3100-topic1 (1)

8/17/2019 3100-topic1 (1)

1/15

© Chinese University, CSE Dept. Software Engineering / 1 - 1

Software Engineering

Topic 1:

Software Engineering: A Preview

Your a!e: """"""""""""""""""""

Co!puter Science # Engineering Depart!ent

The Chinese University of $ong %ong

8/17/2019 3100-topic1 (1)

2/15

© Chinese University, CSE Dept. Software Engineering / 1 - &

What Is Software Engineering?

Software Engineering: ' (!u)ti-person constructionof !u)ti-version software.*

+ ' ter! invente in the )ate 1s. + ot 0ust progra!!ing.

+ Dea)ing with co!p)e syste!s.

+ Stanar techni2ues an too)s are invente an

app)ie in this fie).

8/17/2019 3100-topic1 (1)

3/15


Why Software Engineering?

1. 4rowing software sca)e an cost + 'n orer of !agnitue growth in every 1 years.

+ Techni2ues app)ica5)e to s!a)) syste!s cou)

not 5e sca)e up.

&. Co!p)eity of app)ications

+ The e!an for software operations increases at

a faster rate than software engineer6s

prouctivity

8/17/2019 3100-topic1 (1)

4/15



3. 8!pact of software fai)ure + 9ac of iscip)ine !aes software

easy to 5e !isuse.

+ ;u)tip)e copies of software !ae

software fai)ures sprea fast.

8/17/2019 3100-topic1 (1)

5/15

© Chinese University, CSE Dept. Software Engineering / 1 - <


7. Evo)ution of software + Software crisis was ientifie in 16s.

+ Software crisis is sti)) software crisis toay.

– Code is easy to change, but software is hard to

replace. reict an !eet software eve)op!ent """""". + ;easure an e!onstrate software """""".

h S f if C l

8/17/2019 3100-topic1 (1)

6/15

© Chinese University, CSE Dept. Software Engineering / 1 -

The Software Life Cycle

(The “Waterfall Moel!"

1. =e2uire!ent 'na)ysis an Specification + 'fter a feasi5i)ity stuy of custo!er6s e!an

+ 8entify an ocu!ent the eact re2uire!ents forthe syste!

+ 8nvo)ve custo!er, eve)oper, an user + ("""""" the pro5)e! is*

&. Design + ' software syste! is eve)ope to !eet the

re2uire!ents

+ 'rchitectura) ? etai)e esign

+ ("""""" to so)ve the pro5)e!*

8/17/2019 3100-topic1 (1)

7/15

© Chinese University, CSE Dept. Software Engineering / 1 - @


3. Coding and Module Testing (Unittesting)

+ To prouce the actua) coe for the custo!er

+8eas on !ou)es AunitsB + ivie an con2uer

+ or 5reaown structure

rea the syste! own into """"""""""

+ ;ou)es are teste iniviua))y*

8/17/2019 3100-topic1 (1)

8/15

© Chinese University, CSE Dept. Software Engineering / 1 - F


7. 8ntegration an Syste! Testing + ;ou)es are integrate an teste as a who)e

syste!

5. eli!ery and Maintenance

+ De)ivery to user for operation

+ Corrective, aaptive, perfective !aintenance

8/17/2019 3100-topic1 (1)

9/15

© Chinese University, CSE Dept. Software Engineering / 1 -

The Waterfall Moel of

the Software Life Cycle

#e$%ire&entsanalysis an

s'ecification

esign an

s'ecification

Coing an

&o%le

testing

Integration

an syste&

testing

elivery an

&aintenance

verify

esign review

esign wal)thro%gh

*or&al ins'ection

*ig%re +,+:

The waterfall &oel of the software life cycle

verify

Coe review

Coe wal)thro%gh verify

Testing res%lts

verify

-'erational environ&ent

e,g,. /ASA &oel

8/17/2019 3100-topic1 (1)

10/15


Ty'ical Software Cost istri0%tion

Syste& Ty'e Phase Costs (1" #e$%ire&ents2esign I&'le&entation Testing

Co&&an an control Syste&s 34 56 73

S'ace0orne syste&s 73 56 34

-'erating syste&s 77 +8 96

Scientific syste&s 33 54 76

%siness syste&s 33 5; 5;

8/17/2019 3100-topic1 (1)

11/15


#elative Penalty of Error Correction

*ig%re +,5:

#elative cost vs, 'hase

8/17/2019 3100-topic1 (1)

12/15

© Chinese University, CSE Dept. Software Engineering / 1 - 1&

Possi0le Software evelo'&ent Paths

*ig%re +,7:

Many 'ossi0le 'aths

to evelo' software

8/17/2019 3100-topic1 (1)

13/15


Well>Engineere Software

+, The software sho%l 0e &aintaina0le

5, The software sho%l 0e relia0le

7, The software sho%l 0e efficient

3, The software sho%l offer an a''ro'riate %serinterface

9, The software sho%l 0e &eas%ra0le for trae>off

st%y

8/17/2019 3100-topic1 (1)

14/15


Ty'ical Trae>-ff St%y

Cost

+,6

(+661" Efficiency or #elia0ility

“The law of

8/17/2019 3100-topic1 (1)

15/15

© Chinese University, CSE Dept. Software Engineering / 1 - 1<

To'ic + Concl%sion

• e efine what software engineering is• e ep)aine why software engineering is

neee

• e escri5e a funa!enta) software )ifecyc)e

• e epicte a we)) engineere software

3100-topic1 (1)

Documents

Transcript of 3100-topic1 (1)