A Meta-model for Dynamic Workflow Evolution

Berraouna Abdelkader

, Amirat Abdelkrim

and Meslati Djamel

University Mohammed Chérif Messaadia, 41000, Souk Ahras, Algeria

University Badji Mokhtar-Annaba, BP 12, 23000, Annaba, Algeria

Keywords: Meta-model, Workflow, Dynamic Evolution, Components.

Abstract Workflow systems such as they are today do not provide sufficient flexibility needed to deal with certain

situations that may arise during the execution, especially in critical environments such as medical systems

and banking systems. In this context, this paper treat the adaptive workflow based on Meta-Model approach

and components-based software approach. These provide granularity, flexibility and reliability needed for

effective and safe development of the workflow. The work is both in terms of the development process and

in terms of the support platform, which should ensure the adaptability and propose a generic component-

oriented framework to build, run and develop dynamic workflow templates. Our research objectives are: First,

the proposal of a proper workflow development approach that takes into account the evolution of these

systems appearance. Then the realization of a framework environment that takes advantage of the component

approach and the meta-model approach and its features.

1 INTRODUCTION

Companies in different fields have always shown

interest for information technology, and this interest is

growing. Thus was born an undeniable dependence of

computers in this area and it has become impossible

for a company to survive without the support of

adequate information technology.

One of these technologies is the "workflow" is

used to describe the automatic task execution cycle

time, validation methods, and to provide each player

the information necessary for the execution its task.

The workflow application fields are diverse as

financial services, telecommunications, the public

sector and even creative areas such as the service

industry and the media. With changing needs in this

wide range of areas, we have identified a gap in

research in the adaptation and flexibility of workflow.

(Kolar et al., 2013)

Given the level of competitiveness and the

environment in which businesses currently it is vital

to be able to change workflow systems either statically

or dynamically. However, workflow systems such as

they are today do not provide sufficient flexibility

needed to deal with certain situations that may arise

during the execution, especially in critical

environments such as health care systems and banking

systems. In this context, this paper deals with the

adaptive workflow based on both approaches, the

Meta-Model approach and the approach based

software components (Reichert and Dadam, 1997)

(Weske,1997) (López-Fernández et al,2015)(Tiwari

and Chakraborty ,2015). These provide granularity,

flexibility and reliability needed for effective and safe

development of the workflow. The work is both in

terms of the development process and in terms of the

support platform, which should ensure the adaptability

and propose a generic component-oriented framework

to build, run and develop dynamic workflow

templates. Our research objectives are:

First, we propose a workflow development

approach that takes into account the evolution of these

systems appearance. Then the realization of a

framework environment that takes advantage of the

component approach and the meta-model approach

and its characteristics. The motivations of this work

are many. In fact, dynamic evolve workflow systems

will help increase competitive businesses, reduce

costs has required the adaptation and evolution of

these systems and possibly improve the working

environment through active support, reliable and

adapted to change as needed. Thus it will be possible

for these companies to deal with different types of

change and crisis situations by adapting to new

contexts.

Abdelkader, B., Abdelkrim, A. and Djamel, M.

A Meta-model for Dynamic Workﬂow Evolution.

In Proceedings of the 1st International Conference on Complex Information Systems (COMPLEXIS 2016), pages 59-65

ISBN: 978-989-758-181-6

The rest of the paper is organized as follows:

section 2 presents some of basic concepts and

terminology of the dynamic workflow. Section 3

outlines the similar work and highlights the

motivation of this work. Section 4 presents a summary

and discussion of existing approaches. Section 5

describes an introduction to the proposed framework

and will end with a conclusion and some perspectives.

2 CONCEPTS AND

TERMINOLOGY OF DYNAMIC

WORKFLOW

Before presenting the existing approaches for the

modeling of adaptive workflow we first present

several related concepts.

-Workflow: A workflow is a software tool dedicated

to the management tool processes. This tool define,

manages and executes processes by implementing

programs whose execution order is pre-defined in a

computer representation of the logic of these

procedures ( Workflow Management Coalition –

Glossary 1996).

- WorkFlow Engine: is a software service that

provides all or part of the execution environment of a

Workflow( Workflow Management Coalition –

Glossary 1996).

-Workflow Management System: is a complete

system that is used to define, manage and execute

processes by implementing programs whose

execution order is pre-defined in a computer

representation of the logic of these procedures

(Workflow Management Coalition – Glossary 1996).

