Web Services Architecture Usage Scenarios Selected Use Cases

Web Services Architecture Usage Scenarios Selected Use Cases & Usage Scenarios Michal Zaremba W 3 C Working Group Note 11 February 2004 8. 10. 2003 1

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” 8. 10. 2003 2

Use Cases Template • • • 8. 10. 2003 Description Scope Stakeholders/Interests Actors & Goals Usage scenarios 3

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 8. 10. 2003 4

Use Cases • Travel agent use case, static discovery • Travel agent use case, dynamic discovery • EDI-like purchasing 8. 10. 2003 5

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 8. 10. 2003 6

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 8. 10. 2003 7

EDI-like purchasing – usage scenarios • Typical Widget Purchase • Transaction Log Mismatch • Small. Co Incorrectly Thinks They Weren't Paid • Small. Co Really Wasn't Paid 8. 10. 2003 8

Usage Scenarios • Thirty-four usage scenarios e. g. : – – – 8. 10. 2003 S 001 Fire-and-forget to single receiver S 002 Fire-and-forget to multiple receivers S 003 Request/Response S 004 Remote Procedure Call (RPC) S 006 Multiple Faults S 010 Request with acknowledgement S 030 Third party intermediary S 031 Communication via multiple intermediaries S 032 Caching S 035 Routing S 036 Tracking S 037 Caching with expiration 9

Usage Scenario - Remote Procedure Call (RPC) 8. 10. 2003 10

Usage Scenario - Request with Acknowledgement 8. 10. 2003 11