Methodologies for Design of Service-Based Systems - Intentional Perspectives on Information Systems Engineering - page 306

In the life cycle proposed by Papazoglou [ 8] , the initial phase is the plan-
ning phase, in which the business needs are analyzed, the technological landscape
reviewed, new requirements are conceptualized and related to existing applications.
The planning phase in this proposed approach is very similar to that of traditional
software development methodologies.
Also in [ 5] the adoption of existing approaches in the initial design phase is
advocated. Use cases and scenarios are proposed for the initial phases, where initial
scenarios are designed and merged and integrated using consolidated techniques.
Business process modelling techniques are also considered, but the difficulty of
integrating process models in initial phases is analyzed, and process models are
described as more adequate for later design stages. However, the use of fragments
of process models in conjunction with scenarios might have the advantage of link-
ing scenarios to executable components. Process models can also be annotated with
quality of service and information derived from run-time execution which might
be useful for composing services at run time. However, while some consideration
is given to run-time aspects, there is not a direct link to the run-time adaptation
aspects.
An innovative approach for linking business goals and services has been pro-
posed by Colette Rolland and her group, first in [ 6] , then refining this work in [ 10]
to a full fledged service-oriented design approach. The main proposal is to start
describing services already in business terms, which makes it easier to transform
requirements into executable applications considering the specific characteristics of
services and their adaptivity. One of the problems of considering services already
in the first design phases is that services are often described in terms of their func-
tionalities, thus focusing on their provided interfaces and operations. The original
proposal in [ 6] is to move from function-driven service oriented computing (SOC)
to intention-driven SOC. The intention-driven approach has the advantage of focus-
ing on the purpose, the intention, behind a service, rather than on its functional
view.
The advantage of intentional service description is that it allows considering
variability, i.e. allowing the representation of alternative variations of a service or
alternative service compositions to achieve the same intention.
The classical SOA architecture is therefore transformed in [ 10] into an ISOA
(intentional SOA) architecture, in which service discovery is goal oriented and
binding becomes connected to adaptation. In addition, the intention-based ser-
vice description can be presented at different abstraction levels, thus allowing
the description of services at different granularities, which are used then in the
subsequent design and construction phases.
In this way, specific characteristics of services illustrated in the previous sec-
tion can be already considered in the initial design phases, and the derivation of
executable processes based on service composition made easier.
Maps are proposed in [ 10] for modelling intention-driven compositions of ser-
vices. A central point in this approach is that a service permits the fulfilment of
an intention, given an initial situation and terminating in a final situation, when the
intention is viewed as a goal for the service (Fig. 3) .