Patent Publication Number: US-8996473-B2

Title: Checking compatibility of extended and core SAM schemas based on complex goals

Description:
BACKGROUND 
     Businesses are increasingly service-driven, where a service can, for example, represent a part of or a complete business process. In some examples, the business process depicts the lifecycle of a business object (BO). A number of actions constrained by a set of business policies can result in the BO transitioning from an initial state to a final state during its lifecycle. Constraints can vary for different customized business processes. The validity of a business process can depend on the ability of a BO to reach a final state. 
     SUMMARY 
     Implementations of the present disclosure include computer-implemented methods for evaluating a validity of an extended status and action management (SAM) schema. In some implementations, actions include receiving the extended SAM schema, the extended SAM schema being stored as a computer-readable document in memory and being an extension of a core SAM schema, providing one or more goals, each goal representing an intention of the core SAM schema, the one or more goals being provided in a computer-readable document stored in memory and comprising one or more primary goals that each express an intention of a process underlying the core SAM schema, and processing the one or more goals using a computer-executable model checking tool for evaluating the validity of the extended SAM schema. 
     In some implementations, actions further include providing an extended finite state machine (FSM) based on the extended SAM schema, the extended FSM representing states of the extended SAM schema and transitions between states, the extended FSM being provided as a computer-readable document and being stored in memory, wherein processing further comprises processing the extended FSM. 
     In some implementations, processing the extended FSM and the one or more goals includes generating one or more traces, each trace defining a path of status vectors and actions that are possible through the extended SAM schema. 
     In some implementations, processing the extended FSM and the one or more goals further includes determining that at least one status vector of each primary goal of the one or more goals appears in at least one trace, determining that every maximal finite trace of the one or more traces ends in a status vector of any goal, determining that from every status vector of any infinite trace, a status vector of any goal is reachable, and in response, indicating that the extended SAM schema is valid. 
     In some implementations, processing the extended FSM and the one or more goals further includes determining that no status vector of a primary goal of the one or more goals appears in any trace, and in response, indicating that the extended SAM schema is invalid. 
     In some implementations, processing the extended FSM and the one or more goals further includes determining that at least one maximal finite trace of the one or more traces does not end in a status vector of a goal, and in response, indicating that the extended SAM schema is invalid. 
     In some implementations, processing the extended FSM and the one or more goals further includes determining that from at least one status vector of any infinite trace, no status vector of any goal is reachable, and in response, indicating that the extended SAM schema is invalid. 
     In some implementations, each state is associated with a status vector, the status vector being defined as a ordered set of variable values. 
     In some implementations, each transition is associated with an action that can be performed to change a status vector. 
     In some implementations, the extended SAM schema represents constraints on actions that can be performed to transition between states. 
     In some implementations, a primary goal represents a desired goal of the process. 
     In some implementations, the one or more goals further comprise one or more recovery goals, each recovery goal representing an acceptable goal of the process. 
     In some implementations, at least one recovery goal is specific to the extended SAM schema and is not a goal of the core SAM schema. 
     In some implementations, the process includes a business process. 
     In some implementations, the core SAM schema is determined to be valid. 
     In some implementations, the extended SAM schema is provided based on a business object (BO) extension that points to a core BO, the BO extension comprising business object node (BON) extensions, each BON extension pointing to a respective BON of the core BO. 
     In some implementations, the core SAM schema is provided based on the core BO. 
     The present disclosure also provides a computer-readable storage medium coupled to one or more processors and having instructions stored thereon which, when executed by the one or more processors, cause the one or more processors to perform operations in accordance with implementations of the methods provided herein. 
     The present disclosure further provides a system for implementing the methods provided herein. The system includes one or more processors, and a computer-readable storage medium coupled to the one or more processors having instructions stored thereon which, when executed by the one or more processors, cause the one or more processors to perform operations in accordance with implementations of the methods provided herein. 
     It is appreciated that methods in accordance with the present disclosure can include any combination of the aspects and features described herein. That is, methods in accordance with the present disclosure are not limited to the combinations of aspects and features specifically described herein, but also include any combination of the aspects and features provided. 
     The details of one or more implementations of the present disclosure are set forth in the accompanying drawings and the description below. Other features and advantages of the present disclosure will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  depicts an example process in accordance with implementations of the present disclosure. 
         FIG. 2A  depicts an example context within which implementations of the present disclosure can be applied. 
         FIG. 2B  depicts an example object model. 
         FIG. 3  depicts an example status and action management (SAM) schema providing constraints on actions that can be executed in the example context of  FIG. 2A . 
         FIG. 4  depicts an example state diagram based on the example SAM schema of  FIG. 3 . 
         FIG. 5  depicts an example extended SAM schema based on the SAM schema of  FIG. 3 . 
         FIG. 6  depicts an example state diagram based on the example extended SAM schema of  FIG. 5 . 
         FIG. 7  is a schematic illustration of example computer systems that can be used to execute implementations of the present disclosure. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     Implementations of the present disclosure are generally directed to modeling intentions of a business process that is expressed in an extended status and action management (SAM) schema as goals, and validating the extended SAM schema against the goals. More particularly, intentions of the business process can be modeled as one or more primary goals and one or more recovery goals. In some examples, a core SAM schema is provided and the one or more primary goals and the one or more recovery goals are provided for the core SAM schema. A core finite state machine (FSM) is provided based on the core SAM schema. The one or more primary goals and the one or more recovery goals are validated against the core FSM to determine whether the core SAM schema, and thus an underlying core business process, correctly fulfills the intentions for which the business process is provided. An extended SAM schema is provided based on the core SAM schema. An extended FSM is provided based on the extended SAM schema. The extended SAM schema is validated against at least the one or more primary goals and one or more recovery goals to determine whether the extended SAM schema, and thus an underlying extended business process, correctly fulfills the intentions for which the core business process is provided. In some examples, the one or more recovery goals can be different for the core SAM schema and the extended SAM schema. 
     In some examples, the extended. SAM schema is valid if the extended SAM schema can potentially reach every primary goal, and, if the extended SAM schema cannot reach a primary goal in a course of execution, the extended SAM schema at least reaches a recovery goal in that course of execution. In some examples, the extended SAM schema is invalid if the extended SAM schema cannot reach one of the primary goals, or the extended SAM schema cannot reach a recovery goal in a course of execution in lieu of a primary goal. 
     In short, the present disclosure provides a constraint-driven general model (core SAM schema) with a verification process, the model addressing challenges associated with correctness of the constraints with respect to specified business goals. An extended model (extended SAM schema) can be provided based on the general model, the extended model also addressing challenges associated with correctness of the constraints with respect to specified business goals. 
       FIG. 1  depicts an example process  100  in accordance with implementations of the present disclosure. In some implementations, the example process  100  can be provided using one or more computer programs that are executed using one or more computing devices. 
     A core SAM schema is received ( 102 ). In some examples, the core SAM schema can be provided as a computer-readable document that is received from computer-readable memory. For example, the core SAM schema can be provided in a machine-readable specification language, discussed in further detail herein. A core FSM is generated ( 104 ). In some examples, the core FSM is generated based on the core SAM schema and can be provided as computer program code. One or more goals of the core SAM schema are defined ( 106 ). In some examples, the one or more goals represent intensions of the core SAM schema and can be defined in a machine-readable specification language. The core SAM schema is verified based on the core FSM and the one or more goals ( 108 ). In some examples, the core FSM and the one or more goals are provided to a computer-executable model checking tool as respective computer-readable documents. The computer-executable model checking tool processes the core FSM and the one or more goals, as discussed in further detail herein, to determine a validity of the core SAM schema. 
