Q&A: Types Of Socket Applications Supported By Microsoft

The information in this article applies to:

• Microsoft Windows NT Workstation versions 3.5 and 3.51
• Microsoft Windows NT Server versions 3.5 and 3.51
• Microsoft LAN Manager version 2.2c
• Microsoft TCP/IP-32 for Windows for Workgroups version 3.11b
• Microsoft Windows for Workgroups version 3.11
• Microsoft Windows 95

SUMMARY

This article contains questions and answers regarding the different types of socket application supported by MS-DOS and the Microsoft Windows operating system.

MORE INFORMATION

What is a socket application?

A socket interface was first provided with Berkeley UNIX (BSD) in the eighties. It was designed as a network interprocess communication (IPC) mechanism for the built-in TCP/IP. A socket defines a bi-directional end point for combination between processes.

A socket has three primary components:

   The interface to which it is bound
   The port number to which it will send or receive data
   The type of socket--either stream or datagram

A server application listens on a well-known port over all installed network interfaces. A client generally initiates communication from a specific interface from any available port.

What is Windows Sockets?

The Windows Socket (WinSock) specification defines a network programming interface for Microsoft Windows that is based on the Socket interface popularized in Berkeley Unix. The WinSock API is a library of functions that implement the Windows Socket specification. WinSock augments the Berkeley socket implementation by adding Windows-specific extensions to support the message-driven nature of Windows operating systems.

There are a few other proprietary windows socket APIs (WSOCKETS, and WIN_SOCK). For more information see the following article in the Microsoft Knowledge Base:

   Article-ID: Q98599
   Title:      Differences Among WIN_SOCK.DLL, WSOCKETS.DLL, and
               WINSOCK.DLL

What is WINSOCK.DLL?

WINSOCK.DLL is a dynamic-link library (DLL) that provides Windows Sockets version 1.1 API for TCP/IP Windows Socket applications. WINSOCK.DLL is offered in current version of all Microsoft TCP/IP stacks:

   MS-DOS TCP/IP for Lanman 2.2C
   MS-DOS TCP/IP for Microsoft Network 3.0 Clients
   Microsoft TCP/IP for Windows for Workgroups
   Microsoft TCP/IP-32 for Windows for Workgroups
   Microsoft TCP/IP for Windows NT 3.5x
   Microsoft TCP/IP for Windows 95

   Article-ID: Q94069
   Title:      Microsoft TCP/IP Protocol Comparison and FAQ

Microsoft WINSOCK.DLL complies with Windows Socket Specification version 1.1. Support for previous versions of the Sockets specification is not provided. WINSOCK.DLL does not provide support for Raw Sockets(SOCK_RAW), DOS Sockets, or vendor-specific implementations.

For instruction about downloading the WinSock specification from Microsoft, see the following article in the Microsoft Knowledge base:

   Article-ID: Q85965
   Title:      Microsoft Socket API Specification version

WSOCK32.DLL is a dynamic-link library (DLL) that provides Windows Sockets API for 32-bit TCP/IP Windows Socket applications and 32-bit IPX/SPX Windows Socket Applications. WSOCK32.DLL is offered in Windows NT and 95.

Can Microsoft WINSOCK.DLL be used with third-party TCP/IP stacks?

No. WINSOCK.DLL and WSOCK32.DLL will be provided by the vendor providing the TCP/IP stack. The DLL and the protocol stack implementation cannot be mixed and matched with other TCP/IP and DLL implementations. For example, you cannot use WINSOCK.DLL provided by Microsoft with FTP's TCP/IP stack or vice versa.

What type of Socket applications are supported by MS-DOS TCP/IP stacks?

MS-DOS TCP/IP for Lanman 2.2c and Microsoft Network Clients 3.0 support DOS Socket application and WinSock 1.1 application. Sockets.exe in MS-DOS TCP/IP is a terminate-and-stay-resident (TSR) program; it allows MS-DOS socket applications to run if they've been written with the Microsoft TCP/IP Sockets Development Kit Version 1.0, using the DOS Socket Library (DOS_SOCK.LIB) available in the Development Kit. WSOCKETS.DLL is provided in Lanman 2.2 SDK to make Windows calls look as identical as they do in MS- DOS.

The SOCKETS.EXE and WSOCKETS.DLL do NOT implement the Windows Sockets API standard.

In order for a Windows Socket application to function with MS-DOS TCP/IP, SOCKETS.EXE must be loaded before Windows startup and WINSOCK.DLL must exist in the application search path.

Is it possible to run a 32-bit Windows Socket application with Windows 3.x?

Yes. Win32s 1.1 contains a thunking layer that converts 32-bit Windows Sockets calls (using WSOCK32.DLL) to 16-bit Windows Sockets calls (using WINSOCK.DLL).

Does a Windows Sockets application work over any protocols other than TCP/IP?

Yes. In Windows NT and 95, sockets support is also extended to IPX/SPX. Both 16-bit and 32-bit IPX/SPX Windows sockets are supported over NWLINK in Windows NT and 95.

Does MS Network Client 3.0 support MS-DOS/Windows IPX/SPX Socket applications?

No. MS-DOS/Windows IPX/SPX Socket applications running in a Virtual machine of Windows 95 can be interfaced with NWLINK via WSOCK.VXD. WSOCK.VXD supports 16-bit Windows Sockets application over 32-bit TCP/IP and IPX/SPX Windows Socket.