FILE: VBFTP.EXE: Implementing FTP Using WinInet API from VB

 Last reviewed: October 24, 1997
Article ID: Q175179
The information in this article applies to:
  • Microsoft Visual Basic Professional and Enterprise Editions for Windows, versions 4.0, 5.0

SUMMARY

VBFTP.EXE is a sample that implements FTP connection, download, and upload using the WinInet FTP API from Visual Basic. It demonstrates the APIs and techniques to set FTP connection attributes and transfer mode that are not exposed inthe MS Internet Transfer Control.

The sample requires Visual Basic SP2 or Visual Studio SP2 installed to run because it uses the updated comctl32.ocx from those Service Packs.

When adding FTP functionality to your application, it is important to understand the capability and limitation of each of the different Internet technologies. At the lowest level, you could use the Microsoft Winsock Control to send commands directly to FTP server port 21. The sequence and syntax of the commands you send to the server would have to follow the specification of the FTP protocol. The WinInet FTP API wraps the socket code and most low-level FTP commands and provides a set of much simpler task-oriented APIs that do not require detailed knowledge of FTP protocol. However, there is a chance that some FTP servers use FTP commands not implemented by WinInet. If this happens, you have to use the Microsoft Winsock Control to communicate with the server directly at the protocol level. Test your FTP server with the VBFTPJR sample before you decide whether to choose WinInet API or the Winsock Control. The Microsoft Internet Transfer Control, on the other hand, offers a more simplified interface than WinInet but offers less flexibility and cannot be used if you want to customize the connection and transfer mode.

If you are using a proxy to access an FTP server, the proxy has to be capable of handling FTP commands and cannot be a CERN proxy. Please see the following article in the Microsoft Knowledge Base for more information: 

   ARTICLE-ID: Q166961
   TITLE     : HOWTO: FTP with CERN-Based Proxy Using WinInet API
The following file is available for download from the Microsoft Software Library: 

 ~ vbftp.exe (size: 47597 bytes)
For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from Online Services

Keywords          : VB4WIN vb5all kbsample
Technology        : kbInetDev
Version           : WINDOWS:4.0,5.0
Platform          : WINDOWS
Issue type        : kbhowto

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Last reviewed: October 24, 1997
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