Essentials of OVID Using UML based notation to capture system requirements and design.

Overview of Socio-cognitive Engineering General requirements Theory of Use Design Concept Contextual Studies Task model Design space System specification ImplementationDeployment Evaluation

Use of OVID UML General requirements Theory of Use Design Concept Contextual Studies Task model Design space System specification ImplementationDeployment Evaluation * also used for business process models and software engineering * *

Why UML? CASE tools support UML and can be used to facilitate communication within a project team  design can be partitioned for teams  control levels and versions software design and business process are already documented in UML  can teach other disciplines to use OVID subset May use ‘gatekeeper’ to help others understand

Summary of UML used Class diagrams  for users, goals  for objects and views Activity diagrams  for old tasks and new tasks Use cases  for function specification

Summary of UML used State models  for object and view states  Harel diagram from UML  state tables added from Schlear and Mellor* Sequence Diagrams  for detailed tasks * see

Class diagrams (users and goals) General requirements Theory of Use Design Concept Contextual Studies Task model Design space System specification ImplementationDeployment Evaluation

Class diagrams (users and goals) Describe the stakeholders in the system  users (roles)  indirect users  customers, buyers, managers… Describe the goals they have  quantitative goals  qualitative goals

Class diagrams (users) Actors represent groups of users Subclass hierarchy shows levels of grouping Can also show other relationships

Class diagrams (users) Record attributes of users in the role Focus on things that make them different Use when recruiting subjects for studies or validation

Class diagrams (goals) Goals are states that users want to reach Use class showing goal Connect users who have that goal Attributes show how to measure the goal

Class diagrams (goals) Break down goals until all users have different goals Goals can be quantitative or qualitative  Defines how it is validated

Activity diagrams General requirements Theory of Use Design Concept Contextual Studies Task model Design space System specification ImplementationDeployment Evaluation

Activity diagrams Capture tasks in detail  both existing practice and new design  capture activity, goals reached, decisions made Use swimlanes to show how several users and/or systems participate in activity  know who does what and when  crossing between lanes = communication

Activity diagrams One lane for each participant  users and system Place activities, states and decisions in the right lane

Use cases General requirements Theory of Use Design Concept Contextual Studies Task model Design space System specification ImplementationDeployment Evaluation

Use cases Describe the functions the system will enable  at the end of design space analysis Relate each case to the goals it satisfies Capture details to aid design priority  How many users know of this case – via connections to goals and hence users  How often this case is used

Use cases Define functions that you will include in the design  in CASE tools the use cases can contain other diagrams such as activity diagrams Show which users will need which functions

Class diagrams (objects and views) General requirements Theory of Use Design Concept Contextual Studies Task model Design space System specification ImplementationDeployment Evaluation

Class diagrams (objects and views) Define the objects the users will know  name and description lead to metaphor  attributes Describe how the user will see the objects as multiple views  which attributes are seen when  transition between views

Finding objects to model Identify the objects - review nouns that are found in the task models Sort the objects utilizing a simple table (optional – can do directly into modelling if desired) Define each object with 1 clause (no jargon) in ways users would understand them Put objects in model (including definitions, attributes and operations) and define relationships between objects ConcretePeopleFormsUsersAbstract Real things you can touch or walk away with Those who are managed by the system or have things saved for them Existing paperwork or other system Those who operate the system or directly interact with the system Anything else Hotel Room Credit card Key GuestReservation Folio Guest Reservation clerk Front Desk clerk Night auditor Authorization Stay Dates

Class diagram for user objects Create classes for each object the users need Names and descriptions should be as simple as possible Add attributes and operations as you design

Relationships for objects For many-to- many relationships add an object to represent the relationship An existing form is often the right object for this

Core hotel model

Finding views Review most frequent or most commonly used tasks (in use cases) first Note the objects involved in activities as swimlanes are crossed Define a view of that object that has the necessary information

Class diagram for views View classes have stereotype of > Attributes show which parts of objects are used for an interaction Can connect users to show where they start

State models General requirements Theory of Use Design Concept Contextual Studies Task model Design space System specification ImplementationDeployment Evaluation

State models Show how objects and views change with events in the system  what is the lifecycle of each object  does the view state match the object Harel diagrams for ‘normal’ events State tables for exceptions

State model as Harel diagram Use state diagrams (Harel Diagrams) to show normal processes for an object or a view Transition names should correspond to operations Convert to state tables to examine all combinations of states and transitions

State models (state tables) Harel diagrams can be transcribed to state tables  normally gives a sparse table  empty cells represent events you have not designed for – fill in all empty cells by making design decisions – consider ‘if the user was trying to do that, what would they expect to happen?’

State table OpenInputsProcess [valid data] Proces s [invalid data] Reenter input Check-inClose out [Initial]To receivin g input Receivin g input To receivin g input To confirme d To invalid Confirme d To [final] InvalidTo receivin g input To [final] Rows: States, Columns: Operations

State Table OpenInputsProcess [valid data] Process [invalid data] Reenter input Check-inClose out [Initial]To receiving input Not available to the user Receiving input Open is an internal action so not available to the user To receiving input To confirmed To invalid Must be invalid Not allowed ConfirmedNot allowed - no changes are allowed once a reservation is confirmed To [final]Not allowed InvalidNot allowedTo receiving input Not allowedTo [final] Rows: States, Columns: Operations

Sequence diagrams General requirements Theory of Use Design Concept Contextual Studies Task model Design space System specification ImplementationDeployment Evaluation

Sequence diagrams Alternative to activity diagrams  expressed as ‘messages’ or ‘methods’  normally only needed for fine grain design such as when relating to complex state models  no decisions/branching available

Realising design Models considered by  graphic design  software design Class diagrams (objects) lead to data design Class, activity and sequence diagrams with state models lead to program design Class (views) and activity diagrams with state models lead to window/web page/dialog designs

Sequence diagram To read these diagrams – Read down a column to determine the order of activities performed by the entity (an actor, object or view)

Models As Input To Presentation View Design

Objects in many views

Objects retain identity

Same objects, two tasks Making a reservation Checking in

Views math sequences The state diagrams clarify the interaction information that was left to interpretation in the Abstract View Knowing which steps are supported by an object completes the information needed to plan its view in the composition

Paper prototype

Medium fidelity prototype

Flow between views

Another realisation

Presentation model

Resources OMG UML resources page  Rational UML resources page  OVID book  Designing for the User with OVID: Bridging User Interface Design and Software Engineering by Dave Roberts, Dick Berry, Scott Isensee, John Mullaly  Published by Macmillan Technical Publishing 1998, 187 pages ISBN Ease of Use web site and OVID section  