docs/master

annotate ch01.roff @ 40:7b620f6b1e97

style: TOC is in corporate design now; Extended AB macro and renamed it to H-.
author markus schnalke <meillo@marmaro.de>
date Tue, 15 May 2012 22:33:57 +0200
parents 6a9abf543297
children af8c46461924
rev   line source
meillo@39 1 .RN 1
meillo@39 2
meillo@0 3 .H0 "Introduction
meillo@0 4 .P
meillo@32 5 This chapter introduces MH, its history, concepts and how it is used.
meillo@32 6 Then, it describes nmh's code base and community to give the reader
meillo@32 7 a better understanding of the state from which mmh started off.
meillo@32 8 Further more, this chapter lists the motivation and goals of the mmh project.
meillo@32 9 This chapter introduces MH, nmh and mmh to the reader and outlines
meillo@32 10 the mmh project itself.
meillo@8 11
meillo@0 12
meillo@28 13 .H1 "MH \(en the Mail Handler
meillo@0 14 .P
meillo@2 15 MH is an electronic mail system, originating in the RAND Corporation.
meillo@32 16 Most important for this thesis is that MH defines a mail handling concept.
meillo@32 17 In fact, MH had started as a design proposal, not as an implementation,
meillo@32 18 and in spirit it had remained this way. This is similar to Unix, which
meillo@32 19 influenced the world rather in being a set of system design concepts
meillo@32 20 than in being a specific software product.
meillo@27 21 .P
meillo@27 22 XXX Link to the Unix phil.
meillo@27 23 .P
meillo@27 24 XXX comparision to monolithic mail systems.
meillo@27 25 .P
meillo@27 26 XXX Differenciation of MUA and mail system.
meillo@2 27
meillo@11 28 .U2 "History
meillo@2 29 .P
meillo@2 30 MH is an electronic mail system, originating in the RAND Corporation.
meillo@32 31 In 1977 at RAND Corporation, Norman Shapiro and Stockton Gaines
meillo@32 32 had proposed the design
meillo@32 33 of a new mail handling system, called ``Mail Handler'' (MH),
meillo@32 34 to superseed RAND's old monolithic ``Mail System'' (MS).
meillo@27 35 Two years later, in 1979, Bruce Borden took the proposal and implemented a
meillo@32 36 prototype of MH.
meillo@32 37 Before the prototype had been available, the concept was
meillo@32 38 believed to be practically unusable because of being too slow.
meillo@32 39 But the prototype proved successful and replaced MS thereafter.
meillo@32 40 In replacing MS, MH became an all-in-one mail system.
meillo@2 41 .P
meillo@32 42 A decade later, the University of California at Irvine had started to use MH.
meillo@2 43 They also took over its development and pushed MH forward.
meillo@32 44 This was the time when the Internet appeared, UCB implemented
meillo@32 45 the TCP/IP stack, and Allman wrote Sendmail.
meillo@32 46 MH was extended as emailing got more features.
meillo@32 47 The development of MH was closely related to the development of email
meillo@32 48 RFCs. In the advent of MIME, MH was the first implementation of this new
meillo@32 49 email standard.
meillo@2 50 .P
meillo@2 51 In the nineties, MH had been moved into the public domain, making it
meillo@32 52 attractive to Free Software developers.
meillo@32 53 The Internet had started to become popular and in 1997,
meillo@32 54 Richard Coleman initiated the ``New Mail Handler'' (nmh) project,
meillo@32 55 a fork of MH, based on the \fILBL changes\fP by Van Jacobson, Mike Karels
meillo@32 56 and Craig Leres.
meillo@32 57 Colman intended to modernize MH and improve its portability and
meillo@32 58 MIME handling capabilities.
meillo@32 59 This should be done openly within the Internet community.
meillo@32 60 The development of MH stopped soon after the development of nmh had started.
meillo@32 61 Today, nmh almost completely replaced the original MH.
