Chapter 3 Requirements Analysis

Transcription

1 Chapter 3 Requirements Analysis Intr SDLC is prcess by which rg. mves frm as-is (current) system t t-be (new) system Outputs frm planning phase: system request, feasibility study, prject plan Analysis = breaking a whle int its parts in rder t understand the parts nature, functin, and interrelatinships Final deliverable f analysis phase is the system prpsal If accepted, n t design phase A bit f verlap btwn the tw deliverables frm analysis phase are really the 1 st step in design In many ways, the requirements determinatin step is the single mst critical ne f the whle SDLC Failing t determine the crrect requirements is a majr cause f prject failure Requirements Determinatin What is a Requirement? Requirements = statement f what the system must d r what characteristics it needs t have Analysis stage reqs. fcus n business needs, s they are ften called business requirements Types: Functinal = relates directly t a prcess the system has t perfrm r inf it needs t cntain (eg. able t search fr inventry) Either prcess-riented r infrmatin-riented Nnfunctinal = behaviural prperties that the system must have, such as perfrmance and usability (eg. user interface) Operatinal Perfrmance Security Cultural and plitical (eg. currency, cmpany plicy) Requirements Definitin Straightfrward text reprt lists functinal/nnfunctinal requirements in an utline frmat Smetimes reqs. might be ranked/priritized Mst bvius purpse: prvide inf needed by ther deliverables in the analysis phase Mst imprtant purpse: define the scpe f the system it tells analysts exactly what the final system needs t d Establishes users expectatins fr system Determining Requirements Need bth business and IT perspectives Study by Standish Grup: lack f user invlvement = tp reasn fr IT prject failure

2 The analyst will use ne f the several techniques t acquire inf frm users, and then critically analyze it and use it t craft the requirements definitin Creating the Requirements Definitin Iterative and nging prcess thrughut analysis phase Steps: 1) Determine the kinds f functinal/nnfunctinal requirements they will cllect 2) Use requirement-gathering techniques t cllect inf and list business requirements identified 3) Wrk with entire prject team and users t verify/change/cmplete the list and help priritize Key t prject success: keeping requirements list tight and fcused Requirements Analysis Techniques Prcess invlves 3 steps: Understanding the existing situatin (as-is) Identify imprvements Define requirements fr new system (t-be) Nte that requirements analysis and requirements-gathering g hand in hand; they happen cncurrently and are cmplementary activities 3 requirements analysis techniques, discussed belw Business Prcess Autmatin (BPA) Used when basic business reqs utline in system request fcus n emplying cmputer technlgy in sme aspect f the business prcess, but leave the basic manner in which the rganizatin perates unchanged Imprve rganizatinal efficiency, but have least impact/value fr the business Tw ppular activities in the BPA technique: Prblem Analysis (mst straightfrward and cmmnly used) Ask users/managers t identify prblems with the as-is system and describe hw t slve them Imprvements tend t be small/incremental n significant benefits Tend nly t address symptms t underlying prblems Rt Cause Analysis Fcuses n prblems first, rather than slutins Users generate list f prblems and priritized them Users/analysts then generate all pssible rt causes until true underlying cause(s) is revealed Business Prcess Imprvement (BPI) Basic business requirements target mderate changes t the rganizatin s peratins Can imprve efficiency and effectiveness Primary fcus is n imprving business prcesses, less fcus n as-is system Three ppular activities in the BPI technique:

3 Duratin Analysis Requires detailed examinatin f amunt f time it takes t perfrm each prcess in the current system Cmpare ttal time it takes t cmplete a prcess with the sum f its parts the larger the difference, the mre it needs t be verhauled Likely cause is bad fragmentatin in prcess Prcess integratin changing fundamental prcess s that fewer peple wrk n the input (wider respnsibilities fr staff) Parallelizatin changing prcess s that individual steps are perfrmed at the same time Activity-Based Csting Examines cst f each majr prcess, identify the mst cstly prcesses, and fcus imprvements n thse Infrmal benchmarking Studying hw ther cmpanies perfrm a business prcess t learn hw yur cmpany can d things better Business Prcess Reengineering (BPR) Used t change the fundamental way in which the rganizatin perates bliterating the current way f ding things Majr changes t take advantage f new ideas/technlgy Fcus: new ideas, new ways f ding business Three ppular activities in BPR: Outcme Analysis Fcus n understanding fundamental utcmes that prvide value t custmers Think abut it frm the custmer s perspective Technlgy Analysis Develp list f imprtant/interesting technlgies and then identify hw each culd be applied t the business prcess Activity Eliminatin Wrk t identify hw the rganizatin culd eliminate each and every activity in the business prcess Cmparing Analysis Techniques Each has its strengths/weaknesses Cmpanies will have wide range r prjects, technique shuld be chsen t fit the nature f the prject Varying ptential value, cst, breadth f analysis, and risk BPR > BPI > BPA fr the abve measures Requirements-Gathering Techniques Requirements-Gathering in Practice Imprtant side effects: building plitical supprt fr the prject, establishing trust/rapprt between prject team and users Carefully determine wh is included in the requirements-gathering prcess all f the key stakehlders must be included

