Message Path Model

Message Path Model

In figure * we can see the sender and receiver drawn as circles. These are to be interpreted either as Mail-"user"-identities on the respective servers (Mail storage and Notification), or as computers or programs which act upon the respective identities, as is the case for example with dial-up conected PC's, or mailing robots.

The lines represent a "protocol" which realizes the corresponding activity

Sending a message:

Post:

a Sender deposits a message for zero, one or more recipients on the Mail Storage Server.

Notify:

a mail storage server creates notification messages to each recipient (if any). There can be zero, one or more notification messages, in dependence of the intended message interchange.

(Notification) delivery:

upon receipt of a Notification message the Notification Servers takes action to make the intended Recipient eventually know of the existence of a message posted to its identity.

The notification message may be discarded upon certain criteria without notification delivery, it may be stored until somebody scans the Notification Server for "new messages", or it can trigger an imediate action.

Reading a message:

(Message) collection order:

a Notification Server can be instructed by a Recipient to retrieve messages, selected out of the list of Notifications available for this Recipient, eventually matching criteria defined by the Recipient or by the owner of the Server.

Collect:

a Notification Server can contact a Mail Storage Server to retrieve a posted message asociated with a certain Notification Message. After acomplishing this step, the Message is copied over to the Notification Server.

Optionally the Notification Server can collect messages in advance without a collection order.

The collection includes eventually selection of messages with predefined criteria about contents or meta-data (Sender, Mail Storage Server, transport or protocol confiability) defined by the Recipient (inclusive/exclusive) or by the owner of the Server (exclusive). (Notes in parentesis = recomended behaviour).

(Message) retrieval order:

a Notification Server can be instructed to hand out messages to the Recipient.

Retrieve:

a Recipient can initiate a message retrieval operation directly. This implies a conection to the Mail Storage Server which holds the message, and copy the message from there to the local computer - be it the Notification Server or any Workstation the Recipient is using.

This is an optional function.

Scan:

a Recipient can scan a certain Mail Storage Server for publically available Messages, or for Messages posted for the Recipient itself.

This is an optional function.

Actors:

Sender, Recipient:

are virtual identities, which can be originators or recipients of messages. They can be asociated with human beeings, with mail robots (computer programs) or with client computers, accessing Storage or Notification Servers upon a Sender/Recipient identy.

(Mail/Message) Storage Server:

Is a computer (host) which allows certain Senders to deposit a message dedicated to zero one or more Recipients. The asociation of a particular Sender with a particular Storage Server can be verified at any time via a Directory Service that is not part of the message path.

The Storage Server provides physical storage room for the message, and means to notify the recipient - eventually repetedly, to autentify collect and retrieve attempts and to deliver messages.

Notification Server:

Is a computer (host) which is dedicated to reception of Notification Messages to certain Recipients. The asociation of a particular Recipient with a Notification Server can be verified at any time via a Directory Service that is not part of the message path.

Directory:

Is a means by which an Actor can proove to a known extent of trust the asociation of a virtual identity with a Message or with another Actor.

Known extent of trust means, that an Actor can take decisions based on the source of information - the particular Directory.

More profane: a Directory can be a local Blacklist or Whitelist, a keyserver, a username lookup, a "real" directory service like LDAP, and even an arbitrary piece of information, like the Return Address of a traditional Email.

Message Path Model