Process scheduling

Managing workload within workflow-management-systems

7024669

Abstract

A computerized method of managing workload within a Workflow-Management-System (WFMS), the WFMS having a process-model, the process-model including one or more activities being the nodes of an arbitrary graph, and directed edges of the graph defining a potential control-flow within the process-model. The method comprises a determination-step, wherein the process-model is analyzed if a priority-execution-indicator is assigned to the activity within the process model; and a launching step, wherein, in the affirmative case of the determination-step, the WFMS launches execution of the activity in the activity's execution-environment with an execution priority specified according to the priority execution indicator. Moreover the WFMS can set its own execution priority, and processing-related messages for communication are set to the execution priority specified.


Claims

What is claimed is:

1. A computerized method of managing workload within a Workflow-Management-System (WFMS) said method being executable by said WFMS on at least one computer system, wherein said WFMS comprises a process model, said process model comprising one or more activities being the nodes of an arbitrary graph, and directed edges of said graph defining a potential control flow within said process model, said method comprising the steps of:

analyzing said process model to determine if a priority execution indicator is assigned to one of said one or more activities within said process model; and wherein said process model is further analyzed to determine if there is a priority execution specification associated with said activity,

when said analyzing step indicates that there is a priority execution indicator for an activity, said WFMS launching execution of said activity with an execution priority specified according to said priority execution indicator; and

when there is no priority execution specification of said activity, analyzing for a priority execution specification of a performance sphere comprising said activity, said performance sphere comprising a sub-graph of said process model associating a process execution indicator to activities within said performance sphere.

2. A method of managing workload within a WFMS according to claim 1, further comprising, when said analyzing step indicates that there is a priority execution indicator, said WFMS setting its own execution priority for WFMS internal processing to the execution priority specified according to said priority execution indicator.

3. A method of managing workload within a WFMS according to claim 2, further comprising, when said analyzing step indicates that there is a priority execution indicator, setting the priority of one or more messages relating to the processing of said activity are set to the execution priority specified according to said priority execution indicator.

4. A method of managing workload within a WFMS according to claim 2, wherein said activity requires a specific execution-environment and wherein said launching further comprises mapping said priority execution indicator to a value in accordance to said WFMS's specific execution-environment.

5. A method of managing workload within a WFMS according to claim 3, wherein said one or more messages are communicated along a communication-system and wherein said launching further comprises mapping said priority execution indicator to a value in accordance to said communication-system.

6. A method of managing workload within a WFMS according to claim 3, said launching further comprises said WFMS launching execution of said activity directly by calling said activity with said execution priority.

7. A method of managing workload within a WFMS according to claim 3, wherein said launching further comprises said WFMS launching execution of said activity indirectly by sending said activity a message set to said execution priority and said activity being responsive by setting its execution priority accordingly.

8. A method of managing workload within a WFMS according to claim 1, further comprising, when said analyzing step indicates that there is a priority execution specification for said activity, assigning the priority execution indicator of said priority execution specification of said activity to said activity.

9. A method of managing workload within a WFMS according to claim 1, further comprising, when a priority execution specification of said performance sphere is located, assigning the priority execution indicator of said priority execution specification of said performance sphere to said activity.

10. A method of managing workload within a WFMS according to claim 1, further comprising, when a priority execution specification is not located for said performance sphere, analyzing said process model for a priority execution specification associated with said process model and assigning the priority execution indicator of said priority execution specification of said process model to said activity.

11. A method of managing workload within a WFMS according to claim 1, wherein said activity requires a specific execution-environment and wherein said launching further comprises mapping said priority execution indicator to a value based on said activity's specific execution environment.

