Atoms of processing.
Spignite operation is a simple, atomic operation on a file from the set. Such operation may set some meta-data (attributes), analyze content etc; may define output links (which is also a metadata) or can even change the content of a file.
Spignite operations are defined on phases. Don't worry, the API is made in such way you can't get it wrong.
There are two methods that define an operation: