entity control & boundary classes

8/19/2019 Entity Control & Boundary Classes

1/49

Engr. Abdul-Rahman MahmoodMS, PMP, MCP, QMR(ISO9001:2000)

[email protected] [email protected]

alphapeeler.sf.net/pubkeys/pkey.htm http://alphapeeler.sourceforge.net

pk.linkedin.com/in/armahmood http://alphapeeler.tumblr.com

www.twitter.com/alphapeeler [email protected]

www.facebook.com/alphapeeler [email protected]

abdulmahmood-sss alphasecure mahmood_cubix 48660186

[email protected] [email protected]

http://alphapeeler.sf.net/me http://alphapeeler.sf.net/acms/

VC++, VB, ASP

Object Oriented Analysis &

Design

Teaching skills, Project Management


2/49


3/49

Professor

name

empID

create( )

save( )

delete( )

change( )

Class Name

Attributes

Operations

Review: Class Recall, a class is an abstraction Describes a group of objects with common:

Properties (attributes) Behavior (operations) Relationships Semantics

A class is an abstraction in that it Emphasizes relevant characteristics; suppresses others Consists of the three sections indicated

First section: Class name

Second section: structure (attributes)

Third section: behavior (operations)

For analysis classes, these entries are sufficient!


4/49

Class Diagrams

Sequence Diagrams

Use Case

Use

-

Case Model Design Model

Use Case Use

-

Case Realization

Collaboration Diagrams

Review: Use-Case Realization

Not what we have so far.

These are Design Classes. More later


5/49

Review: Use-Case Realization Remember: a use-case realization describes

how a particular use case is realized within the

Design Model, in terms of collaborating objects.

A use-case realization is one possible realization of

a use case. A use-case realization in the Design Model can be

traced to a use case in the Use-Case Model.

A realization relationship is drawn from the use-case

realization to the use case it realizes. A use-case realization can be represented using

set of diagrams (the number and type may vary)

Different organizations may have their own way

of doing these things…(and naming them…)


6/49

Review: Use-Case Realization The diagrams that may be used to realize a use

case realization may include:

Interaction Diagrams (sequence and/or

collaboration diagrams) can be used to describe

how the use case is realized in terms of collaborating

objects.

These diagrams model the detailed collaborations

of the use-case realization.

Class Diagrams can be used to describe the classes

that participate in the realization of the use case, as

well as their supporting relationships.

These diagrams model the context of the use-case

realization.


7/49

Review: Use-Case Realization In our Use Case Analysis step, the use-case

realizations' diagrams are outlined.

Exactly what this entails will be discussed ahead and

form part of the fourth deliverable.

In subsequent design activities (Use-Case Design)these class diagrams will be considerably refined

and updated according to more formal class

interface definitions.


8/49

A designer: responsible for the integrity of the

use-case realization. Must coordinate with the designers responsible

for the classes and relationships employed in theuse-case realization.

The use-case realization can be used by classdesigners to understand the class’s role in theuse case and how the class interacts with otherclasses. This implies that a team will/may distribute

responsibilities for each class to developers.

This information can be used to determine/refinethe class responsibilities and interfaces.

Let’s find the classes from different behaviors theclasses must provide…


9/49

Identifying Candidate Classes from Behavior

Will use three perspectives of the system to identify

these classes. The ‘boundary’ between the system and its actors The information’ the system uses The ‘control logic’ of the system

Will use stereotypes to represent these perspectives(boundary, control, entity) These are conveniences used during analysis that will

disappear or be transitioned into different design elementsduring the design process.

Will result in a more robust model because these are thethree things that are most likely to change in system andso we isolate them so that we can treat them separately. That is, the interface/boundary, the control, and the key

system entities.….


10/49

Find Classes From Use-Case Behavior

The complete behavior of a use case has to be

distributed to analysis classes We must ‘identify’ these classes – identify, name,

and briefly describe in a few sentences.


11/49

Discovering Classes Analysis classes represent an early conceptual model for

‘things in the system which have responsibilities andbehaviors’.

Analysis classes are used to capture a ‘first-draft’, rough-cut of the object model of the system.

Analysis classes handle primary functional requirements,

interface requirements, and some control - and modelthese objects from the problem domain perspective.


12/49

Kinds of Analysis Classes Three things likely to change in a system:

The boundary between the system and its actors(interfaces…)

The information a system uses (data), and The control logic of the system (who does what)

So, we isolate the different kinds of analysis classes Each of these has a set of canned duties &

responsibilities Again, the distinction between these classes is used in

analysis but goes away in design or becomes less of anissue, as we transition these analysis classes into designartifacts / design entities to accommodate the problemdomain representations in a solutions space.


13/49

System

boundary

Use-case

behavior

coordination

Systeminformation

What is an Analysis Class?Can use with the name of the stereotype

In guillemets or as symbols with unique icons.

Finding a candidate set of classes is the first

part of transforming a mere statement of

required behavior to a description of how the

System will work.


14/49

Analysis Classes - Early Conceptual Model

The analysis classes, taken together, represent an early

conceptual model of the system. This conceptual model evolves quickly and remains

fluid for some time as different representations andtheir implications are explored.

Analysis classes are early conjectures of the compositionof the system; they rarely survive intact intoimplementation.

Many of the analysis classes morph into something elselater on (subsystems, components, split classes,

combined classes). They provide us with a way of capturing the required

behaviors in a form that we can use to explore thebehavior and composition of the system.

Analysis classes allow us to "play" with the distributionof responsibilities, re-allocating, as necessary.

A i C A Fi t St


15/49

Use Cases AnalysisClasses

SourceCode

ExecDesignElements

Use-Case Analysis

Ana ysis C asses: A First StepTowards Executables

(…from a structural perspective; static)


16/49

Analysis class

stereotype

What is a Boundary Class? Insulates the system from changes in the outside Several Types of Boundary Classes

User interface classes – classes that facilitatecommunication with human users of the system Menus, forms, etc. User interface classes….

System interface classes – classes which facilitatecommunications with other systems.

These boundary classes are responsible for managing thedialogue with the external system, like getting data froman existing database system or flat file…

Provides an interface to that system for this system Device Interface Classes – provide an interface to devices

which detect external events – like a sensor or … One boundary class per use case/actor pair


17/49

Customer

The Role of a Boundary Class

A boundary class is a class used to model interaction between the system’s surroundings

and its inner workings; Involves transforming and

Boundary Classes model parts of the system that depend on its surroundings. Entity

and control classes model parts that are independent of the system’s surroundings.

Examples of boundary classes: Classes that handle GUI or communications protocols.

Actors can only communicate with boundary classes.

Boundary classes identify the system’s boundaries.

External

Database??


18/49

Boundary Classes - more Identify boundary classes for things mentioned in

the flow of events of the use-case realization. Consider the source for all external events and

make sure there is a way for the system to detecttheseevents. (user inputs/responses? Connection to

existing external data…) One recommendation: for the initial identification

of boundary classes is one boundar y class peractor/use-case pair. This class can be viewed as having responsibility for

coordinating the interaction with the actor. This may be refined as a more detailed analysis is

performed. This is particularly true for window-based GUI

applications, where there is typically one boundary

class for each window, or one for each dialog.


19/49

Course Catalog SystemRegister for CoursesStudent

RegisterForCoursesForm

CourseCatalogSystem

Example: Finding Boundary Classes One boundary class per actor/use case pair:

•The RegisterForCoursesForm contains a Student's "schedule-in-progress".

It displays a list of Course Offerings for the current semester from which the

Student may select to be added to his/her Schedule.

•The CourseCatalogSystem interfaces with the legacy system that provides the

complete catalog of all courses offered by the university.

G id li B d Cl


20/49

Guidelines: Boundary Class –User Interface classes

User Interface Classes

Concentrate on what information is presented to the user Do NOT concentrate on the UI details Analysis Classes are meant to be a first cut at the abstraction

of the system. The boundary classes may be used as ‘holding places’ for GUI

classes. (Addressed in much more detail later) Do not do a GUI design in analysis, but isolate all

environment-dependent behavior. (Likely you may be ableto reverse engineer a GUI component and tailor it.)

The expansion, refinement and replacement of these

boundary classes with actual user interface classes is avery important activity of Class Design – later If prototyping the interface has been done, these screen

dumps or sketches may be associated with a boundaryclass.

Only model the key abstractions of the system – not everybutton, list, etc. in the GUI.

G id li B d Cl


21/49

Guidelines: Boundary Classes –System and Device System and Device Interface Classes

Concentrate on what protocols must be defined Note that your application must interface with an

existing ‘information source.’ Do NOT concentrate on how the protocols will be

implemented If the interface to an existing system or device is

already well-defined, the boundary classresponsibilities should be derived directly fromthe interface definition.

If there is a working communication with theexternal system or device, make note of it forlater reference during design.


22/49

Glossary

Business-Domain Model

Environment Independent

Analysis class

stereotype

Use Case

Architectural Analysis

Abstractions

What is an Entity Class? (recall: boundary, entity,control…)

Key abstractions of the system

Entity classes show the

logical data structure,

which will help us

understand what thesystem is supposed to

offer to its users.

Sources for entity

Classes:

Glossary

Use-Case Flow of

Events

Business domain

model


23/49

Entity Classes Entity classes represent stores of information in the

system

They are typically used to represent the key concepts the

system manages.

Entity objects (instances of entity classes) are used to

hold and update information about some phenomenon,such as an event, a person, or some real-life object.

(Chapter advisor, memorabilia, university, student,

correspondence_item, International_Secretary, …)

They are usually persistent, having attributes andrelationships needed for a long period, sometimes for the

life of the system.

The main responsibilities of entity classes are to

store and manage information in the system.

Th R l f E tit Cl


24/49

Store and manage inform at ion in the system

Customer

The Role of an Entity Class

The values of its attributes and relationships are often given by an actor.

Entity objects are independent of the environment (actors)

Entity objects can have complicated behavior;

however, unlike other objects, this behavior

is strongly related to the phenomenon the entity

object represents.


25/49

Example: Finding Entity Classes Use use-case flow of events as input

Key abstractions of the use case Traditional, filtering nouns approach

Underline noun clauses in the use-case flow of events Remove redundant candidates Remove vague candidates Remove actors (out of scope) Remove implementation constructs Remove attributes (save for later) Remove operations

E l C did t E tit


26/49

Student

CourseOffering

Schedule

Example: Candidate EntityClasses Register for Courses (Create Schedule)

A specific offering for a course

including days of week and times

The courses a student has selected for current semester

A person enrolled in classes at the university


27/49

Candidate Entity Classes Sometimes there is a need to model information

about an actor within the system. This is not the

same as modeling the actor (actors are external.

by definition). These classes are sometimes

called “surrogates”. For example, a course registration system

maintains information about the student which is

independent of the fact that the student also

plays a role as an actor of the system. This information about the student that is stored in a

‘Student’ class is completely independent of the ‘actor’

role the student plays; the Student class (entity) will

exist whether or not the student is an actor to the


28/49

• Entity class :

– Persistent data

(used multiple times and in many UCs)

– Still exists after the UC terminates (e.g. DB storage)

• Boundary class: – (User) interface between actors and the system

– E.g. a Form, a Window (Pane)

• Control class: – Encapsulates business functionality

• Proposed in RUP (Rational Unified Process)

Analysis Classes


29/49

9-29 © Prentice Hall, 2007


30/49



31/49


What Is an Analysis Class? A class that represents initial data and behavior

requirements, and whose software and hardware-oriented details have not been specified

Analysis class diagram – a UML diagram showing

analysis classes and their relationships


32/49


Stereotypes of Analysis Classes

Mostly

corresponds toconceptual data

model classes

Encapsulates

connectionsbetween actors

and use cases

Mostly performs

behaviorsassociated with

inner workings of

use cases


33/49



34/49


What Is a Sequence Diagram?

A UML diagram that shows the interactionbetween objects to perform critical pieces of usecase behavior in a time-ordered manner

Interactions are in the form of messages

Behavioral responsibilities are assigned to

message recipients


35/49


Messages are passed between objects, and may contain parameters


36/49


Symbols in a Sequence Diagram

Box or class stereotype symbol representsobjects.

Dotted vertical line represents object’s lifetime.

Thin bars represent focus of control, periods oftime when object is behaving (fulfillingresponsibilities).

Labeled horizontal lines represent messagespassing between objects.


37/49



38/49


Typically, actors interact with

boundary classes, which inturn interact with control

classes, which in turn interact

with entity classes.


39/49


What Is Robustness Analysis?• Involves analyzing the narrative text of each of the use

cases and identifying a first-guess set of the objectsinto entity, boundary, and control classes

• Requires completeness checks and adherence todiagramming rules


40/49



41/49


What Is a Communication Diagram? A UML diagram that shows the interactions between

objects to perform critical pieces of the use casebehavior

Unlike sequence diagrams, communication diagrams

have no spatial representation of time; sequences ofmessages are shown by numbering.


42/49



43/49


Drawing Analysis Class Diagrams• Analysis classes are completed by including

operations, which fulfill the responsibilities taken bythe analysis class.

• In addition, attributes and relationships from theconceptual data model are retained and refined.


44/49


Operations (behaviors)

are depicted in the

lower third of a class

box.

Operations fulfill theclass’s responsibilities.

EXAMPLE


45/49

EXAMPLE

The UNIVERSITY OF BUTERE (UBT) registration system is

briefly described thus: You have been asked to streamline, improve, and automate

the process of assigning professors to courses and theregistration of students such that it takes advantage of

prevailing web technologies for on-line real time, locationindependent access.

The process begins by professors deciding on which coursesthey will teach for the semester. The Registrar’s office thenenters the information into the computer system, allocatingtimes, room, and student population restrictions to eachcourse. A batch report is then printed for the professors toindicate which courses they will teach. A course catalogue isalso printed for distribution to students.


46/49

Students then select what courses they desire to take and

indicate these by completing paper-based course advisingforms. They then meet with an academic advisor who

verifies their eligibility to take the selected courses, that thesections of the courses selected are still open, and that the

schedule of selected courses does not clash. The typicalstudent load is four courses. The advisor then approves thecourses and completed the course registration forms forthe student. These are then sent to the registrar who keysthem into the registration system – thereby formallyregistering a student. If courses selected are not approved,the student has to select other courses and complete thecourse advising forms afresh.

EXAMPLE


47/49

Most times students get their first choice, however,in those cases where there is a conflict, theadvising office talks with the students to getadditional choices. Once all students have been

successfully registered, a hard copy of the students’schedule is sent to the students for verification.Most student registrations are processed within a

week, but some exceptional cases take up to two

weeks to resolve.

Once the initial registration period is over,professors receive a student roster for each classthe are scheduled to teach.

EXAMPLE


48/49

Analysis Phase Class Diagram


49/49

DESIGN PHASE CLASS DIAGRAM

entity control & boundary classes

Documents