12. A data processing program for execution in a data processing system comprising software code portions for performing a method for managing workload within a Workflow-Management-System (WFMS) said method being executable by said WFMS on at least one computer system, wherein said WFMS comprises a process model, said process model comprising one or more activities being the nodes of an arbitrary graph, and directed edges of said graph defining a potential control flow within said process model, said method comprising the steps of:

analyzing said process model to determine if a priority execution indicator is assigned to one of said one or more activities within said process model wherein said process model is further analyzed to determine if there is a priority execution specification associated with said activity,

when said analyzing step indicates that there is a priority execution indicator for an activity, said WFMS launching execution of said activity with an execution priority specified according to said priority execution indicator; and

when there is no priority execution specification of said activity, analyzing for a priority execution specification of a performance sphere comprising said activity, said performance sphere comprising a sub-graph of said process model associating a process execution indicator to activities within said performance sphere.

13. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine for performing method steps for managing workload within a Workflow-Management-System (WFMS) said method being executable by said WFMS on at least one computer system, wherein said WFMS comprises a process model, said process model comprising one or more activities being the nodes of an arbitrary graph, and directed edges of said graph defining a potential control flow within said process model, said method comprising the steps of:

analyzing said process model to determine if a priority execution indicator is assigned to one of said one or more activities within said process model wherein said process model is further analyzed to determine if there is a priority execution specification associated with said activity,

when said analyzing step indicates that there is a priority execution indicator for an activity, said WFMS launching execution of said activity with an execution priority specified according to said priority execution indicators; and

when there is no priority execution specification of said activity, analyzing for a priority execution specification of a performance sphere comprising said activity, said performance sphere comprising a sub-graph of said process model associating a process execution indicator to activities within said performance sphere.

14. A system for managing workload in a computer system comprising:

a Workflow-Management-System (WFMS) on at least one computer in said system, said WFMS comprises a process model, said process model comprising one or more activities being the nodes of an arbitrary graph, and directed edges of said graph defining a potential control flow within said process model;

at least one processor component for analyzing said process model to determine if a priority execution indicator is assigned to one of said one or more activities within said process model wherein said process model is further analyzed to determine if there is a priority execution specification associated with said activity,

an activity launching component for causing said WFMS to launch execution of said activity, when said analyzing step indicates that there is a priority execution indicator for an activity, said WFMS launching execution of said activity with an execution priority specified according to said priority execution indicator; and

when there is no priority execution specification of said activity, said at least one processor component analyzing for a priority execution specification of a performance sphere comprising said activity, said performance sphere comprising a sub-graph of said process model associating a process execution indicator to activities within said performance sphere.


Description

FIELD OF THE INVENTION

The present invention relates to the area of performance and workload management within a Workflow-Management-System (WFMS).

BACKGROUND OF THE INVENTION

A new area of technology with increasing importance is the domain of Workflow-Management-Systems (WFMS). WFMS support the modeling and execution of business processes. Business processes executed within a WFMS environment control which piece of work of a network of pieces of work will be performed by whom and which resources are exploited for this work. The individual pieces of work might be distributed across a multitude of different computer systems connected by some type of network.

The product "IBM MQSeries Workflow" represents such a typical modern, sophisticated, and powerful workflow management system. It supports the modeling of business processes as a network of activities. This network of activities, the process model, is constructed as a directed, acyclic, weighted, colored graph. The nodes of the graph represent the activities which are performed. The edges of the graph, the control connectors, describe the potential sequence of execution of the activities. Definition of the process graph is via the IBM MQSeries Workflow Definition Language (FDL) or the built-in graphical editor. The runtime component of the workflow manager interprets the process graph and distributes the execution of activities to the right person at the right place, e.g. by assigning tasks to a work list according to the respective person, wherein said work list is stored as digital data within said workflow or process management computer system.

Business processes quite often consist of parts that are time critical, while others are not. In particular, time critical may be those parts of a process that are carried out automatically (i.e., without any user intervention). The only method that has been proposed to control the processing behavior of a set of activities in terms of workload balancing is via the support of a workload management system (WLMS). Even if the WFMS may exploit the support of a WLMS to achieve its processing targets, this is limited to certain processing environments only, since highly sophisticated operating systems like IBM's MVS system do provide this type of technology. Especially within a heterogeneous distributed processing environment, in which WFMS do operate, WLM-technology is missing on most of the involved systems.

