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Paper Prototyping.

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Presentation on theme: "Paper Prototyping."— Presentation transcript:

1 Paper Prototyping

2 They probably know much more about the problem than you do. They probably have some ideas about how to solve the problem. They are your best resource for discovering your own mistakes before you start to code. Customers and users should be your friends

3 Risk: an unwanted event that has negative consequences Risk impact: the loss that would result if a risk turns into a problem – Measured in time, quality, cost Risk likelihood: probability that the risk will turn into a problem – Risk exposure = impact * likelihood Risk control: the degree to which you can reduce exposure

4 Risk management – Risk assessment Risk identification Risk analysis Risk prioritization – Risk control Risk reduction Risk management planning Risk resolution

5 Example risks in an e-commerce application Risk: mobile phones (unexpectedly) need to be supported – Impact: 30% of revenue? Likelihood: ??? Risk: credit card validation component cannot handle debit cards – Impact: 10% of revenue? Likelihood: ???

6 Risk management and prototyping Traditional requirements-gathering – Good for controlling risks regarding what the system should do – But don’t know what the system should look like Prototyping – Good for controlling risks regarding what the system should look like – Not so good for non-visual aspects of the system

7 Top ten risks Personnel shortfalls Unrealistic schedules and budgets Developing the wrong software functions Developing the wrong user interface Gold plating Continuing stream of requirements changes Shortfalls in externally performed tasks Shortfalls in externally furnished components Real-time performance shortfalls Straining computer science capabilities Personnel shortfalls Unrealistic schedules and budgets Developing the wrong software functions ** Developing the wrong user interface *** Gold plating *** Continuing stream of requirements changes ** Shortfalls in externally performed tasks * Shortfalls in externally furnished components * Real-time performance shortfalls Straining computer science capabilities *

8 The general idea of prototyping 1.You depict what you think the system should look like. 2.You test the prototypes with customers or (preferably) users. 3.You fix up the prototypes and use what you learn to implement the real system.

9 Waterfall kinds of processes Requirements analysis Design Implementation Operation Testing Prototyping

10 Spiral kinds of processes Draft a menu of requirements Establish requirements Plan Analyze risk & prototype Draft a menu of architecture designs Analyze risk & prototype Draft a menu of program designs Establish architecture Establish program design ImplementationTestingOperation Plan

11 Different kinds of prototypes Throwaway prototypes – Paper prototypes : sketches on pieces of paper – Low-fidelity prototypes : implemented with a tool (e.g.: Photoshop) Evolutionary prototypes – High-fidelity prototypes : implemented on the target platform… not fully functional, but destined to be incorporated into the final product

12 Paper prototypes Sketch on paper and/or post-it notes Don’t worry (much) about colors, fonts, icons Doesn’t need to be beautiful Does need to show all important UI elements Does need to be intelligible by users

13 Example system Here are the functional requirements: System will have web pages for mobile phones where citizens can report panhandlers Certain users called “volunteers” will view reports and “claim” panhandlers After visiting a claimed panhandler to offer social services (e.g.: counseling), a volunteer can mark a panhandler’s report as “done”

14 Example system Here’s a panhandler report state chart New (just reported) Claimed (by volunteer) Done (visited by volunteer) Report status claimunclaim mark done succeeds

15 “Testing” prototypes Pretend to be the computer while a user tries to perform a use case with your prototype Let the user interface speak for itself – So shut up and see if the user can do it himself!!! If the user misunderstands the user interface, then fix it on the spot if you can. – Principle: the user is always right (in prototyping)

16 UC#1: Report panhandler Actor: any user Preconditions: user views site in mobile browser Postconditions: system records report Flow of events: – User selects a city – User enters information about the panhandler – System validates inputs – System records report in database

17 1.User selects a city 2.User enters information about the panhandler 3.System validates inputs 4.System records report in database

18 UC#2: Process panhandler Actor: volunteer (member of task force) Preconditions: volunteer logged in via mobile browser Postconditions: – Volunteer reviews list or map of panhandlers – Volunteer marks report as “claimed” – System records report as claimed – Volunteer visits the panhandler – Volunteer marks report as “done” – System records report as done

