The history of the development of the OSI model is, for some reason, a little-known
story. Much of the work on the design of OSI was actually done by a group
at Honeywell Information Systems, headed by Mike Canepa, with Charlie Bachman
as the principal technical member. This group was chartered, within Honeywell,
with advanced product planning and with the design and development of prototype
systems.
In the early and middle '70s, the interest of Canepa's group was primarily
on database design and then on distributed database design. By the mid-70s,
it become clear that to support database machines, distributed access, and
the like, a structured distributed communications architecture would be
required. The group studied some of the existing solutions, including IBM's
system network architecture (SNA), the work on protocols being done for
ARPANET, and some of the concepts of presentation services being developed
for standardized database systems. The result of this effort was the development
by 1977 of a seven-layer architecture known internally as the distributed
systems architecture (DSA).
Meanwhile, in 1977 the British Standards Institute proposed to the International
Organization for Standardization (ISO) that a standard architecture was
needed to define the communications infrastructure for distributed processing.
As a result of this proposal, ISO formed a subcommittee on Open Systems
Interconnection (Technical Committee 97, Subcommittee 16). The American
National Standards Institute (ANSI) was charged to develop proposals in
advance of the first formal meeting of the subcommittee.
Bachman and Canepa participated in these early ANSI meetings and presented
their seven-layer model. This model was chosen as the only proposal to be
submitted to the ISO subcommittee. When the ISO group met in Washington,
DC in March of 1978, the Honeywell team presented their solution. A consensus
was reached at that meeting that this layered architecture would satisfy
most requirements of Open Systems Interconnection, and had the capacity
of being expanded later to meet new requirements. A provisional version
of the model was published in March of 1978. The next version, with some
minor refinements, was published in June of 1979 and eventually standardized.
The resulting OSI model is essentially the same as the DSA model developed
in 1977.
Copyright 1998
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