Lesson plan
Interceptor pattern
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.
Article summary
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.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.