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Anemic domain model is the use of a software domain model where the domain objects contain little or no business logic (validations, calculations, business rules etc.). ==Overview== This pattern was first described〔http://www.martinfowler.com/bliki/AnemicDomainModel.html〕 by Martin Fowler, who considers the practice an anti-pattern. He says: In an anemic domain design, business logic is typically implemented in separate classes which transform the state of the domain objects. Fowler calls such external classes ''transaction scripts''. This pattern is a common approach in Java applications, possibly encouraged by technologies such as early versions of EJB's Entity Beans,〔 as well as in .NET applications following the Three-Layered Services Application architecture where such objects fall into the category of "Business Entities" (although Business Entities can also contain behavior).〔http://msdn.microsoft.com/en-us/library/Ee817664(pandp.10).aspx〕 Fowler describes the transaction script pattern thus: "Most business applications can be thought of as a series of transactions. A transaction may view some information as organized in a particular way, another will make changes to it. Each interaction between a client system and a server system contains a certain amount of logic. In some cases this can be as simple as displaying information in the database. In others it may involve many steps of validations and calculations. A Transaction Script organizes all this logic primarily as a single procedure, making calls directly to the database or through a thin database wrapper. Each transaction will have its own Transaction Script, although common subtasks can be broken into subprocedures." In his book "Enterprise Application Patterns", Fowler noted that the transaction script pattern is OK for many simple business applications, and avoids the need for a complex OO-database mapping layer. ==Benefits== * Clear separation between logic and data〔http://blog.inf.ed.ac.uk/sapm/2014/02/04/the-anaemic-domain-model-is-no-anti-pattern-its-a-solid-design/〕 (Procedural programming). * Works well for simple applications. * Results in stateless logic, which facilitates scaling out * Avoids the need for a complex OO-Database mapping layer. * It follows the Single Responsibility principle giving a class no more than one reason to change (the data changes). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Anemic domain model」の詳細全文を読む スポンサード リンク
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