Ｓさんは，在庫管理システム（以下，システムという）を構築するプロジェクトに参加することになった。 システムの開発計画は，プロジェクトにおける成果物及び完了基準を明確にした上で，作業分割，作業内容定義，作業順序設定，作業期間見積り，スケジュール作成の五つのステップに分けて順に実施される。 (1) 作業分割では，WBS（Work Breakdown Structure）を用いて，成果物の作成作業を細分化する。WBS は，全体の作業を分割し，その構成要素を階層構造として整理したものである。 (2) 作業内容定義では，分割した各作業の成果物と工数を定義する。 (3) 作業順序設定では，作業間の前後関係を決定する。 (4) 作業期間見積りでは，作業の工数を要員数で割ることで，作業期間を求める。 (5) スケジュール作成では，各作業期間を基に開始日と終了日を決定する。 Ｓさんは，先輩の指導の下で，図に示す WBS によるシステムの作業分割を実施した。 作業分割の図では, 最初の段階でシステム開発作業全体にかかわるものとサブシステムに着目して分割している。S さんが図のサブシステムごとに, 次の段階で行った作業分割の説明として, 適切なものはどれか。 図 WBS によるシステムの作業分割 - システム - システム要件定義 - 「網掛け」 - サブシステム1 - 「網掛け」 - ソフトウェア方式設計 - ソフトウェア詳細設計 - 「網掛け」 - ソフトウェアインタフェース詳細設計 - 画面設計 - 画面一覧 - 画面フロー - 画面レイアウト - 画面入出力項目 - 帳票設計 - 帳票一覧 - 帳票レイアウト - … - データベースの詳細設計 - … - 「網掛け」 - … - サブシステム2 - 「網掛け」 - … 注 「網掛け」の部分は, 表示していない。
平成22年度 春期 ITパスポート試験 問90
This question's explanation and your answers so far.
問 90
- ア
正解 The correct answer is ア. Following the hierarchy in the diagram from the top, the first stage (directly under the topmost “System”) lines up “System requirements definition,” which spans the entire system development effort, together with “Subsystem 1” and “Subsystem 2.” What the question asks about is the next stage: on what basis the work was arranged directly under “Subsystem 1.” Placed there are “Software architecture design” and “Software detailed design” (plus boxes hidden by shading), and these are all names of development processes (phases) such as design, construction, and testing. In other words, Mr. S divided the work of each subsystem by development process. Note that at the stages further down, “Software detailed design” is broken down by design target into “Software interface detailed design” and “Database detailed design,” below that into “Screen design” and “Report design,” and at the lowest level into concrete units of work and deliverables such as “Screen list,” “Screen layout,” and “Report layout.” A WBS works this way: at each stage it picks one viewpoint and subdivides the work hierarchically.
Incorrectイ
“System requirements definition” sits directly under the topmost “System” in the diagram — that is, it is a sibling box lined up beside the subsystems at the first stage, carved out as work that spans the entire system development effort. It is not placed under a subsystem, so the diagram cannot be read as dividing a subsystem by the items of the requirements definition. In fact, what lines up under Subsystem 1 is “Software architecture design” and “Software detailed design,” not the names of requirements-definition items.
Incorrectウ
If the work had been divided by individual pieces of software, the boxes under Subsystem 1 would be the names of individual pieces of software (programs or products). What is actually lined up there, however, is “Software architecture design” and “Software detailed design” — names of processes that merely happen to contain the word “software.” Do not be pulled along by the surface appearance of the wording; you need to tell whether a name refers to a target or to a process.
Incorrectエ
A module is a structural unit of a program handled from detailed design onward; it does not appear at a level as high as immediately below a subsystem. In the diagram too, under Subsystem 1 come process names, below them design targets such as “Software interface detailed design” and “Database detailed design,” and even at the lowest level units of work and deliverables such as “Screen list” and “Report layout.” No box divided on the basis of module names appears at any stage.
- A WBS (Work Breakdown Structure) is a diagram that breaks a project's work down hierarchically from higher to lower levels, subdividing it until it reaches the smallest manageable units (work packages). As a rule, each stage is divided using a single chosen viewpoint; in this diagram the viewpoint switches as the breakdown goes deeper: the whole system → by subsystem → by development process → by design target → individual pieces of work and deliverables.
- For WBS questions, first identify which box the stage in question sits directly under, then read what basis was used to name the child boxes lined up there (are they names of targets, or names of processes?). Here the boxes are process names — “Software architecture design” and “Software detailed design” — so the basis of the division is the development process.