Petri nets are on service researc change manag ment approache onitoring. Also simple finite s es emergency a ion as in case of ll change mana evaluation of c.
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ScienceDirect IERI Procedia 4 (2013) 99 – 109
20013 Internattional Confference on Agricultural A l and Naturaal Resourcees Engineeriing
Convventional Usage of Finitee State Machine M over Peetri net In nWeb S Service C Change M Manage ement Frrameworrk Thirum maran.Ma , Dhavachellvan.Pb, Aiishwarya.D Dc, K.Rajakkumarid aDepartment of Computer C sciencee and Engineering g, Pondicherry Enngg College, Indiia. bDepartment off Computer sciencce and Engineering, Pondicherry University, India. cDepartment of Computer C science and Engineering g, Pondicherry Enngg College, India. dDepartment of Computer C sciencee and Engineering g, Pondicherry Enngg College, Indiia
Abstract Finite state machine and Petri P nets are onne among the vaarious conceptu ual and computational models that have been n widely used in analyzinng diverse web service researcch areas. In thhis paper a com mparison of usiing finite state machine and Petri P nets for modeling a web service change managgement framew work is analyzeed with experim mental analysis. Though therre are many existing chhange managem ment approaches to satisfy thee normal chang ges, they fail too there is no pproper support for efficient change evaaluation and moonitoring. Alsoo complex struucture called Peetri nets is usedd to model the ooverall system functionality when a chaange whereas simple finite state s machine can c be used fo or the same representation siince the processs of change managemennt only includees emergency and a minor chaanges. Using FSM, F only a specific s logic ccan be extracteed instead of exacting thee overall functiion as in case off Petri nets. Thuus for the evalu uation of changes implementeed, FSM is very y efficient for the represennting the overalll change management. In this paper, we are going g to see how w FSM is efficient in modelin ng the change managemennt and also the evaluation e of changes c implem mented using cerrtain change facctors when com mpared to Petri nets. n
EllsevierbyB.V. © Puublished © 2013 2013 The Authors.by Published Elsevier B.V.
Open access under CC BY-NC-ND license.
Selection and peer revview r responsibility y of Informat tion Enginee ering Researcch Institute Selection nand peer review under under responsibility of Information Engineering Research Institute Keywords: Web W Services; Change Mangementt;Change factors;;Finite State Mach hine;Petri nets.
1. Introdu uction Changee managementt is a set of prrocesses that are a employed to ensure thaat significant cchanges are im mplemented to a businness process during its maintenance m p phase. The purpose p of thhe change maanagement prrocess is to ensure thaat: Business riisk is managedd and minimized; Standard dized methodss and proceduures are used for f efficient and promppt handling of o all changess; all changess to service assets a and connfiguration iteems are recorded in the configurattion managem ment system; and all authoorized changees support buusiness needs and goals. Hence H there arises the need for an effective e fram mework managging those ch hanges withouut affecting thhe business fu unctionality. ment frameworrk is proposedd for making minor m alterations to businesss logic but whose w effect Here Channge Managem is more prronounced to the profitabillity of the orgganization. So o the changess in business logic of the web w service must be doone very quicckly within the given time constraint as the services consumed c by the providers and clients must not be affected there t by mannaging the chhanges at the runtime. Wee focus on creating enviro onment for v to the t business logic l so that it i is feasible to t make frequuent modificaations in a serrvice which dynamic variations aids servicce provider annd serves him m to satisfy cliients’ newfang gled quests. Such S environm ment is useful in the run-
2212-6678 © 2013 The Authors. Published by Elsevier B.V. Open access under CC BY-NC-ND license. Selection and peer review under responsibility of Information Engineering Research Institute doi:10.1016/j.ieri.2013.11.016
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time management of web services and to exactly spot the solution to the service provider’s maintenance element. There are many models that subsist for Business Process Management in which the process is recycled for the overall process changes. However, the problem with these solutions is that they only support the process level flexibility and not the application/service level flexibility. On the other hand this Business Logic Management framework tries to append that service level flexibility. These changes are done at the Business analyst level instead of being done at the Developer level, which reduces the hierarchy level in change management and thus implies a reduction in time and cost requirements. Here comes the need for an efficient model representation which provides clear visualization of the process of change management and the evaluation of changes implemented for the analyst to understand the system easily. Petri nets provide a graphical notation for the formal description of the dynamic behavior of systems and are particularly well suited to systems which exhibit concurrency, synchronization, mutual exclusion and conflict whereas finite state machines is a mathematical model of computation used to design both computer programs and sequential logic circuits. Though Petri nets have been used in the application areas such as Software design, Workflow management, Process Modeling, Data analysis, Concurrent programming, Reliability engineering, Diagnosis, Discrete process control and Simulation, finite state machine plays an efficient role in representing the evaluation of change implemented. Also Petri net is not only a significant burden placed on the analyst in order to specify complex models, but in addition the graphical representation may become too complex to be useful and understandable. In order to provide simple understandable and useful representation for the inexperienced non specialist analyst, finite state machine can be used for implementing the framework. This paper fully concentrates on the advantages of using FSM over Petri nets for change management and evaluation of changes implemented. 