An objective of the present invention is to provide an approach for performance-improved processing of time critical parts of a process model also operating within a heterogeneous and distributed environment.

SUMMARY OF THE INVENTION

The foregoing and other objectives of the invention are realized by the present invention comprising a computerized method of managing workload within a Workflow-Management-System (WFMS), said WFMS comprising a process-model, said process-model comprising one or more activities as the nodes of an arbitrary graph, and directed edges of said graph defining a potential control-flow within said process-model. The method comprises a determination-step, wherein said process-model is analyzed if a priority-execution-indicator is assigned to said activity within said process-model. The method comprises a launching-step, wherein, in the affirmative case of said determination-step, the WFMS launches execution of said activity in the activity's execution-environment with an execution-priority specified according to said priority-execution-indicator.

By taking over workload management functions the WFMS becomes independent of the availability of a workload load management system (WLMS). Thus the current teaching can be applied to almost all state-of-the-art systems which is a significant advantage in a distributed and inhomogeneous processing environment. Thus no platform limitations for workload management do apply anymore. Incorporating the workload priorities already within a process model makes this definitions most transparent. On this level the specifications can be easily modified with no changes, or only minor changes, to the activity implementation. With increasing system complexity and increasing parallel execution of workload within in a system the advantages of the current invention increase as more important activities will succeed within the competition for processing resources.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail with specific reference to the appended drawing wherein:

FIG. 1 shows the example of the definition of a process model including priority specifications on the level of a performance sphere as well as on the activity level;

FIG. 2 is a diagram reflecting the mapping of the canonical execution priority scheme within the process model to the particular operating system priorities available to execute the individual activities;

FIG. 3 visualizes the basic structure of a WFMS being based on message queuing as a communication paradigm reflecting the significant extent of benefit which can be achieved by also setting the priorities of the involved messages accordingly;

FIG. 4 reflects the handling of messages between various WFMS components for the processing of an activity without applying the current teaching;

FIG. 5 reflects changes of the handling of messages compared to the situation in FIG. 4, if the current teaching of assigning execution priorities to involved messages in the execution process of an activity is applied. Changes are indicated by an asterisk (*);

FIG. 6 reflects changes of the handling of messages compared to the situation in FIG. 5, if the current teaching of performance spheres is included. Changes are indicated by an asterisk (*); and

FIG. 7 depicts a summarizing overview on the proposed method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The current invention is illustrated based on IBM's MQSeries Workflow workflow management system. Of course any other WFMS could be used instead. Furthermore the current teaching applies also to any other type of system which offers WFMS functionalities not as a separate WFMS but within some other type of system.

Moreover, if the current teaching is referring to a "message", this has to be understood as a general exchange of information via some sort of communication system and is not limited specifically to a messaging system.

Introduction

The following is a short outline on the basic concepts of a workflow management system based on IBM's MQSeries Workflow WFMS as far as it is of importance for the current invention:

From an enterprise point of view the management of business processes is becoming increasingly important. Business processes, or process for short, control which piece of work will be performed by whom and which resources are exploited for this work, (i.e. a business process describes how an enterprise will achieve its business goals). A WFMS may support both the modeling of business processes and their execution.

Modeling of a business process as a syntactical unit in a way that is directly supported by a software system is extremely desirable. Moreover, the software system can also work as an interpreter basically getting as input such a model. The model, called a process model or workflow model, can then be instantiated and the individual sequence of work steps can be determined, depending on the context of the instantiation of the model. Such a model of a business process can be perceived as a template for a class of similar processes performed within an enterprise; such that it is a schema describing all possible execution variants of a particular kind of business process. An instance of such a model and its interpretation represents an individual process, i.e. a concrete, context-dependent execution of a variant prescribed by the model. A WFMSs facilitates the management of business processes. It provides a means to describe models of business processes (build time) and it drives business processes based on an associated model (run time). The meta model of IBM's WFMS MQSeries Workflow, including the syntactical elements provided for describing business process models and the meaning and interpretation of these syntactical elements, is described next.

