imapext-2007
view docs/drivers.txt @ 0:ada5e610ab86
imap-2007e
| author | yuuji@gentei.org |
|---|---|
| date | Mon, 14 Sep 2009 15:17:45 +0900 |
| parents | |
| children |
line source
1 /* ========================================================================
2 * Copyright 1988-2006 University of Washington
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 *
11 * ========================================================================
12 */
14 c-client Driver Characteristics
15 Mark Crispin
16 11 December 2006
19 Drivers are code modules that support different mailbox storage
20 technologies. A mailbox storage technology may be implemented by
21 1) files and directories on the local system
22 2) a database
23 3) a network protocol.
25 In the case of files and directories on the local system, a
26 driver supports a particular mailbox format. Mailbox formats are
27 discussed in more detail in the file formats.txt.
29 As of the date this document was written, there was no bundled
30 support for any databases in c-client. However, it should not be
31 particularly difficult to write a driver that communicates with a
32 database.
34 Network protocols supported by c-client drivers are the Internet
35 Mail Access Protocol (all versions: IMAP4rev1, IMAP4, IMAP2bis, and
36 IMAP2); the Post Office Protocol (version 3); and the Network News
37 Transport Protocol (NNTP). In addition, c-client also supports NNTP
38 and the Simple Mail Transport Protocol (SMTP) for mailbox transport.
40 By default, all drivers are enabled. There is little benefit to
41 be gained by disabling a driver, with one exception. The mbox driver
42 implements the behavior of automatically moving new mail from the
43 spool directory to the "mbox" file on the user's home directory, if
44 and *only* if the "mbox" exists and is in mailbox format. The mbox
45 driver is listed under EXTRADRIVERS; if you wish to disable it just
46 remove it from that list and rebuild.
48 I. Special name "INBOX"
50 The following rules to select INBOX and its format apply in
51 the order given if "black box mode" is not in effect:
52 1) mbox format is selected if file ~/mbox exists, and is in unix
53 format or is zero-length.
54 2) mx format is selected if file ~/INBOX/.mxindex exists.
55 3) mbx format is selected if file ~/INBOX exists and is in mbx format.
56 4) tenex format is selected if:
57 a) file ~/mail.txt exists, and is in tenex format or is zero-length.
58 b) file ~/INBOX exists and is in tenex format.
59 5) mtx format is selected if:
60 a) file ~/INBOX.MTX exists, and is in mtx format or is zero-length.
61 b) file ~/INBOX exists and is in mtx format.
62 6) mmdf format is selected if the spool directory file exists and is
63 in mmdf format.
64 7) unix format is selected if the spool directory file exists and is
65 in unix format.
66 8) the dummy driver is selected if the spool directory file does not
67 exist, or exists and is empty.
69 If "black box mode" is not in effect, messages are automatically
70 transferred ("snarfed") from the spool directory to an INBOX in mbox,
71 mx, mbx, tenex, and mtx formats.
73 The following rules to select INBOX and its format apply in the order
74 given if "black box mode" is in effect:
75 1) mx format is selected if file ~/INBOX/.mxindex exists.
76 2) mbx format is selected if file ~/INBOX exists and is in mbx format.
77 3) tenex format is selected if file ~/INBOX exists and is in tenex format.
78 4) mtx format is selected if file ~/INBOX exists and is in mtx format.
79 5) mmdf format is selected if file ~/INBOX exists and is in mmdf format.
80 6) unix format is selected if file ~/INBOX exists and is in unix format.
81 7) the dummy driver is selected if ~/INBOX does not exist, or exists
82 and is empty.
84 II. Special Name #mhinbox
86 #mhinbox always refers to the directory "inbox" in the MH path, which
87 is declared in the ~/.mh_profile file. Messages are automatically
88 transferred from the spool directory to #mhinbox mailbox.
91 III. Special Prefix "#mh/"
93 Any name prefixed with "#mh/" always refers to a directory in the MH
94 path, which is declared in the ~/.mh_profile file. For example, the name
95 "#mh/foo" refers to directory "foo" in the MH path.