     An extended SAM schema is received ( 110 ). In some examples, the extended SAM schema can be provided as a computer-readable document that is received from computer-readable memory. For example, the extended SAM schema can be provided in a machine-readable specification language, discussed in further detail herein. An extended FSM is generated ( 112 ). In some examples, the extended FSM is generated based on the extended SAM schema and can be provided as computer program code. The extended SAM schema is verified based on the extended FSM and the one or more goals ( 114 ). In some examples, the extended FSM and the one or more goals are provided to a computer-executable model checking tool as respective computer-readable documents. The computer-executable model checking tool processes the extended FSM and the one or more goals, as discussed in further detail herein, to determine a validity of the extended SAM schema. 
     In general, SAM schemas provide a consistent approach to status modeling and implementation activities of data objects (e.g., a business object (BO), or business object node (BON)). More particularly, a SAM schema can be defined at design-time and can be provided as a schema model that is stored in computer-readable medium. The SAM schema includes preconditions for performing actions with each precondition identifying how a status affects whether an action is allowed to be performed at runtime by a data object node instance having the status. A status schema instance is created for a particular object node instance that is used in a computer-based process. The status schema instance corresponds to the status schema model. 
     In some examples, one or more BOs can be associated with a business process and can be manipulated during execution of the business process. In some examples, manipulation of a BO can result in the BO transitioning from one status to another status. In some examples, a BO is provided as a hierarchical structure of BO nodes (BONs). In some examples, BON can correspond to a header of the BO, and one or more BONs can correspond to respective one or more items that make up the BO. As used herein, reference to a SAM schema of a BO can indicate a SAM schema of a BON (e.g., the SAM schema can refer to a header or an item of a BO, or the BO itself, as applicable). 
     In some examples, during execution of a business process, a method that changes attribute values of the BO can be executed. Consequently, the BO (e.g., a BON of the BO) can transition from one status to another status. In some examples, a status can be defined as the combination of the current attribute values of a BON at a given point in time. In some examples, a status of the BO can be defined based on the respective statuses of the BONs that make up the BO. In some examples, an attribute of BON can be classified into categories. Example categories can include standard attributes (e.g., a customer name) and status variables. In some examples, status variables are additional attributes that describe milestones in a lifecycle of the BON. Status variables can provide an aggregated and interpreted view of the status of the BON. In some examples, the status of a BON can be defined based on the values of the status variables at a given point in time. In some examples, the status can be provided as a BO attribute and a modeled entity of SAM that represents the lifecycle of a BON (the result of a processing step). Consequently, a status variable specifies a certain milestone in the lifecycle of a BON (e.g., “order confirmed”). In terms of the business process, this status is indicative of the current status of the business process. Accordingly, a status is a named result of a process step within the business process that is a precondition for a following process step. 
     During the lifecycle of a BO, the BO can enter various statuses. In order to change a status, an action can be performed on the BO. In some examples, it is not desirable to enable state changes from any status to any other status and/or to enable actions with any status as a precondition for a state change. Consequently, the SAM schema refines a BO (BON) model, discussed in further detail below, in terms of a constraint-based model that governs the lifecycle of the BO (BON). In some examples, the SAM schema is intended to define all possible statuses of a BON, possible actions that can be performed on the BON, the resulting statuses, and preconditions in terms of statuses that have to be reached to perform a certain action. In other words, the SAM schema provides a constraint-based model that defines constraints between statuses and actions. Consequently, the SAM schema is a status schema model type. In some examples, a status schema includes the status variables of a BON, the possible status transitions to the values of these status variables (i.e., triggered by actions) and of preconditions that guard changes to the status variables. At design time, for a given BON, various status schemas can be defined and, when the BON is initialized, one of the status schemas is selected and loaded into the runtime. During runtime (e.g., execution of the modeled process), status changes of a BO occur as they are modeled. Consequently, it can be ensured that no changes other than modeled changes occur and required changes actually do occur. In order to do so, the SAM schema (constructed during the design time) is loaded and evaluated at runtime. Accordingly, a SAM schema describes the expected runtime behavior of a BON in a certain business context and represents the relationship between the status of a BON and its actions, and actual variable values provided during runtime can be compared to the SAM schema to ensure the modeled process is executed as expected. 
     In summary, a status schema can include multiple elements. Example elements include the multi-valued status variables, the actions, and edges that define a relationship between a status value and an action. As discussed above, the status variables and the corresponding values represent the status of a BON, where a status variable contains multiple possible status values. At runtime, every status variable will have exactly one of the possible status values at any given time. The actions represent the methods that can be performed on the BON. For any given action, whether the action is allowed to be performed can depend on the current status of the BON. The edges represent preconditions that connect status values with actions. The preconditions provide that the actions can only be executed if the status variables have certain required values. However, preconditions do not lead to automatic execution of the corresponding actions (i.e., just because a precondition for a particular action is fulfilled, the particular action is not automatically executed). In some examples, if an action that is allowed by the preconditions is called, the action changes the state of the BO and executes exactly one of possibly several status transitions that originate therefrom. In some examples, edges can be provided between one status value of one variable to another status value of another variable, indicating that one status update directly triggers another status update (e.g., synchronizing). 
     In some implementations, example elements of a status schema can include advanced modeling elements. In some examples, advanced modeling elements can extend simple SAM modeling. By way of non-limiting example, an advanced modeling element can enable creation of a header status by aggregating various item status values. 
     Intentions of the business process can be modeled as one or more primary goals and one or more recovery goals. For example, the primary goals and the recovery goals reflect the intention behind building the SAM schema (e.g., the purpose of the SAM schema). Each of the primary goals and the recovery goals can be represented as a set of status vectors. In some examples, and as discussed in further detail herein, each of the primary goals and the recovery goals can be further represented using wildcards and/or logic operators. In some examples, a primary goal can be provided as a tuple of status values (optionally including wildcard(s) and/or logic operator(s)) that achieve a goal of the business process (i.e., a desired outcome). In some examples, a recovery goal can be provided as a tuple of status values (optionally including wildcard(s) and/or logic operator(s)) that achieve an acceptable goal of the business process (i.e., an acceptable outcome). In some examples, a goal can be intermediate to achieving an end goal of the business process. Examples are discussed in further detail below. 
     A FSM can be generated based on the SAM schema. In some implementations, the FSM includes nodes and edges between nodes. In the following, we refer to nodes without incoming edges as root nodes, we refer to nodes without outgoing edges as leaf nodes, and we refer to all other nodes as intermediary nodes. In some examples, a root node of the FSM can represent an initial status (e.g., of a BON) and arbitrary nodes can represent final outcomes of status transitions (i.e., primary goals and/or recovery goals). Nodes on a trace between an initial status and a goal that are neither initial status nor goal can each represent an intermediate status (e.g., of the BON) between the initial status and the goals. Edges between nodes can represent actions that can be performed to transition from one status to another status. 
