Inbound, asynchronous flow

In an asynchronous request-response process for inbound AS messages, the external partner establishes and uses one connection to send the message and the MDN request, the internal partner establishes and uses another connection to send the MDN.

The following figure illustrates the flow for AS2 inbound, asynchronous messages. The flow discusses the use of HTTP response codes. This information is not relevant for the AS3 protocol. Although the flow is similar, the AS3 protocol uses FTP connection semantics.

The asynchronous flow of an inbound message is as follows:

  1. The external partner generates a message, requests an asynchronous message disposition notification (MDN), and establishes a connection to the B2B Gateway. When the B2B Gateway receives the message, it closes the connection. If using the AS2 protocol, this is when the B2B Gateway sends the HTTP 200 OK before closing the connection.
  2. The B2B Gateway forwards the message to the internal partner.
  3. The internal partner receives the message.
  4. The B2B Gateway generates an asynchronous MDN, establishes a new connection to the external partner, and sends the MDN.
  5. The external partner receives the MDN and closes the connection. The B2B Gateway marks the transaction as complete. If using the AS2 protocol, this is when the external partner sends the HTTP 200 OK before closing the connection.
Figure 1. Flow for inbound, asynchronous messages
Flow for inbound, asynchronous messages. Image previously described in text.

If the B2B Gateway does not deliver the asynchronous MDN to the external partner for an inbound transaction, the transaction is regarded as a pending inbound transaction.