Introduction to the RPC Specification

This document specifies both portability and interoperability for the Remote Procedure Call (RPC) mechanism. The specification contains material directed at two audiences:

• It provides a portability guide for application programmers.

• It provides both portability and interoperability specifications for those who are implementing or porting RPC or who are testing an RPC implementation.

This document may be thought of as an implementation specification, covering both portability and interoperability, that contains within it an application portability guide. The application portability guide consists of Part 2, RPC Application Programmer's Interface and Part 3, Interface Definition Language and Stubs.

Although the portability specification is part of the broader implementation specification, it has been designed to stand alone so that it may be used by application programmers without reference to the other parts of the implementation specification.

Note:

In order to make the portability specification independent, some material is repeated, especially between Introduction to the RPC API and Remote Procedure Call Model .

Portability

The portability specification describes the concrete syntax and semantics of the Application Programmer's Interface (API) to RPC. It consists of:

• an introduction to the RPC API that describes the RPC programming model and gives general guidelines for portable usage (see Introduction to the RPC API )

• a reference section for the data types used in the RPC API (see RPC API Manual Pages )
• a set of reference pages for the RPC run-time library routines; these specify the calling syntax and semantics for the interfaces (see RPC API Manual Pages )

• a reference to the Interface Description Language (IDL) (see Interface Definition Language )

• a mapping of IDL data types to ISO C data types (see IDL to C-language Mappings )

• an RPC stub specification that defines stub characteristics required for portability (see The Application/Stub Interface ).

The portability specification is narrowly focussed on providing a guide to portable usage of the RPC API. It describes behaviour that is common to all implementations. Whenever implementation-specific behaviour is referenced, it is clearly marked as such. Similarly, the specification generally avoids examples or tutorial descriptions. Whenever usage guidelines are provided, they are clearly marked as such.

All behaviour that is not specifically marked as implementation-specific or a usage note, is considered to be required. All implementations must conform to the specified behaviour. Programmers can rely on the specified behaviour to be portable among conforming implementations.

Services and Protocols

The implementation specification includes a set of service and protocol specifications. The protocol specifications describe how implementations of the RPC client and server run-time systems communicate. The service specifications describe a set of abstract services that the RPC run-time system must implement.

The service and protocol specifications include:

• an abstract specification of the RPC model (see Remote Procedure Call Model )

• an abstract specification of a set of RPC service primitives (see RPC Service Definition )

• abstract specifications of the RPC connectionless and connection-oriented communications protocols. These are given as sets of statecharts and associated descriptive materials. This includes an abstract specification of the underlying transport services required by the RPC protocols. (The protocol specifications are contained in Statechart Specification Language Semantics , RPC Protocol Definitions , Connectionless RPC Protocol Machines and Connection-oriented RPC Protocol Machines .)

• byte stream specifications of the formats of RPC Protocol Data Units (PDUs) used by the connectionless and connection-oriented protocols (see RPC PDU Encodings ) and common authentication verifier encodings (see Security )

• a specification of the Network Data Representation (NDR); this specifies a set of NDR data types and the byte stream formats in which they are communicated between client and server run-time environments (see Transfer Syntax NDR )

• a mapping of IDL data types to NDR data types (see IDL to C-language Mappings )

• an RPC stub specification that defines the stub characteristics required for interoperation (see Interoperability Requirements on Stubs )

• a specification of information stored in and retrieved from name services (see Binding, Addressing and Name Services , Protocol Identifiers , and the DCE: Directory Services specification).

• a UUID specification (see Universal Unique Identifier )

• IDL data type declarations (see IDL Data Type Declarations )

• the endpoint mapper protocol (see Endpoint Mapper Interface Definition )

• the conversation manager protocol (see Conversation Manager Interface Definition )

• the remote management interface (see Remote Management Interface ).

