Xiaofei Xu
email: xiaofei@hit.edu.cn

Chao Ma

Zhongjie Wang

A Value-Oriented Iterative Service Modeling Process

Keywords: business perspective, value perspective, value-awareness, expected values, rationality

In order to help service designers build high-quality service models quickly and accurately, this paper presents a value-oriented iterative service modeling process. This modeling process combines service business perspective and service value perspective together, and it is executed interactively between service model space and service value space, simultaneously, some value-awareness activities (e.g. value proposition, value analysis, value optimization, etc) are executed iteratively among different layers in the whole model process, so as to make service models can support the implementation of the expected values to a great extent. At last the rationality of the modeling process is explored.

Introduction

In recent years modern service industry was developing fast, and it has become the new economic growth point. The accurate execution of service business needs to be supported by service systems. Service engineering methodology is used to help service designers and service developers define, describe, design, optimize and implement the high-quality service systems accurately and quickly, which is viewed as a focus of research in service engineering field [START_REF] Papazoglou | Service-Oriented Computing Research Roadmap[END_REF] . Service modeling process is an important part of service engineering methodology [START_REF] Xu | Methodology for service engineering[END_REF] . Service modeling process is used to carry on requirement analysis, business design, model transformation and mapping for service systems. IBM SSME research group believes "service is the interactive process and behaviors between service providers and customers to create and share value" [START_REF] Jim | Steps toward a Science of Service Systems[END_REF] . According this, various tangible and intangible values are regarded as the output of service systems [START_REF] Ma | Preliminary Discussions on Several Characteristics of Service Value[END_REF] . Service values are an important characteristic of service systems. Service systems can be gradually transformed from service models by utilizing model-driven approach, so the quality of service models determines the quality of the service systems. The sole criterion for evaluating the quality of a service model is whether and to what degree the model can support the implementation of the values that are expected by both customers and providers [START_REF] Xu | Value-Aware Service Model Driven Architecture and Methodology[END_REF] . Therefore, it is necessary to carry on value-awareness activities in the whole service modeling process, so as to obtain a high-quality model.

Value-awareness means that "the value is regard as the basis of the service model design and decision-making in each phase of service life cycle, and before moving to the next phase, the value-oriented service model analysis must be executed to insure the implementation of all the expected values". In service modeling process, the corresponding value-awareness activities include value proposition, value expressing, value keeping, value decomposition, value analysis and value optimization. In order to better carry on value-awareness activities, this paper presents a value-oriented iterative service modeling process.

In this modeling process, not only service functional modeling from business perspective is needed, but also service value modeling from value perspective is needed, and this modeling process is executed interactively between service model space and service value space to insure the consistency in service models and value models. Service systems may refer to various stakeholders. At the beginning of the modeling process, these stakeholders understand the service systems partially and simply, therefore value-oriented model analysis, model optimization and feedback need to be executed iteratively to modify and deepen the understanding of service system incessantly.

The remainder of this paper unfolds in the following manner. Section 2 introduces service modeling theory. Section 3 presents a value-oriented iterative service modeling process. And then the rationality of the modeling method is explored in section 4, followed by conclusions in the last section.

Service modeling theory

For now, there are lots of study results of service modeling method from different perspectives (e.g. traditional software engineering, model-driven, domain analysis, semantics-driven).

From the traditional software engineering perspectives, the typical methods include SOMA [START_REF] Arsanjani | SOMA: A method for developing service-oriented solutions[END_REF] , SODA [START_REF] Nigam | Service Oriented Development of Applications (SODA) in Sybase Workspace[END_REF] and SOUP [START_REF] Mittal | Service Oriented Unified Process (SOUP)[END_REF] . By means of some methods such as domain decomposition, target service modeling, SOMA built service models, and then identified a set of self-existent service. And aiming at each service, some aspects (e.g. component specification, service interface specification, information, etc.) of the service are designed. At last a specific technique is selected to implement the services and combine these services tighter to realize a service system according to the layered structure. SODA can carry on various analysis and verification for service models, and support the flexible reuse, the reverse engineering, the automatic code generation, and so on. SOUP is a software method that is used to built and manage SOA project by utilizing RUP and XP. RUP is used to initially build the new service systems, and XP is used to analyze, assemble, reuse and optimize the existing service systems.

