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AGENT-ORIENTED INFORMATION SYSTEMS ANALYSIS AND DESIGN 103
Figure 7.2 Actor Diagram for a Media Shop

Increase Depender X Dependee
Market Share
Dependency Goal Task
Actor
Consult Media Items Legend Ressource Softgoal
Catalogue

Buy Media Media Continuous Media Quality Media
Customer Items Shop Supply Supplier Packages Producer

Happy Continuing
Customers Business

Figure 7.3 focuses on one of the (soft)goal dependencies identified for Media Shop, namely,
Increase Market Share. To achieve that softgoal, the analysis postulates a goal Run Shop that can
be fulfilled by means of a task Run Shop. Tasks are partially ordered sequences of steps intended
to accomplish some (soft)goal. In Tropos, tasks can be decomposed into subtasks but also goals,
whose collective fulfillment completes the task. In Figure 7.3, Run Shop is decomposed into goals
Handle Billing and Handle Customer Orders, tasks Manage Staff and Manage Inventory, and
softgoal Improve Service, which together accomplish the top-level task. Subgoals and subtasks can
be specified more precisely through refinement. For instance, the goal Handle Customer Orders
is fulfilled either through tasks Order By Phone, Order In Person, or Order By Internet, while
the task Manage Inventory would be collectively accomplished by tasks Sell Stock and Enhance
Catalogue. These decompositions eventually allow us to identify actors who can accomplish a
goal, carry out a task, or deliver some needed resource for Media Shop. Such dependencies in
Figure 7.3 are, among others, the goal and resource dependencies on Media Supplier for supplying,
in a continuous way, media items to enhance the catalogue and sell products, the softgoal depen-
dencies on Customer for increasing market share (by running the shop) and making customers
happy (by improving service), and the task dependency Accounting on Bank Cpy to keep track
of business transactions.

LATE REQUIREMENTS ANALYSIS

For our example, the Medi@ system is viewed as a fully fledged actor in the actor diagram depicted
in Figure 7.4. With respect to the actors previously identified, Customer depends on Media Shop
to buy media items while Media Shop depends on Customer to increase market share and make
customers happy (with Media Shop service). Media Supplier is expected to supply Media Shop
with media items in a continuous way since it depends on the latter for continuing business. It can
also use Medi@ to determine new needs from customers, such as media items not available in the
catalogue, while expecting Media Producer to provide him/her with quality packages. As indicated
earlier, Media Shop depends on Medi@ to process Internet orders and on Bank Cpy to process
business transactions. Customer, in turn, depends on Medi@ to place orders through the Internet,
to search the database for keywords, or simply to browse the online catalogue. With respect to
relevant qualities, Customer requires that transaction services be secure and available, while Media