The aim of the service and protocol specifications is to provide a complete mapping from RPC call semantics to the byte streams that RPC run-time clients and servers interchange using underlying services. The RPC service primitives provide an abstract implementation of the specified RPC call semantics and serve to map the specified semantics to the specified protocol machines. The PDU formats give the byte streams that the protocol machines exchange using the underlying transport services. The NDR specification, along with the mapping of IDL to NDR data types, defines how the call data exchanged in the RPC PDUs is encoded.

Except for the byte stream specification and the stub specification, the service and protocol specifications are abstract. They describe the behaviour that conforming implementations must follow, but they do not prescribe any specific means for implementing this behaviour.

Implementations that conform to this specification interoperate according to the following rule: client and server applications, conforming to the same IDL source (but not necessarily the same ACS), correctly implement the specified RPC interface semantics for each remote procedure call operation specified in the IDL source.

Except when specified otherwise, IDL compiler behaviour and the stub, including the stub to run-time interface, are implementation-dependent. Therefore, the above rule applies when stubs are generated using the local implementation's IDL compiler. There is no requirement that stubs for a given language are portable among implementations.

Conformance Requirements

To conform to this document, implementations must meet the following requirements:

• Implementations must support the endpoint selection rules in Endpoint Selection .

• Implementations must support the manager selection rules in Interface and Manager Selection .

• Implementations must support the search algorithm in Section 2.4.5.

• Implementations must support the API naming, syntax and semantics, as defined in RPC API Manual Pages . Implementations may extend the set of status codes documented in RPC API Manual Pages .

• Implementations must support the naming, syntax and semantics for IDL, as given in Interface Definition Language .

• Implementations must support the naming, syntax, and semantics for stubs, as given in Stubs .

• Implementations must support the semantics defined in Remote Procedure Call Model .

• Implementations must support the NSI syntax and naming, as defined in Binding, Addressing and Name Services .

• Implementations must support the service semantics defined in RPC Service Definition .

• Implementations must follow the conformance rules specified in RPC Protocol Definitions .

• Implementations must support the syntax of the PDU encodings in RPC PDU Encodings .

• Implementations must support the Authentication Verifier encodings, as defined in Security .

• Implementations must support the rules and encodings for NDR, as given in Transfer Syntax NDR .

• Implementations must support the syntax, semantics and encoding for UUIDs, as defined in Universal Unique Identifier .

• Implementations must support the naming and semantics for protocol sequence strings, as defined in Protocol Sequence Strings .

• Implementations must support the naming and semantics for the name_syntax arguments, as defined in Name Syntax Constants .

• Implementations must support the naming and semantics for security parameters, as defined in Authentication, Authorisation and Protection-level Arguments .

• Implementations must support the naming and encodings for comm_status and fault_status, as defined Reject Status Codes and Parameters .

• Implementations must support the mapping from IDL types to NDR types, and from NDR types to defined ISO C types, as defined in IDL to C-language Mappings .

• Implementations must support the portable character set, as defined in Portable Character Set .

• Implementations must use the endpoint mapper ports, as defined in Endpoint Mapper Well-known Ports for the corresponding protocols.

• Implementations must adhere to the rules for protocol identifier assignment, as defined in Protocol Identifiers .

• Implementations must adhere to the mappings for Directory Service attributes, as defined in the DCE: Directory Services specification.

• Implementations must provide defaults for the protocol machine values specified in Architected and Default Values for Protocol Machines .

• Implementations must obey the special protocol tower encoding rules specified in Protocol Tower Encoding .

• Implementations must support the syntax and semantics of the dce_error_inq_text routine specified in The dce_error_inq_text Manual Page .

• Implementations must adhere to the mappings for transfer syntax UUIDs, as defined in IDL Data Type Declarations .

• Implementations must support the endpoint mapper semantics, as defined in Endpoint Mapper Interface Definition .

• Implementations must support the conversation manager semantics, as defined in Conversation Manager Interface Definition .

• Implementations must support the remote management semantics as defined in Remote Management Interface .

Footnotes

1.

This document specifies ISO C-language bindings for data types and interfaces.

Please note that the html version of this specification may contain formatting aberrations. The definitive version is available as an electronic publication on CD-ROM from The Open Group.