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1.4 +Introduction
1.5 +============
1.6 +
1.7 +The fburl software provides an extension for Lightning/Iceowl (the calendar
1.8 +extension for Mozilla Thunderbird/Icedove) that can obtain free/busy URL
1.9 +details from LDAP directories registered as address books. Thus, when the
1.10 +free/busy dialogue is opened, availability information for event participants
1.11 +may be shown if their contact details are supplied by an LDAP directory, if
1.12 +those details include an FBURL property, and if that property refers to a
1.13 +valid iCalendar VFREEBUSY component residing on an accessible Web server.
1.14 +
1.15 +More information about FBURL can be found in the following document:
1.16 +
1.17 +http://tools.ietf.org/html/rfc2739
1.18 +
1.19 +Other Sources of Free/Busy Information
1.20 +======================================
1.21 +
1.22 +Although not currently supported by this software, FBURL information could be
1.23 +obtained from vCard objects:
1.24 +
1.25 +https://tools.ietf.org/html/rfc6350#section-6.9
1.26 +
1.27 +In Thunderbird, this would involve opening an address book and obtaining a
1.28 +card object (from a non-LDAP source) that can provide the FBURL property.
1.29 +Unfortunately, the built-in address books do not seem to support the FBURL
1.30 +property. Moreover, when vCard information is imported, properties such as
1.31 +FBURL that are not part of the traditional set of vCard properties are
1.32 +discarded.
1.33 +
1.34 +Although not directly related to FBURL and over-the-Web free/busy resource
1.35 +retrieval, such information may also be exchanged using iMIP and normal e-mail
1.36 +communications:
1.37 +
1.38 +https://tools.ietf.org/html/rfc6047
1.39 +
1.40 +Thunderbird supports iMIP for VEVENT and VTODO components but not for
1.41 +VFREEBUSY components. Support for VFREEBUSY would require received components
1.42 +to be recorded in a suitable repository so that they may then be consulted by
1.43 +a specific free/busy provider when scheduling events. The sending of VFREEBUSY
1.44 +components would involve access to the user's schedule and the construction of
1.45 +iCalendar output from such information. Control over free/busy sharing would
1.46 +need to be exercised, probably requiring configuration settings to indicate
1.47 +whether such information is sent along with other iMIP payloads and with whom
1.48 +such information may be shared.
1.49 +
1.50 +With iMIP, the effective "FBURL" of a contact would in fact be the e-mail
1.51 +address of that contact or, more accurately, the address expressed using the
1.52 +mailto URI scheme. Thus, wider support for FBURL in vCard-handling and in
1.53 +Thunderbird address books would let users indicate that they can expect
1.54 +free/busy information via iMIP from certain contacts and, in their own vCard
1.55 +details, that they will publish their own availability details via iMIP.
1.56 +
1.57 +Contact, Copyright and Licence Information
1.58 +==========================================
1.59 +
1.60 +See the following Web pages for more information about this work:
1.61 +
1.62 +http://hgweb.boddie.org.uk/fburl
1.63 +
1.64 +The author can be contacted at the following e-mail address:
1.65 +
1.66 +paul@boddie.org.uk
1.67 +
1.68 +Copyright and licence information can be found in the docs directory - see
1.69 +docs/COPYING.txt for more information.