doc/tech-notes/introduction.html

   1 <HTML><HEAD><TITLE>Alpine Technical Notes: Introduction</TITLE></HEAD><BODY>
   2 <H1>Introduction</H1>
   3
   4 <H2><A NAME="design">Design Goals</A></H2>
   5
   6 Throughout <EM>Alpine</EM> development, we have had to strike a balance
   7 between the
   8 need to include features which advanced users require and the need to keep
   9 things simple for beginning users.  To strike this balance, we have tried
  10 to adhere to these design principles:  <P>
  11
  12 <DL COMPACT>
  13
  14 <DT>
  15
  16 <DD> - The model presented to the user has to be simple and
  17 clear.  Underlying system operation is hidden as much as possible.
  18
  19 <DT>
  20
  21 <DD> - It's better to have a few easily understood commands that can be
  22 repeated than to have some more sophisticated command that will do the job
  23 all at once.
  24
  25 <DT>
  26
  27 <DD> - Whenever the user has to select a command, file name, address,
  28 etc., the user should be given (or can get) a menu from which to make the
  29 selection. Menus need to be complete, small, organized and well thought
  30 out.
  31
  32 <DT>
  33
  34 <DD> - <EM>Alpine</EM> must provide immediate feedback for the user with each
  35 operation.
  36
  37 <DT>
  38
  39 <DD> - <EM>Alpine</EM> must be very tolerant of user errors.  Any time a user is
  40 about to perform an irreversible act (send a message, expunge messages
  41 from a folder), <EM>Alpine</EM> should ask for confirmation.
  42
  43 <DT>
  44
  45 <DD> - Users should be able to learn by exploration without fear of doing
  46 anything wrong. This is an important feature so the user can get started
  47 quickly without reading any manuals and so fewer manuals are required.
  48
  49 <DT>
  50
  51 <DD> - The core set of <EM>Alpine</EM> functions should be kept to a
  52 minimum so new
  53 users don't feel "lost" in seemingly extraneous commands and concepts.
  54 <P>
  55
  56 </DL> <P>
  57
  58 Just as there were goals relating to the look and feel of <EM>Alpine</EM>,
  59 there were
  60 equally important goals having to do with <EM>Alpine</EM>'s structure-the
  61 things that
  62 users never see but still rely on every time they use <EM>Alpine</EM>.
  63 While <EM>Alpine</EM>
  64 can be used as a stand-alone mail user agent, one of its strongest assets
  65 is its use of the Internet Message Access Protocol (IMAP) for accessing
  66 remote email folders.  In addition, <EM>Pine</EM> (the predecessor of <EM>Alpine</EM>) was one of
  67 the first programs to
  68 support the Multipurpose Internet Mail Extensions (MIME) specification.
  69 With MIME, <EM>Alpine</EM> users can reliably send any binary file to any other
  70 person on the Internet who uses a MIME compliant email program.  <P>
  71
  72 The decision to use IMAP and MIME reflects the importance of
  73 interoperability, standardization and robustness in <EM>Alpine</EM>.  As you work
  74 with <EM>Alpine</EM> more, you will see other features which reflect
  75 the same values.
  76 For example, <EM>Alpine</EM> enforces strict compliance with RFC 2822, implements a
  77 strong mail folder locking mechanism and verifies a process before
  78 overwriting any files (e.g. addressbook, expunging messages).  <P>
  79
  80 <H2><A NAME="components">Alpine Components</A></H2>
  81
  82 If you have picked up the <EM>Alpine</EM> distribution, then you already know that
  83 <EM>Alpine</EM> comes in a few different pieces.  They are:  <P>
  84
  85 <DL COMPACT>
  86
  87 <DT> <EM>Alpine</EM>
  88
  89 <DD> The main code from which the <EM>Alpine</EM> program is compiled.  <P>
  90
  91 <DT> <EM>Pico</EM>
  92
  93 <DD> <EM>Pico</EM> is the name for the <EM>Alpine</EM> composer.
  94 The <EM>Pico</EM> code is used in two
  95 ways:  (1) it is compiled on its own to be a stand-alone editor and, (2)
  96 it is compiled as a library for <EM>Alpine</EM> to support composition
  97 of messages within <EM>Alpine</EM>.
  98 <EM>Pico</EM> is <EM>Alpine</EM>'s internal editor invoked when users
  99 need to fill in header lines or type the text of an email message.  <P>
 100
 101 <DT> <EM>Imap</EM>
 102
 103 <DD> An API for IMAP.  Includes the C-Client library, which is compiled
 104 into <EM>Alpine</EM>, and the IMAP server <EM>IMAPd</EM>.
 105 C-Client implements the IMAP
 106 protocol and also negotiates all access between <EM>Alpine</EM> and
 107 the mail folders
 108 it operates on, even if the folders are local.
 109 The C-Client routines are used for email folder parsing
 110 and interpreting MIME messages. <EM>IMAPd</EM> is a separate server that handles
 111 IMAP connections from any IMAP-compliant email program.  When <EM>Alpine</EM>
 112 accesses a remote mailbox, the <EM>Alpine</EM> program is the IMAP client and the
 113 <EM>IMAPd</EM> program is the IMAP server. Of course, <EM>Alpine</EM> can
 114 use any IMAP-compliant IMAP server, not just <EM>IMAPd</EM>. <P>
 115
 116 </DL>
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