98 IV. Special prefix "#news."
100 Any name prefixed with "#news" always refers to a newsgroup. For
101 example, the name "#news.comp.mail.misc" refers to newsgroup
102 "comp.mail.misc".
105 V. All Other Names
107 The driver is selected by generating a file name from the mailbox
108 name, and then examining the data of the object with the resulting
109 name. The formats are checked in order: mx, mbx, tenex, mtx, mmdf,
110 unix, and phile. The dummy driver is selected if the file is empty.
112 The file name is generated according to certain rules, based upon the
113 prefix of the mailbox name. On UNIX, the following rules apply:
115 Prefix Interpretation of Suffix
116 ------ ------------------------
117 / [black box] preceeds a user name; "/foo/bar" means
118 "black box user foo's mailbox bar"
119 [not black box] preceeds an absolute path name.
120 ~ [not black box] preceeds a user name; "~foo/bar" means
121 "UNIX user foo's mailbox bar"
122 #ftp/ preceeds UNIX user ftp's mailbox name
123 #public/ preceeds UNIX user imappublic's mailbox name
124 #shared/ preceeds UNIX user imapshared's mailbox name
126 All other names are interpreted in the context of the UNIX user's home
127 directory (not black box), the black box user's black box directory
128 (black box), or UNIX user ftp's home directory (anonymous).
130 The strings "..", "//", and /~ are forbidden in names in:
131 black box mode
132 #ftp, #public, or #shared names
133 anonymous users
135 Anonymous users may only access:
136 INBOX (belonging to UNIX user ftp)
137 files in or below UNIX user ftp's home directory
138 #ftp, #news, and #public namespace
140 VI. Driver Comparison
142 The following information about the local file drivers is an
143 elaboration of a table compiled by Osma Ahvenlampi.
145 Driver CA CE UID Kwd Sub NFS Performance Layout
146 ------ -- -- --- --- --- --- ----------- ------
147 unix no no yes yes no limited fair file
148 ;;; traditional UNIX format
149 mbox no no yes yes no limited fair file
150 ;;; traditional UNIX format, INBOX only, using ~/mbox with automatic
151 ;;; moving from the mail spool directory.
152 mmdf no no yes yes no limited fair file
153 ;;; default on SCO systems
154 mbx yes yes yes yes no no very good prefile
155 ;;; best performing local file driver; preferred format at UW
156 tenex yes no no limited no no good prefile
157 ;;; compatible with UNIX MM
158 mtx yes no no limited no no very good prefile
159 ;;; PC Pine standard format; compatible with TOPS-20; identical to tenex
160 ;;; but instead CRLF newlines instead of LF
161 mx yes buggy yes yes yes no poor ixdir
162 ;;; fullest function; *not* recommended due to performance problems and bugs;
163 ;;; to be redesigned/rewritten
164 mh yes no no no yes yes very poor dir
165 ;;; compatible with mh; #mhinbox for INBOX, #mh/ prefix for all other names
166 news yes no yes no yes yes very poor ixdir
167 ;;; local news spool access; #news. prefix for all names
168 phile no no no no no yes good file
169 ;;; reads arbitrary file as a single readonly message
171 IMPORTANT: the "performance" ratings are relative to other drivers,
172 and not necessarily to other software which implements those formats.
173 They relate to the driver's performance in typical operations such as
174 an IMAP "FETCH ALL".
176 Key to headings:
177 CA: concurrent read/write access
178 CE: expunge permitted in concurrent read/write access
179 UID: sticky UIDs
180 Kwd: keyword flags
181 Sub: subfolders
182 NFS: usable over network filesystems (NFS, AFS, etc.)
183 Layout: file - single file
184 prefile - file with preallocated space for state
185 dir - directory, messages are files
186 ixdir - directory, messages are files, with helper index
188 In addition, drivers imap, nntp, and pop3 support IMAP4rev1, NNTP, and
189 POP3 protocols respectively.