2. Literature survey Xumin Liu et al. [1] proposed an Ev-LCS, an end-to-end framework that specifies, reacts to, and verifies top-down changes in a LCS. This framework first propose a formal model which provides the grounding semantics to support the automation of change management and a set of change operators that allow specifying a change in a precise and formal manner by proposing a set of algorithms to automatically implement them. It then proposes a change enactment strategy that actually implements the changes. Dimitris Apostolou et al. [2] proposed an ontology-based approach for developing and maintaining e-Government services that can effectively deal with changes which enables the systematic response of e-Government systems to changes by applying formal methods for achieving consistency when a change is discovered and also enables the knowledgeable response of service designers and implementers to changes by utilizing design rationale knowledge. Florian Rosenberg et al. [3] proposed a domain-specific service selection mechanism and system implementation to address the issue of runtime adaptation of composite services that implement mission-critical business processes by making use of a domain-specific language called VieDASSL which can be used by domain experts to define the runtime adaptable selectors based on the QoS attributes in the adaptive QoS model. This approach ensures that changes in the QoS model and selectors can be handled at runtime without the disruption of the business processes by assuming the units of measurement for each QoS attribute are fixed and cannot be dynamically adapted. Bassam Atieh Rajabi and Sai Peck Lee [4] proposed two formalism of BPEL namely Graph based and Rule based formalism. The rigidity in graph based models incurs problems lack of runtime criteria (flexibility, dynamic and adaptability, which compromises the ability of the graph based processes to react to dynamic changes in BP and exceptional circumstances whereas the common objective of BRMS is to integrate complex process logic into a process model to support dynamic changes. To increase flexibility in process execution, Constraint based BP management approach is used which supports the evolution of BP. In [5], An adaptive and flexible framework is proposed to integrate OO diagramming technique and PN modeling language ( i.e. the graph based which has the visual appeal of being intuitive and explicit, even for those who have little or no technical background and rule based modeling language which requires good understanding of propositional logic and the syntax of logical expressions) in order to increase the representation capability for graph based modeling to support the dynamic changes in the runtime instances. In order to generate the BPEL code automatically, Yanhuna Du et al [6] proposed the Petri Net approach that automatically can verify the composition of partially incompatible services and also serves the time in such a way which will generate the BPEL code. This approach consist of 3 phases: Modeling composition of services is modeled as open WorkFlow Nets (oWFNs) which are composed by using the mediation transaction (MTs). Automatic verification of composition uses graph called Modular reachability graph (MRG) of composition is constructed and analyses the compatibility that can significantly improve the problem of state space explosion. In order to save the time, techniques called Event-condition Action (ECA) rule based is
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developed. Haochen Li, Zhiqiang Zhan et al. [7] proposed a solution that automates the change management process with machine learning method and assesses the solution from the business-driven perspective. This system analyzes the RFC and obtains the related CIs automatically and also automatically retrieves the most similar change solution. By automating the Change Management process with Business Driven Perspective, this system reduces the service interruption time and cost while doing the changes. To achieve the accuracy and efficiency, system returns valuable change solution that supports the collection of RFC (Request for Change) by comparing it with other system that will provide the optimal solution. Thus, the solution with the neural network of retrieving the similar RFC gives practical decision and also validates the change solution when selected for automatic change management process. Sabri MTIBAA and Moncef TAGINA [8] present a change management framework for a citizen-centric healthcare service platform. A combination between Petri nets model to handle changes and reconfigurable Petri nets model to react to these changes are introduced to fulfill healthcare goals. In [9], Using Petri nets based process modeling allows application of different analysis techniques. These techniques can be used to examine the behavior of the process and to calculate its performance measures. Transforming Petri net model into graph model gives possibility of using classical graph processing algorithms. This paper discusses the reasons, which impose Petri nets as a conceptual standard for modeling and analysis of workflow. Petri nets notation is used for representation of the main routing constructs as well as for the workflow process description. The correspondence of Petri-net-based model and graph model is demonstrated.S. Mtibaa and M. Tagina [10] present a distributed telemedicine environment reaping from both the benefits of Service Oriented Approach (SOA) and the strong telecoms capabilities. We propose an automated approach to handle changes in a distributed telemedicine environment. A combined Petri nets model to handle changes and Reconfigurable Petri nets model to react to these changes are used to fulfill telemedicine functional and non functional requirements. 