     As discussed in further detail herein, the FSM can be processed to determine whether the SAM schema correctly fulfills the intentions under which the SAM schema was built (i.e., the SAM schema meets its goal). From a business perspective, a SAM schema meets its goal if the SAM schema can potentially reach every primary goal. If, under some circumstances, the schema cannot reach a primary goal, the SAM schema should at least end up in a recovery goal. In some examples, loops can be present in the SAM schema. In some examples, if the loop repeatedly ends at a primary goal or a recovery goal, the loop is okay and the SAM schema is still considered valid. Formally, a schema meets a goal if and only if the following example conditions hold: at least one status vector of every primary goal appears in at least one trace; every maximal finite trace ends in a state vector of any primary goal or recovery goal; and from every status vector(s) of every infinite trace (i.e., loop), a status vector of any primary goal or recovery goal is reachable starting from the status vector(s) (e.g., by the same trace or another trace). 
     Implementations of the present disclosure are discussed in further detail herein with reference to an example context. The example context includes a service-based business processes, invoicing processing in particular. It is appreciated, however, that implementations of the present disclosure are applicable to other contexts. 
     In the evolving world of service-based business processes, there is an increasing demand on customizability and reliability. A service can be perceived as a part of or a complete business process. A service can be composed of a series of atomic actions that perform small tasks. The actions can move a BO from one state, or status, to another status. In some examples, the BO can be an electronic document representing a product in supply-chain management or an item of sale in an online store. In some examples, status changes can occur by executing an action during the business process. A number of possible goals in such business processes can be defined by some final states (e.g., product shipped, order cancelled). Executability of the actions and firing of the events are constrained or guided by strict business rules, which can vary for different customers. 
       FIG. 2A  depicts an example context within which implementations of the present disclosure can be applied. The example context includes a service-based business process, an invoicing process  200 , in particular. The example invoicing process  200  includes a data entry sub-process  204 , an approval sub-process  206  and a posting sub-process  208 . In the examples context, an invoice object  210  (i.e., invoice BO) is provided and is linked to multiple invoice objects  212   a - 212   n . Actions are provided and are controlled by business constraints, as discussed in further detail below with reference to  FIG. 3 . Each action can move the invoice object  210  through the data entry sub-process  204 , the approval sub-process  206  and the posting sub-process  208 . 
     At any point in the invoicing process  200 , the status of a BO is defined by a set of status variables. In the example context, an example status variable can be provided as Data_Entry. Potential values of the Data_Entry status variable within the data entry sub-process  204  can include “finished” and “in process.” An example action that can cause the invoice BO to move from one status to another during the data entry sub-process  204  can include “finish data entry processing.” In some examples, the data entry sub-process  204  can be projected as an invoicing service. Consequently, the actions provided within the data entry sub-process  204  can define the lifecycle of the invoice BO. To ensure reliability of such business processes, the constraints can be validated, as discussed herein, so that the invoice BO moves through the correct execution statuses and ends up in one of the primary goal or recovery goal statuses. 
       FIG. 2B  depicts an example object model  250 . The example object model  250  is provided as a BO model that includes a core BO model  252  and a constraint-driven lifecycle model  254  referred to as the SAM schema model. In some examples, the core BO model  252  describes static features or components associated with the BO, and the SAM schema model  254  describes the dynamics, or lifecycle, of the BO. The multi-part modeling of the present disclosure enables the added flexibility of attaching different SAM schema models to the same BO model for the different business cases. Further, the BO and the schema can be extended as needed without affecting the core BOs. The constraints are defined based on execution statuses, where status transitions are caused by actions and events. 
     As discussed in detail above, a BO can include attributes or variables. The attributes are initialized at the time of instantiation of the BO and can assume different values during the business process that acts on the BO. In the example of  FIG. 2A , the invoice BO  210  in the invoicing process  200  can include attributes such as Order ID, number of order items, and amount. As also discussed above, a BO is associated with a number of status variables (SV), each SV representing the status of the BO during a sub-process of the lifecycle of the BO and having a set of values associated therewith, including an initial value. In the example context, the Data_Entry SV can assume one of the values “finished” and “in process.” The status variables of a BO together represent the combined status or state of the BO. During the business process, actions are performed that cause status transitions. In the example object model  250  of  FIG. 2B , actions can be referenced as atomic actions (AA). In the example context, the “finish data entry processing” action moves the BO from the “in process” status to the “finished” status. 
     In some examples, a SV can be affected by several AAs, while an AA only affects a single SV or no SV at all. In some examples, the effect of an AA on a SV can be deterministic or non-deterministic (i.e., the AA sets the SV always to a specific value, or to one of several possible values depending on some user input or attributes of the BO). In the example context, the “modify” action can display options and, based on user input selecting an option, moves the BO non-deterministically to either the “saved” status or the “submitted” status. 
     Status transitions are caused by actions, events, and/or derivations. In some examples, an event is fired when a SV has a certain value, and causes a specific status transition that can be used to synchronize the values of different SVs. For example, a “in approval” status value of an Approval SV, discussed in further detail below, causes an event to synchronize the value of the Data_Entry SV to “finished.” 
     In some examples, a derivation is provided as a means to dynamically determine status information from multiple SVs. A derivation also enables distribution of the status information of a parent BON to multiple descendent BONs and vice versa and modeling dependencies among BONs. For example, and with reference to  FIG. 2A , if an invoice is rejected, a status can be set to “void.” 
     The BO model of the present disclosure provides a strong foundation for designing flexible and customizable business processes to meet varying consumer requirements. The BO model further provides a general framework that can be extended for different types of BOs. 
       FIG. 3  depicts an example SAM schema  300  providing constraints on actions that can be executed in the example context of  FIG. 2A . More particularly,  FIG. 3  depicts a Data_Entry SV  302 , an approval SV  304  and a Posting SV  306 . Example values for the Data_Entry SV  302  include “finished”  308  and “in process  310 . An example action that can be executed to transition the Data_Entry SV  302  between values includes “finish data entry processing”  312 . Example values for the Approval SV  304  include “not started”  314 , “approval not necessary”  316 , “in approval”  318 , “rejected”  320  and “approved”  322 . Example actions that can be executed to transition the Approval SV  304  between values include “app_submit”  324  (submit for approval), “reject”  326  and “approve”  328 . Example values for the Posting SV  306  include “not posted”  330 , “void”  332  and “posted”  334 . An example action that can be executed to transition the Posting SV  306  between values includes “post”  336 . 
       FIG. 3  provides a graphical representation of constraint types that can be defined in the example BO model (e.g., of  FIG. 2B ). In the depicted example, an action is enabled if any one of the “Allowed_by” and all of the “Required” conditions (constraints) are true, and all of the “Inhibited_by” conditions (constraints) are false. Each of these conditions can be more complex if, for example, values of multiple SVs are joined using logical operators (e.g., AND, OR). In the example constraints of  FIG. 3 , “post”  336 , which affects the value of the Posting SV  306 , is executable when the Approval SV  304  has the value of either “approval not necessary”  316  OR “approved”  322  AND (&amp;) the Posting SV  304  has the value “not posted”  330  (i.e., the invoice has not been posted). 
     In some implementations, the BO model depicts a SAM model and can be defined using a machine-readable specification language. An example specification language can be denoted by the acronym SAMLA (e.g., SAM LAnguage). In the example context, an example specification can be provided as: 
                                BON BusinessObj {        STATUS_VARS Data_Entry, Approval, Posting        VARIABLE Data_Entry         VALUES finished, in_process         INITIAL in_process        VARIABLE Approval         VALUES not_started, approval_not_necessary, in_approval,         rejected, approved         INITIAL not_started        VARIABLE Posting         VALUES not_posted, void, posted         INITIAL not_posted        ACTIONS ACT_Finish_Data_Entry_Processing,         ACT_App_Submit, ACT_Reject, ACT_Approve, ACT_Post        SCHEMAS Schema1       }                    
where a BON represents a BO model. Generally, and as depicted in the example above, a BON specification defines the list of SVs, the set of values for each SV including the initial value, the AAs, and schemas associated with the BO. In some implementations, an example schema model can be provided as:
 
