PUBLIC ANSWERS TO EXERCISES PAI2 c)* Constraint on availability and throughput The system will accept connections 24 hours a day, every day, with a maximum downtime of 5 minutes a month, which can occur only between 12: 30 a.m. and 1: 30 a.m. North American Eastern Time When available, the system will at all times be able to manage 200 simultaneous connections, and process 2000 transactions per minute E4.8 No public answer E4.9 p. 119 Writing non-functional requirements These build on the answers to f4..5 abov a)*Police information system When the user is connected to the over a local area network, the system shall respond with complete responses to all inputs within 0. 5s at peak system load When the user is connected over a wireless connection at 9600bps, the system shall respond with omplete responses to all inputs within 3s at peak system load The system shall be capable of handling 50 simultaneously connected users, and 300 user interactions (events originating from users)per minute The system shall not consume more than 200MB of RAM while running at peak capacity The system shall not consume more than 56Kbps of bandwidth per connected user(averaged over any Is tir The system shall achieve a reliability level of no more than 1 failure per 10 user hours, with none of those failures rendering the system totally inoperable The system shall be available 99.9% of the time with no period of down time exceeding 2 minutes The system shall be designed so that large numbers of additional functions can be added with little The system shall be designed so that it could be adapted to the needs of other police departments with programming The server shall be able to run on a Windows 2000(or higher)equipped system, with a 1. 4 GHz or faster Intel processor, 300MB or more of RAM, and 15GB or more of disk space The client software shall be able to run on EMP-4500 police car terminals, as well as on EMP-4500 emulators running on desktop computers E4.10 P. 122 Practising interview techniques This is a purely practical exercise E4. 11 P. 124 Practising brainstorming techniques This is a purely practical exercise E4. 12 No public answer E4. 13 No public answer E4. 14 No public answer E4.15 pp 129-130 Describing the type of requirements document needed. a)" Software controlling a manned spacecraft sent to Mars There would need to be a considerable amount of detailed technical requirements documentation Technical terminology could be used since all readers would be expected to have a technical background. There would probably initially be a very high-level description of the missions overall objectives used to obtain funding for the mission. Then there would be a requirements document for the high-level system requirements of the combined hardware-software system. Next, the system would be allocated into hardware and software subsystems, which in turn would each be divided into several subsystems. At each level there would probably be general and detailed requirements documents. The rationale for this level of detail is that a spacecraft is novel, is technically complex, will involve many different people with different types of expertise to develop, is difficult or impossible to change once launched, and is expensive(with high failure cost and hence a high level of required reliability ) THESE ANSWERS SUPPORT THE BOOK OBJECT ORIENTED SOFTWARE ENGINEERINGPUBLI C A NSW ERS T O EX E RCISE S PA12 T HE SEAN SW E RS SU PPORTT HEBO OK O BJ ECT O RI E NTEDSO FTW AR E E NG INE ER ING : c )*Constr aint on a vaila bility a nd throughput • - T he system will ac ce pt conne ctions 24 hours a da y, ever y day, w ith a ma ximum dow ntime of 5 minute s a month, w hic h ca n occ ur only be twe en 12:30 a .m. a nd 1:30 a.m. North A me r ic an Ea ste rn T ime. - W he n a va ila ble, the syste m w ill a t a ll times be a ble to mana ge 200 simulta neous conne ctions, a nd proce ss 2000 tr a nsac tions pe r minute . E 4.8 No public answe r. E 4.9 p. 119 W riting non-func tional requirem ents. T he sebuild on thea nsw er s to E 4.3 -E 4.5 a bove. a )*Polic einf ormation system • W he n the user is c onnec te d to the over a loca l a re a netw or k, the syste m sha ll re spond with complete r esponse s to all inputs w ithin 0.5s at pe ak system load. • W he n the user is c onnec te d ove r a w ire le ss conne ction a t 9600bps, the syste m sha ll re spond with c omple ter e sponses to a ll inputs within 3s at pe ak syste m loa d. • T he system shall be c apable of ha ndling 50 simulta neously c onnec te d use r s, a nd 300 use r inte ra ctions ( events or igina ting f rom use rs)perminute. • T hesystem shall not consumemorethan 200MB of RA M w hile running at pe ak c a pa city. • T hesystem shall not consume morethan 56Kbps of ba ndwidth pe r conne cte d use r (a ver age d ove r any 1s time pe r iod) • T he system shall a chieve a r eliability le ve l of no more than 1 fa ilure pe r 10 use r hours, w ith none of thosefa ilure s r ende r ing thesystem tota lly inoper a ble. • T hesystem shall be a va ila ble 99.9% ofthe time with no per iod of dow n time e xc ee ding 2 minute s. • T he system shall be designed so tha t lar ge numbe rs of a dditiona l f unctions c an be a dde d with little r eprogra mming. • T he system shall be designed so tha t it c ould be a dapte d to the ne eds of other police de pa rtments with minima l re progr a mming. • T he se rver shall be a ble to run on a W indow s 2000 ( or higher ) e quipped syste m, w ith a 1.4 G Hz or f aste rI nte l pr oce ssor, 300MB or mor e ofRA M, and 15G B or mor e ofdisk spac e . • T he c lie nt softw ar e sha ll be a ble to run on E MP-4500 police ca r ter minals, as w e ll a s on E MP-4500 e mula tor s r unning on de sktop c ompute rs. E 4.10 p. 122 P rac tising intervie w te c hniques. T his is a pur ely pra c tica l e xe r cise . E 4.11 p. 124 P rac tising brainstorm ing tec hnique s. T his is a pur ely pra c tica l e xe r cise . E 4.12 No public answe r E 4.13 No public answe r E 4.14 No public answe r E 4.15 pp. 129- 130 D esc ribing thetypeof requirem ents doc um ent nee ded. a )*Sof tw arec ont rolling a manne d space c raftse ntto M ars • T he re would nee d to be a c onsider able amount of de taile d tec hnica l r equir eme nts doc ume ntation. T ec hnica l ter minology c ould be used sinc e a ll re ade rs w ould be expec te d to have a tec hnica l bac kgr ound. T he re would probably initially be a ve ry high- le ve l desc ription of the mission’s over a ll objec tives used to obta in funding f or themission. Then ther ew ould bea re quire ments document f orthe high- level syste m re quire ments ofthe combine d har dwa re - softw ar e syste m. Ne xt, the syste m w ould be a lloc a te d into har dw a re a nd sof tw ar e subsyste ms, w hic h in tur n would e a ch be divide d into sever a l subsyste ms. A t e ac h level ther e w ould pr oba bly be gener a l and deta iled re quire me nts docume nts. T he r ationale f or this le ve l of de tail is tha t a spa ce c ra ft is nove l, is te chnic ally complex, w ill involve ma ny dif fe r ent people w ith dif f er ent type s of expe r tise to de ve lop, is diff icult or impossible to cha nge onc e launc hed, a nd is e xpe nsive( with high fa ilurecost and hencea high le vel ofr equir ed re lia bility)