- Workflow Service: is a software service that

consists of one or more workflow engines of the same

type used to define, manage and execute workflow

process (Workflow Management Coalition – Glossary

1996).

- Dynamism: is characteristic related to evolution of

the process model or to changes in the business

environment or business process reengineering

efforts. These changes are made in the time of

conception and involve a significant problem (Sadiq

et al., 2001) .In this characteristic the proposed

solution should reduce the number of situations needs

of change.

-Adaptability: Is the process capability to deal with

exceptional cases and a non-standard behavior. This

can be partially solved in time by adjusting the design

(Adapter accurately) the structure of the process

model (Kolar et al., 2013).

- Flexibility: is a characteristic of the process model

related to loose or partially defined model structures

specified in design-time. The full specification of the

process is finalized at the time of execution and may

be different for each process instance. Flexibility is the

main objective of this work (Kolar et al,2013).

3 EXISTING APPROACHES FOR

MODELING DYNAMIC

WORKFLOW

An example of a commercial workflow that allows

some dynamic adaptations is Tibco iProcess Suite

(version 10.5), which provides an orchestration

component "Orchestrator" which allows dynamic

allocation of sub-process variations in the execution

time. It requires a construction called dynamic event

to be modeled explicitly contains a number of sub-

processes listed as an "Array". When execution

reaches the dynamic event node, it will execute the

members of the «Array " on predefined conditional

basis, the table must be set statically before the process

is instantiated there is no possibility of modifications

execution.

Another trading system, CSR (Version 5.4) allows

an ad hoc manual execution adaptation such as

(reorganization of tasks, cancellation, repetition,

delay, termination).

The ADEPT2 prototype (Reichert et al ,2005)

supports the change process at runtime (ie, add, delete

and modify the sequence of tasks) to the model level

(dynamic evolution) and at Instance (ad hoc changes).

These modifications are made to a traditional

homogeneous model and must be achieved through

manual intervention of an administrator, summarized

in a high-level interaction. The system is also

responsible for the "jump forward" and "backward

jumps" in the process instances, but only by the

authorized person.

The system YAWL (Yet Another Workflow

Language) provides support for flexibility and

dynamic exception handling through the concept of

worklets, extensible directory of autonomous sub-

processes with associated selection rules this approach

provides direct a dynamic change and development

processes without intervention outside the system or

stop.

(Minoret al ,2014) Present a Case-based reasoning

(CBR) approach for automated workflow adaptation

through the reuse of experience.

This approach helps the expert in the execution of

these adaptations by an automated method. The

COMPLEXIS 2016 - 1st International Conference on Complex Information Systems

method uses the recorded case workflow adaptation in

adaptations of the past. The recorded changes can be

automatically transferred to a new workflow that is in

a similar situation changes, it uses CFCN the

workflow modeling language that was developed by

the University of Trier.

(Kolar et al., 2013) Proposes an approach based on

the constraints in the design process. This combined

approach is for business situations, including a rigid

structure to the process model causes a flexible

limitation.

It offers design process model that is suitable for

the modeling of ad hoc processes within BPMS

systems. The pattern may be used to define a process

structure in the declarative constraint- based manner.

In addition, it presents an application of the approach

in a real project, a BPMproject end to end for an

insurance company.

In (Tayade and Chavan, 2012), the authors have

taken an approach to identify the change as an ongoing

process, and integration of the processes of change in

the workflow process itself which is predefined and

can predefined and can be fixed in execution time.

The framework presented introduced the concept of a

flexible workflow process comprising a core and one

or more types or roles of flexibility in this kernel; the

following Figure shows briefly the basic structure of a

workflow modeling language:

Figure 1: The structure of a workflow modeling language.

The system includes four components as shown in

the following Figure :

Figure 2: FWMS Architecture.

 Work Node Manager

This is the basic component of the work process all

working nodes are stored in the nodes of the database

with the appropriate classification.

 Work Process Manager

Manages the workflow templates and instances,

including creating, editing, deleting and querying

workflow.

 User's Task Manager

This component manages users there's including the

verification of the user connections and

disconnections.

 Work Process Executor

This component represents the system core, includes

eight main components - runtime components, Service

task, Repository Service, Management service,

Service of history, identity service, DAOFactory core.