                                SCHEMA Schema1 {        ACTION ACT_Finish_Data_Entry_Processing                       ALLOWED_BY   Data_Entry = in_process         REQUIRED   Posting = not_posted                  ACTION ACT_App_Submit                       ALLOWED_BY   Approval = not_started &amp;           Posting = not_posted        ACTION ACT_Reject         ALLOWED_BY   Approval = in_approval        ACTION ACT_Approve         ALLOWED_BY   Approval = in_approval        ACTION ACT_Post         ALLOWED_BY   (Approval = approval_not_necessary           OR approved) AND           Posting = not_posted        ...                  SYNCHRONIZE Approval = approval_not_necessary OR        in_approval                         TO Data_Entry = finished        ...       }                    
In general, and as depicted in the above example, a schema specification defines the constraints on each AA, the state transitions caused by each AAs (i.e., the possible values of the associated SV if the action is performed), and events such as status synchronizers.
 
     Multiple types of constraints can be defined for each AA. In some examples, an action is executable if any one of the ALLOWED_BY constraints is true (i.e., multiple constraints joined by logical OR operations), all REQUIRED constraints are true (i.e., multiple constraints joined by logical AND operation), and none of the INHIBITED_BY constraints is true (i.e., each condition is negated and then, joined by logical AND). In some examples, the CAUSES part of an ACTION specification in the schema indicates the effect of the action. In some examples, CAUSES having two or more parts indicates that the result of the AA is non-deterministic (e.g., the modify action in the example schema model above). In some examples, SYNCHRONIZE denotes an event that sets a second SV to the specified value when a first SV is assigned a certain value. 
     As discussed herein, a goal specification can be provided and can be used to validate the BO model. In general, goals can include primary goals and recovery goals and can be provided as complex conditions, which may hold in a single state or in sets of states. In some examples, goals can be defined as desired assignments of a set of SVs that can be combined using logical operators. In the example context, an example goal specification can be provided as: 
                                            //Goal and goal category specification           GOAL goal_1 STATE Approval = approved AND                   Posting= posted           GOAL goal_2 STATE Approval = rejected AND                   Posting = not_posted           GOAL_CATEGORY goalcat_1 SET (goal_1 OR goal_2)                        
A goal category is specified using pre-defined goal states, which are combined with logical and set operators. In general, goal categories are specified at the end of the goal specification for verification purposes.
 
