Information Technology Reference
In-Depth Information
«EV_CommunityContract»
Phone Repair
Enterprise Object Types
Roles
«EV_Community»
Phone Repair
«EV_ObjectiveOf»
Policies
«EV_Process»
Phone Repair
Community Behaviour
«EV_Objective»
Phone Repair Objective
FIGURE 2.1: Anatomy of a community specification.
is general, and is used in structuring other kinds of collaboration; for example,
we can also speak of roles in an interaction.
Figure 2.1 illustrates the main elements involved in specifying a commu-
nity; more detail of the relationship between these key concepts is given af-
ter this initial introduction. Here, and throughout the topic, the PhoneMob
specification is used as a running example; further supporting detail from this
specification can be found in appendix A.
First, we have the behaviour of the community, which is normally de-
fined as a composition of processes addressing separate business concerns.
This composition itself results in a process, and is represented in figure 2.1 as
a UML activity stereotyped
«
EV Process
»
. The process is parameterized by
the community's roles. In addition, the community will generally also have
a number of policies, which allow aspects of its behaviour to be modified to
react to changing circumstances. These policies perform an important func-
tion in allowing the community's behaviour to be modied dynamically to
satisfy changing requirements. The way policies allow controlled flexibility so
that the objectives can still be guaranteed as situations change is discussed in
detail in chapter 10. Finally, there are declarations of a number of support-
ing enterprise objects owned by the community and used to represent its
internal state and resources.
The community is described by a community contract . Making this
description (which is effectively a community type) explicit in the specification
helps the design to capture dynamic processes, such as negotiation of the rules
under which the community operates; it gives a reflexive representation of the
behaviour and of the roles in it, the policies and the local objects. The contract
also includes a declaration of the objective of the community.
The high-level description typically states the scope and field of appli-
cation for the enterprise specification in question. The scope is expressed in
terms of the behaviour the system is to exhibit. For example, the PhoneMob
ODP system may have a scope that expresses its key functions such as keep-
