OSF DCE Application Development Guide--Core Components

OSF DCE Application Development Guide—Core Components
Figure 12-1. A Binding
Network
address
Network
Server’s systemClient’s system
Server
Endpoint
Client
Client
RPC & comm. protocols
Binding information includes the following components:
• Protocol sequence
A valid combination of communications protocols presented by the runtime as a
character string. Each protocol sequence includes a network protocol, a transport
protocol, and an RPC protocol that works with them.
An RPC server tells the runtime which protocol sequences to use when listening for
calls to the server, and its binding information contains those protocol sequences.
• Network addressing information
Includes the network address and the endpoint of a server.
— The network address identifies a specific host system on a network. The format
of the address depends on the network protocol portion of the protocol sequence.
— The endpoint acts as the address of a specific server instance within the host
system. The format of the endpoint depends on the transport protocol portion of
the protocol sequence. For each protocol sequence a server instance uses, it
requires a unique endpoint. A given endpoint can be used by only one server per
system, assigned by the local system on a first-come, first-served basis.
• Transfer Syntax
The server’s RPC runtime must use a transfer syntax that matches one used by the
client’s RPC runtime. A transfer syntax is a set of encoding rules used for the
network transmission of data and the conversion to and from different local data
representations. A shared transfer syntax enables communications between systems
that represent local data differently. DCE RPC currently uses a single transfer syntax,
Network Data Representation (NDR). NDR encodes data into a byte stream for
transmission over a network. A transfer syntax such as NDR enables machines with
different formats to exchange data successfully. (The DCE RPC communications
protocols support the negotiation of transfer syntax. However, at present, the
outcome of a transfer-syntax negotiation is always NDR.)
• RPC protocol version numbers
The client and server runtimes must use compatible versions of the RPC protocol
specified by the client in the protocol sequence. The major version number of the
RPC protocol used by the server must equal the specified major version number. The
minor version number of the RPC protocol used by the server must be greater than or
equal to the specified minor version number.
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