Use Case Development for Data Quality Screening Service

1. Use Case Development for Data Quality Screening Service Or: what to do when someone asks you - “What is your use case”? Or: Earth Science Use Cases for Dummies Facilitated by Peter Fox (RPI) and others Abridged for DQSS by Chris Lynnes (NASA/GSFC)

2. Semantic Web Methodology and Technology Development Process Adopt Technology Approach Leverage Technology Infrastructure Science/Expert Review & Iteration Rapid Prototype Open World: Evolve, Iterate, Redesign, Redeploy Use Tools Evaluation Analysis Use Case Develop model/ ontology Small Team, mixed skills

3. Software and wetware1 • ‘Before you make the software interoperable, you need to make the people interoperable2’ 1attributed to SCEC PI Tom Jordan, USC 2 talk by Ian Jackson, chief of operations, British Geological Survey, presented at the American Geophysical Union, Dec. 2008

4. Developed for NASA TIWG A Use Case is a… • prose description of a system's behavior when interacting with the outside world • technique for capturing functional requirements of business systems and, potentially, of an IT system to support the business system • collection of possible sequences of interactions between the system under discussion and its Users (or Actors), relating to a particular goal

5. Developed for NASA TIWG Constructing Use Cases • A Use Case must be documented (or it is useless) • A Use Case should be implemented (or it is not well scoped) • Any system behavior that is irrelevant to the Actors should not be included in the use case. • The collection of Use Cases should define all system behavior relevant to the Actors to assure that their goals will be carried out properly.

6. Developed for NASA TIWG Use Case • Is used to identify: objects ~ resources, processes, roles (aka actors), requirements, etc. • Should iterate with experts on wording and details at least once

7. Developed for NASA TIWG Roles and skill-sets needed • Facilitator *** (usual key skills, knows method) • Domain experts (literate, knows resources; data, applications, tools, etc.) • Modelers (to extract objects) • Software engineers (architecture, technology) • Scribe (to write everything down) • The social aspect is key - it is a team effort

8. Developed for NASA TIWG Use Case Example: • Make a collection of netCDF model run datasets available for internet access with web browsing to find suitable data and access to the data via Matlab.

9. Developed for NASA TIWG Use Case Examples: • Provide browse and quick look access to a broad variety of climate, weather and ocean data.

10. Developed for NASA TIWG Use Case Examples: • Provide high-performance data transfer of specific climate model data products into the CDAT tool for analysis independent of their storage format, organization or location on the internet

11. Two Levels of Use Case Developed for NASA TIWG

12. Developed for NASA TIWG Elements of a Use Case • http://wiki.esipfed.org/index.php/SolutionsUseCase_Template • Start with the Plain Language Description • Short Definition • Purpose • Describe a scenario of expected use • Definition of Success

13. Developed for NASA TIWG “Short Definition” Element • Describe the use case in plain sentences • Avoid specifying technical solutions or implementation choices

14. Developed for NASA TIWG “Purpose” Element • A plain language description of • why this use case exists • what problem is to be solved • what a successful outcome would be • what the impact would be • Aka the ‘business case’

15. Developed for NASA TIWG “Scenario of expected use” element • A verbose description of one instance of a problem to be solved • what resources are generally needed (if known) • what a successful outcome and impact may be • who might be expected to do the work or provide the resources and • who might be expected to benefit from the work. • List any performance or metric requirements for this use case and any other other considerations that a user would expect.

16. Developed for NASA TIWG “Definition of Success” Element • Quick test that would show whether or not the case is working as described.

17. Developed for NASA TIWG At this stage… • Use case modelers should have a good sense of what the use case goal is. • They proceed on to the next stage to extract details. • They may contact other team members, e.g. domain experts, one-on-one for additional information. • The eventual result will be a Formal Use Case.

18. Developed for NASA TIWG Formal Use Case Description • Use Case Identification • Revision Information • Definition • Successful Outcomes • Failure Outcomes

19. Developed for NASA TIWG Use Case Elaboration • Actors • Primary Actors • Other Actors • Preconditions • Postconditions • Normal Flow (Process Model) • Include pictures, mockups, etc. if possible • Alternative Flows • Special Functional Requirements • Extension Points

20. Developed for NASA TIWG Non-functional requirements • Performance • Reliability • Scalability • Usability • Security • Other Non-functional Requirements