問17
頻出度★☆☆
ある情報システムの構築において, ビジネスプロセス上の独立した業務機能という視点で部品化して情報システムを構築しておく。そして, 将来の変更や他の情報システムの開発に, それらの部品を容易に利用できる仕組みを作り上げたい。この方法に適合する考え方として, 適切なものはどれか。
平成23年度 秋期 ITパスポート試験 問17
ストラテジ系システム戦略 › 情報システム戦略
This question's explanation and your answers so far.
解説
問 17
Incorrectア
ASP (Application Service Provider) refers to a service provider that rents out the functions of business application software to customers over a network such as the Internet, and to that form of provision. Users do not buy and install the software themselves; they pay a usage fee and use the functions they need. This is a concept about how a system is procured and used, not a way of thinking about how to divide the inside of a system into components when designing it. It does not explain the componentization from the perspective of business functions or the mechanism for reusing components that the question asks about, so it is wrong.
Incorrectイ
DOA (Data Oriented Approach) is a development technique in which you first analyze and organize the structure of and relationships among the data handled in the business, and then design the system on the foundation of that data model. It rests on the premise that data changes less often than business procedures (processing), and it improves maintainability by placing a stable data structure at the base. Because its focus is always on data, it approaches the problem from a different angle than the division by functional unit that the question describes as componentization from the perspective of independent business functions in the business process. It is also worth remembering DOA in contrast with POA (Process Oriented Approach), which centers on processing procedures, and OOA (Object Oriented Approach), which bundles data and procedures together as objects.
Incorrectウ
ISP (Internet Service Provider) is a business that provides users with an environment for connecting to the Internet — what is commonly called an Internet access provider. It handles communication services such as providing the connection line and issuing email addresses, and it belongs to an entirely different field from design concepts or development methodologies for information systems. It is included as a choice only because it looks similar to SOA in spelling; there is not a single element that links it to the content of the question, so it is wrong.
- エ
正解 The correct answer is エ. SOA (Service Oriented Architecture) is a design concept in which independent functional units of the business are carved out as components called services, and the whole information system is built by combining (linking) those services. The unit of a service here is not a technical component decided for the convenience of the program, but a meaningful cluster of business functions within the business process, such as check inventory, assess credit, or issue an invoice. The wording in the question, dividing the system into components based on the perspective of independent business functions in the business process, is exactly a description of this unit of componentization. In addition, SOA makes each service callable through a standardized interface (a common specification such as Web services) and hides its internal implementation. As a result, the side using a service can call its function without knowing the internals, and conversely the service side can rebuild its internals without affecting the users. Consequently, when the business changes, you can respond simply by changing the combination of services, and the same service can also be called and reused from other information systems. This corresponds precisely to the latter half of the question, a mechanism that lets these components be easily reused in future changes or in the development of other information systems. In other words, the concept that satisfies all of the question's requirements — componentization by unit of business function, plus ease of change and reusability — is SOA.
ここがポイント
- The definition of SOA (Service Oriented Architecture) — a way of thinking in which independent business functions in the business process are carved out as components called services and linked through standardized interfaces to build the system. The key points are that the unit of componentization is a business function rather than a technical component, and that the internal implementation is hidden so the parts are loosely coupled. The results are ease of responding to business changes (changeability) and reusability from other systems.
- Telling apart confusingly similar three-letter acronyms — in contrast to SOA (a service-oriented design concept), ASP is a service provider and a form of provision in which applications are rented out over a network, and ISP is a provider of Internet connectivity; neither is a design method for systems. DOA is a development technique that starts from the data structure, and it is contrasted with POA (process-centered) and OOA (object-oriented). The key to solving the question is discerning whether it is asking about a design concept or about a provider and a service model.
用語