Class ScheduleExpression

A calendar-based timeout expression for an enterprise bean timer.

Each attribute used to define a calendar-based timeout schedule has two overloaded setter methods, one that takes a String and one that takes an int. The int version is merely a convenience method for setting the attribute in the common case that the value is a simple integer value.

For example,

scheduleExpression.second(10)

scheduleExpression.second("10")

The attributes that specify the calendar-based schedule itself are as follows:

• second : one or more seconds within a minute

  Allowable values: [0,59]

• minute : one or more minutes within an hour

  Allowable values : [0,59]

• hour : one or more hours within a day

  Allowable values : [0,23]

• dayOfMonth : one or more days within a month

  Allowable values:

  • [1,31]
  • [-7, -1]
  • "Last"
  • {"1st", "2nd", "3rd", "4th", "5th", "Last"} {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"}

  "Last" means the last day of the month

  -x (where x is in the range [-7, -1]) means x day(s) before the last day of the month

  "1st","2nd", etc. applied to a day of the week identifies a single occurrence of that day within the month.

• month : one or more months within a year

  Allowable values :

  • [1,12]
  • {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", Dec"}

• dayOfWeek : one or more days within a week

  Allowable values :

  • [0,7]
  • {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"}

  "0" and "7" both refer to Sunday

• year : a particular calendar year

  Allowable values : a four-digit calendar year

Each attribute supports values expressed in one of the following forms

• Single Value. This constrains the attribute to only one of its possible values.

   
   Example: second = "10"
   Example: month = "Sep"

• Wild Card. "*" represents all allowable values for a given attribute.

   Example: second = "*"
   Example: dayOfWeek = "*"

• List. This constrains the attribute to two or more allowable values or ranges, with a comma used as a separator character within the string. Each item in the list must be a single value or range. List items cannot be lists, wild cards, or increments. Duplicate values are ignored.

   Example: second = "10,20,30"
   Example: dayOfWeek = "Mon,Wed,Fri"
   Example: minute = "0-10,30,40"

• Range. This constrains the attribute to an inclusive range of values, with a dash separating both ends of the range. Each side of the range must be a single attribute value. Members of a range cannot be lists, wild cards, ranges, or increments. If x is larger than y in a range "x-y", the range is equivalent to "x-max, min-y", where max is the largest value of the corresponding attribute and min is the smallest. The range "x-x", where both range values are the same, evaluates to the single value x. The day of the week range "0-7" is equivalent to "*".

   Example: second = "1-10"
   Example: dayOfWeek = "Fri-Mon"
   Example: dayOfMonth = "27-3" (Equivalent to "27-Last , 1-3")

• Increments. The forward slash constrains an attribute based on a starting point and an interval, and is used to specify every N seconds, minutes, or hours within the minute, hour, or day, respectively. For the expression x/y, the attribute is constrained to every yth value within the set of allowable values beginning at time x. The x value is inclusive. The wild card character (*) can be used in the x position, and is equivalent to 0. The use of increments is only supported within the second, minute, and hour attributes. For the second and minute attributes, x and y must each be in the range [0,59]. For the hour attribute, x and y must each be in the range [0,23].

   Example: minute = "∗/5" (Every five minutes within the hour)

  This is equivalent to: minute = "0,5,10,15,20,25,30,35,40,45,50,55"

   Example: second = "30/10" (Every 10 seconds within the minute, starting at second 30) 

  This is equivalent to: second = "30,40,50"

  Note that the set of matching increment values stops once the maximum value for that attribute is exceeded. It does not "roll over" past the boundary.

   Example : ( minute = "∗/14", hour="1,2")

  This is equivalent to: (minute = "0,14,28,42,56", hour = "1,2") (Every 14 minutes within the hour, for the hours of 1 and 2 a.m.)

The following additional rules apply to the schedule specification attributes:

• If the dayOfMonth attribute has a non-wildcard value and the dayOfWeek attribute has a non-wildcard value, then any day matching either the dayOfMonth value or the dayOfWeek value will be considered to apply.
• Whitespace is ignored, except for string constants and numeric values.
• All string constants (e.g., "Sun", "Jan", "1st", etc.) are case insensitive.

Schedule-based timer times are evaluated in the context of the default time zone associated with the container in which the application is executing. A schedule-based timer may optionally override this default and associate itself with a specific time zone. If the schedule-based timer is associated with a specific time zone, all its times are evaluated in the context of that time zone, regardless of the default time zone in which the container is executing.

None of the ScheduleExpression methods are required to be called. The defaults are :

• second: "0"
• minute: "0"
• hour: "0"
• dayOfMonth: "*"
• month: "*"
• dayOfWeek: "*"
• year: "*"
• timezone : default JVM time zone
• start : upon timer creation
• end : no end date

Applications must not rely on the getter methods that return the attributes of a calendar-based timeout schedule to return them in the same syntactic format in which they were passed in to a ScheduleExpression method or supplied to the Schedule annotation, and portable implementations must not assume any particular syntactic format. Implementations are required only to preserve semantic equivalence.