4 Respect time cmmitment yu ask the participants t make Cmmn prcess: interviews with senir managers and then JAD sessins with users f all levels 5 mst cmmn requirements-gathering techniques discussed belw Interviews Mst cmmn Usually ne-n-ne 5 basic steps: 1. Selecting interviewees schedule with list f interviewees, purpses, date/time/place Include peple at different levels, as they have different perspectives 2. Designing questins 3 types: clsed-ended (specific, required answer), pen-ended (leave rm fr elabratin), prbing (fllw-up n what has just been discussed, encurage expansin/cnfirmatin f inf) Anticipate the type/level f inf the interviewee is likely t knw Tw fundamental appraches t rganizatin f questins: Tp-dwn begin with brad/general issues and wrk twards mre specific questins Apprpriate fr mst interviews mst cmmn apprach Enables interviewee t raise big-picture issues befre becming engrssed in details Bttm-up start specific, mve t brad questins May be preferred when analyst has a lt f inf abut issues and just needs t fill in details 3. Preparing fr the interview Knw rder f questins, anticipate pssible answers, priritize questins Infrm interviewee f reasn fr interview, areas f discussin 4. Cnducting the interview First gal: build rapprt/trust; be prfessinal, unbiased, independent Explain why yu are there and why the interviewee was chsen Write careful ntes Make sure yu understand the issues being discussed Separate facts frm pinin Allw interviewee t ask questins r prvide any additinal infrmatin; explain what will happen next 5. Pstinterview fllw-up Prepare an interview reprt cntaining ntes, infrmatin cllected and summarized Send this t the interviewee t read and infrm yu f clarificatins/updates Jint Applicatin Develpment (JAD)

5 Prject team, users, management wrk tgether t identify requirements Structured prcess where users meet under directin f a facilitatr Prblem: suffers frm traditinal grup prblems reluctance t challenge pinins, dminatin by a few peple, lack f participatin New frm: electrnic JAD (e-jad) annymus Steps (similar t interview) 1. Selecting participants mix f levels 2. Designing sessin length, cverage, agenda 3. Preparing fr the sessin participants shuld understand the gal f the sessin 4. Cnducting the sessin frmal agenda and grund rules Facilitatr s key functins: ensure the grup sticks t agenda, help grup understand technical terms/jargn, recrd input n public display area 5. Pst-JAD Fllw-up prepare pst-sessin reprt and circulate it amng attendees Questinnaires Used when there is a large number f peple frm whm inf and pinins are needed Steps: 1. Select participants select a sample/subset wh are representative 2. Design questinnaire clearly written, little rm fr misunderstanding, grup related questins 3. Administering Questinnaire key issue is getting peple t respnd 4. Fllw-up prcess them and develp a reprt Dcument Analysis Used t understand the as-is system Reprts, mems, charts, manuals, frms Eliminate useless parts, add in required parts that are missing Observatin Watching prcesses being perfrmed Gd way t check validity f inf gathered frm ther surces Selecting the Apprpriate Techniques See Figure 3-13, p. 131 Type f inf Depth f inf Breadth f inf Integratin f inf User invlvement Cst Summary Analysis

6 Fcus n capturing business requirements Deliverables: requirements definitin, use cases, prcess mdels, data mdel => cmbined in a system prpsal Requirements Determinatin Turns high level explanatin f business requirements int mre precise list Functinal and nnfunctinal requirements Requirements Analysis Techniques 3 steps f analysis: understanding current system, identifying imprvements, develping requirements fr t-be system 3 techniques: BPA, BPI, BPR Requirements-Gathering Techniques 5 techniques: Interviews, JAD, questinnaires, dcument analysis, bservatin