Information Technology Reference
In-Depth Information
it will work, and others (in the second list) will be concerned with how the
activity is managed. Thus, there need to be, at least:
An agreement in the enterprise viewpoint that the federation is neces-
sary, with a clear statement of its objectives and the level of resource
sharing and devolved control needed, in terms of management and se-
curity policies. This agreement needs to be confirmed at the highest
management level of the participating organizations. In the example,
a memorandum of understanding (or MoU for short) stating the objec-
tives is prepared by the two CTOs and signed by Marcus and his opposite
number.
The agreement of the joint business processes, and of any associated
business services, that will articulate the federation. Eleanor works with
her counterpart to document the required business processes and the sit-
uations in which they are to be invoked.
The development of a shared information model for the activities covered
by the federation agreement. Ira extracts a subset from the PhoneMob
information model, dealing with the properties of customers and users,
and agrees it with technical staff from Factotum, who do not yet have an
integrated information model for their systems.
An agreement in the computational viewpoint on the resource discovery
mechanisms and the publication strategy for services and on the compu-
tational interfaces to be supported by each participant. This federation
links two specific parties, so open publication is not needed. The two
organizations can simply exchange service description, involving compu-
tational interface signatures in a suitable language, such as WSDL or
IDL specifications; there is no need for more visible publication mecha-
nisms in the computational view. The PhoneMob computational model
is extended to include a mapping to the agreed interface definitions.
Decisions on the engineering and technology solutions to support the
actual communication between participants and assignment of responsi-
bilities for any message transformations required to match the internal
conventions of the participants. Nigel has no problem here at first be-
cause the communication between organizations uses normal web services
conventions, but some of the information items being transferred have
dierent representations from the PhoneMob's internal usage. These
need to be transformed, and an interceptor is introduced into their web
services support platform, tightly bound to it.
These considerations are primarily concerned with the design of the federa-
tion. There also need to be plans for its deployment and ongoing management.
These include:
