ONC+ Developer's Guide

Overview of Interface Routines

RPC has multiple levels of application interface to its services. These levels provide different degrees of control balanced with different amounts of interface code to implement, in order of increasing control and complexity. This section gives a summary of the routines available at each level.

Simplified Interface Routines

The simplified interfaces are used to make remote procedure calls to routines on other machines, and specify only the type of transport to use. The routines at this level are used for most applications. Descriptions and code samples are in the section Simplified Interface.

Table 2–1 RPC Routines—Simplified Level


Routine	Function
`rpc_reg()`	Registers a procedure as an RPC program on all transports of the specified type
`rpc_call()`	Remotely calls the specified procedure on the specified remote host
`rpc_broadcast()`	Broadcasts a call message across all transports of the specified type

Standard Interface Routines

The standard interfaces are divided into top level, intermediate level, expert level, and bottom level. These interfaces give a programmer much greater control over communication parameters such as the transport being used, how long to wait before responding to errors and retransmitting requests, and so on.

Top-Level Routines

At the top level, the interface is still simple, but the program has to create a client handle before making a call or create a server handle before receiving calls. If you want the application to run on all transports, use this interface. You can find the use of these routines and code samples in Top-Level Interface.

Table 2–2 RPC Routines—Top Level


Routine	Description
`clnt_create()`	Generic client creation. The program tells `clnt_create()` where the server is located and the type of transport to use.
`clnt_create_timed()`	Similar to `clnt_create()` but enables the programmer to specify the maximum time allowed for each type of transport tried during the creation attempt.
`svc_create()`	Creates server handles for all transports of the specified type. The program tells `svc_create()` which dispatch function to use.
`clnt_call() ()`	Client calls a procedure to send a request to the server.

Intermediate-Level Routines

The intermediate level interface of RPC enables you to you control details. Programs written at these lower levels are more complicated but run more efficiently. The intermediate level enables you to specify the transport to use. Intermediate-Level Interface describes the use of these routines and code samples.

Table 2–3 RPC Routines—Intermediate Level


Routine	Description
`clnt_tp_create()`	Creates a client handle for the specified transport
`clnt_tp_create_timed()`	Similar to `clnt_tp_create()` but enables the programmer to specify the maximum time allowed
`svc_tp_create()`	Creates a server handle for the specified transport
`clnt_call() ()`	Client calls a procedure to send a request to the server

Expert-Level Routines

The expert level contains a larger set of routines with which to specify transport-related parameters. Expert-Level Interface describes the use of these routines and code samples.

Table 2–4 RPC Routines—Expert Level


Routine	Description
`clnt_tli_create()`	Creates a client handle for the specified transport
`svc_tli_create()`	Creates a server handle for the specified transport
`rpcb_set()`	Calls `rpcbind` to set a map between an RPC service and a network address
`rpcb_unset()`	Deletes a mapping set by `rpcb_set()`
`rpcb_getaddr()`	Calls `rpcbind()` to get the transport addresses of specified RPC services
`svc_reg()`	Associates the specified program and version number pair with the specified dispatch routine
`svc_unreg()`	Deletes an association set by `svc_reg()`
`clnt_call()()`	Client calls a procedure to send a request to the server

Bottom-Level Routines

The bottom level contains routines used for full control of transport options. Bottom-Level Interface describes these routines.

Table 2–5 RPC Routines—Bottom Level


Routine	Description
`clnt_dg_create()`	Creates an RPC client handle for the specified remote program using a connectionless transport
`svc_dg_create()`	Creates an RPC server handle using a connectionless transport
`clnt_vc_create()`	Creates an RPC client handle for the specified remote program using a connection-oriented transport
`svc_vc_create()`	Creates an RPC server handle using a connection-oriented transport
`clnt_call()()`	Client calls a procedure to send a request to the server