Developing applications over IPX/SPX using TLI

Using the SAP protocol

Novell networks consist of clients and servers. Servers provide clients on the network with a variety of services:

file servers: provide clients with file services, for example, reading and writing to operating system files.
application servers: provide clients with application-level services, for example, reading and writing to a database.
login servers: provide clients with the ability to act as terminals for the server's native operating system.

SCO IPX/SPX allows SCO OpenServer systems to act as servers on Novell networks. IPX/SPX servers can provide clients with both application and file services. The default configuration provides clients with login services.

A network needs a method of advertising available services. NetWare uses the Service Advertising Protocol (SAP). SAP allows service nodes such as file servers, print servers, and application servers to advertise their services and addresses.

With SCO IPX/SPX, you can use the Service Advertising Protocol daemon (SAPD) to advertise an application's services. Applications using SAPD's services are called application servers because they have services to offer clients on the network. These applications are loaded on computers running NetWare or SCO IPX/SPX. You can also query SAPD to initiate a session between an advertising service and a client application.

To use SAPD, you should already be familiar with the IPX protocol and understand IPX addresses.