Patent Publication Number: US-9836518-B2

Title: Modeling recurring events in a data store

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of and claims benefit to U.S. Pat. No. 9,262,368, filed Oct. 22, 2012, which application is a continuation of U.S. Pat. No. 8,321,416, filed Oct. 12, 2011, which application is a continuation of U.S. Pat. No. 8,065,282, filed Feb. 5, 2009, which application is a continuation of U.S. Pat. No. 7,499,942, filed Dec. 28, 2005, each of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     In a data storage system, many of the objects stored may be related to time. Examples of data storage systems include message data storage systems, such as Microsoft Exchange, for example, databases, such as SQL Server, for example, and the like. Events such as meetings, appointments, and tasks, for example, have a very clear time relationship. Even less obvious events, such as movies, baseball games, and the Tour de France, for example, can have time relationships. An object such as a message may have several time relationships (e.g., time sent, time received, time forwarded, time read, etc.). Modeling simple time relationships, such as time sent, for example, may be simple. All that may be needed is to add a property of type “time” to the object. 
     The problem, however, gets much more complicated when the relationship between the object and time is not 1-to-1 (a single time at which a meeting occurs, or a single time at which a message was received) but rather 1-to-many. Examples of such relationships are “recurring” events, such as a meeting that repeats every week, or a task that must be performed quarterly. It is not beyond the realm of possibility that eventually a message store may even need to track all the different times a message was read (for example, for regulatory reasons). 
     In the past, the solution has been to model time-based relationships for each object type separately. Such a solution, however, makes the task of providing a unified view of time-related objects (such as a calendar of not only meetings but also other objects) very difficult to implement, support, and extend. For example, it is common for a meeting to repeat every week, except on holidays. If each time-based relationship were modeled separately, then an “exception” would need to be added to each, and added consistently with the same rules (what holidays exist? On what day do they fall? etc.). To resolve these issues, it would be desirable to have a unified scheme to model recurring time relationships regardless of the underlying object (e.g., message, meeting, appointment, etc.). 
     In known systems, there may be grammar for recurrence, but no grammar for exceptions. An example of an exception might be “the 28 th  occurrence of this meeting, which usually falls on Monday, should fall on Tuesday.” A typical calendaring program, however, may fail to detect that the Tuesday on which the 28 th  occurrence of the meeting is to be held is a holiday. Typically, such a system is implemented via an object (e.g., calendar entry) with annotations that describe the recurrence requirements and the exceptions. However, there is typically no way for the end-user to see the exceptions. 
     SUMMARY 
     As disclosed herein, time-related properties may be modeled independent of a base object. Rather than storing time properties with the object, they may be stored independently. A given object may be stored once, even if it has a recurrent time property. The description of a “meeting,” for example, may be stored once. Each occurrence of that object over time may be stored in a “timeslot” (e.g., object &lt;foo&gt; occurs at time ‘t’ on day ‘d’). If it is a recurring property, recurrence information may be stored independently. “Exception” information may be stored independently as well. 
     Thus, a methodology is disclosed for consistent representation of recurrence patterns and exceptions on any object. An object-independent model may be developed for representing recurring, time-based properties with exceptions. A process for developing such an object model, and a computing system having such an object model developed on it are also disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram depicting example object relationships for modeling recurring events in a message store. 
         FIG. 2  is a block diagram providing an example scenario wherein recurring events in a message store are modeled. 
         FIG. 3  is a block diagram showing an example computing environment in which aspects of the invention may be implemented. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a block diagram depicting example object relationships for modeling recurring events in a message store. As shown, a task, meeting, or other item may be represented by an object  100 . The object  100  may have an ItemID  102 , which is a unique identifier associated with the object  100 . Time and scope information may exist in a Timeslot table  110 . A timeslot  110  may be defined by a TimeSlot ID  112 , an ObjectID  113 , an item Type  114 , and related event scope information such as a start time  115  and an end time  116 . A Recurrence may be defined in a Recurrence table  120  by a Timeslot ID  122  and any recurrence information  124 . An Exception  130  may be an additional Item entry  100  that is linked by an Exception table  130  using a MasterID  132  and an ExceptionID  134 . 
     If sub-items are allowed, such as sub-tasks, then a Parent-Child Relationship table  140  may link them together. The table  140  links the parent object  142  to one or more child objects  144 . “pk” is a typical shorthand for “primary key,” which is a unique identifier for an object in a data store. “fk” is a typical shorthand for “foreign key,” which is a reference to a unique identifier in the data store. 
     Using this model, an application can quickly build a unified calendar, or similar time-relationship application, using timeslot and object—the time, object, and relationship are recorded. The recurrence and exception information are more “rationale”—why timeslot contains the data it does—and so that any changes to the object or relationship can be made with full knowledge of the reasons behind the relationships that were created. For example, if a meeting is rescheduled from every Thursday to every Monday, it is possible that exceptions may be added (for example, an occurrence of the meeting may now fall on Labor Day), or removed (it now avoids Thanksgiving Day). 
