Creating Calendar-Based Timer Expressions

Timers can be set according to a calendar-based schedule, expressed using a syntax similar to the UNIX cron utility. Both programmatic and automatic timers can use calendar-based timer expressions.

Table 16–1 Calendar-Based Timer Attributes

Attribute	Description	Allowable Values	Default Value	Examples
second	One or more seconds within a minute.	0 to 59	0	second="30"
minute	One or more minutes within an hour.	0 to 59	0	minute="15"
hour	One or more hours within a day.	0 to 23	0	hour="13"
dayOfWeek	One or more days within a week.	0 to 7 [Both 0 and 7 refer to Sunday.] Sun, Mon, Tue, Wed, Thu, Fri, Sat	*	dayOfWeek="3" dayOfWeek="Mon"
dayOfMonth	One or more days within a month.	1 to 31 -7 to –1 [A negative number means the xth day or days before the end of the month.] Last [1st, 2nd, 3rd, 4th, 5th, Last] [Sun, Mon, Tue, Wed, Thu, Fri, Sat]	*	dayOfMonth="15" dayOfMonth="-3" dayOfMonth="Last" dayOfMonth="2nd Fri"
month	One or more months within a year.	1 to 12 Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec	*	month="7" month="July"
year	A particular calendar year.	A four-digit calendar year.	*	year="2010"

Specifying Multiple Values in Calendar Expressions

You can specify multiple values in calendar expressions in the following ways:

• Using Wildcards in Calendar Expressions

• Specifying a List of Values

• Specifying a Range of Values

• Specifying Intervals

Using Wildcards in Calendar Expressions

Setting an attribute to an asterisk symbol (*) represents all allowable values for the attribute.

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Example 16–9 Calendar Expressions with Wildcards

The following expression represents every minute:

minute="*"

The following expression represents every day of the week:

dayOfWeek="*"

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Specifying a List of Values

To specify two or more values for an attribute, use a comma (,) to separate the values. A range of values are allowed as part of a list. Wildcards and intervals, however, are not allowed.

Duplicates within a list are ignored.

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Example 16–10 Calendar Expressions with a List of Values

The following expression sets the day of the week to Tuesday and Thursday:

dayOfWeek="Tue, Thu"

The following expression represents 4:00 AM, every hour from 9:00 AM to 5:00 PM using a range, and 10:00 PM:

hour="4,9-17,20"

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Specifying a Range of Values

Use a dash character (-) to specify an inclusive range of values for an attribute. Members of a range cannot be wildcards, lists, or intervals. If the range is of the form x-x, it is equivalent to the single-valued expression x. If the range is of the form x-y and x is greater than y, it is equivalent to the expression x-maximum value, minimum value-y. That is, the expression begins at x, rolls-over to the beginning of the allowable values, and continues up to y.

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Example 16–11 Calendar Expressions Using Ranges

The following expression represents 9:00 AM to 5:00 PM:

hour="9-17"

The following expression represents Friday through Monday:

dayOfWeek="5-1"

The following expression represents the 25th day of the month to the end of the month, and the beginning of the month to the 5th day of the month:

dayOfMonth="25-5"

It is equivalent to the following expression:

dayOfMonth="25-Last,1-5"

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Specifying Intervals

The forward slash (/) constrains an attribute to a starting point and an interval. It is used to specify every N seconds, minutes, or hours within the minute, hour or day. For an expression of the form x/y, x represents the starting point and y represents the interval. The wildcard character may be used in the x position of an interval, and is equivalent to setting x to 0.

Intervals may only be set for second, minute, and hour attributes.

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Example 16–12 Calendar Expressions Using Intervals

The following expression represents every 10 minutes within the hour:

minute="*/10"

It is equivalent to:

minute="0,10,20,30,40,50"

The following expression represents every two hours starting at noon:

hour="12/2"

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