meillo@0 62
meillo@11 63 .U2 "Concepts
meillo@0 64 .P
meillo@8 65 MH is a toolchest, modelled after the Unix toolchest. It consists of a
meillo@32 66 set of tools, each covering a specific task of email handling. The programs
meillo@8 67 operate on a common mail storage. The specific format of the mail storage
meillo@32 68 characterizes MH in the same way like the format of the file system
meillo@32 69 characterizes Unix.
meillo@32 70 The mail storage consists of \fImail folders\fP (directories) and
meillo@32 71 \fPmessages\fP (regular files).
meillo@32 72 Each message is stored in a separate file in the format it had been
meillo@32 73 received (i.e. transfer format). The files are named with ascending numbers
meillo@32 74 in each folder.
meillo@32 75 MH tools maintain a \fIcontext\fP, which includes
meillo@32 76 the current mail folder and current message.
meillo@32 77 Processes in Unix have a similar context, containing the current working
meillo@32 78 directory, for instance. In contrast, the process context is maintained
meillo@32 79 by the Unix kernel automatically, whereas MH tools need to maintain the MH
meillo@32 80 context themselves.
meillo@32 81 The user can have one MH context or multiple ones, he can even share it
meillo@32 82 with other users.
meillo@32 83 Messages can have symbolic names. These can be automatically updated
meillo@32 84 position names like being the next or the last message,
meillo@32 85 or user-settable group names for arbitrary sets of messages.
meillo@32 86 These names are called sequences.
meillo@32 87 Sequences can be bound to the folder or to the context.
meillo@2 88 .P
meillo@32 89 New MH tools are built out of or on top of existing ones easily \(en
meillo@32 90 a property common to toolchests.
meillo@32 91 Multiple versions of the same command with different default values
meillo@32 92 are created very easily. This provides shortcuts and tayloring.
meillo@32 93 Form templates for new messages or for replies are easily exchangable.
meillo@32 94 Generally, output is adjustable with format files.
meillo@32 95 The configuration is stored in a file that is called the user's \fIprofile\fP.
meillo@32 96 MH encourages the user to taylor and automate the mail handling.
meillo@32 97 Almost everypart of the system can be adjusted to personal preference.
meillo@32 98 The system is well scriptable and extendable.
meillo@32 99 As the MH toolchest was modelled after the Unix toolchest, the
meillo@32 100 properties of the latter apply to the former as well.
meillo@8 101
meillo@32 102 .U2 "Versions
meillo@27 103 .P
meillo@27 104 Three versions of MH are available today:
meillo@32 105 .IP "Old MH"
meillo@32 106 In most cases this version had been replaced by nmh,
meillo@32 107 but some systems might still provide old MH.
meillo@32 108 The main reasons to still use old MH are historical reasons.
meillo@32 109 MH provides hardly any benefits over nmh.
meillo@27 110 The development of old MH has stopped after the 6.8.4 release in
meillo@27 111 February 1996.
meillo@32 112 .IP nmh\0
meillo@27 113 The most widespread version of MH was forked off version 6.8.3 in December
meillo@32 114 1996. It is based on the \fILBL changes\fP.
meillo@32 115 Backward-compatibility to old MH is provided by having new featues deactivated
meillo@32 116 by default. In consequence, the user needs to activate them explicitely to
meillo@32 117 be able to use them.
meillo@32 118 Throughout the previous years, the work on nmh was mostly maintenance work.
meillo@32 119 Development revived in December 2011 and stayed busy since then.
meillo@32 120 .IP mmh
meillo@32 121 This descendent of nmh is the subject of this thesis.
meillo@32 122 It had started as an experimental version, but became de facto a fork.
meillo@8 123
meillo@27 124 .U2 "Example Session
meillo@27 125 .P
meillo@32 126 Following is an example mail handling session with mmh.
meillo@32 127 It should be mostly compatible with nmh and old MH.
