Service provider interface

Service provider interface (SPI) is an API intended to be implemented or extended by a third party. It can be used to enable framework extension and replaceable components.

From Java documentation:

The concept can be extended to other platforms using the corresponding tools. In the Java Runtime Environment, SPIs are used in:

• Java Database Connectivity
• Java Cryptography Extension
• Java Naming and Directory Interface
• Java API for XML Processing
• Java Business Integration
• Java Sound
• Java Image I/O
• Java File Systems

• Plug-in (computing)
• Java (programming language)
• Java (software platform)

• Replaceable Components and the Service Provider Interface (.pdf at The Software Engineering Institute CMU)
• Official Java API documentation: java.util.class and [http://com/javase/4/docs/api/java/util/spi/package-estary.html java.util.spi package