3. Features of finite state machine vs petri nets 3.1 Schema driven Since all the modifications are done at the schema level for the analyst’s ease of understanding the functionality of the program, finite state machine plays a major role implementing the schema in case of change management and change evaluation. With the help of finite state machine, it is possible to transform the schema into finite state machine or vice versa. Thus finite state machine is fully schema driven whereas Petri nets are not schema driven since it is process driven (i.e. the process can be transformed to Petri nets or vice versa) which is not easily understood by the analyst. 3.2 Extracting Particular Logic In the process of change management, before doing changes it is necessary to extract a particular logic where we are going to do changes since change management framework mainly concentrates on doing emergency changes or simple changes. This is possible when we make use of finite state machine since it represents the logic through rules, functions or parameters whereas it is not possible to extract a particular logic by Petri nets. Petri nets can extract the origin of the process or the whole process even though our aim is to do minor changes. 3.3 Trace point By making use of finite state machine, we can trace each and every statement in the code easily. Especially in the change management of web services, we can trace a specific statement in the code where we are going to do changes whereas if we use Petri nets, it is not possible to reach particular statement in the code since it can exhibit only the part of the code in which the change has to be made. Also in the process of evaluation of the changes made, if any error occurs, it can traced at a specific location where the error has occurred by making use of finite state machine whereas in case of Petri nets, it will denote a specific part of the code where the error has occurred. 3.4 Rollback If an error occurs in the process of evaluation of the changes made, current state (state containing error) of the
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program can be rolled back to the previous state without affecting the original process of the program (i.e. without modifying the original code of the program)if we use finite state machine. But this may not be possible in case of Petri net since it rolls back to the origin of the whole process. thus whenever an error occurs while using Petri nets, the control reaches the origin of the process thereby increasing the time and space complexity in order to reach the state (from which it has been rolled back) for doing further different changes to make the system work according to change request. 3.5 Reachability In finite state machine, all the states are reachable since finite state machine consists of only finite number of states whereas sometimes it is not possible in case of Petri nets since they are state transition systems. State transition systems differ however from finite state automata in several ways: In a state transition system the set of states is not necessarily finite, or even countable. In a state transition system the set of transitions is not necessarily finite, or even countable. 3.6 Possibility of deadlock There is a possibility of deadlock in case of Petri net (this may not be always possible) since it has been used to model a variety of concurrent and discrete event distributed systems. But there is no possibility of deadlock in finite state machine since it is a mathematical model of computation used to design both computer programs and sequential logic circuits. 3.7 Time and Space complexity Finite state machine can exist in only state at a given time whereas Petri nets can exist in more than one state at a given time. Thus finite state machine is less complex than Petri nets. Also finite state machine consumes less time and space because of its simple structure and simple processing where Petri net consumes more time and space because of its complex structure and complex processing. 3.8 Structure Finite state machine consists of two main components namely state and transition whereas Petri netsconsists of four main components namely places, transition, arcs and tokens. In other words, since the finite state machine consists of only states, an input symbol and transitions, it is very simple and easily understandable whereas Petri net is a directed bipartite graph with two node types called places and transitions. The nodes are connected via directed arcs. Connections between two nodes of the same type are not allowed. Places are represented by circles and transitions by rectangles. The directed arcs describe which places are pre- and/or post conditions for which transitions (signified by arrows) occurs. These things make Petri nets structurally more complex than finite state machine. 3.9 Theoretical foundations for logic Since finite state machine have full support for the theoretical foundation for logic, it is more is applicable for modeling sequential processing associated with logical set theory whereas since Petri net have no support for theoretical foundation of logic, it is more applicable for modeling concurrent processing associated with event and condition.
