Abstract:
Disclosed herein are systems, methods, and computer-readable storage media for consistently associating a user ID with a user. In one aspect, a method may comprise receiving a data request at a transceiver accessible by a server computing device, wherein, in response to receiving the data request, the server computing device is configured to: access, by one or more processors coupled to the transceiver, a first value embedded in a first cookie associated with a first expiration time; set a second cookie embedded with a second value; and reset the first cookie responsive to receiving an indication that the first cookie is expiring, wherein to reset the first cookie comprises replacing the first cookie with a third cookie set with a value equal to the first value and a third expiration time later than the first expiration time. Other embodiments are disclosed and claimed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is related to U.S. patent application Ser. No. 13/287,827, filed Nov. 2, 2011 and entitled SCHEDULED SPLIT TESTING, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to identifying website users and, more specifically, to consistently assigning a website user with a user identification (ID) utilizing web cookies. 
     2. Introduction 
     Websites often assign user IDs to visitors and typically store each visitor&#39;s user ID in a persistent cookie in the visitor&#39;s browser. This user ID may be used in numerous ways to enhance the user&#39;s experience on the site, for example, to personalize the presentation of content or to enhance the web publisher&#39;s tracking and reporting capabilities. All persistent cookies expire, and if a user ID cookie expires mid-session, while the visitor is actively engaging with the site, that user may experience confusing or unattractive content. For example, while conducting a test of different page layouts, certain users may have been randomly selected to view a particular page layout. The specific layout ID may be stored in a cookie for each particular user. When rendering a web page, the cookie may be used to indicate the layout that should be shown to this user. If the cookie were to expire either between visits or during a visit, the user might be assigned to view another layout, resulting in a potentially confusing “flip” from one layout to another. 
     Content publishers have attempted to remedy such situations with existing technology, for example, by continually re-setting the cookie with a new expiration date on every response from the web server. However, the continual re-setting of cookies introduces certain inefficiencies and overhead into the website operation, such as the addition of unnecessary web traffic in each of the site&#39;s responses to user requests. Another solution involves setting the cookie&#39;s expiration date to a distant future date, for instance, ten years from the current date. These methods do not provide a satisfactory solution in all cases. As such, there may be a need for improved methods of persisting cookies, for example, in support of providing consistent user experiences. 
     SUMMARY 
     Disclosed herein are systems, methods, devices, and non-transitory computer-readable storage media for consistently associating a user ID with a website visitor over a series of visits to a website. A user ID may be associated with a user so that every time the user visits a website, or navigates among pages within the website, the user may be treated consistently. For example, a user enrolled in a test being conducted at a particular website and shown a specific variation of the website may be provided with the same variation upon subsequent visits to the website. In another example, a user browsing a news content website may be presented with certain advertising consistent with previous browsing patterns. 
     In certain embodiments, a user ID may be embedded in a file, for example, a cookie, stored on a user device accessing the website to consistently identify the user upon each visit. In one embodiment, the user ID may be stored in a persistent cookie, which may be associated with an expiration time. According to existing technology, when a persistent cookie expires, a user may be treated inconsistently upon a subsequent visit or even during a single session. Accordingly, embodiments may operate to consistently treat users, inter alia, using a combination of session cookie values and persistent cookie values to identify a user over multiple sessions. Session cookies expire when a user terminates the client application. Setting a user ID in both a persistent cookie and a session cookie according to embodiments, the user ID stored in the session cookie may be used to reset the persistent cookie responsive to an indication that the persistent cookie has expired or may expire at a future time. 
     A persistent cookie may be determined to be expiring in multiple ways. For instance, according to certain embodiments, failure to send a persistent cookie with a website request may indicate that the persistent cookie is expiring or has expired. In response to an indication that a persistent cookie is expiring, embodiments provide that the user ID from a session cookie may be used to reset the persistent cookie. In one embodiment, a session cookie sent as a result of a content request may be utilized as an indication that the persistent cookie is expiring, such that the persistent cookie may be reset responsive to a successful return of a session cookie. 
     In certain embodiments, two persistent cookies may be used to associate the same user ID to a user upon subsequent visits. For example, a first persistent cookie may be embedded with the user ID and associated with an expiration time, and a second persistent cookie may be embedded with a value indicative of the expiration time associated with the first persistent cookie. As such, the expiration time of the first persistent cookie may be determined through the second persistent cookie. The retrieved expiration time may be used to determine whether the first persistent cookie is expiring and, if so, the first persistent cookie may be reset. 
