Abstract:
A persistent data storage system comprising a code development system for defining a plurality of memory storage device identifiers. A configuration database system for associating a tag with a database storage address and with one of the memory storage device identifiers. The code development system for recovering data stored in a persistent electronic data memory associated with each of the memory storage device identifiers during initialization of a database. The configuration database for causing code developed by the code development system to cause data stored at the database storage address to be stored in the persistent electronic data memory if the data stored at the database storage address is changed.

Description:
RELATED APPLICATIONS 
       [0001]    This application is related to the following commonly owned and co-pending applications, which are filed concurrently herewith: attorney docket number 013628.00580 (11CXT0009), entitled “Regular Expression Selection for Configurable Application Data Steering;” attorney docket number 013628.00581 (11CXT0012), entitled “Database Hierarchical Inheritance;” and attorney docket number 013628.00582 (11CXT0013), entitled “Asynchronous Process Notification.” 
     
    
     TECHNICAL FIELD 
       [0002]    The application relates generally to multi-component systems, and more specifically to a multi-component process notification system that uses a database for communication activities, with persistent storage. 
       BACKGROUND OF THE INVENTION 
       [0003]    An unsolved problem in a multi-component system is the dissemination of data that defines changes to system/component states, settings, or configurations to other interrelated systems/components. In a modularized system consisting of independently developed components, it is not feasible for each system that changes information to know the systems that must react to the change. It is also not efficient for each system to frequently check to see if a change has occurred. 
         [0004]    A further problem relates to allowing two classes of information in a system to be access through the same means. These two types of information are transient data and persistent data. Transient data is not preserved when the system ceases operation, so that when the system is next started the values of the transient data are lost. Persistent data is stored in such a way that when the system ceases operation and is subsequently restarted, the values of the persistent data are retained. As the underlying storage methods are different, the means of accessing and changing these two classes of data are distinct, and the distinction creates two problems which be addressed. The first is that the classification of each data item in the system must be done at the beginning of the project. The second is that each access must know the classification of the data item so that it can be access properly. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with the present disclosure, a persistent data storage system is provided that includes a code development system for defining a plurality of memory storage device identifiers, such as identifiers for flash memory devices. A configuration database system, such as for managing the configuration of a multi-functional peripheral, associates a tag with a database storage address and with one of the flash memory device identifiers. The code development system recovers data stored in a persistent electronic data memory associated with each of the flash memory device identifiers during initialization of a database, such as when a device is turned on. The configuration database causes code developed by the code development system to cause data stored at the database storage address to be stored in the persistent electronic data memory if the data stored at the database storage address is changed. 
         [0006]    Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0007]    Aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, and in which: 
           [0008]      FIG. 1  is a diagram of a system for configuring and accessing a configuration database in accordance with an exemplary embodiment of the present invention; 
           [0009]      FIG. 2  is a diagram of system for providing system manager functionality in accordance with an exemplary embodiment of the present disclosure; 
           [0010]      FIG. 3  is a diagram of a system for providing configuration database functionality in accordance with an exemplary embodiment of the present disclosure; 
           [0011]      FIG. 4  is a flow chart of an algorithm for processing a key to identify a default node in accordance with an exemplary embodiment of the present disclosure; 
           [0012]      FIG. 5  is a flow chart of an algorithm for persistent storage of data associated with a node in a configuration database in accordance with an exemplary embodiment of the present disclosure; 
           [0013]      FIG. 6  is a flow chart of an algorithm for generating notification data for a database node in accordance with an exemplary embodiment of the present invention; 
           [0014]      FIG. 7  is a flow chart of an algorithm for determining whether a node may be accessed based on a current locked state of the node and a visa supplied with an access request in accordance with an exemplary embodiment of the present invention; and 
           [0015]      FIG. 8  is a flow chart of an algorithm for unlocking a node in accordance with an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    A detailed description of embodiments of the present disclosure is presented below. While the disclosure will be described in connection with these drawings, there is no intent to limit it to the embodiment or embodiments disclosed herein. On the contrary, the intent is to cover all alternatives, modifications and equivalents included within the spirit and scope of the disclosure. 
         [0017]      FIG. 1  is a diagram of a system  100  for configuring and accessing a configuration database in accordance with an exemplary embodiment of the present invention. System  100  can be implemented in hardware or a suitable combination of hardware and software, and can be one or more software systems operating on a multi-function peripheral processor, a digital signal processor or other suitable general or special purpose processing systems. 
