Chapter 18. Base Patterns


An object that encapsulates access to an external system or resource.



Interesting software rarely lives in isolation. Even the purest object-oriented system often has to deal with things that aren’t objects, such as relational database tables, CICS transactions, and XML data structures.

When accessing external resources like this, you’ll usually get APIs for them. However, these APIs are naturally going to be somewhat complicated because they take the nature of the resource into account. Anyone who needs to understand a resource needs to understand its API—whether JDBC and SQL for relational databases or W3C ...

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