The ‘association’ – the interaction – between the actors and the system is
indicated by a line between the actor and the system boundary. Notice that the
line is not arrowed, since it does not show the ﬂow of data. It just shows the
existence of a relationship between the system and the actor.
Using context dia
Context diagrams can be developed by BAs based on the research they have done
through interviews, workshops and so forth. Having drawn a diagram a BA then
needs to review it with the various actors to check that it does represent their
understanding of how they will use the proposed system. If the system is
replacing an existing one, study of that earlier system’s documentation will also
reveal the various interfaces that will be needed, particularly with other systems
and with time.
However, context diagrams are also a powerful tool for use during a workshop
with the various stakeholders (Technique 14). The BA (or other facilitator) can
draw a box representing the proposed system on the whiteboard or ﬂipchart, and
then ask participants to shout out the names of the actors they think need to
interact with it. Alternatively participants can be invited to come up and add
actors themselves. This way, the group can generate very quickly a diagram that
shows the scope of the proposed system and the way it ﬁts in with the wider
world. If time permits, the group can then go on to explore the types of function
within the system with which each actor will interact – and thus begin to develop
a more detailed use case diagram (Technique 62).
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