meillo@32 128 Details might vary but the look'n'feel is the same.
meillo@32 129 .P
meillo@32 130 XXX shell mail handling session follows ...
meillo@27 131
meillo@27 132
meillo@28 133 .H1 "nmh: Code and Community
meillo@2 134 .P
meillo@8 135 In order to understand the state, goals and dynamics of a project,
meillo@8 136 one needs to know its history. MH comes from a time before the
meillo@8 137 Internet, a time before networking became universal, a time when
meillo@8 138 emailing was small, short and simple. Then it grew, spread and
meillo@8 139 adopted to the changes. The core-concepts, however, remained the
meillo@8 140 same. During the XXX a small group of students at the University of
meillo@8 141 California, actively worked on MH. They added features and optimized,
meillo@8 142 like it is common for scientific work. This is still in pre-ANSI C
meillo@8 143 times. The source code contains many ancient parts. Code constructs
meillo@8 144 specific to BSD or hardware of that time are usual.
meillo@2 145 .P
meillo@8 146 Nmh started eight years after the ANSI C standard had been
meillo@8 147 established. A more modern coding style entered the code base. Still
meillo@8 148 a part of the developers come from ``the old days''. The developer
meillo@8 149 base became more diverse and thus the code. Programming practices
meillo@8 150 from different decades merged into the project. Different coding
meillo@8 151 styles came together. It appears as if multiple peers added code
meillo@8 152 parts, resulting in a conclomeration rather than an homogenic
meillo@8 153 of-one-cast mail system. Still, the basic concepts hold it together.
meillo@8 154 They were mostly untouched throughout the years.
meillo@8 155 .P
meillo@8 156 Although, at the surface, nmh is a toolchest, meaning a collection
meillo@8 157 of completely modularized small programs, on the source code level,
meillo@8 158 it is much more interweaved. Parts of the basic functions are
meillo@8 159 collected in a MH standard library, which is good, but often
meillo@8 160 separate functions are compiled into programs, for effiency reasons.
meillo@8 161 This lead to intricate innards.
meillo@8 162 The advent of MIME rose the complexity of email by a magnitude. This
meillo@8 163 is visible in nmh. The MIME-related parts are the most complex ones.
meillo@8 164 It's also visible that MIME support had been added on top of the
meillo@32 165 old MH later. The MH style made this easily possible, but it
meillo@8 166 also lead to duplicated functions (e.g. \fLshow\fP, \fLmhshow\fP)
meillo@8 167 and had not been thoroughly included into the concepts (e.g. the
meillo@8 168 user-visible access to whole messages and MIME parts are inherently
meillo@8 169 different).
meillo@8 170 .P
meillo@8 171 For compatibility's sake, it is a common understanding to have the
meillo@8 172 default settings to be compatible, requiring any new feature to be
meillo@8 173 explicitely enabled. This puts a burden on new users, because nmh
meillo@8 174 out-of-the-box keeps staying in the same ancient style, where users
meillo@8 175 usually want to have it practical for modern emailing.
meillo@8 176 But of course, this depends on if nmh is seen to be a front-end or a
meillo@8 177 back-end.
meillo@8 178
meillo@8 179
meillo@27 180 .H1 "mmh
meillo@28 181 .P
meillo@28 182 I started to work on my experimental version, which I call
meillo@28 183 \fImmh\fP (for \fImeillo's mail handler\fP), in Fall 2011.
meillo@28 184 In December, when I announced that I would work on an experimental
meillo@28 185 version, the activity in nmh suddenly rose. Suddently the community
meillo@28 186 started to move.
meillo@28 187 After long years of mostly idling, nmh became actively developed again.
meillo@28 188 What a great result!
meillo@28 189 Hence, while I was working on mmh, the community was working on nmh
meillo@28 190 too. My own work went in parallel and mostly unrelated.
meillo@28 191 .P
meillo@28 192 Because of several circumstances, my experimental version is rather
meillo@28 193 a fork today, although this may change again in the future.
