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\documentstyle[blackandwhite,small,trademark] {NRslides}

\title {PP --- A Message Transfer Agent}

\author {S.E. Kille \\
Department of Computer Science \\
University College London}

\date {October 1988}
\raggedright

\begin {document}

\maketitlepage

\begin {bwslide}
\ctitle {What is PP}

\begin {itemize}
\item A Message Transfer Agent:

\begin {itemize}
\item Multiple Message Transfer Protocols, including X.400
\item Protocol and Format Conversion
\item Suitability for high levels of traffic
\end {itemize}
\item Use on \unix/.
\item Openly Available as a part of the ISODE
\item A name and not an acronym
\end {itemize}


\end {bwslide}

\begin {bwslide}
\ctitle {Why PP}

\begin {itemize}
\item  Current RFC 822 based MTAs such as MMDF or Sendmail have:
\begin {itemize}
\item Support for multiple UAs
\item Support for a range of protocols
\item Integrated within the \unix/ environment
\item No support for X.400
\item Not suitable to extend for X.400
\end {itemize}

\item X.400 MTAs considered for replacing the older MTAs have:
\begin {itemize}
\item X.400
\item Not a lot else (procrustean)
\item Wrong price
\item Caveat: I may not have looked at {\em your} MTA
\end {itemize}

\item PP Aims to
\begin {itemize}
\item Support {\em full} X.400 functionality --- not just the protocols

\item Provide good local functionality

\item Be available at the right price --- free

\item Encourage a higher standard of X.400 implementation
\end {itemize}

\end {itemize}

\end {bwslide}



\begin {bwslide}
\ctitle {Goals (1)}

\begin {itemize}
\item Provision of a clean interface for message submission and
delivery, to support a wide range of User Agents.
\begin {itemize}
\item Procedural
\item Protocol
\end {itemize}

\item Support for all of the Message Transfer Service Elements specified by
the 1984 and 1988 versions of X.400.

\item Support for some services not provided by X.400.

\item Specific support to facilitate the handling of multimedia
messages.

\item Robustness and efficiency required to support high levels of
traffic.

\item Scheduling of message delivery in a sophisticated manner, to 
optimise local and communication resources.
\end {itemize}
\end {bwslide}

\begin {bwslide}
\ctitle {Goals (2)}

\begin {itemize}
\item Provision of a range of management, authorisation and monitoring
facilities.

\item Reformatting between body part types in a general manner.

\item Support for multiple address formats (initially two).

\item Use of
standardised OSI Directory Services.

\item Support for message protocol conversion in an integrated
fashion.

\item Full access to the Message Transfer Service for applications
other than Inter-Personal Messaging.

\end {itemize}
\end {bwslide}


\begin {bwslide}
\ctitle {Process Structure}
\vspace{2ex}
\diagram[p]{structure}
\end {bwslide}


\begin {bwslide}
\ctitle {Queue Structure}
\begin {itemize}
\item Each queued message is represented by a text encoded file, with
functionality corresponding to the P1 envelope, with extensions. This
includes the following per-message parameters:
\begin {itemize}
\item Message Originator
\item Message ID
\item Trace Information
\item Open-ended list of encoded information types
\end {itemize}

And include the following per-user parameters:
\begin {itemize}
\item Unique key
\item Address of the recipient 
\item Sequence of channels to process the message
\item Processing status
\end {itemize}


\item A \unix/ directory containing:
\begin {itemize}
\item The original message
\item Converted variants of the original message
\item Associated Delivery Notifications
\end {itemize}

\end {itemize}

\end {bwslide}


\begin {bwslide}
\ctitle {Queue Example (part 1)}

\footnotesize
\begin {verbatim}
Start-of-MsgEnvPrm  
Message-type User-Mpdu  
Message-size 257  
Queued-date "880919163408+0000"  
Departure-date  
Inbound-channel x400in  
Inbound-host cs.ucl.ac.uk  
Number-warnings 0  
Warning-time 0  
Return-time 0  
Content-type p2  
Encoded-info EncTypes undefined  
Priority normal  
PerMsg-Flags disclose-recipients  
PerMsg-Flags return-contents  
MsgId Country GB  
MsgId Admin GOLD 400  
MsgId Prmd UK.AC  
MsgId string "880919152949+0000"
Trace Country GB  
Trace Admin GOLD 400  
Trace Prmd UK.AC  
Trace arrival-time "880919152949+0000"
Trace action relayed  
Trace End-of-unit  
Trace Country GB  
Trace Admin GOLD 400  
Trace Prmd UK.AC  
Trace arrival-time "880919163413+0000"  
Trace action relayed  
Trace End-of-block  
\end{verbatim}
\end {bwslide}