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4 .Case stu udy The figuree 1(a) and 1(b)) shows the reepresentation of loan approv val using bothh Petri net andd finite state machine. m In case of Peetri nets, whennever a changee request com mes, the whole process is exxtracted from tthe origin wheereas in case of finnite state machhine, only a sppecific logic set s is extracted d. For example, In a Bankinng system, con nsider a change reqquest with thee description that certain amount a of tax must be added to all kindds of loans.
PETRI NET N FOR WHOLE W PROCESS OF LO OAN AP PPROVAL
FSM FOR THE WHOLE W LOG GIC OF LOA AN A APPROVAL
P1 q0 E E1 0
P2
P3
E2
F3
E3 10
q1 P P4 E E4
P6
P5
P8
P P7
1 1 1
E5
E6
1
F9
E7 F6
P10
P9
P11
P12 F8
F F7
113
10
12
11
E8 P13 q2
1
P14
F10 1
10
F11 E9 21
End H
WHOLE E PART IS EXTRACTED E WHILE DO OING CHANGES Figure 1(a)
BUT ONLY A SPE ECIFIC PART T IS RACTED WH HILE EXTR DOIN NG CHANGES S. Figure 1(b)
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educatiional loans” (refer ( table 1 and 2 ). Whiile using Petri nets, it is neecessary to exxtract the wh hole process from the origin. o In the above mentiioned examplee, the extract ion includes {P1, P2, P3, P4, P5, P6, P7, P P8, P9, P10, P11, P12, P13, P114} which reppresents the set s of places and {E1, E2, E3, E4, E5, E6, E7, E8 , E9} set of M, time and space s compleexity is reducced whereas transitionss (refer table 3 and 4). Thhus with the help of FSM it is very much larger in case of Peetri nets sincee it involves extracting e thee whole proceess from the origin o even t do minor chhanges. though thee main aim is to 4.1 Evaluaation of changges 02
q0
q0
F4
0
0
0
F3
F3 12
01
01
q1 1
q1 1
1
1
1 1
1
1
1
F9
F6
F9
F6
F8
F7
13
10
13
10
12
11
F8
F7
12
11
1
q2
1
q2
F10 F10 1
1
20
20
F11 F F11
21
E
21
H H
BU USINESS POL LICY ENFOR RCEMENT Figgure 2(a)
DER OF EXE ECUTION ORD Figure 2(b)
While evaluating thhe changes made m using change factorss, FSM playss a major roole in implem menting the m withoutt any complexxity and also provides a cllear visualizaation for the analyst a who evaluationn of changes made doesn’t neeed to have much m knowleedge in prograamming for understanding u g the functionnality of the system. By making usse of the changge factors andd FSM, it is eaasy to detect the t errors or violation v of poolicies or deviiation of the existing syystem beyondd a particular context c with the t help of nu umber of transsitions in statee transition tab ble after the doing channges or depenndendability. The T change faactors used arre Business poolicy enforcem ment, order off execution, code consiistency and similarity meassure.
