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The File Transfer Protocol (FTP) is the most common application
protocol used to upload and download files between a local system and a
server. In addition to basic file transfer capabilities, FTP
also enables a client application to perform common file and directory
management functions on the server, such as renaming and deleting files
or creating new directories. The SocketTools ActiveX Edition also
supports secure file transfers using SSH (SFTP) and SSL/TLS (FTPS) by
simply specifying an option when establishing the connection.
The following properties, methods and events are available for use
by your application:
Initialize
Initialize the control and validate the runtime license key for the
current process. This method is normally not used if the control is
placed on a form in languages such as Visual Basic. However, if the
control is being created dynamically using a function similar to
CreateObject, then the application must call this method to
initialize the component before setting any properties or calling any
other methods in the control.
Connect
Connect to the server, using either a host name or IP address.
The method has several options related to security as well as the
general operation of the control. If the local system is behind a firewall or a route
which uses Network Address Translation (NAT), it is recommended that
you make sure the Passive property is set to true before
establishing the connection. This will ensure that your application
only uses outbound connections to the server.
Login
Authenticate the client session, providing the server with a user
name, password and optionally an account name. It is also possible to
use an anonymous (unauthenticated) session by providing empty strings
as the username and password. If the UserName and Password properties
are set prior to connecting, the user will automatically be logged
in. This method is only necessary if the application needs to access
the server using different user accounts during the same session.
Disconnect
Disconnect from the server and release the memory allocated for that
client session. After this method is called, the client session is no
longer valid.
Uninitialize
Unload the Windows Sockets library and release any resources that
have been allocated for the current process. This is the last method
call that the application should make prior to terminating. This is
only necessary if the application has previously called the
Initialize method.
File Transfers
The control provides several methods which can be used to transfer
files between the local and server. This group of methods are high
level, meaning that it is not necessary to actually write the code to
read and/or write the file data. The control automatically handles the
lower level file I/O and notifies your application of the status of the
transfer by periodically generating progress events.
GetData
This method transfers a file from the server to the local
system, storing the file data in memory. This can be useful if your
application needs to perform some operation based on the contents of
the file, but does not need to store the file locally. The file data
can returned in a string or byte array.
GetFile
This method transfers a file from the server and stores it in a
file on the local system. This method is similar to how the GET
command works for the command-line FTP client in Windows.
GetMultipleFiles
This method transfers multiple files from the server and stores
them in a directory on the local system. A wildcard may be specified
so that only files which a certain name or those that match a
particular file extension are downloaded. This method is similar to
how the MGET command works for the command-line FTP client in
Windows.
PutData
This method creates a file on the server containing the data
that you provide. This can be useful if your application wants to
upload dynamically created content without having to create a
temporary file on the local system. The data may be specified either
as a string, or as the contents of a byte array.
PutFile
This method uploads a file from the local system to the server.
This method is similar to how the PUT command works for the
command-line FTP client in Windows.
PutMultipleFiles
This method transfers multiple files from the local system to a
directory on the server. A wildcard may be specified so that
only files with a certain name or those that match a particular file
extension are uploaded. This method is similar to how the MPUT
command works for the command-line FTP client in Windows.
File Management
In addition to performing file transfers, the File Transfer Protocol
control can also perform many of the same kinds of file management
methods on the server as you would on the local system.
DeleteFile
Delete a file from the server. This operation requires that the
current user have the appropriate permissions to delete the file.
GetFileSize
Return the size of a file on the server without actually downloading
the contents of the file.
GetFileStatus
Return status information about the file in the form of a structure.
This typically specifies the ownership, access permissions, size and
modification time for the file. It is similar to opening a directory
on the server and reading information about the file, but with less
overhead.
GetFileTime
Return the modification time for the specified file on the server.
This can be used by you application to determine if the file has been
changed since the time that you last uploaded or downloaded the
contents.
RenameFile
Change the name of a file or move a file to a different directory.
This operation requires that the current user have the appropriate
permissions to rename the file. If the file is being moved to another
directory, the user must have permission to access that
directory.
SetFileTime
Update the modification time for a file on the server. This method
requires that the current user have the appropriate permissions to
change the last modification timestamp for the file. Note that this
is not supported on all servers and in some cases may be restricted
to specific accounts.
GetFilePermissions
Return the access permissions for a file on the server. This can be
used to determine if a file can be read, modified and/or deleted by
the current user. For users who are familiar with UNIX file
permissions, it is the same type which is used by the control.
SetFilePermissions
Change the access permissions for a file. This method is supported on
most UNIX based servers, as well as any other server that supports
the site-specific CHMOD command.
Directory Management
The control also provides a set of methods which can be used to
access and manage directories or folders, including the ability to list
and search for files, create new directories and remove empty
directories from the server.
ChangeDirectory
Change the current working directory on the server. This is similar
to how the CD command is used from the command-line to change the
current directory in Windows. If a path is not specified in the file
name, the current working directory is where files will be uploaded
to and downloaded from.
MakeDirectory
Create a new directory on the server. This requires that the current
user have the appropriate access permissions in order to create the
directory.
OpenDirectory
Open the specified directory on the server. This is the first step in
returning a list of files in the directory. After the directory has
been opened, information about the files it contains can be returned
to the application. The directory path may also include wildcards to
only return information about a certain subset of files based on the
file name or extension.
ReadDirectory
Return information about the next file in the directory that has been
opened. This method is called repeatedly until it indicates that all
of the files have been returned.
RemoveDirectory
Remove an empty directory from the server. This operation requires
that the current user have the appropriate permissions to delete the
directory. For safety, it is required that the directory does not
contain any files or subdirectories or the operation will fail.
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