問25
頻出度★★☆
システム開発作業において, 新たに構築又は再構築する業務の機能を明確にし, それに基づいて情報システム化の範囲とその機能を具体的に明示するプロセスはどれか。
平成26年度 秋期 ITパスポート試験 問25
ストラテジ系システム企画 › 要件定義
This question's explanation and your answers so far.
解説
問 25
Incorrectア
External design is the stage that takes the what to build decided in requirements definition and designs the interfaces visible to users (screen layouts, report formats, input/output data, methods of linking with external systems, and so on). It does not decide the scope of the information system itself; it starts from an already fixed scope and set of functions and works out how they will be realized from the user viewpoint, so it is wrong.
Incorrectイ
Internal design is the stage that designs the internal structure of the system (how programs are divided, module composition, internal data structures, the flow of processing logic, and so on) from the developer viewpoint in order to realize what external design specified. It designs the how, which users never see, and is not the stage that specifies business functions or the scope of the information system, so it is wrong.
Incorrectウ
Programming is the stage that actually writes source code according to the specifications fixed in internal design and produces a working program. It comes quite late in the development process, by which time what to build has already been decided, and it is not a process that specifies scope and functions, so it is wrong.
- エ
正解 The correct answer is エ (Requirements definition). Requirements definition is the stage at the very beginning of system development that clarifies what the users and the business side want to achieve. Specifically, it (1) clarifies the functions and procedures of the business itself that will be newly built or rebuilt (business requirements definition), (2) draws the line for how much of that will be realized by the information system, that is, the scope of the information system, and (3) documents in concrete terms the functional requirements the system must have (what it can do) and the non-functional requirements (performance, reliability, security, and so on). The phrases in the question, clarifies the functions of the business and concretely specifies the scope of the information system and its functions, correspond one to one with this requirements definition process. Requirements definition decides what to build (What), not how to build it (How), and its deliverable, the requirements definition document, is the starting point for all of the later design, programming, and testing work.
ここがポイント
- The standard order of system development stages is requirements definition, external design, internal design, programming, testing, and operation. Remember it by the split that requirements definition decides what to build (What), while design onward decides how to build it (How).
- In requirements definition, you fix the scope of the information system based on the business requirements, and concretely define the functional requirements (the functions the system provides) and the non-functional requirements (performance, availability, security, operability, and so on). If this is left vague, rework occurs in later stages.
用語