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CODE CONSISTEN NCY
SIIMILARITY M MEASURE
q0
q0
0
0
F3
F3
01
10
q1
q1 1
1
1
1 1
1
F9
F9
1
F6
1
F6
F8
F7
13
10
13
10
12
11
F8
F7
12
11
1
q2
1
q2 F10
1
20
F11
F10 1
20
F11
E 21
H
Figure 2(c)
f using finitte state machine Figure 3 Measure of change factors
21
H
Figure 2(dd)
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M. Thirumaran et al. / IERI Procedia 4 (2013) 99 – 109 Table 1
TA BL Rules
Functions
Get_details()
Account Creation
Loan input details
R2
R3
P1
address
P2
occupation
P3
occupation_address
P4
Annual_income
P5
Accnt_type
P6
Guardian_name
P7
name
P1
address
P2
occupation
P3
occupation_address
P4
Annual_income
P5
Accnt_type
P6
R4 Property_checking()
Income_checking()
Funds_available()
F8
F9
F10
R5 Total_loan_amount_paid()
F11
PO1
F2->F1,F4
PO2
F3->F2,F5
NULL
F4->F1
PO4
F5->F2
NULL
F6->F3,F5
PO3
F7->F3,F5
PO4
F8->F3,F5
NULL
F9->F3,F5
NULL
F10->F3,F5
PO5
F11>F5,F6, F7,F8, F9, F10
address
F7
NULL
P2
F3
F6
NULL
P7
F4
F5
Dependenc y
P8 P8
Valid_address()
Get_loandetails
Policy
Guardian_name Valid_account()
Account_balance()
Loan Approval
F2
name
Accnt_no Accnt_no
Transaction_checking()
Eligibility checking
F1
R1
create()
Account Validity
Parameters
property
P9
Property_owner
P10
Property_address
P11
Property_worth
P12
Type_of_loan
P13
Actual_loan_amount
P14
Accnt_no
P8
Accnt_no
P8
No_of_transactions
P15
No_of_days
P16
totalBalance
P17
Accnt_no
P8
Type_of_loan
P13
minBalance
P18
Actual_loan_amount
P14
Accnt_no
P8
property
P9
Property_worth
P12
Property_address
P11
minWorth
P19
Type_of_loan
P13
Accnt_no
P8
Occupation
P3
Annual_income
P5
Type_of_loan
P13
Occupation_address
P4
Accntno
P8
type_of_loan
P13
Interest_rate
P20
Actual_loan_amount
P14
Accnt_no type_of_loan
P8 P13
interest_rate
P20
Actual_loan_amount
P14
Total_loan_amount
P21
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M. Thirumaran et al. / IERI Procedia 4 (2013) 99 – 109 Table 2
TABLE 2 POLICIES
DESCRIPTION
PO1
Account should be created only if the address is a valid address.
PO2
Single person should hold the account
PO3
Total balance should be greater than the specified minimum balance except for the person with military as occupation
PO4
Property owner should be the loan borrower except in case of student for educational loan
PO5
No tax or interest rate for educational loans
Table 3
Table 4
TABLE 3 PLACES Loan request
SYMBOLS P1
Valid Address list
P2
Valid Account list
P3
Valid Account for eligibility checking
P4
Minimum income list
P5
Minimum property worth Minimum balance
TABLE 4 TRANSITIONS Getting loan input details Validating address Validating account Income checking Property worth checking Balance checking Transactions checking Calculating interest Calculating total loan amount to be paid
P6 P7
Minimum number of transactions
P8
Account with valid income Account with valid property worth
P9 P10
Account with valid balance
P11
Account with valid number of transactions
P12
Interest rates for various loan types
P13
Eligible account for loan approval
P14
SYMBOLS E1 E2 E3 E4 E5 E6 E7 E8 E9
Figure 3 shows the measures of the change factors code consistency (cc1) , similarity measure (sm1) , order of execution (ooe1) and business policy enforcement ( bpe1) through finite state machine. For every change request, business logic related with that request is retrieved and finite state machine is constructed whereas while using petri net, states and transitions are constructed for whole business processes. The evaluation of time taken for petri net construction , finite state machine construction , rule detection time , function detection time and overall change execution at the model level for every change request is given in the experimental analysis. 5 .Experimental analyses The overall time taken for execution of a change in petri nets and finite state machines vary based on the following considerations. Overall execution time of the change using petri net is given using the following formula
Tot Tdt
Rtt
Where Tot Time taken for token transition Tdt Time taken for transition decision Time taken for real transition Rtt Whereas overall execution time of change using finite state machine is given using the following formula -
Rtt Where Rtt Time taken for real transition As there are no tokens in finite state machines and no time is taken for decision making in a transition. In this case, directly state transition table is considered and the transition from one node to another node is made
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easily. Similarly the space taken by petri net and finite state machine during a change is given using the following formulae – Space complexity For petri nets =
Pi
CR
TOST SST TDST TLT
Where P Process i Process id CR Change Request TO ST Storage taken for processes’ tokens SST Storage taken for state and their details TDST Storage taken for transition and their details TLT Storage taken for transition logging Space complexity For finite state machine = Where BL i CR SST TLT
BLi
CR
SST TLT
Business logic retrieved for change request Process id Change Request Storage taken for state and their details Storage taken for transition logging
Apart from time complexity and space complexity, the time taken for detecting a rule within the model, the time taken detecting a function, time taken for the model construction are also evaluated and shown in the following table. The overall experiment is done using Netbeans IDE6.9.0. Table 5 Performance evaluation of FSM and Petri net
The above table gives performance evaluation analyzed for 30 change requests where RdtinFSM gives rule detection time in FSM ( Finite state machine ) and RdtinPnet gives rule detection time in Petri net model. Similarly Fdt time is function detection time, Et is execution time of the change, Pct is Petri net construction time , Fct is finite state machine construction time and Sc is space complexity which is measured in terms of turing machine tapes. Since Petri net uses , direct processes, the number of tapes taken is very larger when compared the number of tapes used by finite state machine .