The meta-model approach is used (explicitly or

implicitly) to identify structures and types of

workflow model of constituent components. A set of

primitives is typically defined in which change

operations can be performed a certain model or

bodies. Examples of this approach include

ADEPTflex (Reichert and Dadam ,1997) WASA

(Weske ,1997) and WIDE (Casati et al,1997). The

syntactic correctness and modifications can be made

by users.

A meta-model describes the structure of models and

allows reasoning on models like the Knowledge of

first Level.

Some object-oriented languages such as Java,

describe the same way the classes, meta-classes and

objects. In software engineering, it is with the concept

of UML meta-model was developed. The meta-model

describes the models: classes, objects, attributes,

relationships and self-described, also means the model

of the model. It can be defined as the representation of

a particular view on model.

In the Components-based approach the modeling

goal is the construction of more complex models,

through reusing consistent and functional models.

Each of them is a process component. When modeling

components we should consider the following issues:

 Building an information base on reusable

components

 Determine the function of each component in

the new process model

 Dynamic composition of heterogeneous

components.

A Meta-model for Dynamic Workﬂow Evolution

4 SUMMARY AND DISCUSSION

OF EXISTING APPROACHES

We studied several approaches proposed in the

literature about workflow flexibility, we can mention

some features on the dynamic evolution of workflow:

The Factors of Evolution in Workflow

Management Systems (Hanet al., 1998)

- Change in the environment.

- Technical progress.

Ad-hoc Diversions During Workflow Execution

(Hanet al ,1998)

- Refinement of dynamic workflow model.

- User intervention.

- An unpredictable event.

- System failure.

Classification of Adaptive Workflow Adaptations

Levels (Hanet al ,1998)

- Adaptation to the context level domain.

- Adaptation in process Level

- Adaptation at Resource Level

- Adaptation to the infrastructure level.

Generally, there are two types of changes:

1 ad-hoc changes

2 Evolutionary change.

Ad-hoc changes are handled case by case. To

provide customer-specific solutions or handle rare

events, the process is suitable for one or more cases.

Evolutionary change is often the result of

reengineering efforts. The process is modified to

improve customer responsiveness and improve

efficiency.

Dynamic workflow refers to the extension of the

workflow process so that when the change occurs, the

process model may be modified or completed, rather

than build a new model. The change can be considered

(which concern only the current instance) or may need

to be applied either temporarily or permanently. The

adaptation is done on two levels.

- level process model

- level instances

In instances running must be managed when the

process model from which it was instantiated it (the

instance should be canceled, restarted) so the

workflow must provide support for changes to the

process model job but incremental and ad hoc changes

can be arranged as required.

From several criteria identified for comparison, we

present a subset of them: the nature of flexibility,

formalism and flexibility techniques. According to

(

Workflow Reference Model, 1995) WFMS can be

characterized as a support for three areas functional:

- The Build-time Functions involved in the

definition and possibly modeling, workflow

process and its constituent activities.

- Run-time Functions involved in the control of

workflow processes in an operational environment

and scheduling to handle various activities as part

of each process.

- Run-time Interactions with human users and its

implementation tools available for the various

stages of activity.

The study of literature allowed us to distinguish two

main types of flexibility based on the ability to cope

with changes that may be incorporated into the process

definitions when building or running time.

- Posterior Flexibility by adapting the process

definition or one of its instances during execution.

The approaches that offer this kind of flexibility

are based on prescriptive modeling formalisms. It

could be considered that the definition of processes

and the resulting are not really flexible, but rather to

adapt or evolve. In fact, these approaches can not

anticipate the ability to change at time of construction,

it is the most common situation found in the literature.

Prescriptive modeling formalisms are well suited

to specify business processes that require a high

degree of control and prediction and for which the

need for change is an exception such as production

workflow.

- Flexibility Priori or by Selection based on

modeling formalisms that can offer the ability to cope

with environmental change without changing process

definitions. This means that this capacity should be

integrated into the process definitions during

construction. The process definition should be

specified in a sufficiently flexible to adapt with the

environment without breaking execution.

Consequently, the workflow service should be able to

run the specification "incomplete" process definitions.

5 PROPOSED FRAMEWORK

We focused specifically on workflow modeling

approaches based components and meta-model, the

control and data integration are implemented from a

model based components. Then, the process is seen as

a set of inter operative components. Data

dependencies are reduced by encapsulating the

components behind well-defined interfaces. This

allows dynamically changing workflow systems, and

proposing a generic component-oriented framework

to build, run and develop dynamic workflow

templates.

