UML and Systems Analysis

MIS3502: Application Integration and Evaluation

Paul Weinbergweinberg@temple.edu

Presentation by David Schuff

Review: What is Systems Analysis and Design?

Systems Analysis Analysis of complex, large-scale

systems and the interactions within those systemshttp://en.wikipedia.org/wiki/Systems_analysis

Systems Design The process of defining the hardware

and software architectures, components, models, interfaces, and data for a computer system to satisfy specified requirementshttp://en.wikipedia.org/wiki/Systems_design

Notice that they are not the same!

Basically…

Systems Analysis is the process of modeling the problemRequirements-oriented What should we do?

Systems Design is the process of modeling a solutionFunctionality-orientedHow should we do it?

Why model?

Creating a blueprint for an application Before you start coding The idea is to minimize having to go

back and make changes later

Why consider SAD in a programming course?

The business analysts

The development

team

Analysis Design Development

What this means

A developer must be able to turn the design into code

But a good analyst should be able to understand all parts of system developmentConduct an analysisDevelop a designImplement the design (coding)

Example: Bjork’s ATM example

An Example of Object Oriented Design, An ATM Simulation, Russell Bjork http://www.math-cs.gordon.edu/local/courses/cs211/

ATMExample/

What we’ll look at…

Use case diagrams

Use case descriptionsActivity diagrams

:Controller :Customer :Order

Interaction diagrams

Analysis Models Design Models

Class name

Attributes

Operations

Customer

name

findName()

Design class diagrams

All diagrams adapted from “Systems Analysis and Design in a Changing World”, 3rd EditionSatzinger, Jackson, Burd, Thompson Publishing, 2004.

Problem Statement

What is the application supposed to accomplish? Use words, not code Be as descriptive as possible Potential sources of information

Forms, reports Engineering drawings Real world object specifications Interviews

Problem statement for ATM application

Services one customer at a time Must be able to handle 10 customers an hour Customer inserts ATM card and enters PIN to begin Transactions

Cash withdrawals --- in $20 increments Deposits Transfers Balance inquiries

Immediate transaction validation with the bank Standard error procedures

Pin error, rejection due to inadequate balance Reports

Use Case Diagram

Use case: sequence of events that represents an interaction between the user and the system

CashWithdrawal

Deposit

Transfer

Invalid PIN

Session

Partial list of use cases from Bjork

example

Customer(actor)

Bank(actor)

Use Case Descriptions

For each use case, include The services the system provides to the user The sequence of events The desired outcome

Users of systems (called actors) can be people organizations other systems

Use Case Description:Deposit transaction (ATM)

A deposit transaction is started from within a session when the customer chooses deposit from the menu of possible transaction types. The customer chooses a type of account to deposit to (e.g. checking) from a menu of possible accounts, and then chooses a dollar amount by typing it on the keyboard. The system sends the customer's card number, PIN, chosen account and amount to the bank, which either approves or disapproves the transaction. If the transaction is approved, the machine accepts an envelope from the customer containing cash and/or checks and then issues a receipt. (If the customer does not insert the envelope within a specified period of time, this operation times out and the deposit transaction is aborted.) If the transaction is disapproved due to an incorrect PIN, the Incorrect PIN extension is executed. All other disapprovals are reported to the session, which initiates the Failed Transaction Extension. The bank is notified whether or not an approved transaction was completed in its entirety by the machine; if it is completed then the bank completes crediting the customer's account for the amount - contingent on manual verification of the deposit envelope contents by an operator later.

Activity diagram

Show which activities occur during a use case

This is for the deposit use caseThe

customer initiates the transaction

Customer ATM

Choose deposit Ask which type of account

Choose accounttype

Send customerinformation to bank

Bank

Incorrect PIN?

Credit customeraccount

Transactioncompleted

Incorrect PINexception

Transactionfailed

Approvetransaction

yes no

yesno

Ask deposit amount

Choose depositamount

Design class diagrams

Shows the attributes and methods of each class

Get the object names and attributes from the noun-phrase analysis What is the object?

Get the methods from the activity diagram What should it do?

Class DepositTransactiontoAccountAmount

DepositTransaction(session, atm, bank)getTransactionSpecificsFromCustomer()sendToBank()finishApprovedTransaction()

Working from the design class diagram

The DepositTransaction class will have Two attributes Four methods

We can tell from this what methods the class will have but not what they do Refer to the use cases,

activity diagrams, and interaction diagrams for detail

Class DepositTransactiontoAccountAmount

DepositTransaction(session, atm, bank)getTransactionSpecificsFromCustomer()sendToBank()finishApprovedTransaction()

Interaction Diagrams

Show how the objects in the application “use” each other

Which methods are called What data is returned

ATM application:Deposit Use Case

:Session :Bank

DepositTransaction(session, atm, bank)

sendToBank()

(approval)

finishApprovedTransaction()

(confirmation)

checkIfCashAvailable(amount)

(confirmation)

initiateDeposit(account, amount)

(confirmation)

:DepositTransaction

(self)getTransactionSpecificsFromCustomer()

Session(session, atm, bank)

:ATM

Customer

Fitting everything together

CashWithdrawal

Deposit

Transfer

Invalid PIN

SessionCustomer

(actor)Bank

(actor) A deposit transaction is started from within a session when the customer chooses deposit from the menu of possible transaction types. The custome r chooses a type of account to deposit to (e.g. checking) from a menu of possible ac counts, and then chooses a dollar amount by typing it on the keyboard. The system sends the customer's card number, PIN, chosen account and amount to the ba nk, which either approves or disapproves the transaction. If the transaction is a pproved, the machine accepts an envelope from the customer containing cash and/or che cks and then issues a receipt. (If the customer does not insert the envelope within a specified period of time, this operation times out and the deposit transaction is aborted.) If the transaction is disapproved due to an incorrect PIN, the Incorrec t PIN extension is executed. All other disapprovals are reported to the session, wh ich initiates the Failed Transaction Extension. The bank is notified whether or not an ap proved transaction was completed in its entirety by the machine; if it is completed then the bank completes crediting the customer's account for the amount - contingent on manual verification of the deposit envelope contents by an operator lat er.

Customer ATM

Choose deposit Ask which type of account

Choose accounttype

Send customerinformation to bank

Bank

Incorrect PIN?

Credit customeraccount

Transactioncompleted

Incorrect PINexception

Transactionfailed

Approvetransaction

yes no

yesno

DepositTransaction(session, atm, bank)getTransactionSpecificsFromCustomer()sendToBank()finishApprovedTransaction()

toAccountAmount

Class DepositTransaction

DepositTransaction(session, atm, bank)getTransactionSpecificsFromCustomer()sendToBank()finishApprovedTransaction()

toAccountAmount

Class DepositTransaction:Session :Bank

DepositTransaction(session, atm, bank)

sendToBank()

(approval)

finishApprovedTransaction()

(confirmation)

checkIfCashAvailable(amount)

(confirmation)

initiateDeposit(account, amount)

(confirmation)

:DepositTransaction

Session(session, atm, bank)

:ATM

Customer

Use case diagramList of all use cases

in the application

Use case descriptions

Textual description of what happens in

each use case

Activity diagramPicture of the

activities described in

each use case

Design class diagrams

List of all methods and attributes in

each object

Interaction diagram

Diagram of how the objects work

together for each use case

Scenarios Objects

Integration and UML: Web Services

We’ll be working with this application later in the course

It uses the MSN Live Search web service to search the web

Microsoft’s web service is a distributed object

Partial interaction diagram for “Search Google” use case

:MSNSearchService

MSNSearchService()

:FormCustomer

Search(SearchResponse)

(search results)

:Label

Text property*

* Because of C#’s convention that uses properties like methods

Things to think about

What if you have to code something not accounted for in the design diagrams?

Does the diagram have to match the code exactly?

What does it mean when……additional detail is required?…specified methods go unused? …different sequencing is required?