         [0018]    As used herein, and by way of example and not by limitation, “hardware” can include a combination of discrete components, an integrated circuit, an application-specific integrated circuit, a field programmable gate array, a general purpose processing or server platform, or other suitable hardware. As used herein and by way of example and not by limitation, “software” can include one or more objects, agents, threads, lines of code, subroutines, separate software applications, one or more lines of code or other suitable software structures operating in one more software applications or on one or more processors, or other suitable software structures. In one exemplary embodiment, software can include one or more lines of code or other suitable software structures operating in a general purpose software application, such as an operating system, and one or more lines of code or other suitable software structures operating in a specific purpose software application. 
         [0019]    System  100  includes system manager  102 . System manager  102  manages the resources of system  100 , such as port handlers  104 , applications  106 , peripheral application programming interface (API)  108 A through  108 N, peripheral  110 A through  110 N and configuration database  114 . The control of resources is managed by the components that need the resources. For example, user interface  112 , system manager  102  and applications  106  do not need to know the address of memory buffers or other resources that are needed by a peripheral  110 A through  110 N, such as a scanner or a printer. By distributing control, system manager  102  can be used for other purposes, such as to determine whether an application can be started. For example, user interface  112  does not need to determine if the printer is currently printing. This architecture eliminates the possibility for system error to be caused, such as from race conditions between an application and a user requesting functions from user interface  112 . 
         [0020]    System  100  further includes peripheral API  108 A through  108 N, which can be a common API for applications  106  that are accessed by system manager  102 . In one exemplary embodiment, user interface  112  can communicate parameters to applications  106  through configuration database  114  instead of the peripheral API  108 A through  108 N for applications  106 . In this manner, the only data that system manager  102  needs to launch an application is the entry point. 
         [0021]    Applications  106  register with system manager  102  by providing a name (as a string), and data that defines how to pass control to each application. For example, this data can include an entry point address, a command line that is used to launch the application, or other suitable data. In this manner, system manager  102  does not need to be pre-loaded with data that defines applications  106  that are built into a product that uses system  100 . System manager  102  can manipulate applications, but does not maintain data that identifies which applications exist. 
         [0022]    When user interface  112  or any other suitable system needs to invoke an application, a request is transmitted to system manager  102 , which can start an application by name, by matching against the members of a class, or in other suitable manners. To match against a class, the requesting system transmits a string to system manager  102 , such as the first bytes from a file to be processed, and a class name. System manager  102  matches the string against the regular expressions registered with each application, looking for a match. If a match is found, the application name is used as if the name had been provided to system manager  102  as the application name. 
         [0023]      FIG. 2  is a diagram of system  200  for providing system manager functionality in accordance with an exemplary embodiment of the present disclosure. System  200  includes system manager  102  and application launcher  202 , application registration  204 , configuration database interface  206 , initialization  208  and application cancellation  210 , each of which can be implemented in hardware or a suitable combination of hardware and software. 
         [0024]    Application launcher  202  can be provided for use with a user interface function and other parts of system  100  that need to start an application or monitor the status of an application. Such user interface functions can also allow the status of the application to be determined. For example, a gross status indicator can be used to provide information about the current execution state of the application, such as whether execution is pending, has been started, has started and failed, has completed, or other suitable state information. Communication of the status between the user interface (or other system) and the application is accomplished using configuration database  114 . 
         [0025]    Applications can be launched into a suitable execution slot by immediately being launched through a start API, by being launched later after a user-defined delay through a delay API (such as to launch applications at a scheduled time), or in other suitable manners. In one exemplary embodiment, system manager  102  can create an activity node and return a node reference through an “activity” parameter. A persistent node can also be used to store application launch information so that a loss of power before the application is launched does not prevent the application from starting. 
         [0026]    Application registration  204  registers applications with configuration database  114  and other suitable systems. In one exemplary embodiment, an application can be named using a hierarchical naming scheme, such as an XML-based scheme, so as to allow the application name to also be a node identifier in configuration database  114 . An application can also be registered as a member of a class. 
         [0027]    Configuration database interface  206  provides an application programming interface or other suitable interface to configuration database  114 . In one exemplary embodiment, configuration database  114  can be used by system manager  102  and other systems to communicate status information or other suitable information for applications or other components of system  100 . System manager  102  thus interfaces with configuration database  114  through configuration database interface  206  to start or terminate applications, to facilitate communications between applications or components, or for other suitable purposes. 