     The foregoing is a summary and, as such, may contain simplifications, generalizations, and omissions of detail. Those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. For a better understanding of the embodiments, additional features and advantages thereof will be set forth in the description which follows, taken in conjunction with the accompanying drawings, and in part will be obvious from the description, or can be learned by practice of the embodiments disclosed therein. The scope of the invention will be pointed out in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary system embodiment. 
         FIG. 2  illustrates an exemplary method embodiment for scheduling users into testing groups utilizing cookies. 
         FIG. 3  illustrates an exemplary system embodiment in which cookies may be used to consistently associate a user ID with a website visitor. 
         FIG. 4  illustrates an exemplary method embodiment for storing a user ID utilizing a persistent cookie and session cookie. 
         FIG. 5  illustrates an exemplary method embodiment in which a persistent cookie is reset responsive to a return of a session cookie. 
         FIG. 6  illustrates an exemplary method embodiment in which two persistent cookies are used to consistently associate a user ID with a website visitor. 
     
    
    
     DETAILED DESCRIPTION 
     Various example embodiments are discussed in the following more detailed description, as represented in the figures, which is not intended to limit the scope of the claims, but is merely representative of those embodiments. While specific embodiments are discussed, it should be understood that this is done for illustrative purposes only. A person having ordinary skill in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the detailed description of example embodiments provided herein. 
     Embodiments as provided herein may be applied in many situations common to web publishing. For example, a website may run tests in which different groups of users are assigned to see different content. During such tests, the user&#39;s ID and/or any associated data are typically stored in a set of cookies. If the cookie expires, the test may be invalidated and the user may have a negative site experience. Accordingly, certain embodiments may operate to prevent such cookies from expiring. 
       FIG. 1  illustrates an exemplary system  100  that includes a general-purpose computing device  100 , including a processing unit (CPU or processor)  120  and a system bus  110  that couples various system components, including the system memory  130 , such as read only memory (ROM)  140  and random access memory (RAM)  150 , to the processor  120 . The system  100  can include a cache  122  of high speed memory connected directly with, in close proximity to, or integrated as part of the processor  120 . The system  100  may copy data from the memory  130  and/or the storage device  160  to the cache  122  for quick access by the processor  120 . In this way, the cache  122  may provide a performance boost that avoids processor  120  delays while waiting for data. These and other modules may control or be configured to control the processor  120  to perform various actions. Other system memory  130  may also be available for use within the computing device  100 . The memory  130  may include multiple different types of memory with different performance characteristics. It can be appreciated that these principles may operate on a computing device  100  with more than one processor  120  or on a group or cluster of computing devices networked together to provide greater processing capability. The processor  120  may include any general purpose processor and a hardware module or software module, such as module  1   162 , module  2   164 , and module  3   166  stored in storage device  160 , configured to control the processor  120  as well as a special-purpose processor, for example where software instructions may be incorporated into the actual processor design. The processor  120  may essentially be a completely self-contained computing system, containing multiple cores or processors (including symmetric or asymmetric multi-core processors), a bus, memory controller, cache, etc. 
     The system bus  110  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. A basic input/output (BIOS) stored in ROM  140  or the like, may provide the basic routine that helps to transfer information between elements within the computing device  100 , such as during start-up. The computing device  100  may further include storage devices  160  such as a hard disk drive, a magnetic disk drive, an optical disk drive, tape drive, or the like. The storage device  160  may include software modules  162 ,  164 ,  166  for controlling the processor  120 . Other hardware or software modules are contemplated herein. The storage device  160  may be connected to the system bus  110  by a drive interface. The drives and the associated computer readable storage media may provide nonvolatile storage of computer readable instructions, data structures, program modules, and other data for the computing device  100 . In one aspect, a hardware module that performs a particular function may include a software component stored in a non-transitory computer-readable medium in connection with the necessary hardware components, such as the processor  120 , bus  110 , display  170 , and so forth, to carry out the function. The basic components are known to those of skill in the art and appropriate variations are contemplated herein, for example, depending on the type of device, such as whether the device  100  is a small, handheld computing device, a desktop computer, a computer server, or other form of information handling device. 
