I'm glad to announce that Xceed FTP for .NET 2.1 is now available for download.
I've been working on this release for the past few months, and I'm very
excited to finally see the FTP FileSystem come to life.
For those not familiar with the Xceed FileSystem, which comes with
Xceed Zip for .NET, here is some code that sheds some light on what you
can do with it. Consider these variables of the same base type:
// A file on disk
AbstractFile first = new DiskFile( @"d:\FileSystem.txt" );
// Another file on disk
AbstractFile second = new DiskFile( @"c:\temp\AnotherFileSystem.txt" );
// A file compressed in a zip file on disk
AbstractFile third = new ZippedFile(
new DiskFile( @"c:\temp\data.zip" ), "FileSystemInAZip.txt" );;
// A file in the isolated storage
AbstractFile fourth = new IsolatedFile( "Isolated.txt" );
// A file in memory (random name)
AbstractFile fifth = new MemoryFile();
// A file compressed in a zip file in memory
AbstractFile sixth = new ZippedFile(
new MemoryFile(), "VolatileFileSystem.txt" );
You can copy files around very easily:
// Copying the first file anywhere else is always the same!
first.CopyTo( second, true );
first.CopyTo( third, true );
first.CopyTo( fourth, true );
first.CopyTo( fifth, true );
first.CopyTo( sixth, true );
And accessing the contents of any file is always the same:
private void DisplayTextFile( AbstractFile file )
{ Console.WriteLine( "Displaying the contents of {0}, which is a {1}.", file.FullName,
file.GetType().Name );
using( StreamReader reader = new StreamReader( file.OpenRead() ) )
{ string line;
while( ( line = reader.ReadLine() ) != null )
{ Console.WriteLine( line );
}
}
Console.WriteLine();
}
// Displaying the contents of those files is always the same!
DisplayTextFile( first );
DisplayTextFile( second );
DisplayTextFile( third );
DisplayTextFile( fourth );
DisplayTextFile( fifth );
DisplayTextFile( sixth );
And why not finish this demonstration by deleting the files we just created.
// And finally, deleting files is the same!
second.Delete();
third.Delete();
fourth.Delete();
fifth.Delete();
sixth.Delete();
Any kind of file is an AbstractFile. Any kind of folder is an
AbstractFolder. This way, a DiskFile, an IsolatedFile, a ZippedFile and
a MemoryFile share a common set of properties and methods for accessing
their metadata and reading/writing their actual data. And a DiskFolder,
an IsolatedFolder, a ZippedFolder and a MemoryFolder share a common set
of methods for discovering child items.
How does the FTP FileSystem come into play? Simply by offering the
same abstraction over files and folders stored on an FTP server. We
could simply add this code to the above sample, and everything works
just as expected!
AbstractFile seventh = new FtpFile(
new FtpConnection( "localhost" ), @"\RemoteFileSystem.txt" );
first.CopyTo( seventh, true );
DisplayTextFile( seventh );
seventh.Delete();
Let's dive a little bit into this implementation of an AbstractFile
and AbstractFolder. Each constructor requires an FtpConnection
instance, which contains information on how to connect to the target
FTP server. Though it looks like a simple information storage class, it
does much more. Each time an FtpFile or an FtpFolder requires
information, or an incoming or outgoing stream on a file's data, it
asks the FtpConnection for an active command channel connection to the
server. This way, a unique command channel is generally required for
accessing many files on the server.
using( FtpConnection connection = new FtpConnection( "ftp.xceed.com" ) )
{ connection.TraceWriter = Console.Out;
FtpFolder root = new FtpFolder( connection );
foreach( AbstractFile file in root.GetFiles( false, "*.txt" ) )
{ DisplayTextFile( file );
}
}
If we comment out the "Console.WriteLine( line );" line in
"DisplayTextFile", we can see the FTP conversation that occurred for
the above code:
Connected to 66.46.177.250:21 on 9/27/2005 @ 2:24:54 PM
< 220 Serv-U FTP Server v6.0 for WinSock ready...
> USER anonymous
< 331 User name okay, please send complete E-mail address as password.
> PASS *****
< 230 User logged in, proceed.
> PWD
< 257 "/" is current directory.
> CWD /
< 250 Directory changed to /
> CWD /
< 250 Directory changed to /
> CWD /
< 250 Directory changed to /
> TYPE A
< 200 Type set to A.
> PASV
< 227 Entering Passive Mode (66,46,177,250,6,238)
> LIST
Data connection established with 66.46.177.250:1774 on 9/27/2005 @ 2:24:56 PM
< 150 Opening ASCII mode data connection for /bin/ls.
< 226-Maximum disk quota limited to Unlimited kBytes
< Used disk quota 0 kBytes, available Unlimited kBytes
< 226 Transfer complete.
Displaying the contents of \FileSystem.txt, which is a FtpFile.
> CWD /
< 250 Directory changed to /
> TYPE I
< 200 Type set to I.
> PASV
< 227 Entering Passive Mode (66,46,177,250,6,240)
> RETR FileSystem.txt
Data connection established with 66.46.177.250:1776 on 9/27/2005 @ 2:24:57 PM
< 150 Opening BINARY mode data connection for FileSystem.txt (1198 Bytes).
< 226-Maximum disk quota limited to Unlimited kBytes
< Used disk quota 0 kBytes, available Unlimited kBytes
< 226 Transfer complete.
Displaying the contents of \appnote.txt, which is a FtpFile.
> CWD /
< 250 Directory changed to /
> TYPE I
< 200 Type set to I.
> PASV
< 227 Entering Passive Mode (66,46,177,250,6,246)
> RETR appnote.txt
Data connection established with 66.46.177.250:1782 on 9/27/2005 @ 2:24:58 PM
< 150 Opening BINARY mode data connection for appnote.txt (109785 Bytes).
