Information Technology Reference
In-Depth Information
used by system designers who are particularly concerned with the infrastruc-
ture of systems.
Since this area has been a target of standardization for quite some time,
a number of standards or specifications already exist to provide such mecha-
nisms for specific technologies, such as Web Services, .NET, JEE or CORBA.
The main value of the engineering viewpoint is in providing a technology-
neutral architectural framework or reference architecture that can be used as
a basic tool for designing new systems or comparing existing infrastructure
technologies for distributed processing. In this way, infrastructure designs can
have a much longer life than the technologies that support them; this allows
these technologies to evolve without invalidating the system designs, which
are a company's major asset.
Another important feature is that the information necessary for confor-
mance testing originates in this viewpoint. Although the actual conformance
testing may be performed against software and hardware artefacts specified
in the technology viewpoint, the basic test requirements are defined in the
technology-independent engineering viewpoint. For instance, observation of a
SOAP message passing from a client PC technology object to a departmental
server technology object may be used to check conformance by comparing it
to the interactions expected at an interface between the corresponding engi-
neering objects that has been identified as a conformance point.
5.2 Objects and Distribution
The major objective of the engineering design is to support the distribution
transparency requirements of the computational objects. As explained in the
previous chapter, computational interactions are at least access and location
transparent. However, more transparency attributes may be specified in the
computational transparency schema specification.
Basic Engineering Objects (or BEOs for short) are a special kind of engi-
neering object, which are used to give a representation of each computational
object in the engineering viewpoint. We are concerned here primarily with
the engineering of machines and of network communication. Some computa-
tional objects may represent human actors, but for these there is just a simple
placeholder BEO; the engineering of communication with them is a matter for
HCI standardization, but is not detailed in this reference framework and so is
not discussed further here.
The set of BEOs can be seen as abstractions of the computational de-
sign. The resulting description hides distinctions between objects with sim-
ilar communications requirements, and retaining only the information about
the computational objects that characterizes them as users of the distribution
platform being provided.
Therefore, the BEO is the primary object to be
