Web Services Architecture
Usage Scenarios
Selected Use Cases & Usage Scenarios
Michal Zaremba
W3C Working Group Note 11 February 2004
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Use Cases & Usage Scenarios
• “A use case is a sequence of interactions
between a service requestor and one or
more services, which achieve measurable
results for the requestor”
• “A usage scenario represents an atomic step
in a path through a use case”
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Use Cases Template
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Description
Scope
Stakeholders/Interests
Actors & Goals
Usage scenarios
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Usage Scenarios Template
• Goal/Context – purpose
• Scenario/Steps – typical operations
• Extensions – variations on the scenario (e.g.
failure modes or exceptions)
• Technologies/Requirements – what is
needed to implement scenario
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Use Cases
• Travel agent use case, static discovery
• Travel agent use case, dynamic discovery
• EDI-like purchasing
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Travel agent use case, static
discovery – usage scenarios
• User requests availabilities about some travel
dates
• User chooses flight and looks for hotels
• User books hotel room and flight
• Developer creates travel agent web service that
queries for airline flights
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Travel agent use case, dynamic
discovery – usage scenarios
• User requests availabilities about some travel
dates
• User chooses flight and looks for hotels
• User books hotel room and flight
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EDI-like purchasing – usage
scenarios
• Typical Widget Purchase
• Transaction Log Mismatch
• SmallCo Incorrectly Thinks They Weren't
Paid
• SmallCo Really Wasn't Paid
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Usage Scenarios
• Thirty-four usage scenarios e.g.:
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S001 Fire-and-forget to single receiver
S002 Fire-and-forget to multiple receivers
S003 Request/Response
S004 Remote Procedure Call (RPC)
S006 Multiple Faults
S010 Request with acknowledgement
S030 Third party intermediary
S031 Communication via multiple intermediaries
S032 Caching
S035 Routing
S036 Tracking
S037 Caching with expiration
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Usage Scenario - Remote
Procedure Call (RPC)
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Usage Scenario - Request with
Acknowledgement
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