     Although the exemplary embodiment described in  FIG. 1  employs a hard disk  160 , it should be appreciated by those skilled in the art that other types of non-transitory computer readable storage media which can store data that are accessible by a computer, such as magnetic cassettes, flash memory cards, digital versatile disks, cartridges, random access memories (RAMs)  150 , read only memory (ROM)  140 , a cable or wireless signal containing a bit stream and the like, may also be used in the exemplary operating environment. Non-transitory computer-readable storage media expressly exclude media such as energy, carrier signals, electromagnetic waves, and signals per se. 
     To enable user interaction with the computing device  100 , an input device  190  may be utilized which represents any number of input mechanisms, such as a microphone for speech, a touch-sensitive screen for gesture or graphical input, keyboard, mouse, motion input, speech and so forth. An output device  170  may also be one or more of a number of output mechanisms known to those having ordinary skill in the art. In some instances, multimodal systems enable a user to provide multiple types of input to communicate with the computing device  100 . The communications interface  180  generally governs and manages the user input and system output. There is no restriction on operating on any particular hardware arrangement and therefore the basic features here may easily be substituted for improved hardware or firmware arrangements as they are developed. 
     For clarity of explanation, the illustrative system embodiment of  FIG. 1  is presented as including individual functional blocks including functional blocks labeled as a “processor” or processor  120 . The functions these blocks represent may be provided through the use of either shared or dedicated hardware, including, but not limited to, hardware capable of executing software and hardware, such as a processor  120 , that is purpose-built to operate as an equivalent to software executing on a general purpose processor. For example, the functions of one or more processors presented in  FIG. 1  may be provided by a single shared processor or multiple processors (the term “processor” should not be construed to refer exclusively to hardware capable of executing software) Illustrative embodiments may include microprocessor and/or digital signal processor (DSP) hardware, read-only memory (ROM)  140  for storing software performing the operations discussed below, and random access memory (RAM)  150  for storing results. Very large scale integration (VLSI) hardware embodiments, as well as custom VLSI circuitry in combination with a general purpose DSP circuit, may also be provided. 
     The logical operations of the various embodiments may be implemented as follows: (1) a sequence of computer implemented steps, operations, or procedures running on a programmable circuit within a general use computer; (2) a sequence of computer implemented steps, operations, or procedures running on a specific-use programmable circuit; and/or (3) interconnected machine modules or program engines within the programmable circuits. The system  100  shown in  FIG. 1  may practice all or part of the recited methods, may be a part of the recited systems, and/or may operate according to instructions in the recited non-transitory computer-readable storage media. Such logical operations may be implemented as modules configured to control the processor  120  to perform particular functions according to the programming of the module. For example,  FIG. 1  illustrates three modules Mod 1   162 , Mod 2   164 , and Mod 3   166 , which are modules configured to control the processor  120 . These modules may be stored on the storage device  160  and loaded into RAM  150  or memory  130  at runtime, or may be stored as would be known in the art in other computer-readable memory locations. 
       FIG. 2  illustrates an exemplary method embodiment for scheduling users into testing groups utilizing cookies. As shown in  FIG. 2 , a user may visit a website  202  resulting in a determination of whether the user has an ID cookie  204 . If the user has an ID cookie  204 , then the user ID may be retrieved from the cookie  206  and the user may be assigned to a test and a variation according to the user ID  208 . If the user does not have an ID cookie  204 , then the user may be assigned a new ID  210  and the ID cookie set with the new ID  212 . The user may then be assigned to a test and a variation according to the user ID  208 . 
     As described herein, embodiments may be configured to treat a user consistently upon each visit to a website. To consistently handle a user upon each visit to a website, a user may be consistently associated with the same user ID. As explained hereinabove, the user ID may be embedded in a cookie stored on a user device and used to consistently identify the user upon each visit. Referring to  FIG. 3 , therein is provided an exemplary embodiment of a system in which cookies may be used to consistently associate the same user ID with a user each time the user visits a web site. 
     As shown in  FIG. 3 , user devices  305  may be configured to communicate with web servers  310  via one or more communication networks  315 . A user device  305  may be any type of computing device or other information handling device configured to communicate with other devices, such as a web server  310 , via a communication network. Non-limiting examples of user devices  305  may include a personal computer (PC), laptop, tablet computing device, smart phone, kiosk, e-reader, and personal digital assistant (PDA). A user device  305  may execute a web browser application or other application configured to interface with the web server and request, retrieve, and present information provided by a web server. In general, a user device  305  is configured to have at least some minimal amount of storage or at least have access to storage, for example, in order to store cookies or other data that uniquely identifies the user and/or user device. 
