Multiple Target Annotations

Multiple Target Annotations

One of the features implemented in the Annotation Server is the allowance of multiple-target annotations.

While an annotation typically targets (meaning is "on") a canvas, this version of the AnnoServer, and the version of extended Mirador it pairs with, allow for an annotation to target another annotation, so that, say, a commentary annotation may target a transcription annotation which in turns targets (or is "on") a canvas. This is the "annotation-on-annotation" feature.

This feature allows one annotation to have multiple targets. While the use case in mind for this feature is to allow an annotation to target multiple canvases (typically this would be two), from the AnnoServer's perspective it should handle any combination of annotation-on-annotation and multiple-target.

At the outset, when a create request is received by the AnnoServer, as part of the processing it will check to see if the "on" element is a simple string or an array. If it is an array, then during the processing to create the required list (see "Required List and Layer" wiki page) it will process for each element in the "on" array. [It will run annotation_controller#handlRequiredListMultipleOn instead of annotation_controller#handlRequiredList and set the canvasses accordingly.