Windows Sockets 2

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	Specs

	SDK

	Additional Information

Windows* Sockets 2 is the exciting new communications software interface for Microsoft's 32 bit Windows operating systems.

What's New

Windows Sockets 2 is now shipping in Windows NT* version 4.0!

Beta Version 1.6 of the WinSock 2 SDK is now available. Download it from our FTP site.

What is WinSock 2?
Simply stated, Windows Sockets 2 is the API for all forms of data communications on Microsoft's 32 bit Windows operating systems. While preserving strict backwards compatibility, Windows Sockets 2 extends today's immensely popular WinSock v 1.1 interface for TCP/IP networks to provide a protocol-independent interface that is optimized to support real-time multimedia communications and able to work across all kinds of communications infrastructures.

WinSock Today: Version 1.1
Windows Sockets (WinSock) is the API specification that has enabled TCP/IP data communications on the Windows platform. Developed by an industry-wide coalition of companies known as the WinSock Group, the wholesale acceptance of Windows Sockets version 1.1 has been a key enabler of the Internet's explosive growth. The Windows Sockets 1.1 interface is available for or included in all versions of the Windows operating systems from Windows 3.1 onward and is supported by virtually all vendors of TCP/IP protocol stacks. The remarkable success of Windows Sockets 1.1, coupled with the promise of comprehensive new features in the next version (while maintaining strict backwards compatibility), has the world of Windows networking eagerly awaiting Windows Sockets version 2.

Windows Sockets Tomorrow: Version 2
Windows Sockets version 2 takes the original standard, and expands its scope, both in depth and breadth. Windows Sockets 2 provides multiprotocol support, quality of service, a layered provider architecture, and numerous performance enhancements over Windows Sockets version 1.1.

Windows Sockets 2 is a network programming interface at the transport level in the OSI reference model. Designed to the WOSA (Windows Open Services Architecture) format it provides both an Application Programmer Interface (API) for applications developers and a Service Provider Interface (SPI) for transport stack vendors.

Features and Benefits
Windows Sockets 2 provides numerous enhancements to the original specification.

Multiprotocol Support
Windows Sockets 2 significantly extends the interface by providing applications with transport independence across a wide range of networks and communications media types such as TCP/IP, OSI or IPX/SPX, analog and digital telephone networks, wireless networks such as cellular and CDPD, and emerging networks such as ATM and cable.

Applications can now be developed for portability across a variety of transports with a common interface for all types of network stacks and communication media.

For protocol stack vendors there is the equivalent benefit of instantly enabling the wealth of communicating applications that will rely on Windows Sockets 2 simply by making their transport protocols accessible via the Windows Sockets 2 SPI.

Quality of Service
Windows Sockets 2 includes mechanisms for applications to negotiate quality of service with a network, thus facilitating its use for multimedia applications. Applications can discover and utilize the quality of service (bandwidth, latency, etc.) offered by underlying networks such as ATM, ISDN, RSVP, and Cable. Virtually all of the major ATM vendors have announced plans for their desktop and server products to leverage WinSock 2.

Multipoint / Multicast
Windows Sockets 2 also provides generic support for both multipoint and multicast which allows applications to discover and utilize capabilities such as IP multicast and ATM point-to-multipoint in a protocol independent manner. Multipoint and multicast enables end user capabilities such as multiplayer games, conferencing, and distance learning.

Real-Time Multimedia Communications
Windows Sockets 2 was specifically engineered to enable a new breed of applications that employ Real-time Multimedia Communications (RMC) such as video conferencing. Besides Quality of Service, there are several other features in WinSock 2 that assist applications with RMC such as overlapped I/O, circular queues and buffer flushing.

Layered Provider Architecture
Windows Sockets 2 includes provisions for inserting layers between the WinSock 2 DLL and the underlying protocol stack that communicates over the wire. A layered protocol could be used to monitor and interdict URL's being accessed, implement secure authentication and encryption, or extend the capabilities of an underlying base protocol.

Event Object Based Notification
In addition to the window message based asynchronous notification of network events in version 1.1, Windows Sockets 2 offers event object based notification in order to facilitate development of application servers and deamons which require no Windows GUI components.