     A web server  310  may be a computing device similar to the device disclosed in  FIG. 1 , and may additionally be configured to host a website. For example, a web server  310  may be configured to communicate with a user device  305  via the communication network  315  wherein the web server  310  may receive a request for web data from the user device  305  and may respond by transmitting the requested web data to the user device  305 . Web data may be any type of data that may be used by the user device  305  to render a webpage, such as, for example, a markup language such as the hyper-text markup language (HTML) or the extensible markup language (XML). The web data may be transmitted from the one or more web servers  310  to the user device  305 . For example, a user may enter a webpage uniform resource locator (URL) into the web browser running on user device  305  and the web browser may be configured to request the content from the appropriate web server  310 . A similar request may be sent upon the user choosing to navigate to a different page or site on the Internet or World Wide Web. 
     When a user device  305  requests web data from a web server  310  for the first time, a user ID may be assigned to the user by the web server  310 . In one embodiment, the user ID may be embedded in a cookie and stored on the user device  305  so that when the user device  305  transmits further requests to the web server  310  resulting from, for example, the user navigating to different pages within the site, refreshing the page, or returning to the site after leaving, the user device  305  may transmit the cookie to a web server  310 , for example, in a request header, and the web server  310  may extract the user ID from the cookie. The user ID may be tied to a particular device, user, account, browser, platform, or combinations thereof. For example, a user ID associated with a particular account may be stored in different cookies for different browsers on one or more computers, such that the same test is applied to the user&#39;s experience in different locations or when using different computing devices. Furthermore, multiple different cookies may exist for different users, such that two users who share the same browser on the same computer, but log into a site as different users, may be treated differently when logging in as each respective user. 
     The user ID may be stored in a persistent cookie according to embodiments, for example, on the user device  305  or on some other local or locally accessible storage. A persistent cookie may be a cookie associated with an expiration time such that the cookie may be configured to be returned to the web server  310  upon request until the expiration time has passed. When a user returns to a site prior to the expiration of the persistent cookie, the user device  305  may send the cookie to the web server  310 , for example, when transmitting a request. The web server  310  may obtain the cookie and extract the user ID embedded therein. If the cookie expires (i.e., the expiration time has passed) during a visit or between visits, the user device  305  will no longer send the cookie with its requests, and the user may be assigned a different user ID, potentially being treated inconsistently with respect to the first part of the visit or previous visits. A client-side tool may identify, display, and otherwise manage these cookies on behalf of the user. Cookie management may include renewing a cookie, deleting a cookie, modifying a cookie, moving a cookie, duplicating a cookie, moving a cookie from one device or browser to another device or browser, and so forth. Alternately, a web-based tool may receive any cookies set in its domain, parse them to extract data, display that data to users, and provide similar functionality. The user ID may be stored in a cookie; however, embodiments are not so limited, as the user ID may also be stored via some other storage mechanism or container. 
     To avoid possible inconsistent treatment resulting from a persistent cookie expiring, embodiments provide that a session cookie may be used in conjunction with a persistent cookie. In general, a session cookie is a cookie which will be deleted after the user closes the browser handling the session. For instance, in a HTTP configuration, a session cookie does not have an expiration date set in the Set-Cookie response header from the server (e.g., web server  310 ). 
     The session cookie may be used to store the user ID so that if the persistent cookie expires in the middle of a user session, the web server  310  may still retrieve the user ID from the session cookie. The web server may also use the user ID retrieved from the session cookie to reset the persistent cookie on the user device. According to embodiments, resetting the persistent cookie may include embedding the user ID into a new persistent cookie, for example, embedded with a different expiration time, which may be stored on the user device  305 , or by changing the expiration time associated with the persistent cookie to a later time. 
       FIG. 4  illustrates an exemplary method embodiment of using a persistent cookie and session cookie to store a user ID. As illustrated, a web server may receive a request from a user device for web data stored on the web server  405 , and the web server may check whether the request contains a persistent cookie  410 . The web server may, for example, use a naming convention to distinguish between persistent and session cookies relevant to the testing system. If the request contains a persistent cookie  415 , the embedded user ID may be extracted  420 . The web server may check whether the request contains a session cookie  425 . If the request does not contain a session cookie  430 , a session cookie may be created and embedded with the user ID extracted from the persistent cookie  435  and the session cookie may be set on the requesting user device  440 . The user ID may be used to return the proper web data to the user device  475  in response to the initially received request. If the request contains a session cookie  430 , the requested web data may be returned  475  based on the user ID value. 
