Bale s are collections of Straw s. Tie s connect two Straw s together, and Needle s have content. Additionally, because Tie s are first class, we can apply metadata and relations to links and not just nodes. Filetype in Figure was created by some service, specifically FileTypeGuessService . To make this fact obvious a tie.
Creator is attached to the tie.
Filetype object with the creator's name attached to that. It is important to note that all objects are derived from a primary interface. A Java interfaces contains the method signatures of all functions that are required to be defined by any class that implements that interface. The primary HDM interface in Haystack is known as haystack.object.Weavable . All Haystack data objects are defined within the Java package haystack.object .