Part 3, Communications describes communications in the SPIRIT environment, excluding management-specific communications, which are defined in Part 4, Distributed Systems Management. It is structured as follows:
Describes the SPIRIT communication model and how it maps to the OSI Reference Model. Describes three protocol suites: OSI Transport and Lower Layer protocols, Internet Transport and Lower Layer protocols, and Application protocols.
SPIRIT assumes a distributed environment. In this environment, multiple platforms are interconnected and communicate with each other. Applications are also distributed; that is, they are segmented and different segments reside on different platforms in the distributed environment.
The first objective of describing communications in the SPIRIT
environment is to enable the harmonious and cooperative operation
of communicating platforms and application segments.
This capability is termed interoperability.
The next objective is to describe the communications options in a meaningful way for Service Providers' procurements. This requires clear and explicit references to protocols, and an unambiguous and technically cohesive description of possible combinations of protocols that can be used in any instance of communications.
A protocol suite is a collection of protocols that work together.
This part provides a method for succinctly and precisely describing protocol suites and relevant APIs. The method is based upon the OSI Reference Model and references International Standardized Profiles (ISPs) and related proforma as appropriate. Using this method, it then describes the SPIRIT protocol suites as:
The basic requirement is to enable communications between any
two SPIRIT Platforms which are connected directly or indirectly
by some physical means.
It must be possible to run OSI and Internet transport and network protocols over common physical networks. The Upper Layer protocols must be independent of the underlying physical-level networks. Either LANs or WANs must be supported as physical-level networks.
Communications services must include the functionality of file transfer and messaging.
Profiles must cover gateways to communicate with other communications services.
Manageability in the distributed environments must be supported.
Time and naming services in the distributed environments must
In particular, support for the X/Open Distributed Computing
Environment (DCE) and ISO X.500 Naming Service is required.
OSI Upper Layer services over TCP/IP-based networks must be available.
Application services (for example, mail, file transfer, directory and distributed transaction processing services) must be supported across local and wide area networks and independent of transport.
APIs must be available to enable creation of applications to emit and accept standard application protocols.
It must be possible for applications to emit and accept application-specific protocols. A transport-independent API to support this requirement is needed.