CST(10)-Transport Stacks Middleware

Modern operating systems like Windows 95, OS/2 Warp Connect, Netware, Windows NT and Unix SVR4 are becoming much more network friendly. They have introduced features that allow multivendor communication stacks and network adapters to easily plug into them.

Here are some of the new operating system features that make that possible:

The Stack Sandwich:

This provides the hooks for snapping multivendor protocol stacks into an operating system. To accommodate multivendor networks, redirectors and API’s. To do that effectively, the operating system must provide well defined interfaces between components. A modern operating system usually ‘sandwiches’ the transport stacks between a transport independent interface at the top of the stacks and a logical interface to the network device drivers at the bottom of the stacks. 

The Logical Network Driver:

This provides a single interface to all the network adapters. The last thing vendors who provide transport stacks want is to write a driver for every possible adapter. And of course, network adapter vendors want to avoid having interface to every possible stack. Microsoft/3Com’s NDIS and Novell’s ODI are the two most widely supported de facto standards for interfacing protocol stacks to network adapter device drivers. They do so by providing a logical network board that makes it easy to interface different network adapters with multiple protocol stacks. Transport stack providers can use NDIS or ODI as the common interface to all network adapters. And network vendors can use NDIS or ODI as the top layer for their network drivers. NDIS and ODI take care of sending and receiving data and managing the adapter card.

The transport independent API’s:

This sits on top of the transport stacks and allows developers to plug their program into a single interface that supports multiple protocols. The Socket interface is becoming the premier choice on most OS platforms for interfacing to multivendor multiprotocol stacks. Other choices include Transport Layer Interface (TLI) used in Netware and many Unix platforms; CPI-C, modern SNA peer-to-peer API that can run on both SNA and TCP/IP stacks.

The Protocol Matchmakers:

This allows applications written for a specific transport such as SNA, to run across other networks, such as TCP/IP or IPX/SPX. This strategy eliminates the need for gateways and works well with existing applications. For ex, a Lotus Notes application written for NetBIOS could be made to run over SNA networks without changing a line of code. IBM’s AnyNet product line is an example of a protocol matchmaker.
CST(10)-Transport Stacks Middleware Reviewed by 1000sourcecodes on 21:46 Rating: 5
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