[Gzz] New PEG: email_storage--marc

[Marc Schiereck]

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PEG email_storage
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:Authors:      Marc Schiereck
:Date:         $Date: 2002/10/28 20:29:03 $
:Revision:     $Revision: 1.1 $
:Date-Created: 2002-10-28
:Status:       incomplete

Issues
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* How are emails stored in a mediaserver.

  - The way header and body of e-mails get separated.

  - The same for multipart-message.

  - How are header-blocks and body-blocks connected.

Rationale
---------

Description
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When saving non-multipart-messages, header and body get
separated and saved in a block respectively. In order
to preserve the connection between header and body the
content-type of the e-mail needs to be changed to
message/external-body. In addition a new access-type, 
called ``storm`` is introduced. It has a parameter 
``block`` which holds the ID of the block containing 
the body.

An example::

    Content-Type: message/external-body;
      access-type="storm";
      block="ID"

This works similar for multipart-messages. The message
header stays untouched. Only the bodies of the individual
parts get stored in mediaserver blocks (one for each
body) while the message header and the heades of the
individual parts get saved in the same block. The 
content-type of the message-parts gets changed to 
message/external-body and the parameters ``access-type``
and ``block`` are added as in non-multipart-messages.

An example for a multipart-header::

    From: Marc Schiereck <address@hidden>
    To: gzz developers list <address@hidden>
    Subject: Sample message 
    Content-type: multipart/mixed;
                  boundary="boundary" 
    --boundary            
    Content-Type: message/external-body;
                  access-type="storm";    
                  block="<ID-part1>"

    --boundary
    Content-Type: message/external-body;
                  access-type="storm";    
                  block="<ID-part2>"

    --boundary--