         [0028]    Initialization  208  performs initialization operations for system manager  102  and configuration database  114 , such as to initialize a number of processor slots, to allocate memory, and to perform other suitable operations. In one exemplary embodiment, an estimated size is obtained to determine an amount of memory to be reserved for the database storage, such as by using an average number of size times a number of database entries or in other suitable manners. Initialization  208  can populate configuration database  114  with initial contents, such as by using a bulk population procedure. Bulk population of the database can be done 1) using an XML stream that adheres to the hierarchical naming schema, 2) by pointing to an object that contains such an XML stream, 3) from streams that follow the proprietary format in which persistent objects are stored, or in other suitable manners. A complementary function can be used to convert a database context into a bulk structure. In another exemplary embodiment, API calls can be used to set the initial contents of nodes associated with the keys of configuration database  114 . 
         [0029]    Application cancellation  210  performs cancellation processing for an application that has been scheduled, an application that is in operation, or other suitable activities. Typically, a cancellation routine is required to cancel an application or activity. An activity can be cancelled where the application itself will not be cancelled, such as a print job for a printer. Two APIs can be provided to assist with canceling such activities. The first API can be a helper function that provides a list of activities that can be canceled, such as with an option to retrieve only the activity of the highest hierarchy if the intention is to cancel the application. The second API can be used to trigger a cancellation of an activity. For example, if an activity has not started (such as a delayed start application), then the node can be deleted and a callback can be made to let the associated client know that the application was cancelled and never started. For an application that has never started, the cleanup function can still be called at the end of the cancellation procedure. 
         [0030]    Application cancellation can provide the callback indirectly, where a piece of code that requires confirmation of a completed cancel is registered for a notification function through configuration database  114  for the node. The reapplication cancellation can also be provided through a configuration database  114  node or in other suitable manners, such as for debugging or other suitable purposes. The calling thread information and current time can also be recorded before submitting the activity to application cancellation  210  for canceling the activity. The activity is deemed canceled when the activity sets its completion status in configuration database  114 . Application cancellation  210  can then delete the activity from an activities tree. 
         [0031]    In operation, system  200  provides system manager  102  functionality that is used to manage operations of the components of system  100  in accordance with the present disclosure. System  200  uses configuration database  114  to communication between components of system  100 . 
         [0032]      FIG. 3  is a diagram of a system  300  for providing configuration database functionality in accordance with an exemplary embodiment of the present disclosure. System  300  includes configuration database  114  and access keys  304 , nodes  306 , default nodes  308 , persistent nodes  310 , notify nodes  312 , access key processor  314 , update processor  316 , code development system  318 , persistent data memory systems  320  and locking system  322 , each of which can be implemented in hardware or a suitable combination of hardware and software. 
         [0033]    Access keys  304  are used to access data stored in configuration database  114 . An access key can be named using a hierarchical naming schema, such as an XML-compliant naming schema. In one exemplary embodiment, an XML-based naming schema might result in an access key having a value of “/A/B/C/D,” were a text string is associated with each of the variables A through D. 
         [0034]    Nodes  306  refer to the data strings stored within configuration database  114 . A node can be characterized as a key value that contains sub-keys, and the terms “node,” “key,” “sub-node” and “sub-key” can refer to the same data structure, but connote different relative meanings. For example, a key is used to locate a node, and the node associated with the key will typically include additional data beyond that data that defines the key. Likewise, a node may have associated sub-nodes, where the key that is used to locate a node can also be used to locate the associated sub-nodes. Data can be stored in a node in a suitable predetermined data format. A node can also have associated sub-nodes, such as default nodes  308 , persistent nodes  310  and notify nodes  312  or other suitable sub-nodes. 
         [0035]    Default nodes  308  are used to provide data for a node that is automatically constructed. In one exemplary embodiment, a node can be automatically constructed in configuration database  114  in order to allow systems and components of system  100  to communicate with each other. In this exemplary embodiment, a default node can be created as a sub-node for a related class, such as a print sub-node for data that defines a print job. The new print sub-node can contain all of the data required for the print job to be processed, and can be created as a print node sub-node, where the default node settings, notification node settings and persistent node settings are used to coordinate processing of the print job, as further described herein. 
         [0036]    A default node value can be stored in configuration database  114  and associated with a node. Access key processor  314  can return the default node value as part of a revised input value. For example, access key processor  314  can be configured to return part of the input value as part of the revised input access key, where a hierarchical naming schema such as an XML-compliant naming schema or other suitable schema are used. In this exemplary embodiment, an XML-based naming schema might result in an input of “/A/B/C/D” to access key processor  314 , and a default node value may exist for “/A/B/C,” “/A/B” or “/A.” The default node value can be used to provide the root for a new input key, such as “/X/Y/Z,” where the entire new input key would be “/X/Y/Z/D.” A default node value can be generated if an associated node value is not stored in the configuration database for an associated key value. 
         [0037]    A node can have a default sub-node that is used to handle a request for information, which is presented by submitting a key value for a node, when there is no associated information stored at the node for that key value. The default sub-node can contain a name of another node that can be searched to satisfy the request. Rather than giving each key a default value, an hierarchal system of inheritance can be provided that determines defaults. For example, if a node value for key is not found in the database, a SOUGHT_NAME variable can be set to be the final name in the key. In this example, if the key is “/A/B/C/D/NumCopies”, then SOUGHT_NAME would be set to “NumCopies”. A SEEKING_NODE variable can be set to be the key with the final slash and name removed. Using the above example, in the above case, SEEKING-NODE would be “/A/B/C/D.” If a default value for SEEKING_NODE exists, a new key is constructed based on the value. In the above example, if the value of “/A/B/C/D/DEFAULT” is “/X/Y/Z”, then the new search is set to be to be “/X/Y/Z/Numcopies,” and the search is repeated using the new key. If the SEEKING_NODE is equal to the root value, such as “/,” then the search has failed. If no value for the default in the SEEKING_NODE exists, the final name is moved from the end of SEEKING_NODE to SOUGHT_KEY. For example, SOUGHT_NAME becomes “D/NumCopies”, and SEEKING_NODE becomes “/A/B/C,” and the search is repeated again. 
         [0038]    Persistent nodes  310  are nodes containing data that is stored in a persistent electronic memory, such as NVRAM. Persistent node data can be stored using string keys and simple values in a tagged, self-describing data structure, unlike the anonymous, untagged (i.e. not self-describing) structures stored in NVRAM with a standard NVRAM API. Storing data in a string-based, self-describing structure is less storage efficient than pure binary encoding, but one benefit of string-based storage is that when different versions of firmware that utilizes the data are stored to a flash memory device, the database remains intact and usable. In an untagged data structure, the data would be preserved, but if the binary layout of the data changed, it would be unusable to new firmware. For such new firmware, any stored values would automatically revert to “factory default” settings. By using a tagged data structure, any new values will assume the factory default values, but any pre-existing values will be preserved. 
         [0039]    To associate a portion f the database with a record in NVRAM or other suitable nonvolatile memory, the value of a persistent node identifier is set to equal the name of the NVRAM object, and a “persistent” key is associated with the node. All nodes or sub-nodes under the node can also be serialized into the object, and nodes at various sections of a database tree can be assigned to the same NVRAM object. 
         [0040]    In one exemplary embodiment, persistent nodes  310  can be used to prevent interruption of scheduled tasks if a loss of power occurs. In this example, if a print job has been created and stored to a print node, the print job can inherit a default persistent node setting, such that the print job node data is backed up in persistent data memory systems  320 , and is only deleted from persistent data memory systems  320  when the print job completes. In this manner, the print job data can be restored if a loss of power occurs before the print job completes. 
         [0041]    Notify nodes  312  are utilized by the configuration database to transmit change data to any component that needs to know when a change occurs to a node. In one exemplary embodiment, a “notify” node or tag (such as a data field contained within a node) can be attached or associated with the selected node. The node associated with the notify tag can contain notification data (such as a single value) , can be a node that contains sub-nodes, or can be other suitable data structures. In this exemplary embodiment, pairs of addresses and parameters can be associated with or stored in the notify node. When the notify node is triggered, each of the functions identified by the address can be called with the given parameter and a reason for why the function is called (such as when the node has changed, when the node has been deleted, or when a new sub-node has been added). 
         [0042]    In another exemplary embodiment, a user interface system can be used to monitor processes such as print jobs. In this exemplary embodiment, control of the print jobs can be coordinated between user interface  112  (which receives user entered control data), system manager  102  (which launches the printer application in response to the user-entered control data), the peripheral  110 A through  110 N (that is associated with the printer) and other components of system  100 , each of which communicate through configuration database  114  by accessing data stored in nodes of configuration database  114 . The print job data can be stored to a new node that is a sub-node of a print node, where the print node includes an associated notify node that notifies the associated printer that a print job is available and needs to be retrieved for processing. The new node can be created using data stored in one or more default nodes associated with the print node or sub-nodes (such as sub-nodes for specific printers or types of print data). As the print job is processed, status updates can be transmitted from the printer back to configuration database  114  (such as “printing,” “offline,” or “finished”), and a notify node associated with the printer status node can transmit the status data to user interface  112 . In this manner, all communication can be handled through configuration database  114  without the need for a communications infrastructure. 