< 226-Maximum disk quota limited to Unlimited kBytes
< Used disk quota 0 kBytes, available Unlimited kBytes
< 226 Transfer complete.
> QUIT
Disconnected from 66.46.177.250:21 on 9/27/2005 @ 2:25:04 PM
Each FtpFolder and FtpFile instance shared the same FtpConnection,
and since no two operations were done at the same time, a single
connection was required, as the log indicates. The FtpConnection object
implements the IDisposable interface, since it keeps any active
connection available until disposed (or finalized).
Now what happens if I try to open two files at the same time, like this?
using( FtpConnection connection = new FtpConnection( "ftp.xceed.com" ) )
{ connection.TraceWriter = Console.Out;
AbstractFile first = new FtpFile( connection, @"\FileSystem.txt" );
AbstractFile second = new FtpFile( connection, @"\appnote.txt" );
using( Stream firstStream = first.OpenRead() )
{ using( Stream secondStream = second.OpenRead() )
{ // In an FTP conversation with an FTP server, only one command
// at a time can be pending. Here, we clearly have two files
// open at the same time on the same FTP server. How? Each file
// has its own connection to the FTP server!
}
}
}
The FtpConnection object will create extra command channel
connections as required. The output shows two command channel
connections were made:
Connected to 66.46.177.250:21 on 9/27/2005 @ 2:38:06 PM
< 220 Serv-U FTP Server v6.0 for WinSock ready...
> USER anonymous
< 331 User name okay, please send complete E-mail address as password.
> PASS *****
< 230 User logged in, proceed.
> CWD /
< 250 Directory changed to /
> TYPE A
< 200 Type set to A.
> PASV
< 227 Entering Passive Mode (66,46,177,250,10,53)
> LIST
Data connection established with 66.46.177.250:2613 on 9/27/2005 @ 2:38:07 PM
< 150 Opening ASCII mode data connection for /bin/ls.
< 226-Maximum disk quota limited to Unlimited kBytes
< Used disk quota 0 kBytes, available Unlimited kBytes
< 226 Transfer complete.
> CWD /
< 250 Directory changed to /
> TYPE I
< 200 Type set to I.
> PASV
< 227 Entering Passive Mode (66,46,177,250,10,54)
> RETR FileSystem.txt
Data connection established with 66.46.177.250:2614 on 9/27/2005 @ 2:38:08 PM
< 150 Opening BINARY mode data connection for FileSystem.txt (1198 Bytes).
Connected to 66.46.177.250:21 on 9/27/2005 @ 2:38:08 PM
< 220 Serv-U FTP Server v6.0 for WinSock ready...
> USER anonymous
< 226-Maximum disk quota limited to Unlimited kBytes
< Used disk quota 0 kBytes, available Unlimited kBytes
< 226 Transfer complete.
< 331 User name okay, please send complete E-mail address as password.
> PASS *****
< 230 User logged in, proceed.
> CWD /
< 250 Directory changed to /
> TYPE I
< 200 Type set to I.
> PASV
< 227 Entering Passive Mode (66,46,177,250,10,55)
> RETR appnote.txt
Data connection established with 66.46.177.250:2615 on 9/27/2005 @ 2:38:09 PM
< 150 Opening BINARY mode data connection for appnote.txt (109785 Bytes).
< 426-Maximum disk quota limited to Unlimited kBytes
< Used disk quota 0 kBytes, available Unlimited kBytes
< 426 Data connection closed, file transfer appnote.txt aborted.
> QUIT
Disconnected from 66.46.177.250:21 on 9/27/2005 @ 2:38:13 PM
> QUIT
Disconnected from 66.46.177.250:21 on 9/27/2005 @ 2:38:13 PM
And the great part about all this is that you don't have to worry
about this while coding. You're just manipulating yet another kind of
AbstractFile or AbstractFolder.
If we get back to the Zip implementation of the Xceed FileSystem,
you can see that a ZippedFile or ZippedFolder (or ZipArchive, the root
ZippedFolder) constructor needs to know which AbstractFile is holding
the actual zip file that should contain this file or folder.
"AbstractFile" truly means "any file", as long as there is an
AbstractFile-derived class somewhere to expose this file. It means that
zipping directly onto an FTP server is no more difficult than zipping
in a regular file on disk.
AbstractFolder source = new DiskFolder( @"d:\Data" );
AbstractFolder localDest = new ZipArchive(
new DiskFile( @"d:\temp\local.zip" ) );
AbstractFolder remoteDest = new ZipArchive(
new FtpFile( new FtpConnection( "localhost" ), @"remote.zip" ) );
// Copying is the same, no matter what is the destination
// file or folder.
source.CopyTo( localDest, true );
source.CopyTo( remoteDest, true );
Code for zipping in "D:\temp\local.zip" is no different than code
for zipping in "ftp://localhost/remote.zip". And obviously, reading or
unzipping from any zip file is the same.
AbstractFolder localSource = new ZipArchive(
new DiskFile( @"d:\temp\local.zip" ) );
AbstractFolder remoteSource = new ZipArchive(
new FtpFile( new FtpConnection( "localhost" ), @"remote.zip" ) );
AbstractFolder dest = new DiskFolder( @"d:\restored" );
// Unzipping text files from any source is the same!
localSource.CopyFilesTo( dest, true, true, "*.txt" );
remoteSource.CopyFilesTo( dest, true, true, "*.txt" );
I really hope this new addition to the Xceed FileSystem will
generate the same enthusiasm we had inventing and developping it. I'm
very interested in hearing your opinions!