A process model is a complete representation of a process, comprising a process diagram and the settings that define the logic behind the components of the diagram. Important components of a MQSeries Workflow process model are:

    • Processes
    • Activities
    • Blocks
    • Control Flows
    • Connectors
    • Data Containers
    • Data Structures
    • Conditions
    • Programs
    • Staff
      Not all of these elements will be described below.


    • Activities are the fundamental elements of the meta model. An activity represents a business action that is from a certain perspective a semantic entity of its own.

    A MQSeries Workflow process model consists of the following types of activities:

    Program activity: Has a program assigned to perform it. The program is invoked when the activity is started. In a fully automated workflow, the program performs the activity without human intervention. Otherwise, the user must start the activity by selecting it from a runtime work list. Output from the program can be used in the exit condition for the program activity and for the transition conditions to other activities.

    Process activity: Has a (sub-)process assigned to perform it. The process is invoked when the activity is started. A process activity represents a way to reuse a set of activities that are common to different processes. Output from the process, can be used in the exit condition for the process activity and for the transition conditions to other activities.

    The flow of control, i.e. the control flow through a running process, determines the sequence in which activities are executed. The MQSeries Workflow workflow manager navigates a path through the process that is determined by the evaluation to TRUE of start conditions, exit conditions, and transition conditions.

    The results that are produced by the work represented by an activity are put into an output container, which is associated with each activity. Since an activity will generally require access to output containers of other activities, each activity is additionally associated with an input container.

    Connectors link activities in a process model. Using connectors, one defines the sequence of activities and the transmission of data between activities. Since activities might not be executed arbitrarily they are bound together via control connectors. A control connector might be perceived as a directed edge between two activities; the activity at the connector's end point cannot start before the activity at the start point of the connector has finished (successfully). Control connectors thus model the potential flow of control within a business process model. Default connectors specify where control should flow when the transition condition of "no other control connector leaving an activity" evaluates to TRUE. Default connectors enable the workflow model to cope with exceptional events. Data connectors specify the flow of data in a workflow model. A data connector originates from an activity or a block, and has an activity or a block as its target. One can specify that output data is to go to one target or to multiple targets. A target can have more than one incoming data connector.

    Process definition includes modeling of activities, control connectors between the activities, input/output container, and data connectors. A process is represented as a directed acyclic graph with the activities as nodes and the control/data connectors as the edges of the graph. The graph is manipulated via a built-in graphic editor. The data containers are specified as named data structures. These data structures themselves are specified via the DataStructureDefinition facility. Program activities are implemented through programs. The programs are registered via the Program Definition facility. Blocks contain the same constructs as processes, such as activities, control connectors etc. They are, however, not named and have their own exit condition. If the exit condition is not met, the block is started again. The block thus implements a "Do Until" construct. Process activities are implemented as processes. These subprocesses are defined separately as regular, named processes with all of their usual properties. Process activities offer great flexibility for process definition. It not only allows construction of a process through permanent refinement of activities into program and process activities (top-down), but also allows building of a process out of a set of existing processes (bottom-up).

    All programs which implement program activities are defined via the Program Registration Facility. Registered for each program is the name of the program, its location, and the invocation string. The invocation string consists of the program name and the command string passed to the program.

    The Prioritization Approach within WFMS

    Business processes are made up of a set of activities. Business processes quite often consist of parts, for instance individual activities or collections thereof, some of which are time critical and some of which are not. For instance, a group of activities can be perceived as a set of services that are related from a business point of view, i.e. a unit of work that must jointly fulfill a performance goal (e.g., a collection of application steps to be performed by a clerk while a customer is waiting for a response). Also, parts of a process that are carried out automatically (i.e., without any user intervention) are such candidates.