     If the request does not contain a persistent cookie  415 , the web server may check whether the request contains a session cookie  445 . If the request contains a session cookie  450 , for example, when the persistent cookie has expired during a user session, the user ID may be extracted from the session cookie  465  and may be used to reset the persistent cookie  470  on the user device. The user ID may be used to return the appropriate web data to the user device  475  in response to the request from the user device. 
     If the request does not contain a session cookie  450 , a user ID may be generated  455  and embedded into both a session cookie and a persistent cookie  460 , which may be stored on the user device. The generated user ID is then used to return the appropriate data to the user device  475 . 
     The example embodiment provided in  FIG. 4  may use session cookies to associate the same user ID with a user, for instance, when the persistent cookie expires during a user session. A persistent cookie, however, can also expire while a user is not in a session. In this type of scenario, neither a persistent nor a session cookie will be transmitted to the web server, and thus the user may be assigned a new user ID and possibly treated inconsistently from previous visits. In one embodiment, the persistent cookie may be reset every time a session cookie is returned. For example, resetting the persistent cookie may consist of changing the expiration associated with the persistent cookie to a later time. As such, the persistent cookie expiration may be consistently set at a certain increment from the time it is being set. In this embodiment, a user may be associated with the user ID embedded in the persistent cookie for at least the increment of time chosen from their last visit to the site. 
       FIG. 5  illustrates an exemplary method embodiment in which a persistent cookie is set in response to a web server receiving a session cookie in a user device request. A web server may receive a request for content from a user device  505  and, in response, may check whether the request contains a persistent cookie  510 . The web server may, for example, use a naming convention to distinguish between persistent and session cookies relevant to the testing system. If the request contains a persistent cookie  515 , the web server may extract the user ID embedded in the persistent cookie  520  and check whether the request contains a session cookie  525 . If the request contains a session cookie  530 , the user ID may be extracted from the session cookie  545  and used to reset the persistent cookie  550 . The user ID may be used to return the proper web content  585  to the user device. According to embodiments, resetting the persistent cookie may include, but is not limited to, updating the expiration associated with the persistent cookie to a later time or embedding the user ID in a new persistent cookie, which is then stored on the user device. 
     If the request contains a persistent cookie but does not contain a session cookie  530 , the web server may create a session cookie embedded with the extracted user ID  535 , and the session cookie may be set and stored on the requesting user device  540 . The web server may reset the persistent cookie  550 , and the extracted user ID may be used to return the proper web content to the user device in response to the request for web content  585 . 
     If a persistent cookie is not sent in the request  515 , the web server may check whether a session cookie is present in the request  555 . If a session cookie is not present  560 , a user ID may be generated  565  and embedded into a persistent cookie and a session cookie  570 , both of which may be returned, for example, in Set-Cookie response headers, and stored on the user device. The generated user ID  565 , by being embedded in the persistent and session cookies  570 , may be used to return the proper web data in response to the user device&#39;s request  585 . If a session cookie is sent in the request  560 , the embedded user ID may be extracted from the session cookie  575  and used to reset a persistent cookie on the user device  580 . The user ID embedded in the persistent cookie  580  may be used to return the proper web data in response to the user device&#39;s request  585 . 
     Two persistent cookies may be configured according to embodiments to associate the same user ID with a user upon each visit to a website. For example, a first persistent cookie may be embedded with the user ID and a second persistent cookie may be embedded with a value indicative of the expiration associated with the first persistent cookie. In one embodiment, the value in the second persistent cookie may be used to determine whether the first persistent cookie is nearing expiration, and, if so, the first persistent cookie may be reset. 
     Referring to  FIG. 6 , therein is provided an exemplary method embodiment utilizing two persistent cookies to ensure that a user ID is consistently associated with a user. A request for web data from a user device may be received at a web server  605 , and the web server may check the request headers for a first persistent cookie  610  (for example, using a naming convention). If the first persistent cookie is not sent in the request  615 , the web server may generate a user ID  620 , and may set a first persistent cookie embedded with the user ID and associated with an expiration time  625 . Data indicative of the expiration time associated with the first persistent cookie may be embedded into a second persistent cookie set by the web server  630 . For example, the data indicative of the expiration may be a date, time, or some combination thereof. The expiration time associated with the second persistent cookie may be set to be the same or later than the expiration time of the first persistent cookie, for example, such that the second persistent cookie will not expire prior to the first cookie. The generated user ID may be used to return the proper web data in response to the user device&#39;s request  675 . 
