTP site); the transaction phase (which involves operations like directory navigation, file listing, and file GET or PUT); and the disconnection phase (which terminates the FTP connection cleanly). Nice and symmetrical, right?

This article copyright Melonfire 2000. All rights reserved.

>>> More PHP Articles          >>> More By Vikram Vaswani, (c) Melonfire

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