     As discussed above, a FSM is generated based on the SAM model (BO model). In some implementations, the SAM model is mapped onto a FSM, and the FSM is used for the verification of the BO and schema models in view of the goals. Each state of the FSM can be represented as a status vector that describes the status of the BO at the particular state. In some examples, the status vector is provided based on each of the SVs of the BO and the respective values of the SVs at the particular state. In some examples, an initial state of the FSM represents a complete assignment of each of the SVs to their initial values. Transition relations capture the fact that the values of the SVs change due to the effects of AAs. 
       FIG. 4  depicts an example state diagram  400  based on the example context. It is appreciated that the example state diagram  400  depicts the invoice process  200  of  FIG. 2A  and reflects the SAM model of  FIG. 3 . The example state diagram includes a root node  402 , intermediate nodes  404 ,  406 ,  408 ,  409  and leaf nodes  410 ,  412 ,  414 , where each node represents a status of, in the example context, an invoice BO, and edges between nodes represent actions (AAs) that can be performed on the BO to transition the status of the BO to another state. Boxes  420 ,  422  indicate that the leaf nodes  410 ,  412 ,  414 , respectively, represent goal states. In the depicted example, the box  420  indicates (two status vectors aggregated to) one primary goal and the box  422  indicates a secondary goal. 
     The example state diagram  400  of  FIG. 4  can depict state transitions of an invoice BO, for example. In some examples, the invoice BO can track the finalization of entering the invoice data before the invoice is submitted for approval. In some examples, the submit for approval (SFA) action determines whether an approval is necessary based on some business logic (e.g., depending on the total amount of the invoice). If no approval is necessary, the invoice can be posted. Otherwise, the invoice has to be rejected or approved. After approval, the invoice can be posted. In some examples, and from a business perspective, the main purpose, or intention, of the invoice BO is the posting of the invoice (the desired outcome). If posting is not possible, processing of the invoice can also be concluded by rejecting the invoice (an acceptable outcome). Semantics are modeled using primary and recovery goals, where a goal is provided as a set of status vectors. As a shorthand notation, wildcards (*) and logical operators can be used. In some examples, the status vectors for the example of  FIGS. 3 and 4  can be provided using the following order of the status variables (Data_Entry, Approval, Posting). In the depicted example, goals can be provided as: 
     Primary goal: (Finished, Approval not necessary|Approved, Posted) 
     Recovery goal: (*, Rejected, *) 
     With continued reference to  FIG. 4 , and as noted above, an example status vector for the invoice BO can be defined as:
         status=(Data_Entry, Approval, Posting),
 
where each of Data_Entry, Approval and Posting is a placeholder for one of the respective, allowed values.
       

     With continued reference to  FIG. 4 , the root node  402  reflects an initial state (S 1 ) of the invoice BO, defined as:
         S 1 =(in_process, not_started, not_posted)
 
An edge  430  represents the “finish_data_entry_processing” (FDE) action that can be performed to transition the invoice BO from the initial state to an intermediate state represented by the intermediate node  404  and defined as:
   S 2 =(finished, not_started, not_posted)
 
An edge  432  represents the “app_submit” (submit for approval (SFA)) action that can be performed to transition the invoice BO from the initial state to an intermediate state represented by the intermediate node  406  and defined as:
   S 3 =(finished, approval_not_necessary, not_posted)
 
An edge  434  represents the “app_submit” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  404  to the intermediate state represented by the intermediate node  406 . An edge  436  represents the “post” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  406  to the final state represented by the leaf node  410  and defined as:
   S 4 =(finished, approval_not_necessary, posted)       

     An edge  438  represents the “app_submit” action that can be performed to transition the invoice BO from the initial state to an intermediate state represented by the intermediate node  408  and defined as:
         S 5 =(finished, in_approval, not_posted)
 
An edge  440  represents the “app_submit” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  404  to the intermediate state represented by the intermediate node  408 .
       

     An edge  441  represents the “approve” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  408  to an intermediate state represented by the intermediate node  409  and defined as:
         S 6 =(finished, approved, not_posted)
 
An edge  442  represents the “post” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  409  to the final state represented by the leaf node  412  and defined as:
   S 7 =(finished, approved, posted)
 
An edge  444  represents the “reject” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  408  to the final state represented by the leaf node  414  and defined as:
   S 8 =(finished, rejected, not_posted)       

     Although an example FSM is graphically represented above (i.e., in  FIG. 4 ), it is appreciated that the FSM can be represented, or encoded in a machine-readable language within a document (e.g., a document that can be processed by one or more computing devices). More specifically, representing the SAM schema in terms of a FSM enables encoding of the SAM schema as input program code of a computer-executable model checking tool for validating the SAM schema. In the encoded schema model (i.e., the FSM), the verification criteria are expressed as logical assertions that can be checked for validity and violations thereof can be reported. 
     As discussed above, the SAM schema (BO model) can be validated based on the FSM and the defined goals (e.g., using a computer-executable model checking tool). To illustrate such validation, the example state diagram  400  and example goals are referenced within the example context discussed above. The example goals can include the final status represented by the leaf nodes  410 ,  412  of  FIG. 4  (i.e., status (S 4 )=(finished, approval_not_necessary, posted), status (S 7 )=(finished, approved, posted), respectively), and the final status represented by the leaf node  414  of  FIG. 4  (i.e., status (S 8 )=(finished, rejected, not_posted)) (hence the respective boxes  420 ,  422 ). In the depicted example, the leaf nodes  410 ,  412  are representative of primary goals and the leaf node  414  is representative of a recovery goal. In some implementations, traces through the FSM can be generated, each trace defining a path of status vectors and actions that are possible through the SAM schema. 
     As also discussed above, a SAM schema meets a goal if and only if at least one status vector of every primary goal appears in at least one trace; every maximal finite trace ends in a status (state) vector of any primary goal or recovery goal; and from every status vectors of every infinite trace (i.e., loop), a status vector of any primary goal or recovery goal is reachable starting from the status vector(s) (e.g., by the same trace or another trace). In the example of  FIG. 4 , the goals represented by the leaf nodes  410 ,  412 ,  414  appear in at least one trace, however, and every maximal finite trace ends in a goal. Consequently, the SAM schema represented by the state diagram  400  of  FIG. 4  is valid. 
     In some examples, if the SAM schema is determined to be invalid, one or more traces that resulted in the invalid status of the SAM schema can be displayed to a user on a display. In this manner, the user can be made aware of problematic traces and can revise the invalid SAM schema to provide a valid SAM schema. 
     Implementations of the present disclosure address extensibility of a core SAM schema to provide an extended SAM schema. In some implementations, requirements for model (SAM schema) extension can include that an extension should not modify the model (because only then extensions and model changes are reconcilable); two extensions should not conflict with each other; extensions should be extensible as well; and extensions should only influence the model in such a way, that the functionality of the BO using the model is not be harmed. 
     In some implementations, a SAM extension adds additional actions to the BON, as well as status variables and an additional model snippet containing the SAM model for the extension. In some examples, the added elements are modeled in a BO extension that points to a BO and that extends the BO. In some examples, the BO extension includes BON extensions, each of which points to a respective BON of the BO. In some examples, the BON extensions have the same names as the BONs that they point to, but the namespaces can be different. In some examples, a BON extension carries the additional (enhanced) actions and (enhanced) status variables (SVs) that are defined as part of the BON extension. Furthermore the BON extension carries a status schema extension pointing to a status schema. In some examples, a status schema extension has the same name as the status schema that it points to, but includes a different namespace. 
     In some implementations, the extensibility of SAM schemas follows rules that ensure that the resulting model does not harm the functionality of the underlying BO. In some examples, the following modeling elements are allowed in a SAM schema extension: status variables, actions, preconditions, status transitions (including actions with multiple status transitions), synchronizers, stateguards and overall derivation. In some examples, the following rules describe which modeling elements are allowed/not allowed between the extension and the underlying (core) SAM schema and the SAM schema extension:
         Underlying (core) SAM schema→Extension:
           Allowed=preconditions and synchronizers   Not Allowed=status transitions or derivation edges   
           Extension→Underlying (core) SAM schema:
           Allowed=inhibiting preconditions and requiring preconditions   Not Allowed=status transitions, enabling preconditions, derivation edges, synchronizers, or neutral preconditions   
               

