軟件工程閲讀（中英文對照）之需求分析(二)

The requirements analysis is important because it will play a major role in determining the design of specific software and hardware systems．
　　Often，systems analysts in medium and large-scale organizations must use an existing system on which they base their requirements analysis．In this case，gaining an understanding of the existing system can be viewed as a background study that is a preliminary phase to the definition phase．A systems analyst would analyze an existing system and produce a written document that would identify the following：
• The needs of the people who use the system；
• The existing inputs，outputs，and processing；
• The flow of information through the system．
　　Once a good understanding of the existing system has been acquired，it serves as a basis for a detailed functional specification in which problems and opportunities to improve effectiveness can be identified and communicated to others[1]．The analyst should always examine the existing system to see if needs can be met without a new system．
　　As information is collected about the current system，it should be organized so that every possible solution and its feasibility can be examined．The systems analyst works with users to analyze the alternatives．In this case，the goal of the background study is to：
• Identify and prioritize system-related problems and costs；
• Identify opportunities to improve systems performance；
• Produce a functional specification．
　　On the other hand，in many cases a systern must be designed to fill a need that did not exist beforehand．New computer systerns are often technology-driven．That is，as a technology becomes feasible to implement，it presents new business opportunities．For example，the automated teller machines（ATMs）presented the banking industry with a new opportunity．In that case，the process did not start with a request from a user，but as an opportunity created by new computer software and hardware．
　　The requirements analysis is one of the most important tasks to undertake，because it answers such questions as：
• What is the user’s problem？
• Will a computer help？
• What is the system required to do？
• What are some preliminary approaches to the problem？
NOTES
[1] “… a businessperson，such as the manager of a department，should consider”是省略關系代詞“that”的限定性定語從句，脩飾主語“questions”，其中“such as…”是插入語，說明“businessperson”。
[2] “to handle”引出的不定式短語，作定語脩飾“a word processing application”；其後which引導的非限制性定語從句脩飾“correspondence”。
[3] 句中有3個“that”，前兩個that，即“that…and that…”引導兩個竝列的賓語從句；最後一個“that”引導定語從句，脩飾“word processing package”。
[4] “in which”到句末爲引導詞是介詞賓語的定語從句；其中“to improve effectiveness”爲不定式短語，作定語脩飾“problems and opportunities”。