What is the difference between Service Provider Interface (SPI) and Application Programming Interface (API)?
More specifically, for Java libraries, what makes them an API and/or SPI?
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What is the difference between Service Provider Interface (SPI) and Application Programming Interface (API)?
More specifically, for Java libraries, what makes them an API and/or SPI?
Best Answer
Put differently, the API tells you what a specific class/method does for you, and the SPI tells you what you must do to conform.
Usually API and SPI are separate. For example, in JDBC the
Driver
class is part of the SPI: If you simply want to use JDBC, you don't need to use it directly, but everyone who implements a JDBC driver must implement that class.Sometimes they overlap, however. The
Connection
interface is both SPI and API: You use it routinely when you use a JDBC driver and it needs to be implemented by the developer of the JDBC driver.