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CS 5150 Software Engineering

CS 5150 Software Engineering. Lecture 2 Software Processes 1. ACSU is initiating a peer mentoring program. Underclassmen: be paired with an upperclassman mentor! Upperclassmen: mentor an underclassman and/or have a PhD/MEng mentor!

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CS 5150 Software Engineering

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  1. CS 5150 Software Engineering Lecture 2 Software Processes 1

  2. ACSU is initiating a peer mentoring program Underclassmen: be paired with an upperclassman mentor! Upperclassmen: mentor an underclassman and/or have a PhD/MEng mentor! To find a mentor or to be a mentor:Fill out a questionnaire to specify your preferences--send an email to cornellcsmentorship@gmail.com for the links. ACSU Bowling /Mentor-Mentee Matching Event: 9/8 at Helen Newman! (*please also fill out the questionnaire)Time: 9/8, 7-9 PMLocation: Helen Newman Bowling Alley (in the basement of HNL)FREE pizza and soda will be served!

  3. The Web Lab Independent Research in Computer Science & Information Science The Web Lab applies supercomputing methods to analyze very large collections of text. See http://weblab.infosci.cornell.edu/. It uses MapReduce programming and the Hadoop distributed file system on a large Linux cluster. Projects for fall 2010: • Studying how the .gov domain changes over time. • Building indexes to very large collections of digitized books. If you are interested, come to a meeting on Tuesday at 4:00 p.m. in the Information Science building, 301 College Avenue.

  4. Administration Project teams • Any announcement to class? • People who would like to form teams? Project Suggestions on the web site Entrepreneurship experiment

  5. Administration Project teams When you have formed your team and reached agreement with your client, please send a message to: wya@cs.cornell.edu and stevepurpura@gmail.com with the names of the team, the client's name, and the topic of the project.

  6. Software is Risky Most software development projects have major problems Problems Does not work as expected Over budget Late delivery Much of software is wasted (perhaps 50% is never used ) Never used Does the wrong thing Users dislike to use it There are no customers etc.

  7. Software is Risky Failures of software development projects can bankrupt companies What is the penalty to the client if software is: late? over budget? does not work or full of bugs? Examples of risk: car anti-lock brakes (no bugs allowed) web browser in cell phone (no delays in release allowed)

  8. Software is Risky Most software projects fail because the software developers build the wrong software! • Understand what the client, the customer, and the users expect of the software • As a developer, provide technical insights and suggestions, but remember: Client satisfaction and customer acceptance are the primary measures of success in a software project.

  9. Minimizing Risk: Incremental Development with Frequent Releases • Recent approaches to software development minimize risk by emphasizing frequent delivery of working software (weeks rather than months). • Client, customers, and users can evaluate the developers' work. • Opportunities to adapt to changing circumstances. • This is one of the basic principles of Agile Software Development.

  10. The Three-way Trade-off Competing goals Every software project has a trade-off between: Functionality Resources (cost) Timeliness What is important to the person who is paying? Example: Start-up companies: Are there real customers who will pay for the product?

  11. Minimizing Risk: Relationship with the Client • Feasibility studies (whether to begin a project). • Separation of requirements (what the client wants) from design (how the developers meet the requirements). • Milestones (how the developers report or demonstrate progress to the clients) and releases. • Acceptance (how the client tests that the software meets the requirements) and user testing. • Handover (ensuring that the client receives a package that can be operated and maintained over a long time period).

  12. Minimizing Risk: Visibility The people who take the responsibility must know what is happening • Managers Must rely on others for reports of progress or difficulties • Software Developers Have difficulty evaluating progress Optimistic Consider reporting a waste time etc. Working software provides excellent visibility.

  13. Teams Most software development is by teams • Effectiveness of team determines success Most large software projects are built on older ones • It is rare to start a new suite of programs from scratch • Building on the work of others is a fundamental skill of software development

  14. Observations about Big Projects • A CS 5150 project is about 0.3 person/years. A big project may be 100 to 10,000+ person years. • Every important program is written by many people, who are constantly changing. • Before a big project is completed the requirements have changed many times. • No large system is ever complete. • A CS 5150 project is about the size of a single increment in a production Agile process.

  15. Software Process Fundamental Assumption: Good processes lead to good software Good processes reduce risk Good processes enhance visibility

  16. Heavyweight and Lightweight Software Development In a heavyweight process, the development team works through the entire development cycle slowly and systematically, with the aim of delivering a complete software product with minimal changes and revision. Example: the Modified Waterfall Model In a lightweight process, the development team releases working software in small increments, and develops the plans incrementally, based on experience. Example:Agile Software Development

  17. Heavyweight and Lightweight Methodologies Heavyweight Lightweight Processes and tools Individuals & interactions Documentation Working software Contract negotiation Customer collaboration Following a plan Responding to change Based on the Manifesto for Agile Software Development: http://agilemanifesto.org/

  18. Variety of Software Processes Software products are very varied... Therefore, there is no standard process for all software engineering projects BUT successful software development projects all need to address similar issues. This creates a number of process steps that should be part of all software projects

  19. Basic Process Steps in all Software Development • Feasibility and planning • Requirements • System and program design • Implementation • Acceptanceand release • Operation and maintenance In a lightweight process, these steps are repeated with each increment

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