A canonical document is a standardized representation that a document might assume while it is passing through your webMethods system. A canonical document acts as the intermediary data format between resources.

For example, in an implementation that accepts purchase orders from companies, one of the steps in the process converts the purchase order document to a company’s standard purchase order format. This format is called the 'canonical' form of the purchase order document. The canonical document is published, delivered, and passed to services that process purchase orders.

By converting a document to a neutral intermediate format, subscribers (such as adapter services) only need to know how to convert the canonical document to the required application format. If canonical documents were not used, every subscriber would have to be able to decode the native document format of every publisher.

A canonical document is a publishable document type. The canonical document is used when building publishing services and subscribed to when building triggers. In flow services, you can map documents from the native format of an application to the canonical format.