     Thus, such a model may include three concepts that are independent of the object itself: a time slot, which may be defined by a start time and end time pair, a recurrence pattern, which indicates how often the item is to occur, and an exception relationship, which identifies two discrete objects that are identical except for the exception. Consequently, an object does not have to know anything about time, recurrence, or exceptions. Any object could be turned into a recurring object without changing the object itself. 
       FIG. 2  is a block diagram providing an example of modeling recurring events in a message store. As shown, a meeting object  202  may be created to indicate that a meeting is to be held at a particular location, and that certain attendees are to be invited. The object  202  may be assigned a unique ItemID (e.g., 5). A timeslot table  204  may be created to indicate the start and end times for the meeting. To tie the timeslot to the meeting defined by the object  202 , the timeslot table may refer to the ItemID of the object  202  (e.g., 5). The timeslot table  204  may also have a unique TimeslotID (e.g., 7) assigned to it. At this point (i.e., without recurrence or exceptions), a calendar entry for each attendee could be entered once, for a meeting, at the location, beginning at the start time, and ending at the end time. 
     Suppose now that the meeting is to recur every Thursday, at the location, beginning at the start time, and ending at the end time. A Recurrence table  206  can be created with recurrence information that indicates that the meeting is to recur accordingly. The Recurrence table  206  may refer to the Timeslot ID of the Timeslot table  204 . At this point (i.e., without exceptions), a calendar entry for each attendee could be entered for a meeting, at the location, beginning at the start time, and ending at the end time, every Thursday. 
     Suppose now that an exception to the recurrence exists on a holiday that falls on a Thursday. An Exception table  208  can be created to indicate that an exception to the recurring condition exists. The Exception table  208  may include an Exception table ID (e.g., 19) that uniquely identifies the Exception table  208 , a Master ID (e.g., 5) that identifies the object to which the exception is taken (e.g., meeting every Thursday), and an Exception ID (e.g., 9) that identifies the object with which the object associated with the Master ID has an exception relationship. 
     A Timeslot object  210  can be created to identify, by start and end time, the time slot during which the excepted meeting would have occurred, but for the exception. The Timeslot object  210  may refer to the ObjectId of the exception  208 . 
     An excepted meeting object  212  may be created to define the excepted meeting. The meeting object  212  may have a unique Item ID (e.g., 9). The meeting object  212  may be identical to the meeting object  202 , or it may differ. For example, the excepted meeting  212  may be held at the same location, and include the same attendees, as the usual recurring meeting  202 . On the other hand, the excepted meeting might occur at a different location and/or include different attendees. 
     A Timeslot object  214  can be created to identify, by start and end time, the time slot during which the excepted meeting is to occur. The Timeslot object  214  may refer to the ObjectId (e.g.,  9 ) of the excepted meeting object  212 . The start and end times defined by the Timeslot object  214  may be the same as the start and end times defined by the Timeslot object  204  (if, for example, meetings held on holidays are held at the same time, but in a different location (e.g., in a local bar rather than in a company conference room)). On the other hand, the start and end times might differ from those defined by the Timeslot object  204  (if, for example, the excepted meeting is to be rescheduled to the preceding Wednesday). 
     If the exception itself is recurrent (e.g., meetings are typically held on Mondays are held on Tuesdays in the summer months; the CEO is an attendee only during the first quarter; meetings that are typically held in a small, shabby conference room are held in the Board room during the first quarter because the CEO is an attendee), a Recurrence object  216  can be set up to cause the exception to recur accordingly. The Recurrence object  216  may refer to the timeslot object  214  that defines when the excepted meeting is to occur. 
     Example Computing Environment 
       FIG. 3  and the following discussion are intended to provide a brief general description of a suitable computing environment in which an example embodiment of the invention may be implemented. It should be understood, however, that handheld, portable, and other computing devices of all kinds are contemplated for use in connection with the present invention. While a general purpose computer is described below, this is but one example. The present invention also may be operable on a thin client having network server interoperability and interaction. Thus, an example embodiment of the invention may be implemented in an environment of networked hosted services in which very little or minimal client resources are implicated, e.g., a networked environment in which the client device serves merely as a browser or interface to the World Wide Web. 
     Although not required, the invention can be implemented via an application programming interface (API), for use by a developer or tester, and/or included within the network browsing software which will be described in the general context of computer-executable instructions, such as program modules, being executed by one or more computers (e.g., client workstations, servers, or other devices). Generally, program modules include routines, programs, objects, components, data structures and the like that perform particular tasks or implement particular abstract data types. Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments. Moreover, those skilled in the art will appreciate that the invention may be practiced with other computer system configurations. Other well known computing systems, environments, and/or configurations that may be suitable for use with the invention include, but are not limited to, personal computers (PCs), automated teller machines, server computers, hand-held or laptop devices, multi-processor systems, microprocessor-based systems, programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. An embodiment of the invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network or other data transmission medium. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices. 
       FIG. 3  thus illustrates an example of a suitable computing system environment  100  in which the invention may be implemented, although as made clear above, the computing system environment  100  is only one example of a suitable computing environment and is not intended to suggest any limitation as to the scope of use or functionality of the invention. Neither should the computing environment  100  be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary operating environment  100 . 
