mod_ical

mod_ical is a iCalendar/jCal/xCal filter for Apache httpd. Allows iCal data to be filtered and made available to client side web clients in iCal, xCal and jCal formats.

The module was built to allow raw iCal data to embedded within websites and javascript applications without server side development.

Downloads

mod_ical is available as RPMs through COPR as follows:

dnf copr enable minfrin/mod_ical

Ubuntu packages are available through PPA.

Features

• Filter iCalendar entries to show the next entry, the last entry, all future entries or all past entries relative to the current date.

• Convert RFC5545 iCalendar streams into RFC6321 xCal XML streams.

• Convert RFC5545 iCalendar streams into RFC7265 jCal JSON streams.

• Control filtering, formatting and timezone conversion based on optional URL query parameters.

Filtering

Entries in the iCalendar stream can be filtered based on the following options:

• none: No filtering, return all entries.

• next: Return the next entry relative to the current date. Can be used to indicate upcoming events in a web application.

• last: Return the last entry relative to the current date. Can be used to highlight the most recently passed event in a web application.

• future: Return all entries whose end is past the current date. Can be used to list all upcoming events.

• past: Return all entries whose end is in the past relative to the current date. Can be used to list all past events.

Conversion

The output format of the iCalendar stream can be controlled through the use of the following filters:

• ICAL: Based on the contents of the Accept header, return the RFC5545 iCal streams, RFC6321 xCal streams or RFC7265 jCal streams depending on the client request. Can be used where control over the desired output format is requested by a client application.

• ICALICAL: Force output to RFC5545 iCal.

• ICALXCAL: Force output to RFC6321 xCal. Can be used where the output is being processed on the server side by XSLT.

• ICALJCAL: Force output to RFC7265 jCal. Can be used where the client is not able to control the Accept header.

Timezones

The default timezone of the calendar can be changed on the fly by providing either an ICalTimezone directive or a "tz" parameter containing the Olson city name.

All date and date-time values in the calendar will be updated to the new timezone appropriately.

This can be used to ensure that dates published to a web application are consistent regardless of the timezone setting of the backend calendar.

Configuration Directives

• ICalTimezone: Override the timezone on the calendar to the given location, for example Europe/London.

• ICalFilter: Set the filtering to 'none', 'next', 'last', future' or 'past'. Defaults to 'past'.

• ICalFormat: Set the formatting to 'none', 'spaced' or 'pretty'. Defaults to 'none'.

• ICalUid: Set an expression which, if it resolves to anything of non zero length, overrides the filter and returns the entry with the given UID. Defaults to unset.

Query Parameters

The configuration directives above can be overridden on a per URL basis by the addition of the following optional query parameters:

• tz: Override the timezone on the calendar to the given location, for example Europe/London.

• filter: Set the filtering to 'none', 'next', 'last', future' or 'past'.

• format: Set the formatting to 'none', 'spaced' or 'pretty'.

• uid: If set, overrides the filter and returns the entry with the given UID.

http://example.com/calendars/upcoming-events.ics?tz=Europe/London&filter=next&format=pretty

Example Configuration

The following example configuration shows how the ICAL filter can be added to the Apache httpd configuration.

LoadModule ical_module modules/mod_ical.so

<Location /calendars/>
  SetOutputFilter ICAL
  ICalFilter none
  ICalFormat pretty
</Location>

Using an additional PATH_INFO at the end of the calendar URL, explicit filters can be assigned to each URL as follows:

AcceptPathInfo on

# create a dedicated JSON view
# http://example.com/breaking-news.ics/json
<If "%{PATH_INFO} =~ /json/">
  SetOutputFilter ICALJCAL
</If>
# create a news view, passed through XSLT
# http://example.com/breaking-news.ics/news
<If "%{PATH_INFO} =~ /news/">
  SetOutputFilter ICALXCAL;XSLT
  TransformOptions +ApacheFS +XIncludes
  TransformSet /news.xsl
</If>

The following is an example of an XSLT stylesheet that could be used in the example above:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xcal="urn:ietf:params:xml:ns:icalendar-2.0" xmlns:date="http://exslt.org/dates-and-times" xmlns="http://www.w3.org/1999/xhtml" version="1.
0">
<xsl:output omit-xml-declaration="yes" method="html"/>
<xsl:template match="/xcal:icalendar">
  <xsl:for-each select="xcal:vcalendar/xcal:components/xcal:vevent">
    <xsl:choose>
      <xsl:when test="xcal:properties/xcal:url">
        <h3 class="vevent"><strong><xsl:text>Join us for </xsl:text><a class="summary"><xsl:attribute name="href"><xsl:value-of select="xcal:properties/xcal:url/xcal:uri"/></xsl:attribute><xsl:value-of select="xcal:properties/xcal:summary/xcal:text"/></a></strong><xsl:text> on </xsl:text><span class="dtstart"><xsl:attribute name="title"><xsl:value-of select="xcal:properties/xcal:dtstart/xcal:date-time"/></xsl:attribute><xsl:value-of select="date:day-in-month(xcal:properties/xcal:dtstart/xcal:date-time)"/><xsl:text> </xsl:text><xsl:value-of select="date:month-name(xcal:properties/xcal:dtstart/xcal:date-time)"/><xsl:text> at </xsl:text><xsl:value-of select="substring(date:time(xcal:properties/xcal:dtstart/xcal:date-time),0,6)"/></span><xsl:text> </xsl:text><span class="description"><xsl:value-of select="xcal:properties/xcal:description/xcal:text"/></span></h3>
      </xsl:when>
      <xsl:otherwise>
        <h3 class="vevent"><strong><xsl:text>Join us for </xsl:text><span class="summary"><xsl:value-of select="xcal:properties/xcal:summary/xcal:text"/></span></strong><xsl:text> on </xsl:text><span class="dtstart"><xsl:attribute name="title"><xsl:value-of select="xcal:properties/xcal:dtstart/xcal:date-time"/></xsl:attribute><xsl:value-of select="date:day-in-month(xcal:properties/xcal:dtstart/xcal:date-time)"/><xsl:text> </xsl:text><xsl:value-of select="date:month-name(xcal:properties/xcal:dtstart/xcal:date-time)"/><xsl:text> at </xsl:text><xsl:value-of select="substring(date:time(xcal:properties/xcal:dtstart/xcal:date-time),0,6)"/></span><xsl:text> </xsl:text><span class="description"><xsl:value-of select="xcal:properties/xcal:description/xcal:text"/></span></h3>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:for-each>

</xsl:template>
</xsl:stylesheet>

For more advanced configurations, see the mod_filter documentation for Apache httpd.

Version

0.0.7: Bugfix release.

Bugs

mod_ical has received light testing with respect to RFC compliance, and RFC compliance violations will be considered bugs and fixed in future versions.

License

mod_ical is released under the Apache License v2.

Dependencies

mod_ical depends on:

• Apache httpd - Apache httpd web server
• libical - Libical iCalendar library
• libxml2 - libxml2 XML library
• json-c - json-c JSON library