. ▁The ▁dis adv antages ▁to ▁using ▁the ▁SD LC ▁method ology ▁is ▁when ▁there ▁is ▁need ▁for ▁iter ative ▁development ▁or ▁( i . e . ▁web ▁development ▁or ▁e - commerce ) ▁where ▁st ake hold ers ▁need ▁to ▁review ▁on ▁a ▁regular ▁basis ▁the ▁software ▁being ▁designed . ▁ ▁A ▁comparison ▁of ▁the ▁strength s ▁and ▁weak ness es ▁of ▁SD LC : ▁ ▁An ▁alternative ▁to ▁the ▁SD LC ▁is ▁rapid ▁application ▁development , ▁which ▁comb ines ▁pro tot yp ing , ▁joint ▁application ▁development ▁and ▁implementation ▁of ▁CASE ▁tools . ▁The ▁advantages ▁of ▁R AD ▁are ▁speed , ▁reduced ▁development ▁cost , ▁and ▁active ▁user ▁invol vement ▁in ▁the ▁development ▁process . ▁ ▁System ▁lif ecycle ▁The ▁system ▁lif ecycle ▁in ▁systems ▁engineering ▁is ▁a ▁view ▁of ▁a ▁system ▁or ▁proposed ▁system ▁that ▁addresses ▁all ▁phases ▁of ▁its ▁existence ▁to ▁include ▁system ▁conception , ▁design ▁and ▁development , ▁production ▁and / or ▁construction , ▁distribution , ▁operation , ▁maintenance ▁and ▁support , ▁ret irement , ▁phase - out ▁and ▁dispos al . ▁ ▁Con cept ual ▁design ▁The ▁concept ual ▁design ▁stage ▁is ▁the ▁stage ▁where ▁an ▁identified ▁need ▁is ▁exam ined , ▁requirements ▁for ▁potential ▁solutions ▁are ▁defined , ▁potential ▁solutions ▁are ▁evaluated ▁and ▁a ▁system ▁specification ▁is ▁developed . ▁ ▁The ▁system ▁specification ▁represents ▁the ▁technical ▁requirements ▁that ▁will ▁provide ▁overall ▁guidance ▁for ▁system ▁design . ▁Because ▁this ▁document ▁determ ines ▁all ▁future ▁development , ▁the ▁stage ▁cannot ▁be ▁completed ▁until ▁a ▁concept ual ▁design ▁review