SAP library

SAP library

One of the design goals for NetWare^® transports for the UNIX^® environment has been to provide an easy to use application programming interface for NetWare service advertising and service queries. The SAP library has been written to accomplish this goal.

The SAP library provides functionality in two modes. The mode used by the library is dependent upon the status of the NetWare SAP daemon (SAPD).

If the SAP daemon is not active, the SAP library is unable to advertise any services to the network.
In this mode, all service queries are handled by passing the request to the network and processing the responses.
If the SAP daemon is active, all of the SAP library functions are supported.
In this mode, the SAP library is an Inter Process Communication (IPC) library designed for processes running on the same platform as the NetWare protocol stack. It provides fast and convenient access to the information that the SAP daemon maintains.

As these functions become part of the Application Programming Interface (API) and Transport products, application developers can use them for the following tasks:

Obtaining SAP information
Authorizing the SAP daemon to advertise an application server
Informing the SAP daemon that the application server is going down

For example, SAP implementations for UNIX processes, such as the Server Advertiser daemon and the Print Server daemon, use these functions.

With the SAP daemon running, none of the SAP library query functions send SAP packets out on the wire; they all obtain their information directly from tables maintained by the SAP daemon in a mapped memory region. Those functions that use mapped memory automatically attach to the mapped memory region at the beginning of each call and detach at the end of the call.

For those processes that desire multiple accesses to the SAP information, SAPMapMemory allows the process to attach to the mapped memory region and remain attached to the mapped memory region until a detach function is used.

All functions in the SAP library use this mapped memory region except for the following:

SAPAdvertiseMyServer
SAPNotifyOfChange
Advertise Service
ShutdownSAP

The functions that use the mapped memory region can only read information; they cannot update or write to it. Hence, the functions that require the updating of information (the four functions listed above) do not use the mapped memory region.