     With reference to  FIG. 3 , an example system for implementing the invention includes a general purpose computing device in the form of a computer  110 . Components of computer  110  may include, but are not limited to, a processing unit  120 , a system memory  130 , and a system bus  121  that couples various system components including the system memory to the processing unit  120 . The system bus  121  may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnect (PCI) bus (also known as Mezzanine bus). 
     Computer  110  typically includes a variety of computer readable media. Computer readable media can be any available media that can be accessed by computer  110  and includes both volatile and nonvolatile, removable and non-removable media. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, random access memory (RAM), read-only memory (ROM), Electrically-Erasable Programmable Read-Only Memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CDROM), digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computer  110 . Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, radio frequency (RF), infrared, and other wireless media. Combinations of any of the above should also be included within the scope of computer readable media. 
     The system memory  130  includes computer storage media in the form of volatile and/or nonvolatile memory such as ROM  131  and RAM  132 . A basic input/output system  133  (BIOS), containing the basic routines that help to transfer information between elements within computer  110 , such as during start-up, is typically stored in ROM  131 . RAM  132  typically contains data and/or program modules that are immediately accessible to and/or presently being operated on by processing unit  120 . By way of example, and not limitation,  FIG. 3  illustrates operating system  134 , application programs  135 , other program modules  136 , and program data  137 . RAM  132  may contain other data and/or program modules. 
     The computer  110  may also include other removable/non-removable, volatile/nonvolatile computer storage media. By way of example only,  FIG. 3  illustrates a hard disk drive  141  that reads from or writes to non-removable, nonvolatile magnetic media, a magnetic disk drive  151  that reads from or writes to a removable, nonvolatile magnetic disk  152 , and an optical disk drive  155  that reads from or writes to a removable, nonvolatile optical disk  156 , such as a CD ROM or other optical media. Other removable/non-removable, volatile/nonvolatile computer storage media that can be used in the example operating environment include, but are not limited to, magnetic tape cassettes, flash memory cards, digital versatile disks, digital video tape, solid state RAM, solid state ROM, and the like. The hard disk drive  141  is typically connected to the system bus  121  through a non-removable memory interface such as interface  140 , and magnetic disk drive  151  and optical disk drive  155  are typically connected to the system bus  121  by a removable memory interface, such as interface  150 . 
     The drives and their associated computer storage media discussed above and illustrated in  FIG. 3  provide storage of computer readable instructions, data structures, program modules and other data for the computer  110 . In  FIG. 3 , for example, hard disk drive  141  is illustrated as storing operating system  144 , application programs  145 , other program modules  146 , and program data  147 . Note that these components can either be the same as or different from operating system  134 , application programs  135 , other program modules  136 , and program data  137 . Operating system  144 , application programs  145 , other program modules  146 , and program data  147  are given different numbers here to illustrate that, at a minimum, they are different copies. A user may enter commands and information into the computer  110  through input devices such as a keyboard  162  and pointing device  161 , commonly referred to as a mouse, trackball or touch pad. Other input devices (not shown) may include a microphone, joystick, game pad, satellite dish, scanner, or the like. These and other input devices are often connected to the processing unit  120   a - f  through a user input interface  160  that is coupled to the system bus  121 , but may be connected by other interface and bus structures, such as a parallel port, game port or a universal serial bus (USB). 
     A monitor  191  or other type of display device is also connected to the system bus  121  via an interface, such as a video interface  190 . In addition to monitor  191 , computers may also include other peripheral output devices such as speakers  197  and printer  196 , which may be connected through an output peripheral interface  195 . 
     The computer  110  may operate in a networked environment using logical connections to one or more remote computers, such as a remote computer  180 . The remote computer  180  may be a personal computer, a server, a router, a network PC, a peer device or other common network node, and typically includes many or all of the elements described above relative to the computer  110 , although only a memory storage device  181  has been illustrated in  FIG. 3 . The logical connections depicted in  FIG. 3  include a local area network (LAN)  171  and a wide area network (WAN)  173 , but may also include other networks. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets and the Internet. 
     When used in a LAN networking environment, the computer  110  is connected to the LAN  171  through a network interface or adapter  170 . When used in a WAN networking environment, the computer  110  typically includes a modem  172  or other means for establishing communications over the WAN  173 , such as the Internet. The modem  172 , which may be internal or external, may be connected to the system bus  121  via the user input interface  160 , or other appropriate mechanism. In a networked environment, program modules depicted relative to the computer  110 , or portions thereof, may be stored in the remote memory storage device. By way of example, and not limitation,  FIG. 3  illustrates remote application programs  185  as residing on memory device  181 . It will be appreciated that the network connections shown are exemplary and other means of establishing a communications link between the computers may be used. 
     One of ordinary skill in the art can appreciate that a computer  110  or other client devices can be deployed as part of a computer network. In this regard, the present invention pertains to any computer system having any number of memory or storage units, and any number of applications and processes occurring across any number of storage units or volumes. An embodiment of the present invention may apply to an environment with server computers and client computers deployed in a network environment, having remote or local storage. The present invention may also apply to a standalone computing device, having programming language functionality, interpretation and execution capabilities.