Stream Me Up, Scotty! (part 1) - Out With The Old... (
Page 2 of 9 )
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.