COMPLEXIS 2016 - 1st International Conference on Complex Information Systems

The idea is to see the workflow as an open process

and its implementation is not finished.

We used the OPC

(Open Process Component)

(Sadiq et al., 2001) mechanism to adopt

implementation, this mechanism allows:

• Dynamic Evolution of Software Developed.

• Flexibility

• The development of a basic component

• Provides a meta-layer model for software

• Enables configuration management

• Provides meta-process support

Figure 3: OPC Framework.

The OPC (Gary et al., 1997) provides an environment

for production processes based components.

In this approach, the process models are constructed

as a set of components that interact through interfaces

well defined. It also offers an infrastructure for

interoperability and reuse components of

heterogeneous processes, built on three levels of

abstraction.

1. The meta-model level that identifies the

fundamental entities of the process and their

relationships.

2. The finite-state machine use for

representation of

the behavior of the process entities

3. An object-oriented framework related to the

process representation formalism and its area of

application.

It provides support for dynamic processes, a

component is defined with the model and the

instantiation information and allows the component

manage its own Evolution, a Component has generic

information (in the framework) and more

specialization (adaptation) in the instantiation.

The first step in the development of our framework

is to design a meta-model (meta-model level) that can

capture all the features and functionality of the various

workflows in the trade business domain

The proposed meta-model is shown in Figure 4In this

meta-model the class Activity is the central part. A

process contains several FlowNode that can be

Avtivity Group,Simple Activity or Control Node. The

class FlowNode has a reflexive association called seq

to define the sequence relationship.

An activity have tow author relation with Resource

class and Actor class.

The class Activity has an attribute state assigned to

the enumeration type State that indicates in which

execution state the activity is currently, this

enumeration has five stats (waiting, running , done

,skipped and failed).

To ensure the control of different activity we have the

class Control that contains three type of control Join,

Fork and Sequence.

The activities in which decisions have to be made are

modeled explicitly with the class Decision. The

conditions for selecting the right path is modeled by

class Guard which is connected to the subsequent

activities. At runtime the user can select the desired

Guard with the select() operation, the Decision

activity can either be an XOR that selects exactly one

path or an OR that can select more than one or AND

that select the both.

Figure 4: Workflow meta-model.

A Meta-model for Dynamic Workﬂow Evolution

6 EXAMPLE PROCESS

MODELING WITH

In this section the metamodel of the previous section

is used to create workflow models. In the first

subsection the workflow is described in natural

language. In next subsection the described workflow

is modeled in GMF tool with the metamodel elements

introduced in this model Resources and data are not

considered in the model because they are not part of

the metamodel. Only activities and control flow

aspects are modeled.

6.1 Process Description

The following example describes globally the

workflow for making an order.

We identify three actors in this system, namely the

customer, accounting service and delivery service.

The action takes place as follows:

The client begins by make an order, giving rise to the

development of a Quote by the Accounting Service

.making quotation activity itself is decomposed into

two sub-avtivity check availability of the ordered

products and calculate the order price.

Quote is the name of a class of system, data stream

are typed the customer can then change its order (back

to the initial activity to order), to cancel (go to final

state) or validate the Quote.

If the costumer validate Quote two actions can be

undertaken in parallel:

- the preparation of the order by the delivery

service.

- invoice processing and payment.

The Accounting Service create invoices and send it

to customer (the object invoices transmitted in the

state sent) this makes the payment and sends the

invoice (which is present in the regulated state).

When the order is ready and confirmed the

payment of the client (by appointment

synchronization of these two activities) the order is

delivered to the client and the treatment is finished.

6.2 Workflow in GMF Tool

The proposed modeling of workflow is shown in

figure 5

Figure 5: Workflow model.

7 CONCLUSIONS

Workflow management systems must provide high

support flexibility with easy and simple ways. This

change can manifest in different forms in the

workflow process, in this article we presented

different approaches for the modeling and the

development of flexible and adaptive workflow with

a comparison and synthesis.

We also presented research aims to develop a

generic component-oriented framework to ensure the

dynamic development prospects as workflow.

In further work we aim to develop and implement this

framework to ensure the dynamic development

workflow

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A Meta-model for Dynamic Workﬂow Evolution