     Further rules can include that a SAM schema extension should not add, change or remove edges that are neither connected to an extension status nor to an extension action. For example, the following are not allowed: adding or deleting preconditions within the core SAM schema adding or deleting status transitions within the core SAM schema. In some examples, an extension should not lead to a deadlock. That is, an extension should, at most, only delay when an action of the core SAM schema can be executed, but should not forbid the action. In some examples, an extension can lead to a deadlock. For example, deadlocks can be allowed for traces that would result in recovery goals in the core SAM schema. In some examples, synchronizers to extensions can originate from any status value of the core SAM schema except values of a derived status variable or values other than the initial value that can be set by a state guard. In some examples, no additional flag indicating when a status value can be used as the origin of a synchronizer can be provided. 
     In general, the example rules discussed above are provided to avoid influencing the behavior of the underlying BO in an illegal way. The rules ensure that the state and the status of a BO are always in synchronization with one another. Further, shortcuts are not achievable using an extension. Accordingly, a status transition from an extension action to a status value of the underlying BO (core status value) is not allowed, because it would then be possible to set a core status value without having the corresponding state of the BO (i.e., the state and the status would be out of synchronization with one another, which is not allowed). The state of the core BO can only be maintained by executing core actions. For this reason, shortcuts (e.g., bypassing a core action) by means of the extension are also not allowed. The integrity of the core BO is only maintained if no core action is bypassed. If a core action were bypassed, new states would be possible in the core, which would not be able to be processed. Further, a bypassed core action would not able to transform the state of the BO corresponding to the status change. Consequently, no modeling elements are allowed that would lead to set a core status or to bypass a core action. 
     In accordance with implementations of the present disclosure, a SAM schema extension that is applied to a core SAM schema (providing an extended SAM schema) can be validated using primary and recovery goals. In some examples, the main condition for extension validity is that no relevant functionality from the core SAM schema is lost in the extension in addition to the syntactic correctness. In some examples, multiple checks are performed to determine extension validity. Example checks can include that the extension must respect the syntax rules for SAM schema extension, the extension goal must be a proper extension of the core goal, and the core plus extension (i.e., the extended SAM schema) must meet the extension goal. 
       FIG. 5  depicts an example extended SAM schema  300 ′ based on the SAM schema  300  of  FIG. 3 . In an example, the invoice process has been extended to include duplicate analyzer business logic. Consequently, in the example of  FIG. 5 , the core SAM schema  300  of  FIG. 3  has been extended to include a Duplicate_Status SV  350  and the actions “mark duplicate”  352  and “mark not duplicate”  354  to provide the extended SAM schema  300 ′ of  FIG. 5 . Example values for the Duplicate_Status SV  350  include “not checked”  356 , “duplicate”  358  and “no duplicate”  360 . For purposes of clarity, reference numbers for elements provided in both  FIGS. 3 and 5  are absent from  FIG. 5 . In the depicted example, constraints include that the Data_Entry SV  302  must have the value of “finished”  310  before the actions “mark duplicate”  352  and “mark not duplicate”  354  can be performed. Further, the action “reject”  326  is disabled. 
       FIG. 6  depicts an example state diagram  600  based on the example extended SAM schema  300 ′ of  FIG. 5 . The example state diagram  600  includes a root node  602 , intermediate nodes  604 ,  606 ,  608 ,  610 ,  612 ,  614 ,  616 ,  618  and leaf nodes  620 ,  622 ,  624 ,  626 ,  628 , where each node represents a status of, in the example context, an invoice BO, and edges between nodes represent actions (AAs) that can be performed on the invoice BO to transition the status of the invoice BO to another state. Boxes  630 ,  632  indicate that the intermediate nodes  610 ,  616 ,  618  and leaf nodes  620 ,  622 ,  624 ,  626 ,  628 , respectively, represent goal states. In the depicted example, the box  630  indicates one primary goal and the box  632  indicates one recovery goal. In some examples, the status vectors for the example of  FIGS. 5 and 6  can be provided using the following order of the status variables (Data_Entry, Approval, Posting, Duplicate_Status). 
     In general, every primary goal of the core SAM schema appears in at least one primary goal of the extended SAM schema, and recovery goals of the core SAM schema can be neglected the extended SAM schema. Further, new recovery goals can be introduced in the extended SAM schema. In the depicted example, the SAM schema extension correctly extends the core goal of  FIG. 4 . For example, the primary core goal corresponds to the only primary extension goal:
         Primary goal: (Finished, Approval not necessary|Approved, Posted)→(Finished, Approval not necessary|Approved, Posted, No Duplicate)
 
This is sufficient to determine that the extension goal is a proper extension of the core goal. To complete the enumeration, the recovery core goal was removed, and a new recovery goal was added in the extension. That is, the recovery goal (*, Rejected, *) is removed by the extension, and a new recovery goal is provided as:
   Recovery goal: (*, *, *, Duplicate)       

     With continued reference to  FIG. 6 , the root node  602  reflects an initial state (S 1 ′) of the invoice BO, defined as:
         S 1 ′=(in_process, not_started, not_posted, not_checked)
 
An edge  650  represents the “finish_data_entry_processing” (FDE) action that can be performed to transition the invoice BO from the initial state to an intermediate state represented by the intermediate node  604  and defined as:
   S 9 =(finished, not_started, not_posted, not_checked)
 
An edge  652  represents the “mark duplicate” (MD) action that can be performed to transition the invoice BO from the initial state to a final state represented by the leaf node  628  and defined as:
   S 2 ′=(finished, not_started, not_posted, duplicate)
 
An edge  654  represents the “mark_not_duplicate” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  604  to the intermediate state represented by the intermediate node  606  and defined as:
   S 10 =(finished, not_started, not_posted, no_duplicate)       

     An edge  656  represents the “app_submit” (SFA) action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  606  to an intermediate state represented by the intermediate node  608  and defined as:
         S 11 =(finished, approval_not_necessary, not_posted, no_duplicate)
 
An edge  658  represents the “mark_duplicate” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  608  to the final state represented by the leaf node  620  and defined as:
   S 3 ′=(finished, approval_not_necessary, not_posted, duplicate)       

     An edge  660  represents the “post” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  608  to the intermediate state represented by the intermediate node  610  and defined as:
         S 4 ′=(finished, approval_not_necessary, posted, no_duplicate)
 
An edge  662  represents the “mark_duplicate” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  610  to the final state represented by the leaf node  622  and defined as:
   S 12 =(finished, approval_not_necessary, posted, duplicate)       

     An edge  664  represents the “app_submit” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  606  to an intermediate state represented by the intermediate node  612  and defined as:
         S 13 =(finished, in_approval, not_posted, no_duplicate)
 
An edge  666  represents the “approve” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  612  to an intermediate state represented by the intermediate node  614  and defined as:
   S 14 =(finished, approved, not_posted, no_duplicate)
 
An edge  668  represents the “post” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  614  to the intermediate state represented by the intermediate node  616  and defined as:
   S 7 ′=(finished, approved, posted, no_duplicate)
 
An edge  670  represents the “mark_duplicate” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  616  to the final state represented by the leaf node  624  and defined as:
   S 15 =(finished, approved, posted, duplicate)       

     An edge  672  represents the “mark_duplicate” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  612  to the intermediate state represented by the intermediate node  618  and defined as:
         S 5 ′=(finished, in_approval, not_posted, duplicate)
 
An edge  674  represents the “mark_duplicate” action that can be performed to transition the invoice  130  from the intermediate state represented by the intermediate node  614  to the final state represented by the leaf node  626  and defined as:
   S 6 ′=(finished, approved, not_posted, duplicate)
 
An edge  676  represents the “approve” action that can be performed to transition the invoice  130  from the intermediate state represented by the intermediate node  618  to the final state represented by the leaf node  626 . An edge  678  represents the “mark duplicate” action that can be performed to transition the invoice BO from the intermediate state represented by the intermediate node  606  to the final state represented by the leaf node  628 .
       