     If the first persistent cookie is sent in the request  615 , the embedded user ID may be extracted from the first persistent cookie  635  and the web server may check the request headers for the second persistent cookie  640 . If the second persistent cookie is sent in the request  645 , the embedded data indicative of the expiration of the first persistent cookie may be extracted from the second persistent cookie  650 . The web server may determine whether the first persistent cookie is expiring based on the extracted data  655 . The web server may determine whether the cookie is expiring in any number of ways. In a first non-limiting example, the web server may check whether the first persistent cookie expires within a set amount of time, such as within the following 48 hours. In a second non-limiting example, the data indicative of the expiration time may be checked against a deadline. For instance, if a test is scheduled to end on a certain date or time, the first persistent cookie may be determined to be expiring if it will expire prior to the date or time that the test is scheduled to end. If the first persistent cookie will expire after the time the test is scheduled to end, the first persistent cookie may be determined to not be expiring. 
     If it is determined that the first persistent cookie is expiring  655 , the first persistent cookie may be reset  660 . According to certain embodiments, the first persistent cookie may be reset by embedding the user ID into a new persistent cookie with a later expiration time and storing it on the user device. The second persistent cookie may also be reset  660 . In one embodiment, resetting the second persistent cookie includes updating the embedded data indicative of the expiration of the first persistent cookie to be indicative of the new expiration time associated with the first persistent cookie. The expiration time associated with the second persistent cookie may also be changed to a later date. The expiration associated with the second persistent cookie may be changed to be the same time or later that the expiration time associated with the first persistent cookie, such that the second persistent cookie may not expire prior to the first persistent cookie. The user ID may be used to return web data to the user device in response to the user device&#39;s request  675 . 
     If the user device does not send a second persistent cookie  645 , the first persistent cookie may be reset and associated with a new expiration time  665 . For example, the first persistent cookie may be reset with an expiration time equivalent to the end of the test, a specified amount of time such (e.g., 48 hours), and the like. Once the first persistent cookie has been reset, data indicative of the expiration time associated with the first persistent cookie can be embedded into a second persistent cookie set by the web server  670 . The expiration time associated with the second persistent cookie may be set to be the same or after the expiration time associated with the first persistent cookie. Both of the persistent cookies may be stored on the user device. The system returns the corresponding web data to the user device in response to the user device&#39;s request based on the user ID  675 . 
     Cookies may be configured according to embodiments to include cryptographic data, such as half of a cryptographic key pair, to ensure that users are not tampering with the cookies to ‘discover’ data or layouts that may be private, confidential, or otherwise sensitive. In this manner, the server may verify that cookies for a particular client are authentic and have not been tampered with, ensuring that only approved client devices participate in the appropriate tests. 
     Embodiments may be implemented in a manner that anonymizes the individual users, so that any information that is collected about the user is not associated with the user&#39;s identity. Rather, a user may be associated with, for example, a unique identifier, from which the user&#39;s true identity may not be determined. 
     Embodiments within the scope of the present disclosure may also include tangible and/or non-transitory computer-readable storage media for carrying or having computer-executable instructions or data structures stored thereon. Such non-transitory computer-readable storage media can be any available media that can be accessed by a general purpose or special purpose computer, including the functional design of any special purpose processor as discussed above. By way of example, and not limitation, such non-transitory computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions, data structures, or processor chip design. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or combination thereof) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a computer-readable medium. Combinations of the above should also be included within the scope of the computer-readable media. 
     Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Computer-executable instructions also include program modules that are executed by computers in stand-alone or network environments. Generally, program modules include routines, programs, components, data structures, objects, and the functions inherent in the design of special-purpose processors, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps. 
     Those having ordinary skill in the art will appreciate that other embodiments may be practiced in network computing environments with many types of computer system configurations, including personal computers, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. Embodiments may also be practiced in distributed computing environments where tasks are performed by local and remote processing devices that are linked (either by hardwired links, wireless links, or by a combination thereof) through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices. 
     The various embodiments described above are provided by way of illustration only and should not be construed to limit the scope. Those skilled in the art will readily recognize various modifications and changes that may be made to the principles described herein without following the example embodiments and applications illustrated and described herein, and without departing from the spirit and scope.