         [0043]    Access key processor  314  can receive an input value, such as an input key, and return the associated node value for the input value if the input value matches an access key. In general, the access key will be stored in a first memory device sector and the associated node data will be stored in a second memory device sector, but the keys and nodes can also or alternatively be stored in separate memory devices. If the input value does not match an access key stored in the first memory device sector, then access key processor  314  generates a revised input value containing a default node value, if one exists. In one exemplary embodiment, access key processor  314  can modify the input key to search for a default node value, such as by using a root portion of the input key to search for an associated default node value or default search key, and returns a search failed indication if no default node value is stored in the second data memory device sector and associated with the portion of the input value. 
         [0044]    Update processor  316  can process notification field data if data associated with a notify node  312  is modified. In one exemplary embodiment, update processor  316  can retrieve a function stored in a sub-field of the notification field and can execute the function, such as to transmit other sub-fields contained within the notification field data to an address stored in a sub-field of the notification field. As previously discussed, the address can be associated with a component of system  100 , such as user interface  112 , one of peripherals  110 A through  110 N, or other suitable components. 
         [0045]    Code development system  318  allows a user to associate default nodes  308 , persistent nodes  310 , notify nodes  312  or other suitable nodes with nodes or components that are stored in configuration database  114  while creating applications for use with system  100 . In one exemplary embodiment, a user can: identify data as being required for a default node, such as to accommodate and configure new peripherals; identify data as being required to be stored as persistent data, such as user preference settings for peripherals; and identify a component or system that should be notified if a node is changed, deleted or if sub-nodes are added, such as for a status indicator on a user interface. Other suitable applications can also or alternatively created using code development system  318 , and code development system  318  provides the functionality for creating applications or other software code that utilizes the data functions and structures disclosed herein. 
         [0046]    Persistent data memory systems  320  are one or more non-volatile data memory devices that are used to store configuration data, such as user preferences. Persistent data memory systems  320  can be updated in conjunction with persistent nodes  310  or in other suitable manners. 
         [0047]    Locking system  322  locks nodes and sub-nodes based on data received from systems and components that access the nodes, to control simultaneous access. The operation to lock a node returns a key, which may be referred to as an access code or visa, that must be presented with subsequent requests to access, in order to unlock the node. In one exemplary embodiment, when a lock is accessed by a function, four parameters can be passed: the context, the name, the visa, and the wait behavior. Likewise, other suitable parameters can be used to access a locked node. 
         [0048]    In one exemplary embodiment, a lock operation performed on a node can be used to implement a “direct lock,” and any sub-nodes that inherit the locked state can be used to implement an “inherited lock.” In this exemplary embodiment, a node with a direct lock may not be locked again, whereas a sub-node with an inherited lock can be locked if the visa is presented. If the visa is correct, a new visa can be returned, where the new visa can be used to access the sub-node and its contents. In this exemplary embodiment, the visa corresponding to the inherited lock can be deactivated, such that it no longer gives access to the sub-node or its contents. When a node is locked, all reads, writes, and locks are prohibited unless the proper visa is passed with the call. Notification and persistent data processing can also be deactivated for a locked node. When a node is unlocked and is not a sub-node of any locked node, any pending notifications and persistent data processing can be performed. 
         [0049]    In operation, system  300  facilitates communication between components and systems of system  100  through configuration database  114 . Through the use of default nodes  308 , persistent nodes  310  and notify nodes  312 , these components and systems can communication with each other and process data, such as data for a multi-function peripheral or other suitable data. 
         [0050]      FIG. 4  is a flow chart of an algorithm  400  for processing a key to identify a default node in accordance with an exemplary embodiment of the present disclosure. Algorithm  400  can be implemented in hardware or a suitable combination of hardware and software, such as by converting the flowchart algorithm to software code that will operate on a multi-function peripheral processor using standard programming techniques. 
         [0051]    Algorithm  400  begins at  402  where a key is received. The key can be received as encoded data from system manager  102  or other suitable systems, and can nave a predetermined data format that is defined by a number of fields and data type (such as alphanumeric). The key can be named using a hierarchical naming convention, such as an XML naming convention, or in other suitable manners. For example, the key can be named A/B/C/D, where A-D can be any suitable text string. The algorithm then proceeds to  404 . 
