RFC 3340 The Application Exchange Core July 2002 4.4 Message Semantics . . . . . . . . . . . . . . . . . . . . 11 4.4.1 The Attach Operation . . . . . . . . . . . . . . . . . . . 11 4.4.2 The Bind Operation . . . . . . . . . . . . . . . . . . . . 13 4.4.3 The Terminate Operation . . . . . . . . . . . . . . . . . 14 4.4.4 The Data Operation . . . . . . . . . . . . . . . . . . . . 15 4.4.4.1 Relay Processing of Data . . . . . . . . . . . . . . . . . 17 4.4.4.2 Application Processing of Data . . . . . . . . . . . . . . 18 4.5 APEX Access Policies . . . . . . . . . . . . . . . . . . . 19 4.5.1 Access Policies in the Endpoint-Relay Mode . . . . . . . . 19 4.5.2 Access Policies in the Relay-Relay Mode . . . . . . . . . 20 5. APEX Options . . . . . . . . . . . . . . . . . . . . . . . 20 5.1 The statusRequest Option . . . . . . . . . . . . . . . . . 22 6. APEX Services . . . . . . . . . . . . . . . . . . . . . . 26 6.1 Use of the APEX Core DTD . . . . . . . . . . . . . . . . . 27 6.1.1 Transaction-Identifiers . . . . . . . . . . . . . . . . . 27 6.1.2 The Reply Element . . . . . . . . . . . . . . . . . . . . 28 6.2 The Report Service . . . . . . . . . . . . . . . . . . . . 28 7. Registration Templates . . . . . . . . . . . . . . . . . . 29 7.1 APEX Option Registration Template . . . . . . . . . . . . 29 7.2 APEX Service Registration Template . . . . . . . . . . . . 29 7.3 APEX Endpoint Application Registration Template . . . . . 30 8. Initial Registrations . . . . . . . . . . . . . . . . . . 30 8.1 Registration: The APEX Profile . . . . . . . . . . . . . . 30 8.2 Registration: The System (Well-Known) TCP port number for apex-mesh . . . . . . . . . . . . . . . . . . . . . . . . 31 8.3 Registration: The System (Well-Known) TCP port number for apex-edge . . . . . . . . . . . . . . . . . . . . . . . . 31 8.4 Registration: The statusRequest Option . . . . . . . . . . 31 8.5 Registration: The Report Service . . . . . . . . . . . . . 32 9. DTDs . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 9.1 The APEX Core DTD . . . . . . . . . . . . . . . . . . . . 32 9.2 The Report Service DTD . . . . . . . . . . . . . . . . . . 34 10. Reply Codes . . . . . . . . . . . . . . . . . . . . . . . 35 11. Security Considerations . . . . . . . . . . . . . . . . . 36 References . . . . . . . . . . . . . . . . . . . . . . . . 36 Authors' Addresses . . . . . . . . . . . . . . . . . . . . 38 A. Acknowledgements . . . . . . . . . . . . . . . . . . . . . 39 B. IANA Considerations . . . . . . . . . . . . . . . . . . . 39 Full Copyright Statement . . . . . . . . . . . . . . . . . 40 1. Introduction Network applications can be broadly distinguished by five operational characteristics: o server push or client pull; o synchronous (interactive) or asynchronous (batch); Rose, et. al. Standards Track