Information Technology Reference
In-Depth Information
External Data Representation (XDR)
—A machine-independent data
representation. Both clients and servers translate data into and out of the
XDR format. This provides a standardized format for all data to over-
come differences in data byte ordering, data type size, and byte align-
ment between different hardware architectures.
➤
Transport Layer Interface (TLI)
—An interface to TCP/IP that allows
the RPC mechanism to be protocol independent. Either a connection-
oriented protocol, such as TCP (Transmission Control Protocol) or a
connectionless protocol (such as UDP) can be selected without making
changes to the client or server code.
➤
Sockets
—Another mechanism that can be used to interface to TCP/IP
that supports protocol independent programming of client/server appli-
cations.
➤
In the TCP/IP model, all of the ONC+ components reside in the
Application Layer. In terms of the OSI model, these components are dis-
tributed among the Session Layer (RPC), Presentation Layer (XDR), and
Application Layer (NFS and NIS+). Note that the applications call XDR
routines to translate the data. Once translated, the data is processed locally
or passed to RPC routines to send the data to a remote system.
Registering RPC Services
In order for systems to use distributed services built on RPC, the programs
that provide the services must be identified (that is, registered). The program
that manages RPC services on a system is the
rpcbind(1M)
daemon. Each
RPC program is assigned a unique number. When an RPC program starts,
it contacts the local
rpcbind
daemon and provides its RPC program number,
version, and so on. When a remote client attempts to use a local RPC serv-
ice, it contacts the local
rpcbind
daemon to obtain information (based on
RPC program number) about the service and to request a connection to the
service. Thus, the
rpcbind
daemon provides a method for local services to
register their availability and remote clients to identify the services and
establish a connection to the services.
The
rpcinfo(1)
command can be used to contact the local or a remote
rpcbind
daemon and request it to list the currently registered RPC services.
The following listing shows the
rpcinfo
command being used to list local
services. By specifying the name of a remote host as a command-line argu-
ment, the
rpcinfo
command can list services on a remote system.
# rpcinfo
program version netid address service owner
100000 4 ticots solaris9.rpc rpcbind superuser
100000 3 ticots solaris9.rpc rpcbind superuser