         [0052]    At  404 , it is determined whether the key matches a key value in the configuration database. The match can be determined using a suitable matching or look-up algorithm, such as an algorithm that searches through an ordered list or other suitable algorithms. If a match is found, the algorithm proceeds to  406  and the value corresponding to the key is retrieved from the database, such as by copying a data field stored in the database that is associated with the key. Otherwise, the algorithm proceeds to  408 , where a name is set. In one exemplary embodiment, the name can be set by using the least significant text string of the hierarchical key name, such as the text string associated with “D” in the example above, or in other suitable manners. The algorithm then proceeds to  410 , where the node is set. In one exemplary embodiment, the node can be the remainder of the key name other than the least significant text string, such as “A/B/C” in the example above. The algorithm then proceeds to  412 . 
         [0053]    Ac  412 , it is determined whether a default name value exists for the node assigned in  410 . If it is determined at  414  that default name has been found, the algorithm proceeds to  416  where a new key is constructed using the default name and the name set at  408 . For example, if the default name value is “X/Y/Z,” then the new key would be “X/Y/Z/D.” The algorithm then returns to  404 . 
         [0054]    If it is determined at  412  that no default name value exists, the algorithm proceeds to  418 , where it is determined whether the key is at a root. For example, using the naming convention discussed above, if the remaining key is “/D,” then the key is at a root (i.e. “/”) and no additional searching can be performed. The algorithm proceeds to  420  where a search failed indicator is generated. Otherwise, the algorithm proceeds to  422  where the name is set. Using the above example, the new name setting when the search for “/A/B/C/D” has not resulted in an associated node or a default for “/A/B/C,” the new name would be “/C/D” for the second default node search. The algorithm then proceeds to  424  where the node is set, such as to “/A/B,” for the example described above. The algorithm then returns to  412 , where a search for a default node for the new node value is performed. 
         [0055]    In operation, algorithm  400  allows a default node value structure to be used in a configuration database that allows default values for nodes to be assigned to identify information for an unidentified node. Algorithm  400  seeks for the default value that is closest to the new node value by checking each node in a hierarchical naming scheme for a default node value, starting with the node closest to the new node in the naming scheme and ending with the root node, after which a search failed indicator is returned. 
         [0056]      FIG. 5  is a flow chart of an algorithm  500  for persistent storage of data associated with a node in a configuration database in accordance with an exemplary embodiment of the present disclosure. Algorithm  500  can be implemented in hardware or a suitable combination of hardware and software, such as by converting the flowchart algorithm to software code that will operate on a multi-function peripheral processor using standard programming techniques. 
         [0057]    Algorithm  500  begins at  502  where a node identifier is received. In one exemplary embodiment, the node identifier can be received when the node is created using a software development kit as part of an application that uses a configuration database to store data associated with the node or in other suitable manners. The algorithm then proceeds to  504 . 
         [0058]    At  504 , a storage identifier is defined, such as by using the software development kit to identify a persistent data memory device, such as a nonvolatile data memory device, a magnetic drive, an optical data storage device or other suitable persistent data memory devices. The algorithm then proceeds to  506 . 
         [0059]    At  506 , a tag is attached to a node that associates the data stored at the node with a storage identifier. In one exemplary embodiment, the tag can be attached to the node when an application is being created or modified by a programmer, such as when the programmer indicates that data should be stored in a persistent data storage device. The algorithm then proceeds to  508 . 
         [0060]    At  508 , the node data is stored in the associated persistent data memory device. In one exemplary embodiment, the node data can be stored when it is created for each node, the node data can be stored after programming for a module or application has been completed, or other suitable processes can be used. The algorithm then proceeds to  510 . 
         [0061]    At  510 , it is determined whether more nodes are to be generated or processed. If is determined that more nodes are to be generated or processed, such as when an application is being developed or compiled, the algorithm returns to  502 . Otherwise, the algorithm proceeds to  512 . 
         [0062]    At  512 , a database is initialized. In one exemplary embodiment, the initialization can be performed for a configuration database when a multi-function peripheral is powered on or in other suitable manners. The algorithm then proceeds to  514 . 
         [0063]    At  514 , persistent node data for the nodes of the database is recovered. In one exemplary embodiment, the nodes of the database with associated tags can be identified, and the data stored in persistent memory devices can be retrieved and used to populate the database. The algorithm then proceeds to  516 . 