19 1.Volunteer reviews list or map of panhandlers 2.Volunteer marks report as “claimed” 3.System records report as claimed 4.Volunteer visits the panhandler 5.Volunteer marks report as “done” 6.System records report as done

20 1.Volunteer reviews list or map of panhandlers 2.Volunteer marks report as “claimed” 3.System records report as claimed 4.Volunteer visits the panhandler 5.Volunteer marks report as “done” 6.System records report as done

21 Some problems revealed by prototype What happens during “validation” of a panhandler report? How does the volunteer navigate from the “list view” to the “map view”? What happens if there are lots and lots of reports… how does the user make sense of it? So what happens when the user marks a panhandler report as “done”?

22 Non-visual problems that the prototype might not catch What if there are duplicate reports? How do new cities get added to the system? Do users need to be authenticated to make a panhandler report? Why/why not? Is the mapping interface really going to run properly in a mobile browser? Sounds risky. Identifying such problems requires techniques beyond prototyping.

23 Low-fidelity prototypes Fidelity = “faithfulness” or closeness to what the ultimate product would look like – Paper prototypes are “ultra low” fidelity Low-fidelity prototypes can be made in – Photoshop – PowerPoint – HTML – Any other tool that’s cheap and easy to use

24 Promoting health awareness with a “know your numbers” card & system

25 Prototype splash-screen for Anaconda, an installer framework for Linux

26 Prototype of what an iPod might look like with a 320x480 resolution

27 Prototype of a site for managing and sharing photos missrogue/ /sizes/o/

28 Paper vs low-fidelity Low-fidelity lets you explore – Colors, fonts, iconography, etc But low-fidelity – Is more expensive – Requires somebody with design “skillz” – Is harder to fix on the fly And neither one can detect certain problems…

29 Diagram Notations

30 Did you plan to build the Enterprise all on your own???? Diagrams are often useful when… – You need to communicate, visualize, or analyze something – And that something has some sort of structure

31 Typical parts of requirements documentation Functional requirements – Unstructured text – Use cases Non-functional requirements – Unstructured text Fit criteria Diagrams – Class diagrams and entity-relationship diagrams – Dataflow, sequence, and state diagrams

32 Use case diagram: shows activities supported by the system Repressed citizen UC#1: Report repressionUC#2: Clarify tweet Concerned public UC#3: View reports UC#3a: View on mapUC#3b: View as RSS feed

33 Notes on use case diagrams Stick man for user Ovals for use cases – Italicize “abstract” use cases Simple arrows when a UC “calls” another Open arrowheads for specialization – Similar to the role that sub-classing plays in OO

34 UML class diagram: shows entities, attributes, relationships User + Twitter username Repression report + source (tweet) + location (geocode) + when (datetime) + details (string) * * Repression view + reports * Google map view + JavaScript RSS View + XML text Repression tweet + user + when (datetime) + text (string) 1 * System boundary Clarification tweet + report + when (datetime) + text (string) *

35 Notes on UML class diagrams One box per kind of entity, listing attributes – Italicize abstract entities, attributes Lines without arrowheads show references – Similar to member variables in OO – Labeled with cardinality (multiplicity) Integers, ranges, or asterisk (for unlimited) Lines with open arrowheads for specialization Lines with regular arrowheads can be used to indicate dependencies – Usually omitted in requirements’ class diagrams

36 Entity-relationship diagram: shows entities, attributes, relationships User Twitter username Repression report source (tweet) location (geocode) when (datetime) details (string) Clarification tweet report when (datetime) text (string) Repression view reports r s p q Google map view JavaScript RSS View XML text yields shows asks about Repression tweet user when (datetime) text (string) writes 1 n

37 Notes on entity-relationship diagrams (ERDs) One box per kind of entity List entities on branches Lines with a diamond show relationships – Diamond label indicates role of relationship Numbers or variables on lines show cardinality

38 Dataflow diagram: shows flow of information Reporter Viewing user Report Twitter DB Send clar req Reports DB Inter- pret Clarify Geocoder RSS View Map View

