1. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Software Development Lifecycles (SDLC’s) 70-451 Management Information Systems Robert Monroe September 20, 2010

2. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Quiz 1.True or false: One reason that the Waterfall SDLC is so popular is that it is a good way to get a first version of the system in the hands of end-users as fast as possible. 2.True or false: Throwaway Prototyping is a type of Rapid Application Development 3.List two stages common to all software development lifecycle models: _______ ________

3. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Goals For Today By the end of today's class you should be able to explain: What a Systems Development Lifecycle model is What tasks are done in each of these stages, and by whom What questions each of the stages answers, and how The principles of Structured, RAD, and Agile SDLC's The primary advantages and disadvantages of each of the SDLC's.

4. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems The Road Ahead: Developing Custom Systems Week 1: –Systems Development Lifecycles –IS Governance Week 2: –Requirements gathering and analysis (2 classes) Week 3: –Models for acquiring IS capabilities (2 classes) Week 4: –Risk management and project planning –Midterm exam

5. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Systems Development Lifecycles

6. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Systems Development Lifecycles (SDLC’s) There are many, many different approaches to selecting, planning, building, and deploying information systems These approaches/processes are commonly referred to as Systems Development Lifecycles (SDLC’s) Most SDLC’s consist of a series of stages in which common tasks are perfomed SDLC’s describe the order, tasks, deliverables, and interactions of the stages

7. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Most SDLC’s Share Common Stages Planning Analysis Design Implementation –Construction / development –Testing –Installation / roll-out Maintenance Planning Analysis Design Implementation: - Construction - Testing - Installation Maintenance

8. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Planning Stage Basic questions to answer in this stage What is the purpose of this project Why are we going to undertake it How are we going to undertake it How long will it take and what resources will we need to complete it? What are the project goals? How will we know if and when we have met them? Who are the key stakeholders? What are our fundamental constraints? Output: Outline of a project plan Planning …

9. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Analysis Stage After project identification, approval and planning comes detailed analysis and design Analysis stage –Business analysis: detailed evaluation and specification of business requirements –Systems analysis: detailed evaluation of how the system will implement business requirements Planning Analysis … Design

10. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Business Analysis The primary output of the business analysis stage is a set of detailed requirements that the information system must satisfy These requirements should: –Be expressed in language that business users understand –Specify what is needed, not how to implement it –Be testable – how do you know if you’ve satisfied it? –Example: The system shall provide a report that lists cumulative sales for a user-specified time period, categorized by product line and region. –The user shall be able to interactively request such a report for any time period for which the system contains sales data –The report shall be shown to the user in no more than 30 seconds –The user shall be able to print a copy of the report

11. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Systems Analysis The Systems Analyst’s role is to figure out how to realize the business requirements for the system through technology The output of the systems analysis is a specification for how the system will function –Commonly known as a Functional Specification Document –Frequently provided from the user’s perspective (screens) –Also includes detailed “non-functional” requirements that specify other attributes of the system such as security, performance, scalability requirements, etc.

12. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Design Stage After (and often in parallel to) the Analysis stage comes the detailed design stage Design stage –User-centric design specifies how the system will work (user interface, funcional details, etc.) –Architecture specifies fundamental system design vocabulary and design rules –Data design describes how system data will be stored and managed Planning Analysis … Design

13. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Designer Responsibilities The User Experience Designer is responsible for designing all of the users’ interactions with the system –Output is likely to be screen mockups, user interface guidelines (colors, fonts, window sizes and layouts, etc), and ‘stories’ describing how people will use the system The Systems Architect is responsible for designing an information system that implements the functional specification, especially the critical system attributes (security, scalability, etc.) –The output of the Systems Architect is generally a document describing the system’s technical architecture The Data Analyst/Architect designs the data structures for the systems –Output is generally a data model

14. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Big Issues: Analysis And Design Managing scope Predicting time, effort, difficulty, and risk Managing change requests Confirming that the functional spec and system design satisfy the business requirements –Get all stakeholders involved early and often! Ensuring the technical architecture can support required system attributes (security, performance, availability, scalability, system volume)

15. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Implementation Stage: Construction and Testing After analysis and design, it is time to implement the system Construction: –Convert the requirements and design into a functioning information system (write software, build user interface, integrate 3 rd party components, write documentation, etc.) Testing: –Confirm that the system meets its requirements Analysis and Design Implementation: - Construction - Testing - Installation … Maintenance

16. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Big Issues: Construction Managing complexity Communication and coordination across a group Dealing with change requests Dealing with discovered problems

17. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Types and Stages of IS Testing Unit test – does this software module work properly? Systems integration test – what happens when I integrate this system’s modules… –…with each other? –…with other systems? User Acceptance Testing –Does the system meet the requirements laid out originally? –Can people use the system to solve their business problems?

18. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Big Issues: Testing Nearly an infinite number of ways that a significant Information System can fail –But you have a very finite amount of time to test it Standard approach is to identify the most likely problems and make sure that they are not problems in this system –Identifying standard failure modes –Testing representative sets of test cases to cover these failure modes

19. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Implementation Stage: Installation Final step of implementation –Install hardware and/or software –Update other affected systems (as needed) –Train users –Go Live! (cross fingers, hope for the best…) –Put user support plan into action Analysis and Design Implementation: - Construction - Testing - Installation … Maintenance

20. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Major Installation Issues Readiness of all affected people and systems –User training and acceptance –All dependent systems integration projects completed Staging the switch-over to the new system with minimal business disruption Four approaches to staging a system rollout

21. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Maintenance Stage Maintenance includes all of the ongoing tasks required to keep a fielded system running, current, stable, secure, and up-to-date with changes in the operating environment –Bug fixes –Security monitoring, patching, and repair –System update and improvement requests –Integration with new systems –Platform upgrades –Performance and capacity tuning and improvement It is sometimes difficult to distinguish between maintaining an existing system and starting a new IS project Maintenance …

22. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems SDLC Models

23. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Structured SDLC Model: Waterfall Planning Analysis Design Construction Testing Installation Maintenance Traditional model Very linear Step A precedes Step B precedes Step C … Commonly used when system must (or can) be fully specified before development begins

24. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Waterfall Model Questions The waterfall method has a notoriously poor record for delivering successful projects –Success rates as low as 10% are regularly claimed! –So why is it so frequently used? –… and why is it so difficult to use successfully? –Is it ever a good idea to use the waterfall method? If not, why? If so, when? –What does it mean to have a 10% success rate? How is that number determined? Is it reflective of reality?

25. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems RAD SDLC Model: Phased / Spiral Start Planning Analysis Design Development Testing Implement Deliver Part 2 Begin Part 3 Maintenance (Part 2) Planning Analysis Design Development Testing Implementation … Planning Analysis Design Development Testing Implementation Maintenance (Part I) Deliver Part 1 Begin Part 2

26. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems RAD SDLC Model: Prototyping Planning Analysis Design Implementation Installation System Prototype System Repeat until complete

27. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems RAD SDLC Model: Throwaway Prototyping Planning Analysis Design Construction Implementation: - Construction - Testing - Installation Design Prototype System Repeat until design complete Analysis Final Design

28. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Agile SDLC Models: Extreme Programming (XP) Key ideas underlying agile methods –Small, frequent iterations with fast feedback loops –Embrace change –Customer-centric –Learn as you go, improve as you go –If something is not working, change it –Working system from very early on Planning Analysis Design Implementation System Repeat until system is complete

29. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Agile Model Questions Proponents of Agile methods claim a much better record for delivering successful projects –A 65% success rate is often quoted Do you trust the 65% number? Why or why not? –What are the advantages of Agile methods? –What are the drawbacks of Agile methods? –What makes them difficult to use successfully? –Under what circumstances might you want to use Agile methods? When might they not be appropriate?

30. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems There Are Many, Many SDLC’s Available Most work well in some situations and poorly in other situations –Choosing the correct SDLC for the correct situation is a skill developed primarily through experience Factors to consider when choosing an SDLC: –Size of organization undertaking the project –Complexity of the project –Routine vs. innovative –Personalities of the people involved Most successful SDLC’s include opportunities for measurement, feedback, and organizational learning

31. Carnegie Mellon University ©2006 - 2010 Robert T. Monroe 70-451 Management Information Systems Goals Recap: By the end of today's class you should be able to explain: What a Systems Development Lifecycle model is What tasks are done in each of these stages, and by whom What questions each of the stages answers, and how The principles of Structured, RAD, and Agile SDLC's The primary advantages and disadvantages of each of the SDLC's.