|  | 15.1 | Basics of the Application Layer
| 15.1.3 | Indirect network support

Within a LAN environment, indirect-application network support is a client-server function. If a client wants to save a file from a word processor to a network server, the redirector enables the word processing application to become a network client.

Redirector is a protocol that works with computer operating systems and network clients instead of specific application programs.

Examples of redirectors are:

- Apple File Protocol
- NetBIOS Extended User Interface (NetBEUI)
- Novell IPX/SPX protocols
- Network File System (NFS) of the TCP/IP protocol suite

The redirector process is as follows:

1. The client requests that the network file server allow the data file to be stored.
2. The server responds by saving the file to its disk, or by rejecting the client's request.
3. If the client requests that the network print server allow the data file to be printed by a remote (network) printer, the server processes the request by printing the file on one of its print devices, or by rejecting the request.

Redirector allows a network administrator to assign remote resources to logical names on the local client. When you select one of these logical names to perform an operation such as saving a file, or printing a file, the network redirector sends the selected file to the proper remote resource on the network for processing. If the resource is on a local computer, the redirector ignores the request and allows the local operating system to process the request.

The advantage of using a network redirector on a local client is that the applications on the client never have to recognize the network. In addition, the application that requests service is located on the local computer and the redirector reroutes the request to the proper network resource, while the application treats it as a local request.

Redirectors expand the capabilities of non-network software. They also allow users to share documents, templates, databases, printers, and many other resource types, without having to use special application software.

Networking has had a great influence on the development of programs like word processors, spreadsheets, presentation managers, database programs, graphics, and productivity software. Many of these software packages are now network-integrated or network-aware. They have the capabilities of launching integrated Web browsers or Internet tools, and to publish their output to HTML for easy Web integration.

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Redirectors