AS4 is a Conformance Profile of the OASIS ebMS 3.0 specification, and represents an open standard for the secure and payload-agnostic exchange of Business-to-business documents using Web services. Secure document exchange is governed by aspects of WS-Security, including XML Encryption and XML Digital Signatures. Payload agnosticism refers to the document type (e.g. purchase order, invoice, etc.) not being tied to any defined SOAP action or operation.
AS4 became a standard in 2013. The majority of the AS4 profiling points constraining the ebMS 3.0 specification are based upon the functional requirements of the AS2 specification. By scaling back ebMS 3.0 by using AS2 as a blueprint, AS4 provides an entry-level on-ramp for Web services B2B by simplifying the complexities of Web services.