         [0064]    At  516 , it is determined whether a node has been updated. In one exemplary embodiment, a node can be used to store user settings for devices such as printers, fax machines, or other suitable peripherals. When a user changes a setting, the setting data can be stored at a node in a configuration database. if a node has not been updated, the algorithm returns and waits for a node to be updated. Otherwise, the algorithm proceeds to  518 . 
         [0065]    At  518 , the node is checked to see if it is locked. If the node is locked, the algorithm proceeds to  522 . If the node is not locked, the algorithm proceeds to  520 . 
         [0066]    At  520 , the updated node data is stored in the persistent data memory device. In one exemplary embodiment, the persistent data memory device can be identified using the tag data and the updated node data can be stored in the associated persistent data memory device using a suitable data storage process. The algorithm then returns to  514 . 
         [0067]    At  522 , the information to update the associated persistent data memory device is queued for later processing by an unlock algorithm. 
         [0068]    In operation, algorithm  500  allows data that should be maintained in a persistent data memory device to be easily identified, updated and recovered. Algorithm  500  can be used by programmers during the application coding process to create a structure within the application code for providing for persistent storage of selected data that is determined by the developer to be suitable for persistent storage, such as user setting selections for peripheral devices. 
         [0069]      FIG. 6  is a flow chart of an algorithm  600  for generating notification data for a database node in accordance with an exemplary embodiment of the present invention. Algorithm  600  can be implemented in hardware or a suitable combination of hardware and software, such as by converting the flowchart algorithm to software code that will operate on a multi-function peripheral processor using standard programming techniques. 
         [0070]    Algorithm  600  begins at  602 , where a related node for an application is identified. In one exemplary embodiment, the node can be identified using a function for retrieving or setting a key value, such as a key value “get” function or a key value “set” function. In this exemplary embodiment, a set function which implies nodes that do not exist can cause those nodes to be created. If a type of the key does not result in a match when a “get” function that uses the key as an argument is called, the function can return an error, whereas if the type of a key does not match when a “set” function is called, the type can be changed. 
         [0071]    A “set” function call can create a key in the context if it does not already exist, and a “get” function call can return a value from a default setting, if a default setting exists. A “set” function call does not change the default. In addition, after a “set” function call, any node having an associated persistent tag is updated in the persistent data memory if it is not locked. If the node is locked, the update can be delayed until all locks are removed from the node. 
         [0072]    After a “get” or “set” function call, notification processing can be performed by looking in the node that contains the changed key for a “notify” tag. If a “notify” tag is present and the node does not have a lock, a configuration database system manager can call each of the entries in the “notify” tag and search for each of the containing contexts. If a context is present and the node is has a lock, the notification can be delayed until all locks are removed from the node, such as where bottom-up processing is necessary so that a subscription to a lower level node does not interrupt subscriptions to a higher level node. 
         [0073]    For a notification “get” or “set” function, an address of the function to be called for notification can be provided, as well as a value for the first argument to be passed to the notification function. Additional data, such as a reason parameter, can be provided that identify a reason that a notifier was called, such as an object add, an object delete, an object change, other suitable reasons or a combination of suitable reasons. Restrictions can also be imposed on the notification function, such as to prevent a configuration database application programming interface from being called from the notification callbacks. The algorithm then proceeds to  604 . 
         [0074]    At  604 , a notification tag is attached to the node. As discussed above, the notification tag can include an address of a function to be called, a value for a first argument, or other suitable data. The algorithm then proceeds to  606 . 
         [0075]    At  606 , it is determined whether any additional nodes are to be processed. If no additional nodes are to be processed, the algorithm proceeds to  608 , otherwise the algorithm returns to  602 . 
         [0076]    At  608 , a system state is monitored, such as by a system manager of a configuration database or other suitable systems. The algorithm then proceeds to  610  where it is determined whether a node has been updated, such as of an object has been added, changed, deleted or if other suitable node updates have o red. If no update has occurred, system state monitoring continues. Otherwise, the algorithm proceeds to  612 . 
         [0077]    At  612 , notification data associated with a node is obtained, as discussed above. The algorithm then proceeds to  614 . 
         [0078]    At  614  it is determined if the node is locked. If the node is not locked, the algorithm proceeds to  616  where the associated function is called, as described above. If the node is locked, the algorithm proceeds to  618 . 
         [0079]    At  616  the notification function is called with the notification function argument and the reason for the notification. The algorithm then proceeds to  608  to wait for the next change. 
         [0080]    At  618  the notification function, the notification function argument, and the reason for the notification are queued for subsequent processing by an unlock algorithm. The algorithm proceeds to  608  to continue monitoring for changes to the node or nodes. 
