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<!-- Module User's Guide -->

<chapter>
	
	<title>&adminguide;</title>
	
	<section>
	<title>Overview</title>
	<para>
		This module provides time recurrence matching functions. The format
		of recurrence definitions is based on Internet Calendaring and 
		Scheduling Core Object Specification (Calendar COS - RFC 2445).
		It also provides a port of the Perl Time::Period module for generic
		time period matching.
	</para>
	</section>

	<section>
	<title>Dependencies</title>
	<section>
		<title>&kamailio; Modules</title>
		<para>
		The following modules must be loaded before this module:
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>None</emphasis>.
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>
	<section>
		<title>External Libraries or Applications</title>
		<para>
		The following libraries or applications must be installed before running
		&kamailio; with this module loaded:
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>None</emphasis>
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>
	</section>
	<section>
	<title>Parameters</title>
	<section>
		<title><varname>separator</varname> (str)</title>
		<para>
			Separator character used to delimit attributes in time
			reccurence definitions.
		</para>
		<para>
		<emphasis>
			Default value is '|'.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>separator</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("tmrec", "separator", ";")
...
</programlisting>
		</example>
	</section>
	</section>

	<section>
	<title>Functions</title>
	<section>
	    <title>
		<function moreinfo="none">tmrec_match(timerec [, timestamp])</function>
	    </title>
	    <para>
			Match a time recurrence rule against the timestamp (UNIX epoch
			format). If the timestamp parameter is missing, the current UNIX
			epoch time is used.
		</para>
		<para>
			The parameters can include pseudo-variables.
		</para>
		<para>
			The timerec paramter is a list of attributes defined by RFC2445,
			delimited by the 'separator' (module parameter) character. The format
			of timerec parameter, using '|' as the separator, is (all in one line
			without white spaces):
		</para>

		<programlisting format="linespecific">
...
[startdate]|[duration]|[frequency]|[until]|[interval]|[byday]
  |[bymonthday]|[byyearday]|[byweekno]|[bymonth]
...
</programlisting>

		<para>
		When an attribute is not specified, the corresponding place must be left
		empty, provided that one or more additional attributes follow.
		</para>
		<para>
		Description of time recurrence attributes:
		</para>
		<itemizedlist>
		<listitem>
			<para>
			<emphasis>startdate</emphasis> - date for the start of the first 
			period.
			</para>
		</listitem>
		<listitem>
			<para>
			<emphasis>duration</emphasis> - the duration of the time period.
			For a recurring interval, the <quote>duration</quote> parameter MUST
			be small enough such that subsequent intervals do not overlap. 
			For non-recurring intervals, durations of any positive length are 
			permitted.  Zero-length duration means <quote>forever</quote>. 
			Negative-length durations are not allowed. See RFC 2445 for
			the format of duration.
			</para>
		</listitem>
		<listitem>
			<para>
			<emphasis>frequency</emphasis> - can be one of the following values: 
			<quote>daily</quote> -
			specify repeating periods based on an interval of a day or more;
			<quote>weekly</quote> - specify repeating periods based on an 
			interval of a week or more; <quote>monthly</quote> - specify 
			repeating periods based on an interval of a month or more; 
			<quote>yearly</quote> - specify repeating periods based
			on an interval of a year or more. These values are case-insensitive.
			</para>
		</listitem>
		<listitem>
			<para>
			<emphasis>until</emphasis> - defines an iCalendar COS DATE or DATE-TIME
			value which bounds the recurrence rule in an inclusive manner. If the
			value specified by <quote>until</quote> is synchronized with the 
			specified recurrence, this date or date-time becomes the last instance 
			of the recurrence. If it is not present, the recurrence is considered 
			to repeat forever.
			</para>
		</listitem>
		<listitem>
			<para>
			<emphasis>interval</emphasis> - a positive integer 
			representing how often the recurrence rule repeats. The default value
			is <quote>1</quote>, meaning every day for a <quote>daily</quote> rule,
			every week for a <quote>weekly</quote>
			rule, every month for a <quote>monthly</quote> rule and every year for
			a <quote>yearly</quote> rule.
			</para>
		</listitem>
		<listitem>
			<para>
			<emphasis>byday</emphasis> - a comma-separated list short codes of days 
			of the week. The days are specified as: <quote>MO</quote> for Monday;
			<quote>TU</quote> for Tuesday; <quote>WE</quote> for Wednesday; 
			<quote>TH</quote> for Thursday; <quote>FR</quote> for 
			Friday; <quote>SA</quote> for Saturday; <quote>SU</quote> 
			for Sunday. These values are case insensitive.
			</para>
			<para>
			Each <quote>byday</quote> value can also be prefixed by a positive 
			(+n) or negative (-n) integer. If present, this indicates the n-th 
			occurrence of the specific day within the <quote>monthly</quote> or 
			<quote>yearly</quote> recurrence. For example, within a 
			<quote>monthly</quote> rule, +1MO (or simply 1MO) represents the first 
			Monday within the month, whereas -1MO represents the last Monday of
			the month. If an integer modifier is not present, it means all days
			of this type within the specified frequency. For example, within a 
			<quote>monthly</quote> rule, MO represents all Mondays within the month.
			</para>
		</listitem>
		<listitem>
			<para>
			<emphasis>bymonthday</emphasis> - a comma-separated
			list of days of the month. Valid values are 1 to 31 or -31 to -1. For 
			example, -10 represents the tenth to the last day of the month.
			</para>
		</listitem>

		<listitem>
			<para>
			<emphasis>byyearday</emphasis> - a comma-separated list of 
			days of the year. Valid values are 1 to 366 or -366 to -1. For example,
			-1 represents the last day of the year (December 31st) and -306 
			represents the 306th day before the last day of the year (March 1st).
			</para>
		</listitem>
		<listitem>
			<para>
			<emphasis>byweekno</emphasis> - a comma-separated list of 
			ordinals specifying weeks of the year. Valid values are 1 to 53 or 
			-53 to -1.
			</para>
		</listitem>
		<listitem>
			<para>
			<emphasis>bymonth</emphasis> - parameter specifies a comma-separated
			list of months of the year. Valid values are 1 to 12.
		</para>
		</listitem>
		</itemizedlist>
		
		<para>
		A recurrence is specified by including the <quote>frequency</quote> 
		parameter, which indicates the type of the recurrence rule. Parameters 
		other than <quote>startdate</quote>
		and <quote>duration</quote> SHOULD NOT be specified unless 
		<quote>frequency</quote> is set.
		</para>
		<para>
		If invalid byxxx parameter values are found (ie, bymonthday=<quote>30</quote> in February), 
		they are simply ignored. 
		</para>
		<para>
		Byxxx parameters modify the recurrence rule matching. The Byxxx rule, as
		an attribute for a period of time which is greater than or equal to the 
		frequency, generally reduces or limits the number of occurrences for the 
		recurrence definition. For example, frequency=<quote>daily</quote> 
		bymonth=<quote>3</quote> reduces the number of
		recurrence instances from all days (if the <quote>bymonth</quote> 
		parameter is not present) to all days in March. Byxxx parameters for 
		a period of time less than the frequency generally increases or expands 
		the number of occurrences of the recurrence. For example, 
		frequency=<quote>yearly</quote> bymonth=<quote>8,9</quote>
		increases the number of days within the yearly recurrence set from 1 
		(if <quote>bymonth</quote> parameter is not present) to 2.
		</para>
		<para>
		If multiple Byxxx parameters are specified, then after evaluating the
		specified <quote>frequency</quote> and <quote>interval</quote> parameters,
		the Byxxx parameters are 
		applied to the current set of evaluated occurrences in the following
		order: <quote>bymonth</quote>, <quote>byweekno</quote>, 
		<quote>byyearday</quote>, <quote>bymonthday</quote>, 
		<quote>byday</quote>; then <quote>until</quote> is  evaluated.
		</para>
		<para>
		Next is an example of evaluating multiple Byxxx parameters.
		</para>
		<para>
		startdate=<quote>20100101T093000</quote> duration=<quote>10H30M</quote>
		frequency=<quote>yearly</quote> interval=<quote>4</quote> 
		bymonth=<quote>3</quote> byday=<quote>SU</quote>
		</para>
		<para>
		First, the interval=<quote>4</quote> would be applied to 
		frequency=<quote>yearly</quote> to match on <quote>every 4th year</quote>
		. Then, bymonth=<quote>1</quote> would be applied to match on 
		<quote>every March, every 4th year</quote>. Then,
		byday=<quote>SU</quote> would be applied to match on <quote>every 
		Sunday in March, every 4th year, from 9:30 to 20:00 </quote>. The start
		and end hours:minutes have been retrieved from the
		<quote>startdate</quote> and <quote>duration</quote> parameters.
		</para>

		<para>
		This function can be used in ANY_ROUTE.
		</para>
		<example>
		<title><function>tmrec_match</function> usage</title>
		<programlisting format="linespecific">
...
	if(tmrec_match("20120101T000000|PT24H|weekly|||SA,SU")
        xdbg("it is weekend!\n");
    if(tmrec_match("20120101T083000|PT10H|weekly|||MO,TU,WE,TH,FR")
        xdbg("it is with working hours\n");
...
</programlisting>
	    </example>
	</section>

	<section>
	    <title>
		<function moreinfo="none">is_leap_year([year])</function>
	    </title>
	    <para>
			Return true if the value from parameter is a leap year. If the
			parameter is missing, then the year from the current time is taken.
		</para>
		<para>
		The parameter can be pseudo-variable.
		</para>
		<para>
		This function can be used in ANY_ROUTE.
		</para>
		<example>
		<title><function>is_leap_year</function> usage</title>
		<programlisting format="linespecific">
...
if(is_leap_year("2010"))
...
</programlisting>
	    </example>
	</section>

	<section>
	    <title>
		<function moreinfo="none">time_period_match(period [, timestamp])</function>
	    </title>
	    <para>
			Matches the point in time specified by the timestamp parameter, or
			the current time if the parameter is missing, against the given
			period specification. Returns 1 if it matches, -1 if it doesn't,
			and a value &lt;= -2 if there was an error.
		</para>
		<para>
			The time period specification follows the Perl Time::Period module.
			It is a string and consists of zero or more sub-period specifications,
			separated by commas. The period matches if at least one of the
			sub-periods matches, or if no sub-periods were given at all (an
			empty string).
		</para>
		<para>
			Each sub-period is a list of one or more scale definitions,
			optionally separated by space characters. The sub-period matches if
			all of the given scales within that sub-period match. For each scale
			given, a single value or a range of values (which is two values
			separated by a hyphen) can be specified. Multiple
			values or multiple ranges (or a combination thereof) within a single
			scale is also possible. If a certain scale is specified more than once,
			the previous values or ranges for that scale are extended by the newly
			given ones. If a particular scale is not mentioned at all within a
			sub-period, then no matching is performed for that scale.
		</para>
		<para>
			The following scales are supported and understood. Each scale also has
			a respective short code, either one can be used. A single scale
			definition consists of the scale name, followed by an opening brace,
			followed by the list of values, followed by a closing brace.
			<itemizedlist>
				<listitem><para>
					<emphasis>year</emphasis> or <emphasis>yr</emphasis>
					- Either given as a full 4-digit number &gt;= 1970, or
					as a 2-digit number, in which case it will be understood
					to be within the current century.
				</para></listitem>
				<listitem><para>
					<emphasis>month</emphasis> or <emphasis>mo</emphasis>
					- Month of the year, either a number between 1 and 12,
					or at least the first 3 letters of a spelled out month
					name, e.g. <quote>jan</quote>, <quote>janua</quote>
					or <quote>january</quote> will all work.
				</para></listitem>
				<listitem><para>
					<emphasis>week</emphasis> or <emphasis>wk</emphasis>
					- Week of the month, a number between 1 and 6. The
					first day of the week is Sunday.
				</para></listitem>
				<listitem><para>
					<emphasis>yday</emphasis> or <emphasis>yd</emphasis>
					- Day of the year, a number between 1 and 366.
				</para></listitem>
				<listitem><para>
					<emphasis>mday</emphasis> or <emphasis>md</emphasis>
					- Day of the month, a number between 1 and 31.
				</para></listitem>
				<listitem><para>
					<emphasis>wday</emphasis> or <emphasis>wd</emphasis>
					- Day of the week, either a number between 1 and 7, or
					at least the first 2 letters of a spelled out weekday
					name (analogous to the <quote>month</quote> scale).
					Sunday is the first day of the week.
				</para></listitem>
				<listitem><para>
					<emphasis>hour</emphasis> or <emphasis>hr</emphasis>
					- A number between 0 and 23. Unlike the Perl Time::Period
					module, <quote>am</quote> or <quote>pm</quote>
					specifications are not supported.
				</para></listitem>
				<listitem><para>
					<emphasis>minute</emphasis> or <emphasis>min</emphasis>
					- A number between 0 and 59.
				</para></listitem>
				<listitem><para>
					<emphasis>second</emphasis> or <emphasis>sec</emphasis>
					- A number between 0 and 60 (to allow for leap seconds).
				</para></listitem>
			</itemizedlist>
		</para>
		<para>
			The parameters can include pseudo-variables. Whitespace (more
			precisely, the space character only) can occur anywhere, but is
			optional. Ranges in all scales (with the exception of the
			<quote>year</quote> scale) are allowed to wrap-around, e.g. a weekday
			scale of <quote>{fri-tue}</quote> is equivalent to
			<quote>{fri-sat,sun-tue}</quote>.
		</para>
		<example>
		<title><function>time_period_match</function> usage</title>
		<programlisting format="linespecific">
...
if(time_period_match("wd{2-6} hr{8-16}, wd{1-5} hr{17} min{0-29}"))
	xdbg("Monday to Friday, 8:00 to 17:30\n");

if(time_period_match("weekday { sat sun }, weekday {mo-fr} hr {17-8},wd{mo-wed}hr{15 16 9}"))
	xdbg("We're closed - open only Monday to Wednesday 10:00-15:00, Thursday and Friday 9:00-17:00");
...
</programlisting>
	    </example>
	</section>
	</section>
</chapter>

