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In the field of software development, an interceptor pattern is a software design pattern that is used when software systems or frameworks want to offer a way to change, or augment, their usual processing cycle. For example, a (simplified) typical processing sequence for a web-server is to receive a URI from the browser, map it to a file on disk, open the file and send its contents to the browser. Any of these steps could be replaced or changed, e.g. by replacing the way URIs are mapped to filenames, or by inserting a new step which processes the files contents. Key aspects of the pattern are that the change is ''transparent'' and used ''automatically''. In essence, the rest of the system does not have to know something has been added or changed and can keep working as before. To facilitate this, a ''predefined interface'' for extension has to be implemented, some kind of ''dispatching'' mechanism is required where interceptors are registered (this may be dynamic, at runtime, or static, e.g. through configuration files) and ''context objects'' are provided, which allow access to the framework's internal state.〔(Schmidt, Stal, Rohnert & Buschmann: "Pattern-Oriented Software Architecture Vol.2: Patterns for Concurrent and Networked Objects", pp. 109--140, April 2001 )〕 == Uses & Context == Typical users of this pattern are web-servers〔(Apache Software Foundation: Tomcat 6.0 Channel Interceptor Reference, accessed 2009-Nov-24 )〕 (as mentioned above), object-〔(OMG, "CORBA v3.1, Part I: Interfaces", Chapter 16 "Portable Interceptors", January 2008 )〕 and message-oriented middleware〔(E. Curry, D. Chambers, and G. Lyons, “Extending Message-Oriented Middleware using Interception”, presented at Third International Workshop on Distributed Event-Based Systems (DEBS '04), ICSE '04, Edinburgh, Scotland, UK, 2004. )〕 An example of implementation of this pattern is the ''javax.servlet.Filter'' interface, which is part of Java Platform, Enterprise Edition. Aspect-oriented programming (AOP) can also be used in some situations to provide the capability of an interceptor, although AOP doesn't use the elements typically defined for the interceptor pattern. 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「Interceptor pattern」の詳細全文を読む スポンサード リンク
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