This section offers a high level view of the Efficient Mail Submission and Delivery Protocol and Format Standards (EMSD-P&FS).
The EMSD-P&FS are used to transfer messages between the EMSD - Server Agent (e.g., a Message Center) and the EMSD - User Agent (e.g., a Two-Way Pager), see Figure 2.
This specification defines the protocols between an EMSD - User Agent (EMSD-UA) and an EMSD - Server Agent (EMSD-SA). The EMSD - P&FS consist of two independent components:
EMSD-FS is a non-textual form of compact encoding of Internet mail (RFC-822) messages which facilitates efficient transfer of messages. EMSD-FS is used in conjunction with the EMSD-P but is not a general replacement for RFC-822. EMSD-FS defines a method of representation of short interpersonal messages. It defines the "Content" encoding (Header + Body). Although EMSD-FS contains end-to-end information its scope is purely point-to-point. EMSD-FS relies on EMSD-P (see 2 below) for the transfer of the content to its recipients.
This is described in the section entitled EMSD Format Standards.
EMSD-P is responsible for wrapping an EMSD-FS message (see 1 above) in a point-to-point envelope and submitting or delivering it. EMSD-P relies on the services of Efficient Short Remote Operation Services (ESROS) as specified in RFC-2188 [1] for transporting the point-to-point envelope. Some of the services of EMSD-P include: message originator authentication and optional message segmentation and reassembly. The EMSD-P is expressed in terms of abstract services using the ESROS notation. This is described in the section entitled Efficient Mail Submission and Delivery Protocol.
It is important to recognize that EMSD-P and EMSD-FS are not end-to-end, but focus on the point-to-point transfer of messages. The two points being EMSD-SA and EMSD-UA. EMSD-P function as elements of the Internet mail environment, which provide end-to-end (EMSD-User to any other Messaging Originator or Recipient) services.
Figure 2 illustrates how the EMSD-P&FS defines the communication between a specific EMSD-UA and a specific EMSD-SA. The Message Transfer System may include a number of EMSD-SAs. Each EMSD-SA may have any number of EMSD-UAs with which it communicates.
The Efficient Mail Submission and Delivery Services use the Efficient Short Remote Operation Services (ESROS). They also use the Duplicate Operation Detection Support Functions as described in the section entitled Duplicate Operation Detection Support Functions. These functions guarantee that an operation is performed no more than once.