39 Notes on dataflow diagrams Each oval is a “function” provided by system. – Each inward arrow is a parameter (labeled) – Each outward arrow is an output (labeled) Each rectangle is an actor – A person, place, or thing that can do stuff and/or initiate events Each “half-rectangle” is a data store Often clearer if you do a separate dataflow diagram for each use case

40 [geocode != null] Message sequence diagram: shows flow of control UserTwitterSystemDatabase Tweet event Read tweets Request to clarify [if geocode == null] Deliver request Geocoder Geocode Create report [if geocode != null]

41 Notes on message sequence diagrams One box per entity involved – E.g.: if you have two users interacting with each other, then you would have two boxes – Each box has a dashed line, showing its “lifetime”, which can end if an object is destroyed Arrows show messages – Also, draw an arrow back if there’s a return value Conditionals are written with brackets [ ] – Loops can be enclosed in a shaded box

42 State chart: shows change over time Raw (just text) In database (geocode == null) Geocoded (geocode != null) Report status recordgeocoding fails & user retweets geocoding succeeds

43 Notes on state charts One box per state Arrows show a possible state transition – Annotated to indicate under what conditions the transition occurs Filled circle shows where you “start” Nested filled circle shows where you “stop”

44 Putting it together: a typical requirements document Requirements definition – Unstructured text: functional & non-functional reqs – Use case descriptions – Class diagrams or ERDs showing external entities Requirements specification – Unstructured text: functional & non-functional reqs – Dataflow diagram – Message sequence diagrams or state charts

45 An example system to support drug and alcohol counseling

46 Requirements definition, functional reqs, unstructured text Before each counseling visit, each counselee takes a survey. After each survey, the system prints a report showing the counselee’s progress. Administrative assistants can add counselees and their counselors to the system. Requirements definition: written from external viewpoint; system is like a “black box”

47 Requirements definition, non-functional reqs, with fit criteria Each survey will be short enough for an average user to complete within 10 minutes. Progress reports will each be 2 pages or less. The system will print progress reports within 2 minutes of a survey’s completion. Users can take a survey using a Windows machine that has a Pentium II 550 MHz CPU, with 0.5 GB of RAM. Requirements definition: written from external viewpoint; system is like a “black box”

48 UC#1: Survey and report Actor: Counselee Precondition: Counselee registered in system Postconditions: – Counselee progress data is recorded in system – Report is printed for use by counselor Flow of events: – Counselee logs in (lastname + PIN) – System collects survey data from counselee – System prints report

49 Class diagram of entities Counselor + reports Counselee + counselor + surveys Survey + questions (String []) + answers (int []) + counselee 1 * User + lastname (string) + PIN (int) 1 * Report + surveys + counselor * * 1 * System boundary

50 Requirements specification, functional reqs, unstructured text Survey data will be stored in the database at the end of the survey, and a report will be sent to the printer. The system will provide screens for adding, editing, and deactivating counselee and counselor records from a database. Requirements specification: written from system’s viewpoint, involving internal details of system

51 Requirements specification, non-functional reqs, with fit criteria 95% of the code will be platform-independent (Java or platform-independent JavaScript). The system will record completed surveys in the database within 30 seconds; reports will be sent to the printer within 30 seconds and emerge within 60 seconds. Requirements specification: written from system’s viewpoint, involving internal details of system

52 Dataflow diagram (note: only shows UC#1) Survey DB Survey Counselee Counselor Create report Printer Pick up Authent icate

53 Message sequence diagram UC#1 [survey complete] CounseleeServerDatabase Log in Printer Present question Answer question Record answers Get report data Send report to printer

54 A few general comments These are just the basic diagrams. – Sufficient for our homework, exams, and probably 90% of what you’ll see after graduation – Fancier versions of these diagrams do exist It’s OK to draw diagrams by hand – As long as you respect the notation – And, at least for homework, scan it into a PDF

55 What’s next for you? Get organized tomorrow in teams to design use cases and then design your paper prototypes based on the functional requirements you had made a note of. Design gallery (Friday): It would be a display of your designs and each one of you should compulsorily give feedback to the other team (two ideas/feedback per person).


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