define the way they acknowledge messages to each other in order to
avoid losing information. Finally, the session layer allows the two computers
to recognize when messages belong to the same stream of conversation, allowing
them to exchange information back and forth in a sustained fashion.
The next two
layers are about making sure that the computers actually understand each other.
Just as two humans can’t communicate if they speak different languages unknown
to each other, computers need to make sure that they speak the same language.
That’s the function of the presentation layer. Finally, even if they speak the
same language, humans speak differently, depending on circumstances. Each
situation is a particular application of our communication capabilities.
Similarly, computers speak about different topics and with different rules
depending on the circumstances. That’s what the application layer does; it
establishes context.
All together, we
see that computers interact in pretty much the same way as humans. They need to
find a communication medium, they need to establish readiness to talk and then
they need various conventions to converse effectively. The physical
characteristics of humans and computers dictate different techniques and
technologies, but the general order of operations, as well as their nature, is
similar. In many cases, it’s just a matter of nuances. While it is customary
for computers to talk through other intermediate computers, it is a less usual
situation with humans. However, there are indeed cases where humans communicate
through intermediaries; for example, through messengers. Conversely, humans
actually establish several channels of communication at once in face-to-face
conversation. Hand gestures, body signals and facial expressions are all part
of communication that accompany the mouth-to-ear channel. Computers are
typically more reserved, using only one channel at a time. In fact, they use
one channel at once like people do when they talk by phone.
The reference
communication model of computers actually expresses a hierarchy of needs. To
communicate, two computers require electricity for a physical link, they need
to associate with each other reliably, and they need to exchange meaningful
information. In the same way, humans need food and links to each other, they
need to be accepted by others and gain their approval, and then they need to
engage in meaningful and fulfilling exchanges. While at this point we will not
claim an immediate parallel between the two models of behavior, we can see that
Maslow, as a psychologist, and the Open Systems Interconnection committee, as
computer scientists, chose to model humans and computers with similar means.
The very commonality of approach will allow us to examine in turn each level of
the human and computer protocols and examine in depth where they converge and
where they differ. In the end, we will suggest that in fact the needs hierarchy
of humans has a parallel adjunct in the application layer of computers.
Similarities and dissimilarities will be equally revealing, and will be the
ferment for subsequent inquiries.
Beginning with
the Open Systems Interconnection reference model as a starting point, a rather
general model of interactions can be constructed that encompasses general human
interactions as well as human to computer and computer-to-computer interactions.
This model of interaction infrastructures
results from merging the connection facilities of the Open Systems
Interconnection reference model, an interaction impetus model based on Maslow’s
hierarchy of needs, and a trust model derived from the physiological basis of
human interactions. At this point, we’re only going to go part of the way
towards this model. Specifically, we’re going to consider the model as based on
the security characteristics of computer networks. We’ll defer the inclusion of
a human trust
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