Operating Characteristics and Restrictions of Named Pipes (101150)

SUMMARY

Named pipes are provided as a LAN Manager or Windows for Workgroups redirector component. The redirector uses the NetBIOS session layer which may be implemented over many data communications protocols such as NetBEUI or TCP/IP (NetBIOS over TCP/IP is sometimes referred to as RFC NetBIOS). Named pipe applications may be restricted in their use by operating system and network protocols.

On other network operating systems such as Novell Netware, named pipes are supported not by the redirector or NetBIOS session layer, but by a Novell IPX/SPX session layer.

NAMED PIPE COMPONENTS

Each application that makes use of named pipes has a "server" component and a "client" component. The server component creates named pipe instances and listens for requests. Clients call the named pipe and the two applications begin communicating.

Named Pipe Server Component

The server component of a named pipe application creates named pipes using a DOSMakeNamedPipe API. Typically, this API is supported by network servers such as LAN Manager Servers, LAN Manager peer service, Windows NT or Windows NT Advanced Server--the only platforms in a LAN Manager or Windows NT environment that can share the InterProcess Communications resource IPC$ over which named pipes transactions are carried. The "server" component of a named pipes application is designed to run on one of these platforms, so that it can support any "client" named pipe application that uses these protocols to connect to the IPC$ resource.

Novell Netware also enables named pipe "server" applications to be supported on OS/2 using the Novell Netware OS/2 requester. In this environment only clients using Novell's IPX/SPX protocols are supported. The Novell NT requester which is still in beta has not been shown to support named pipe server applications.

Named Pipe Client Component

The client component of a named pipe application initiates a connection to a named pipe application using the DOSConnectNamedPipe API. In a LAN Manager or Windows NT environment this is supported once the client has established a connection to the server's InterProcess Communications shared resource (IPC$). This is typically done in a LAN Manager or Windows NT environment by the client performing a NET USE command (for example: NET USE \\SERVERNAME\IPC$).

Therefore any client that can establish a connection to a server's IPC$ resource is capable of running a named pipe "client" application.

In a Novell Netware environment, named pipe client applications communicate with named pipe server applications by establishing a session using the IPX/SPX protocols directly. There is no requirement for them to access a redirector resource such as IPC$.

MULTIPLE CLIENTS

A named pipe server application can use named pipes to communicate with different types of networking clients simultaneously (Windows NT, Windows for Workgroups or DOS/Windows 3.1/LAN Manager) if the underlying protocols are all supported. For example, if the OS/2 LAN Manager server is running the named pipe server application and is using the TCP/IP protocol and all the clients are running TCP/IP, then they all can communicate.

It has not been demonstrated whether a named pipe server application running on an OS/2 LAN Manager server or a Windows NTmachine, and using the appropriate requester, can support named pipe clients simultaneously over the redirector (IPC$ resource) and the Novell IPX/SPX session layer.

MULTIPLE NETWORKS

When two networks are connected by a router or bridge to form a wide area network, named pipe applications may be supported across it. For example, if the Microsoft LAN Manager TCP/IP (using RFC NetBIOS) is used as the data communications protocol on both LANs, and the routers are capable of routing TCP/IP data, then a named pipe client application can communicate to the named pipe server application across the WAN.