     One advantage of the use of primary and recovery goals is that unimportant changes in the status transition, which result from an extension, do not influence the correctness of the extension. To demonstrate that, the state diagram  400  of  FIG. 4  and the state diagram  600  of  FIG. 6  can be compared. The comparison reveals that the edges  432 ,  438 ,  444  and the node  414  of  FIG. 4  have been removed and that the nodes  402 ,  404 ,  406 ,  408 ,  409 ,  410 ,  412  (respectively representing states S 1 , S 2 , S 3 , S 5 , S 6 , S 4 , S 7 ) of  FIG. 4  are intact as respective nodes  602 ,  628 ,  620 ,  618 ,  626 ,  610 ,  614  of  FIG. 6  (respectively representing states S 1 ′, S 2 ′, S 3 ′, S 5 ′, S 6 ′, S 4 ′, S 7 ′). In  FIG. 4 , submission for approval was allowed without explicitly marking the finishing of data entry in the core SAM schema. The removal of that trace (i.e., the edges  432 ,  438 ) does not change the purpose of the SAM schema because the main purpose (e.g., posting) can still be achieved in the extended SAM schema. 
     Another advantage is that the distinction can be made between goals that are to be preserved in an extension and goals that can be neglected. In the depicted example, the rejection functionality was disabled in the extended SAM schema, which does not hurt the primary purpose (e.g., posting). For example, and if the rejection functionality should be provided as such an important feature of the invoice process that any extension should observe it, the rejection functionality could be marked as a primary goal in the state diagram of  FIG. 4 . 
     As a further advantage, primary goals can be organized into groups of status vectors where achieving only one of the status vectors can be deemed to be sufficient enough for an extension to meet that primary goal. As an example, an extension that enforces approval can be provided. Such an extension would remove the status vectors S 3  and S 4  (nodes  406  and  410  of  FIG. 4 ) and the related edges (edges  432 ,  434 ,  436  of  FIG. 4 ). According to the goal definitions, such an extension would still be valid, because at least one way of achieving the primary goal is preserved. If it was instead desired to preserve both ways of posting (with approval and without approval) in any extension, two separate primary goals can be defined. Example, separate primary goals can include S 4  (finished, approval_not_necessary, posted) and S 7  (finished, approved, posted) that are provided in separate primary goal boxes instead of a single box (e.g., the primary goal box  420  of  FIG. 4 ). 
     Referring now to  FIG. 7 , a schematic diagram of an example computing system  700  is provided. The system  700  can be used for the operations described in association with the implementations described herein. For example, the system  700  may be included in any or all of the server components discussed herein. The system  700  includes a processor  710 , a memory  720 , a storage device  730 , and an input/output device  740 . The components  710 ,  720 ,  730 ,  740  are interconnected using a system bus  750 . The processor  710  is capable of processing instructions for execution within the system  700 . In one implementation, the processor  710  is a single-threaded processor. In another implementation, the processor  710  is a multi-threaded processor. The processor  710  is capable of processing instructions stored in the memory  720  or on the storage device  730  to display graphical information for a user interface on the input/output device  740 . 
     The memory  720  stores information within the system  700 . In one implementation, the memory  720  is a computer-readable medium. In one implementation, the memory  720  is a volatile memory unit. In another implementation, the memory  720  is a non-volatile memory unit. The storage device  730  is capable of providing mass storage for the system  700 . In one implementation, the storage device  730  is a computer-readable medium. In various different implementations, the storage device  730  may be a floppy disk device, a hard disk device, an optical disk device, or a tape device. The input/output device  740  provides input/output operations for the system  700 . In one implementation, the input/output device  740  includes a keyboard and/or pointing device. In another implementation, the input/output device  740  includes a display unit for displaying graphical user interfaces. 
     The features described can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. The apparatus can be implemented in a computer program product tangibly embodied in an information carrier, e.g., in a machine-readable storage device, for execution by a programmable processor; and method steps can be performed by a programmable processor executing a program of instructions to perform functions of the described implementations by operating on input data and generating output. The described features can be implemented advantageously in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. A computer program is a set of instructions that can be used, directly or indirectly, in a computer to perform a certain activity or bring about a certain result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. 
     Suitable processors for the execution of a program of instructions include, by way of example, both general and special purpose microprocessors, and the sole processor or one of multiple processors of any kind of computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memories for storing instructions and data. Generally, a computer will also include, or be operatively coupled to communicate with, one or more mass storage devices for storing data files; such devices include magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and optical disks. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, ASICs (application-specific integrated circuits). 
     To provide for interaction with a user, the features can be implemented on a computer having a display device such as a CRT (cathode ray tube) or LCD (liquid crystal display) monitor for displaying information to the user and a keyboard and a pointing device such as a mouse or a trackball by which the user can provide input to the computer. 
     The features can be implemented in a computer system that includes a back-end component, such as a data server, or that includes a middleware component, such as an application server or an Internet server, or that includes a front-end component, such as a client computer having a graphical user interface or an Internet browser, or any combination of them. The components of the system can be connected by any form or medium of digital data communication such as a communication network. Examples of communication networks include, e.g., a LAN, a WAN, and the computers and networks forming the Internet. 
     The computer system can include clients and servers. A client and server are generally remote from each other and typically interact through a network, such as the described one. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. 
     In addition, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims. 
     A number of implementations of the present disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the present disclosure. Accordingly, other implementations are within the scope of the following claims.