         [0081]    In operation, algorithm  600  allows a component to be notified when a change occurs to a related node. Algorithm  600  only provides notification when a change occurs, and does not require the component to periodically issue a query to determine whether a change has occurred. In addition, algorithm  600  avoids other problems that can exist with disseminating information about changes to system state, settings or configuration to other affected systems. 
         [0082]      FIG. 7  is a flow chart of an algorithm  700  for determining whether a node may be accessed based on a current locked state of the node and a visa supplied with an access request. Algorithm  700  implements a wait behavior, where a period of time is used to wait for a node to become accessible if it is not unlocked. Algorithm  700  can be implemented in hardware or a suitable combination of hardware and software, such as by converting the flowchart algorithm to software code that will operate on a multi-function peripheral processor using standard programming techniques. In one exemplary embodiment, the behavior on a visa mismatch is a specification of a period of time to wait for the node to be accessible, where the period of time can be a predetermined period of time, a variable period of time or other suitable periods of time. 
         [0083]    Algorithm  700  begins at  702 , where a node to be access has been identified. A current visa is determined by examining the node to see if it has a direct lock and associated visa. If it determined that a direct lock and visa exists, that visa is used to match for the following steps. If no direct lock and visa exists for the node, then each containing node is examined until a top level of the structure is reached or an inherited lock and visa is found. If it determined that an inherited lock and visa exists, that visa is used to match for the following steps. The algorithm continues with  704 . 
         [0084]    At  704 , if a direct or inherited lock and associated visa were not found, the algorithm continues to  714  and the access is permitted. If any lock was found, the algorithm continues to  706 . 
         [0085]    At  706  the visa found in  702  is compared with the visa supplied. If the visa matches, the algorithm proceeds to  714  and the access is permitted. If the visa does not match, the algorithm continues at  708 . 
         [0086]    At  708 , the time remaining to wait is examined. If there is no remaining time to wait, the algorithm continues to  716  and access is denied. If there is time remaining, the algorithm continues at  712 . 
         [0087]    At  710 , the algorithm waits until either the specified time has elapsed, or a change has been made to the locks which could result in access being allowed. When such a change has occurred, or when the time period has elapsed, the algorithm continues at  712 . 
         [0088]    At  712 , if the wait was for a specific period, the time spent in step  710  is subtracted from the remaining period. The algorithm continues to  702  to attempt again to match the supplied visa with the node to be accessed. 
         [0089]      FIG. 8  is a flow chart of an algorithm  800  for unlocking a node. When a node is unlocked, the visa is set to the value of the immediately containing node if it is either directly or indirectly locked, or to zero if the node is now completely unlocked. Algorithm  800  can be used to implement delayed persistent storage updates and delayed change notifications, as described in algorithms  500  and algorithm  600 . Algorithm  800  can be implemented in hardware or a suitable combination of hardware and software, such as by converting the flowchart algorithm to software code that will operate on a multi-function peripheral processor using standard programming techniques. 
         [0090]    Algorithm  800  begins at  802 , in which a visa of any containing is determined. The algorithm continues with  804 . 
         [0091]    At  804 , if a visa was found, the node is not unlocked as it is indirectly locked by a node which contains it. The algorithm continues with  818 . 
         [0092]    At  806 , the queue of persistent storage updates from algorithm  500  is examined for entries which apply to this node or any sub-nodes. 
         [0093]    At  808 , if no persistent storage updates were found, the algorithm continues with  812 . 
         [0094]    At  810 , the queued persistent storage updates are performed to the associated memory system, and the updates are removed from the queue. In one exemplary embodiment, information may have been updated many times while the node was locked, and the associated memory system can be updated once with the most recent value stored in the node or sub-node. Other suitable update procedures can also or alternatively be used. 
         [0095]    At  812 , the queue of pending change notifications is examined for entries which apply to this node or any sub-nodes. 
         [0096]    At  814 , if no applicable change notifications are found, the algorithm continues with  818 . 
         [0097]    At  816 , the queued pending change notifications are performed by calling the notification functions with their argument, and the reason for change. In one exemplary embodiment, where multiple changes have occurred while the node or sub-node was locked, each function can be called once for each argument regardless of how many changes were queued, where the reason for change argument can the union of the one or more change notification reasons. Other suitable function call processes can also or alternatively be used. 
         [0098]    It should be emphasized that the above-described embodiments are merely examples of possible implementations. Suitable variations and modifications can be made to the above-described embodiments without departing from the principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.