\begin {bwslide}
\ctitle {Queue Example (part 2)}

\footnotesize
\begin{verbatim}
Start-of-MsgEnvAddr  
Origs rno=000 status=done dn=000 reform-nxt=000 
  reform-list=empty ext-id=0   
  resp=n mta-rreq=basic usr-rreq=basic 
  mta=pyr1.cs.ucl.ac.uk   
  outchan=local explicit=0 
  type=a822 subtype=empty   
  orig=/S=alina/OU=CS/O=UCL/PRMD=UK.AC/ADMD=GOLD\ 400/C=GB/ 
  x400=/S=alina/OU=CS/O=UCL/PRMD=UK.AC/ADMD=GOLD\ 400/C=GB/ 
  rfc=alina@cs.ucl.ac.uk
  End-of-addr  
Recip rno=001 status=dliv dn=001 reform-nxt=000 
  reform-list=empty ext-id=1   
  resp=y mta-rreq=basic usr-rreq=basic 
  mta=pamir 
  outchan=x400out explicit=0 
  type=x400 subtype=empty   
  orig=/S=test/OU=mirsa/O=inria/PRMD=aristote/ADMD=PTT/C=Fr/   
  x400=/S=test/OU=mirsa/O=inria/PRMD=aristote/ADMD=PTT/C=Fr/   
  rfc=empty 
  End-of-addr  
\end{verbatim}
\end {bwslide}


\begin {bwslide}
\ctitle {Queue Structure}
\vspace{2ex}
\diagram[p]{dir}

\end {bwslide}


\begin {bwslide}
\ctitle {Message Submission}
\begin {itemize}
\item Submission may be from:
\begin {itemize}
\item Local User Agent
\item Remote User Agent (e.g P3)
\item Protocol Server (e.g. P1)
\end {itemize}

\item Submit process uses a private protocol:
\begin {itemize}
\item Text based (derived from queue structure)
\item Local IPC
\item Superset of features of other protocols
\item Address checking before message copying
\end {itemize}

\item Initial Address checking provides:
\begin {itemize}
\item Routing
\item Conversion control
\item Authorisation
\item Multiple address formats
\end {itemize}

\item Submission of one or more body parts

\end {itemize}
\end {bwslide}



\begin {bwslide}
\ctitle {Conversion}
\begin {itemize}
\item Messages structured as \unix/ directory hierarchy

\item Body part names indicate their type (e.g. ``3.P2.IA5'')

\item Conversion creates new copy of message

\item Unaffected body parts  are linked

\item Format conversion of body parts

\item Message restructuring

\item Protocol conversion
\end {itemize}

\end {bwslide}


\begin {bwslide}
\ctitle {Queue Mangement}

\begin {itemize}
\item The Queue Manager (QMGR) holds representation of queue in memory, and {\
em
never} reads the disk

\item Access to the QMGR is through ROS
\begin {itemize}
\item Use of ROSY from ISODE
\end {itemize}

\item Controls channels, and gives flexible scheduling

\item Management facilities

\item MTA Console
\end {itemize}


\end {bwslide}


\begin {bwslide}
\ctitle {Items for PP 4.0}
\begin {itemize}
\item Protocols
\begin {itemize}
\item P1(1984)
\item SMTP
\item JNT Mail
\item UUCP
\end {itemize}

\item Conversion
\begin {itemize}
\item RFC 987/1026
\item RFC 934
\item UK domain ordering
\end {itemize}

\item User Interfaces
\begin {itemize}
\item Text based X.400 interface
\item MH
\item Assorted RFC 822 interfaces
\end {itemize}

\item Distribution Lists

\item Use of X.500 (QUIPU)

\end {itemize}

\end {bwslide}


\begin {bwslide}
\ctitle {Further Items}
\begin {itemize}
\item MTA Console
\item P1 (1988)
\item Additional body part formatters
\item RFC 987 (1988)
\item P2 $\Leftrightarrow$ P22
\item Message Store (P3/P7)
\item Operation over PSTN
\end {itemize}

\end {bwslide}


\begin {bwslide}
\ctitle {Availability of PP}
\begin {itemize}
\item To be distributed with ISODE 5.0 in January 1989
\item Available by Internet FTP and FTAM from Delaware
\item Available by NIFTP and FTAM from UCL
\item Available by post from Pennsylvania Univ, UCL, CWI and CSIRO
\end {itemize}

\end {bwslide}

\end {document}
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