    Other candidates that are time critical are atomic spheres and processes that implement message broker functionality. Atomic spheres are collections of transactional work items (i.e. activities within the process model) with a common commit scope that thus represent a global transaction. For the purposes of defining such atomic spheres, the process model can be analyzed to identify subgraphs having the property that such a subgraph does not contain any activities which are connected by a path of control connectors which contains at least one activity not contained in said atomic-sphere.

    The derivation of such collections of time critical activities is difficult and cumbersome in non-trivial cases because of the lack of information about the relation of application functions. This information is mostly hidden in special application programs, or the relation changes because of new requirements, because applications are integrated in new ways for interoperability etc. The larger the number of different applications participating in the workload management, the more complex the situation becomes. The situation is even worse in case of integration of different applications, especially if the applications originally have not been designed to work together.

    As is typically the case in heterogeneous distributed processing environment, WFMS cannot rely on the support of an underlying WLMS for managing the processing targets of its managed activities. Current state-of-the-art WFMS neither have the information nor the capabilities to determine which activities to favor over others.

    The present invention utilizes the approach of assigning priority levels to activities already within the process model. Moreover, the process model is enriched with semantic relations of application functions as collections of activities that should be pushed through the system in "optimal time", leading to the concept of performance spheres. Thus, according to the current teaching, priorities can be assigned on multiple levels including on the level of the whole process model, on the level of a new concept of performance spheres, or on the level of individual activities with the later level overriding the settings of the preceding levels. At execution time, the WFMS is responsive to these specifications, allowing it to set the priority with which a particular activity or set of activities should be carried out. The proposed solution uses the facilities of the operating system and middleware, such as message queuing, to control the performance of parts of a workflow, rather than using a workload management system. As such, it can deployed in all environments rather than being limited to certain platforms.

    To identify the priority that should be assigned to an activity or a set of activities, a set of new properties are added to the meta model of the WFMS, wherein the priority definitions are already included in the process model of a business process.

    First a new keyword EXECUTION_PRIORITY is added to the specification of an activity. Valid entries are CRITICAL, HIGH, MEDIUM, and LOW (or any other conceivable enumeration). For consistency, the keyword EXECUTION_PRIORITY may also be attributed to the whole process model. The specification on the process model level serves as a default from which all activities inherit, which means that if nothing is specified on the activity level, the setting at the process level is used.

    Second, a new section PERFORMANCE_SPHERE is added that allows identification of a sub-graph in the process model. The EXECUTION_PRIORITY permits assignment of an execution priority to the sub-graph. Within a performance sphere, the execution priority defined for the sphere becomes the default execution priority for the individual activities. Again, the priority specifications on the activity level may override the specifications on the performance sphere level.

    The specification shown in FIG. 1 shows the definition of a performance sphere. The sphere contains two activities. Referring to FIG. 1, the definition of a performance sphere (100) defining the default execution priority (101) for activities within the performance sphere is shown. Moreover, the definition of two activities (110) and (120) are visualized as part of the above performance sphere (112, 113). Within the specifications of the activity (110), an explicit execution priority (111) is defined, thus overriding the corresponding default execution priority (101) on the level of the encompassing performance sphere. In contrast to that, the specification of the activity (120) comprises no extra priority definition; therefore, it will be executed with the execution priority defined by its encompassing performance sphere (100).

    According the current invention, the WFMS will be responsive to the priority specifications when executing the process model at run-time. The invention lets the WFMS balance its workload along the following dimensions:
    • 1. by setting the execution priority of the activity implementation, and/or
    • 2. by setting the execution priorities of the workflow system itself, and/or
    • 3. by setting the priorities of the messages relating to the processing of said activity for communication within said WFMS and/or with said activity according to the activity's execution priority.

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