Each view of a URDAD model shows one concern, and each is drawn here as the
modelling tool draws it, from a small model of a shop. The terms link to the
glossary, and the
method says how the views are used: a
service, its requirements, who addresses each, and the process, repeated one
level down.
Scope View
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Box with a tab: a responsibility domain, named on its tab.
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Line from a ⊕: containment: the domains it is divided into.
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Dependencies View
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The domains whose services a domain’s processes request, and those services.
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Functional Requirements View
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Ellipse with a handshake: the service contract.
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Figure: a stakeholder: a domain with an interest. Above
the contract, with a solid arrow to it, a domain the contract is published to,
which may request it.
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Red flag pointing left: a pre-condition: what must hold
for the service to be provided. When it does not, the service refuses by
raising its exception.
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Blue flag pointing right: a post-condition: what holds
once the service is provided.
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Dashed line: the stakeholder who requires that condition.
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Responsibility Allocation View
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Who addresses each requirement.
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Box with a gear: the process, realizing the contract
(dashed arrow with a closed head).
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Dashed arrow: from a requirement to the step that addresses it: a request of
a lower-level service (an ellipse), a check, a message sent, or the
response.
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Data Structure View
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Filled diamond: composition: the part belongs to the whole.
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Open diamond: aggregation: the part is shared.
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Open arrow alone: association: a reference.
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Closed triangle: specialization: the structure below has every field of
the one it points to, and more.
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Numbers: multiplicity: 1, 0..1, 1..,
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Process View
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How the process orchestrates its steps, from start (green) to end (red ring).
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Check (red box): tests a pre-condition, and refuses if it does not hold.
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Blue box: a service request: the contract
requested, and the domain providing it in parentheses.
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Green arrow ↓: the request’s success path.
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Yellow bolt ⚡: an exception arm: the refusal named, and what is done about
it.
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Red circle with ×: raise an exception: this service refuses.
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Blue double diamond: where a request’s arms rejoin.
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Two heavy bars: concurrent flows: every lane runs,
and all are joined.
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Diamond: alternate flows: the first conditional flow,
in their order, whose condition holds is taken, else the default; the
double diamond rejoins them.
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Green box with ✉: send a message, to the recipient after →.
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Resp (purple box): populate the response.
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Loops and variables
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Frame headed ∀ x ∈ xs: for each: its body runs once per element of the
collection, one after another (≡) or all at once (|||).
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Frame headed ↻: while: its body repeats while the condition in its footer
holds, at most as often as the header says.
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Def (purple box): define a variable: name a value once, for the steps after it.
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Entity View
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An entity: a business object with an identity, with every
field its views hold.
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