Using Win32 functions in Visual FoxPro Image Gallery
Code examples:
GDI+: Implementing image scrolling with inertia
Obtaining names and positions for shortcuts located on the Windows Desktop
Custom GDI+ class
Writing entries to custom Event Log
Printing Image File, programmatically set print page orientation to landscape
Customizing the frame of top-level form: removing the standard frame (VFP9, Vista)
Winsock: sending email messages (SMTP, port 25)
Browsing Windows Known Folders (Special Folders)
How to find which fonts Windows uses for drawing captions, menus and message boxes
How to display Windows On-Screen Keyboard
How to load a user profile
Detecting changes in connections to removable drives (VFP9)
Displaying icons in the system tray (VFP9)
Capturing keyboard activity of another application with the Raw Input API (VFP9)
Vertical Label control
How to retrieve adapter information for the local computer (including MAC address)
Windows Shell Icons displayed and exported to ICO files (Vista)
Switching between keyboard layouts
How to print FoxPro form
Using Video Capture: displaying on FoxPro form frames and previewing video obtained from a digital camera
GDI+: Scrolling through large image using the mouse
Compressing and decompressing files with Windows API Runtime Library routines
Enumerating raw input devices attached to the system (keyboard, mouse, human interface device)
Generating random cryptographic keys
Peer-to-peer LAN messenger built with Mailslot API functions

User rating: 0/10 (0 votes)
Rate this code sample:
  • ~
More code examples    Listed functions    Add comment     W32 Constants      Translate this page Printer friendly version of this code sample
click to open
Before you begin:
Run this example simultaneously on several computers on a network. All users will be able to exchange plain text messages.

A light-weight solution with no central server, no file sharing, and no access violation, but with automatic user detection.

Note that the communication may require ports 137 to 139 opened on each side. No further configuration is required except the setting a name for the mailslot. Same name have to be used by all participating applications.

A timer control is set to check for inbound messages.

See also:
  • Using mailslots to send messages on the network
  • Using the NetMessageBufferSend to send messages on the network
  • How to create non-blocking Winsock server
  • A client for testing non-blocking Winsock server
  • Using named pipes to pass data between processes
  • Using WM_COPYDATA for interprocess communication
      Members area. Log in to view this example.
      User name:
      Forgot your password?
      Sign up for
    the Membership

    User rating: 0/10 (0 votes)
    Rate this code sample:
    • ~
    8758 bytes  
    Created: 2003-06-06 14:46:00  
    Modified: 2011-12-10 09:20:22  
    Visits in 7 days: 61  
    Listed functions:
    Printer friendly API declarations
    My comment:
    Mailslot name -- in this sample code "foxapp" -- practically keeps all users together. Any other valid file name is appropriate, except some reserved names like "Messengr", "BROWSER" etc.

    A mailslot with name \\.\mailslot\foxapp is created on each computer. That turns such a computer into server receiving messages sent to this mailslot from other computers.

    A computer name is obtained through SYS(0) function.

    * * *
    On start the Tmsg instance creates a mailslot with a name "foxapp", same name for all users in this group should be used: \\.\maislot\foxapp.

    Then Tmsg broadcasts ONLINE and DETECT messages to all available network computers, using wildcard character * as a destination mailslot name: \\*\mailslot\foxapp.

    On receiving DETECT message any existing Tmsg instance automatically sends ONLINE message back to the sender. That is how the new object gets know who else is online.

    On termination the Tmsg instance broadcasts OFFLINE message to all users -- again the wildcard character is used -- to let everyone know that this user is disconnected.

    Maislots provide no confirmation of receipt. For that reason the Tmsg object on receiving a message automatically sends a confirmation back to the sender.

    For sending a message to another computer -- say with DESK3011 name -- the Tmsg object creates file handle using mailslot name \\DESK3011\Maislot\foxapp, and writes message data to this handle using WriteFile function.

    A message has a simple format:
  • sender - 24 bytes -- local computer name
  • confirmation flag - 1 byte
  • system message flag - 1 byte
  • message body - the rest of the message

    The GetMessages method is invoked on each Timer event checking for incoming messages.
  • Word Index links for this example:
    Translate this page:
      Spanish    Portuguese    German    French    Italian offers instant, free translations of text or web pages.
    User Contributed Notes:
    How to open port 137 to 139 | 2010-06-20 22:41:42
    Please tell me how to open communication port 137 to 139
    Thank You

    Copyright 2001-2016 News2News, Inc. Before reproducing or distributing any data from this site please ask for an approval from its owner. Unless otherwise specified, this page is for your personal and non-commercial use. The information on this page is presented AS IS, meaning that you may use it at your own risk. Microsoft Visual FoxPro and Windows are trade marks of Microsoft Corp. All other trademarks are the property of their respective owners. 

    Privacy policy
    Credits: PHP (4.4.9), an HTML-embedded scripting language, MySQL (5.6.33), the Open Source standard SQL database, AceHTML Freeware Version 4, freeware HTML Editor of choice.   Hosted by Korax Online Inc.
    Last Topics Visited (
    28 sec.Example: 'Printing Image File, programmatically set print page orientation to landscape'
    1.85 min.Function: 'GetMenuItemCount'
    6 day(s)Example: 'Winsock: retrieving the host information corresponding to a network address'
     Function: 'AVIStreamLength'
    Function group: 'Windows Multimedia'
     Example: 'How to delete a service object'
     Function: 'inet_addr'
    Function group: 'Windows Sockets 2 (Winsock)'
    Advertise here!