meillo@27 194
meillo@27 195 .U2 "Motivation
meillo@27 196 .P
meillo@27 197 XXX
meillo@27 198
meillo@27 199 .U2 "Why it is worth it
meillo@27 200 .P
meillo@27 201 XXX
meillo@27 202
meillo@27 203 .U2 "Target Field
meillo@27 204 .P
meillo@27 205 XXX Target field and scenarios
meillo@27 206 .P
meillo@27 207 The target user in mind likes Unix and its philosophy.
meillo@27 208 He likes to use programs that are conceptionally appealing.
meillo@27 209 He's familiar with the command line and enjoys its power.
meillo@27 210 He is at least capable of shell scripting and wants to improve his
meillo@27 211 productivity by scripting the mail system.
meillo@27 212 His computer and operating system are from post-ANSI C times.
meillo@27 213 He likes to attach files, exchanges text containing non-ASCII
meillo@27 214 characters, signs or encrypts his messages.
meillo@27 215 He does not use bulletin boards anymore, nor non-mbox style mail
meillo@27 216 drops, nor does he rely on compatibility to nmh.
meillo@27 217 He already has and MTA/MSA and MRA running or is able to set them
meillo@27 218 up.
meillo@27 219 He does not want to have to read a book in order to make his MUA
meillo@27 220 usable.
meillo@27 221 .P
meillo@27 222 XXX Limitations
meillo@27 223
meillo@27 224 .U2 "The Vision
meillo@8 225 .P
meillo@8 226 The general goals of the mmh project are the following:
meillo@8 227 .BU
meillo@8 228 I believe that mmh should be perfectly suited for modern emailing,
meillo@8 229 out-of-the-box.
meillo@8 230 .BU
meillo@8 231 I care less about compatibility and more about conceptionally elegant
meillo@8 232 approaches.
meillo@8 233 .BU
meillo@8 234 I care for general, clear, and simple concepts.
meillo@8 235 .BU
meillo@8 236 I like to create an of-one-style email system. It should feel like
meillo@8 237 cast as one.
meillo@8 238 .BU
meillo@8 239 I plan to remove any optimizations that rises obscurity, unless it
meillo@8 240 appears to be neccessary to make mmh usable at all.
meillo@8 241
meillo@27 242 .U2 "Work to do
meillo@8 243 .BU
meillo@27 244 Remove the MTA and MRA facilities. Mmh shall concentrate on the MUA
meillo@8 245 task. Mail shall enter mmh's mail storage via the system mail drop
meillo@8 246 and it shall leave mmh via the local \fLsendmail\fP command.
meillo@8 247 .BU
meillo@8 248 Remove any further functions that are not related to mmh's main task.
meillo@8 249 Bulletin board support is on example. Also remove support for ancient
meillo@8 250 technologies, like hardcopy terminals.
meillo@8 251 .BU
meillo@8 252 Refactor the source code to meet modern style criteria. Use
meillo@8 253 standardized library functions when possible.
meillo@8 254 .BU
meillo@8 255 Replace performance optimizations by clear and readable code.
meillo@8 256 .BU
meillo@8 257 Reduce the feature set to the commonly used one, removing
meillo@8 258 corner-cases. Set sane default values.
meillo@8 259 .BU
meillo@8 260 Add better attachment support. Add support for digital signatures and
meillo@8 261 encryption.
meillo@8 262 .BU
meillo@8 263 Merge \fLshow\fP and \fLmhshow\fP into one single mail display program.
meillo@8 264 Integrate MIME support deeper and more natural into MH.
meillo@8 265 .BU
meillo@8 266 Provide a ready-to-use setup out-of-the-box.
meillo@27 267
meillo@27 268
meillo@27 269 .H1 "Goals of this Thesis
meillo@27 270
meillo@27 271 .U2 "Methods
meillo@27 272 .P
meillo@27 273 foo