1 CS 501 Spring 2002 CS 501: Software Engineering Lecture 3 Feasibility Studies

2 CS 501 Spring 2002 Administration News group: nntp://newsstand.cit.cornell.edu/cornell.class.cs501 Wednesday evening section this week: Project team formation and discussions Today: Announcements Lecture on Feasibility Studies Discussion of Pfleeger, Chapter 2

3 CS 501 Spring 2002 Administration Project teams: If you have definitely chosen a project, please notify the Teaching Assistants with the names of your team members If you do not have a team you can meet after class Wednesday's recitations session will be to help the people who do not have projects form teams We may ask teams to add extra members A Teaching Assistant will be added to each team.

4 CS 501 Spring 2002 Feasibility Study Before beginning a project, a (usually) short, low-cost study to identify: Client Scope Potential benefits Resources needed: staff, time, equipment, etc. Potential obstacles Where are the risks? How can they be minimized?

5 CS 501 Spring 2002 Feasibility Study A feasibility study leads to a decision: go ahead do not go ahead think again In production projects, the feasibility study often leads to a budget request. In research, a feasibility study is often in the form of a proposal.

6 CS 501 Spring 2002 Example: Library of Congress (Poor Process) Outline Description The Library of Congress required a repository system to store and make accessible very large amounts of highly varied material over long periods of time.

7 CS 501 Spring 2002 Chronology (Bad) CNRI carried out research on architectures for digital libraries CNRI developed prototype repository for Library of Congress. 1998CNRI and Library of Congress realized that the project was going in the wrong direction.

8 CS 501 Spring 2002 Bad Discoveries During Prototype Resistance to change within Library of Congress Technical weakness of Library of Congress Gaps in CNRI architecture

9 CS 501 Spring 2002 Mistakes Confusion of objectives (research and implementation) Failure to involve all stakeholders Over-ambitious (no proper feasibility study)

10 CS 501 Spring 2002 Repository: Research During Prototype 1. CORBA implementation of repository access protocol. 2. Integration of persistent naming through handle system. 3. Use of structural metadata to describe complex objects, elementary typology. 4. Access management framework and implementation. 5. Applet-based middleware for user interfaces. 6. Information visualization program to view the structure of large collections. As research this was excellent, but it did not help the client build a production system.

11 CS 501 Spring 2002 Example: NSDL (Long Process) 1996Vision articulated by NSF's Division of Undergraduate Education 1997National Research Council workshop 1998SMETE-Lib workshop 1999NSDL solicitation demonstration projects (core system) large core integration system funded

12 CS 501 Spring 2002 Why are Feasibility Studies Difficult? Benefits are usually very hard to quantify. Approach is usually ill-defined. Estimates of resources needed and timetable are very rough. (e.g., eCornell) Organizational changes may be needed. (e.g., British auto licensing center.) Therefore, feasibility studies rely heavily on the judgment of experienced people. Mistakes made at the beginning are the most difficult to correct.

13 CS 501 Spring 2002 Techniques for Feasibility Studies Give client appreciation of system: demonstration mock-up walk through Outline budget: n people for m months at $x per month equipment, buildings, etc. Phases/milestones: deliverables at approximate date

14 CS 501 Spring 2002 CS 501: Client In CS 501, you have two clients: The client for the project The professor for the course Can you satisfy them both?

15 CS 501 Spring 2002 Scope What are the boundaries of the project? CS 501 Examples (Fall 2000): Static web pages with open access on the Web [Web Profiler] Used by the general public [Digital Collections] Varying data formats [Legal Information] Thousands of sensors [Data mining] Support for Windows, Mac, Unix [SALSA]

16 CS 501 Spring 2002 Potential Benefits Why are you doing this project? Can you price the benefits? Examples Create a marketable product Improve the efficiency of an organization (e.g., save staff) Control a system that is too complex to control manually New or improved service (e.g., faster response to customers) Safety or security Get a good grade on CS 501

17 CS 501 Spring 2002 Resources Examples: CS 501 Staff: 5 to 7 students, with some help. How many hours per week? What skills do people have? Time: Must be completed by end of semester, including operational system, documentation, presentation Equipment and software: What special needs are there? Client: Will the client be sufficiently available and helpful?

18 CS 501 Spring 2002 Obstacles CS 501 projects Start-up time. Creating a team, scheduling meetings, acquiring software, learning new systems,... Business considerations. Licenses, trade-secrets,... Too ambitious. Nothing to show at the end of the semester... Changing circumstances. Client leaves the university,... What else?

19 CS 501 Spring 2002 How to Minimize Risk? CS 501 Projects Several target levels of functionality: required, desirable, optional phases Visible software process: intermediate deliverables Good communication within team and with Teaching Assistant Good processes lead to good software Good processes reduce risk

20 CS 501 Spring 2002 Feasibility Report A written document For a general audience: client, financial management, technical management, etc. Short enough that everybody reads it. Long enough that no important topics are skipped. In CS 501, I am looking for a well written, well presented document.

21 CS 501 Spring 2002 Discussion of Pfleeger, Chapter 2 Format: State a question. Ask a member of the class to answer. (Sorry if I pronounce your name wrongly.) Provide opportunity for others to comment. When answering: Stand up. Give your name or NetID. Make sure the TA hears it. Speak clearly so that all the class can hear.

22 CS 501 Spring 2002 Question 1: Steps in the Waterfall Process 1. Give a short description of the Piccadilly television advertising project. 2. This project is likely to have some sort of database. Give an example of a requirement that is part of the decision making to use a database. 3. At what stage in the waterfall process, would the decision be made to use a relational database? 4. At what stage in the waterfall process, would the decision be made to use an Oracle database? 5. At what stage in the waterfall process would the database schema be specified?

23 CS 501 Spring 2002 The Waterfall Model Requirements Analysis System design Unit & Integration Testing System Testing Operation & Maintenance Program design Coding Acceptance Testing

24 CS 501 Spring 2002 Question 2: Risk Suppose that a major requirement is changed during the development of a software system. 1. How is this accommodated in the iterative refinement model? 2. How is this accommodated in the waterfall model?

25 CS 501 Spring 2002 Question 3: Acceptance Testing 1.What is the purpose of Acceptance Testing? 2.Where does Acceptance Testing occur in: the waterfall model? iterative refinement? the V model of development? 3. What impact do these differences have on the project risk?

26 CS 501 Spring 2002 Question 4: Prototype and Phased Development 1.How does a prototype differ from phased development? 2. Explain the following figure: Build release 1 Build release 2 Build release 3 Use release 1 Use release 2 Use release 3 Developers Users