imip-agent

docs/wiki/Developing

1465:0c623c86704f
2020-08-03 Paul Boddie Changed diagram font to sans-serif.
     1 = Developing imip-agent =     2      3 To start developing the imip-agent software further, first obtain the code     4 by following the advice on the [[../Downloads|downloads page]]. Obtaining     5 the code directly from the repository is advisable since any changes you     6 make can then be tracked and managed.     7      8 <<TableOfContents(2,3)>>     9     10 == Distribution Contents ==    11     12 The software distribution contains the following directories:    13     14 {{{#!table    15 '''Directory''' || '''Description'''    16 ==    17 `conf`    18 || Example configuration files (see the    19 .. [[../GettingStarted|getting started guide]] for details)    20 ==    21 `docs`    22 || Documentation, including these wiki pages    23 ==    24 `htdocs`    25 || Resources for the [[../CalendarManager|management interface]]    26 ==    27 `imiptools`    28 || A Python package providing mail handling and support for calendar    29 .. object processing    30 ==    31 `imipweb`    32 || A Python package providing Web-related functionality for the    33 .. [[../CalendarManager|management interface]]    34 ==    35 `messages`    36 || Localised messages for the [[../AgentPrograms|agent programs]] and    37 .. [[../CalendarManager|management interface]]    38 ==    39 `tests`    40 || A suite of tests used to verify the behaviour of the software    41 .. (see the [[../Testing|testing guide]])    42 ==    43 `tools`    44 || Tools for [[../Administration|administration]] (see also the    45 .. [[../GettingStarted|getting started guide]])    46 }}}    47     48 At the top level of the distribution, the following files are found:    49     50 {{{#!table    51 '''File''' || '''Description'''    52 ==    53 `imip_person.py`    54 ||<rowspan="3"> The main program files for the    55              .. [[../AgentPrograms|agent programs]]    56 ==    57 `imip_person_outgoing.py`    58 ==    59 `imip_resource.py`    60 ==    61 `imip_manager.py`    62 || The [[../CalendarManager|management interface]] main program file    63 ==    64 `markup.py`    65 || A Python library providing HTML generation support    66 ==    67 `README.txt`    68 || Some basic documentation    69 ==    70 `vCalendar.py`    71 ||<rowspan="3"> Handling of vCalendar and related data formats    72 ==    73 `vContent.py`    74 ==    75 `vRecurrence.py`    76 }}}    77     78 == Architectural Components ==    79     80 The principal components of the software architecture are described below.    81     82 === vContent ===    83     84 The v-prefixed libraries are concerned with the basic interpretation of    85 calendar-related data. For the most part, these libraries should already    86 behave in a predictable and reliable fashion and should not need much    87 further development. There are perhaps some deficiencies in the    88 `vRecurrence` module that are described on the    89 [[../CalendaringSupport|calendaring standards page]].    90     91 It is not inconceivable that a `vCard` module be introduced in the future    92 to handle vCard data, thus enhancing the data about people within    93 imip-agent, perhaps also supporting mechanisms to obtain free/busy and    94 other information about scheduling participants.    95     96 === imiptools ===    97     98 The bulk of the work done in imip-agent happens within `imiptools`. When    99 used from [[../AgentPrograms|agent programs]] launched by the mail system,   100 the different modules support the "handler" functionality that involves   101 obtaining information from calendar data, performing the necessary action   102 related to a scheduling method, and generating responses or notifications.   103 More details are given about these activities in the guide to   104 [[../IncomingMessages|incoming message handling]].   105    106 When used from the [[../CalendarManager|management interface]], the   107 modules support the Web-based functionality as a more general calendar   108 system client, typically handling a single calendar object at any given   109 time.   110    111 The `imiptools.stores` package provides the basis for calendar data   112 persistence. From the very start, the nature of data organisation for   113 calendar users was centred on the storage of each user's free/busy records,   114 since the priority was to generate such records from messages exchanged   115 over e-mail, and the use of plain text files was chosen as the simplest   116 and most transparent approach. Beyond this, the need to retain calendar   117 objects arose, and thus a [[../FilesystemUsage|filesystem-based approach]]   118 was cultivated to manage such data.   119    120 In the future, other persistence mechanisms could be supported. However,   121 aside from performance concerns around access to free/busy schedules,   122 there may be no urgent need to adopt relational database technologies,   123 particularly as each user's data should remain isolated from that of   124 other users, and thus the volumes of data should remain relatively small   125 if managed well enough.   126    127 === imipweb ===   128    129 Most of the `imipweb` package is concerned with the display of calendar   130 information as Web pages and the handling of submitted data over the Web   131 as users interact with those Web pages. The `imip_manager.py` file is   132 deployed as a [[https://tools.ietf.org/html/rfc3875|CGI]] program, and it   133 acts as a simple "switch" that shows the appropriate kind of Web page (or   134 "view") depending on the requested URL, delegating to one of the modules   135 within the `imipweb` package to do so:   136    137 || '''Module'''       || '''View'''        ||   138 || `imipweb.calendar` || Calendar          ||   139 || `imipweb.event`    || Individual events ||   140 || `imipweb.profile`  || User profile      ||   141    142 A general `imipweb.resource` module supports the different views with   143 common functionality. Useful abstractions for period and date information   144 are provided in the `imipweb.data` module. The CGI interfacing is defined   145 in the `imipweb.env` module.   146    147 One of the most awkward aspects of providing a Web interface to events is   148 the need to provide a comprehensive enough representation of period data   149 as expressed in calendar objects that can be held in a form defined in a   150 Web page, interpreted by the program, written back to the form, all   151 without losing information.   152    153 == Localisation ==   154    155 The traditional [[https://www.gnu.org/s/gettext|gettext]] mechanisms for   156 translating labels, messages and other user-readable strings are employed   157 in the imip-agent code. Some tools have been provided to maintain this   158 localisation.   159    160 To extract "messages" from the code, run the `tools/i18n_messages.sh`   161 script:   162    163 {{{   164 tools/i18n_messages.sh   165 }}}   166    167 This produces a file called `imip-agent.pot` in the current directory,   168 and it also attempts to merge any new messages into the existing message   169 translations found in the `messages` directory. Such translation files   170 have the following form:   171    172 {{{   173 messages/xx_XX.imip-agent.po   174 }}}   175    176 Here, `xx` is usually an [[WikiPedia:ISO_639-1|ISO 639-1]] language code,   177 whereas `XX` is usually an [[WikiPedia:ISO_3166-1|ISO 3166-1]] country code.   178    179 Translators should inspect and edit their files in the `messages`   180 directory and then use the `tools/i18n_format.sh` script to generate the   181 translations that the software will use:   182    183 {{{   184 tools/i18n_format.sh   185 }}}   186    187 This installs the "compiled" translations into the `locale` directory in   188 a location of the following form:   189    190 {{{   191 locale/xx_XX/LC_MESSAGES/imip-agent.mo   192 }}}   193    194 The `tools/install.sh` script will copy the `locale` directory into the   195 installation location unless the `--no-locale-dir` option is given. This is   196 provided to allow any centrally-installed translations to take precedence   197 over any locally-available translations.