AS4

Can you use AS4?

You can use AS4 if your software license enables both WebServices and AS4 functionality. To check enabled license keys, select Help > License information on the toolbar in the user interface. The list of enabled license keys must include the following two keys:

  • MessageProtocolAS4
  • MessageProtocolWebServices

AS4 overview

AS4 is a Business to Business (B2B) protocol that extends the functionality of AS2 with ebMS-based Web Services technology. AS4 is easier to implement and lower in cost to set up and operate than traditional B2B protocols.

The main benefits of AS4 compared to AS2 are:

  • Compatibility with Web Services standards
  • Message pulling capability
  • Built-in receipt mechanisms

AS4, like AS2, only supports HTTP for Internet transport.

AS4 provides two conformance profiles for ebMS 3.0:

  • The ebHandler conformance profile – supports both sending and receiving roles, and both message pushing and message pulling for each role.
  • The Light Client conformance profile – supports both sending and receiving roles, but only message pushing for sending and message pulling for receiving. In other words, it does not support incoming HTTP requests, and may have no IP address.

AS4 supports non-repudiation of receipts, similar to the MDN used in AS2, and specified as an XML schema. Non-repudiation receipts are returned using a dedicated signal message and defaults to requiring message recipients to return a signed receipt containing the digests necessary for non-repudiation. The receipt may also contain error handling information if there was some problem with the document exchange.

AS4 supports duplicate message detection and message retry/resending scenarios for when receipts for messages are not received by the sender.

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