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6 . Conclusion The work compares the advantages of using finite state machine over petri nets in web service change management frameworks. The change management model designed supports the business analysts directly in performing the changes instead of depending on the IT analysts. Hence a schema driven process is induced for managing changes with respect to the logics of the services instead of considering the business process workflows of the services. When the process is schema driven, it is analyzed that finite state machine is more efficient than Petri nets because of their sequential processing nature. A change management scenario is built using netbeans IDE and changes are incorporated into the logics via both Petri net and finite state machine. A performance analysis of these two conceptual models are made based on time taken for execution of changes , time taken for construction of the models , time taken for rule detection , time taken for function detection and space used by the models during change execution . From the evaluation of the objective factors, it is inferred that finite state machine suits well than petri nets for the change management model, as emergency changes need to handled in an efficient way in less time. References [1] Xumin Liu, Athman Bouguettaya, Jemma Wu, and Li Zhou, “Ev-Lcs: A System For The Evolution Of Long-Term Composed Services,” IEEE Transactions on Services Computing,Vol. PP, Issue 99, 2011. [2] Dimitris Apostolou , Gregoris Mentzas,Ljiljana Stojanovic, Barbara Thoenssen, Tomás Pariente Lobo,”A collaborative decision framework for managing changes in e-Government services,” Government Information Quarterly 28 (2011) 101–116, PUBLISHED @ ELSEVIER, 2011. [3] Bruno Wassermann, Heiko Ludwig, Jim Laredo, Kamal Bhattacharya, Liliana Pasquale, “Distributed Cross Domain Change Management,” 2009 IEEE International Conference on Web, Services, 978-0-7695-3709-2/09, 2009 IEEE. [4] Bassam Atieh Rajabi, Sai Peck Lee, “Change Management in Business Process Modeling Survey”, 2009 International Conference on Information Management and Engineering, 978-0-7695-1/09, 2009 IEEE. [5] Bassam Atieh Rajabi, Sai Peck Lee, “Runtime Change Management Based on Object Oriented Petri Net,” 2009 International Conference on Information Management and Engineering, 978-0-7695-1/09,2009 IEEE. [6]Haochen Li, Zhiqiang Zhan, “Bussiness-Driven Automatic IT Change Management Based on Machine Learning,” 978-1-4673-0269-2/12, 2012 IEEE. [7] Yanhua Du, Xitong Li, and PengCheng Xiong, “Petri Net Approach to Mediation-Aided Composition of Web Services,” IEEE Tansactions on Automation Science and Engineering, Vol. 9, No. 2, Apr. 2012. [8] Sabri MTIBAA and Moncef TAGINA, “Managing Changes in Citizen-Centric Healthcare Service Platform using High Level Petri Net”, (IJACSA) International Journal of Advanced Computer Science and Applications, Vol. XXX, No. XXX, 2011. [9] Katalina Grigorova, “Process Modelling using Petri Nets”, International Conference on Computer Systems and Technologies – CompSysTech 2003. [10] S. Mtibaa and M. Tagina, “An Automated Petri-Net Based Approach for Change Management in Distributed Telemedicine Environment”, Journal of Telecommunications, Volume 15, Issue 1, July 2012.
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