Multimedia software life cycle What can you infer from this chart? Many real world projects have cost overruns or fail Software engineers need to learn how to build systems that are on time and within budget Think about your estimates per e-learning unit Cost overrun Successful Cancelled Source: The Standish Group

Software engineering defined Software engineering is “multi-person construction of multi-version software” What is the relationship between the size of a program & the time it takes to develop it? Real world software projects involve teams of developers What’s the relationship between program size and the number of people involved? Is it linear (N developers == N time speedup)? Or is it exponential (N developers = NN speedup)? How does multimedia affect the life cycle?

A software life cycle is a process A process is organized in some order or sequence, structuring activities as a whole A process involves activities, constraints and resources that produce an intended output. Each process activity, e.g., design, must have entry and exit criteria—why? A process uses resources, subject to constraints (e.g., a schedule or a budget)

A software process requires resources… What is the moral of the story (about project managers and resources)?

Classic waterfall life cycle Cascades from one stage to the next only after previous stage is complete Gravity only allows the waterfall to go down; it’s very hard to swim upstream

Why would corporate manager types like the waterfall life cycle model? Minimizes change, maximizes predictability Costs and risks are more predictable Each stage has milestones and deliverables: project managers can use to gauge how close project is to completion Sets up division of labor: many software shops associate different people with different stages: Systems analyst does analysis, Architect does design, Programmers code, Testers validate, etc.

Is the waterfall model realistic? Is this diagram a more realistic picture? Is this wild view of the process a good idea? Reality check: software requirements change so embrace change during the process Realistic models allow for cycles How do embrace change, yet hold down costs, increase likelihood of project success, and keep our project managers happy??

Rapid prototyping model A prototype is a partially developed product that enables customers and developers to examine some aspect of a proposed system and decide if it is suitable for a finished product. For the CIMEL project, we developed a prototype UI Potential users and domain experts reviewed the prototype Review panel summarized findings and made recommendations We then developed an alpha version of the interface Allow time for prototypes and improved versions Multimedia authoring tools facilitate prototyping

Iterative and incremental process Incremental development of functionality Early release starts with small, functional subsystem Later releases add additional functionality Iterative development of overall system in each release Delivers a full system in the first release, then changes the functionality of each subsystem with each new release Suppose a customer wants to a word processing package Incremental approach: provide just Creation functions in Release 1, then both Creation and Organization in Release 2, finally add Formatting in Release 3, … Iterative approach: provide primitive forms of all three functions in Release 1, then enhance (making them faster, improving the interface, etc.) in subsequent releases Many organizations combine iterative & incremental

Multimedia and the life cycle Lisa Lopuck’s timeline: What’s different? Why brainstorming instead of analysis? Why build in prototyping & user testing? What’s different during development? How might e-learning further change the life cycle? (See Driscoll’s ADDIE model.) Another view of e-learning milestones

Quiz! What are drawbacks of Waterfall Model? Can prototypes alleviate these drawbacks? Why or why not? Why do many software development shops prefer iterative & incremental models? How does multimedia affect the process? Does this discussion motivate you avoid just hacking? Why or why not?

Analysis (needs/requirements) Lopuck calls this stage “brainstorming”: who, what, why, where, when & how? Audience analysis: Who is it for? Needs analysis: Why develop it? Content analysis: What will it cover? Resource analysis: How and how much? Estimate: When will it get done? Where: platform, marketing and distribution? Use cases can help understand requirements

Example use case (from Fowler and Scott, UML Distilled) Use Case: Buy a Product (A behavior that accomplishes a user goal) Actors: Customer, System Customer browsers through catalog and selects items to buy Customer goes to check out Customer fills in shipping information (address; next-day or 3-day) System presents full pricing information, including shipping Customer fills in credit card information System authorizes purchase System confirms sale immediately System sends confirming email to customer Alternative: Authorization Failure (At what step might this happen?) 6a. At step 6, system fails to authorize credit purchase Allow customer to re-enter credit card information and re-try Alternative: Regular customer (At what step might this happen?) 3a. System displays current shipping information, pricing information, and last four digits of credit card information 3b. Customer may accept or override these defaults Return to primary scenario at step 6 Each user function (button or menu choice) can be modeled by a use case

So, how will you do requirements analysis for your multimedia e-learning project? By Monday, February 2: email me a tentative project title, subject matter expert (someone with experience teaching the material), team members and their tentative roles, preliminary answers to who, what, why, when, how questions By Monday, February 9: 1. Refine answers to who, what, why, when, how questions 2. Write a high-level requirements specification 3. Write 1 or 2 uses cases describing sample behavior (flesh out more use cases for UI design in next iteration)

Design What’s the difference between analysis and design? Storyboards: design content as sequence of scenes or screens Scripts: design content in textual form Flowcharts: show navigational structure Why design in detail before programming? User interface—why a paper prototype?

Implementation How is multimedia development different from systems programming? Why is prototyping a good idea? Programming uses authoring tools Media development involves special tools for graphics, sound, video, etc. User testing, user observations and focus groups

Delivery and maintenance CD-ROM/DVD/memory stick versus Web delivery? Corrective: fixing errors after delivery Adaptive: new environments Perfective: improving behavior or performance Preventive: improving maintainability

Relative costs to fix errors: What can you infer from this graph? Design Testing Maintenance Requirements Implementation Cost to fix an error increases as it is found later and later in the software lifecycle

What is your ultimate goal? Why should you plan for maintenance? Would you like to see your project used? How do you plan and develop for maintenance? Do the analysis and design right 85% of the cost of real world bugs occur during analysis/design Why document as you go (not after-the-fact)? Use cases, scripts, well-commented code, delivery manual (with use cases as a starting point) Why put your document on a web site?