From the model-driven perspectives, the typical methods include the model driven service engineering process [START_REF] Anaby-Tavor | Towards a Model Driven Service Engineering Process[END_REF] , the service model driven architecture (SDMA) [START_REF] Xu | SMDA: A Service Model Driven Architecture[END_REF] . In the model driven service engineering process, the requirement model, the enterprise model, the execution model and the IT management model are respectively built for service systems. The service system is composed of the high level goals, the low level service components and the sensors embedded during runtime. Various phases are connected by utilizing model-driven approach. In SMDA, the service requirement model, the service behavior/capability model and the service execution model are respectively built for service systems. By means of model-driven approach, the three models are gradually built layer by layer, and the whole modeling process is top-down.

From the domain analysis perspectives, the typical methods include the SOA domain analysis method [START_REF] Wang | A Service Modeling Approach with Business-Level Reusability and Extensibility[END_REF] , the framework-based IT service engineering [START_REF] Specht | Weisbecker. Framework-based IT Service Engineering[END_REF] and the rule-based configuration approach [START_REF] Becker | Configurative Service Engineering -A Rule-Based Configuration Approach for Versatile Service Processes in Corrective Maintenance[END_REF] . In the SOA domain analysis method, the VINCA business model is built and instantiated from top to down by utilizing domain analysis approach, simultaneously, the web services are virtualized from bottom to up, at last in the middle the VINCA business model and the web services are combined together. In the framework-based IT service engineering, service templates are used as a model specification to describe service. In rule-based configuration approach, a configurative service system is built to meet the requirements of the group customers by embedding a set of variable parameters into service models and service systems. On this basis, the individual requirements of each customer are taken into consideration, and the concrete values of various parameters in service systems are confirmed, at last the service systems that can meet service requirements are built by utilizing the automatic configuration in combination with manual configuration.

From the semantics-driven perspectives, the agent-based service system design method (Tropos) is a typical method [START_REF] Lau | Designing Web Services with Tropos[END_REF] . In Tropos, the semantics of service business requirements (e.g. knowledge, rules) are defined by means of formal methods, and the requirements are mapped into the concrete service design and service orchestration by carrying on semantics transformation, at last the corresponding service systems is built.

Besides, Gordijn and others presented a multi-perspective service modeling method [START_REF] Gordijn | Requirements Engineering Techniques for e-Services[END_REF] [16] [START_REF] Gordijn | E3-value: Design and Evaluation of e-Business Models[END_REF] . The method refers to three perspectives: a value perspective, a process perspective, and an information systems perspective. The first two perspectives belong to the requirements analysis and business design phase. The last one belongs to the systems implementation phase. During service modeling, firstly, a value network is built from the value perspective, and it is used to analyze the future economic profit of service business. And then from the process perspective the service tasks are decomposed from top to down and those tasks are described by utilizing UML-like language, at last the service process model is obtained. MDA approach is used to build service systems.

In the above methods, the most ones are the multi-perspective or hierarchical modeling methods. They only focus on the traditional functional and quality characteristic of service systems, and ignore the value characteristic. But the value is the most characteristic of service systems. The method presented by Gordijn takes the value characteristic into consideration. It carrying on the economic values calculation in the strategy layer, but it did not take the value as the constraint for the whole service modeling. The value-oriented iterative service modeling process can solve the above problem. It has the three advantages: 1) it focus on value characteristic, and combines service business perspective and value perspective together; 2) it is interactive; 3) it is iterative.

Value-oriented iterative service modeling process is shown in figure 1. From transverse look, this process carries on interactively between service model space and service value space. From fore-and-aft look, this process carries on iteratively among different layers. The goal of this modeling process is take the expected values as the constraints for service modeling, so as to make service model can support the implementation of the expected values. The quantitative analysis of the expected values is taken as the basis of policy-making of various phases in this service modeling process.

Service model and value model

As is shown in figure 1, in service model space, service models are built layer by layer from coarse-grained elements into fine-grained ones. Service model is composed of service functional elements and the relationships among the various elements. It can be denoted as SM=(SE, R), where SE is service functional elements including two kinds: 1) service behaviors; 2) sub-process that is composed of a set of service behaviors. Service behaviors can be denoted as se= (PA, Fe, AO, ST, RES, QoS), where:

PA is the set of participants of se;

Fe is the farter behaviors of se, Fe is transformed into a set of fine-grained behaviors, and se is one of them; AO is the set of action objects which are manipulated by se and whose state are changed by the effect of se; ST is a set of ao's state transitions. In ∀st∈ST, ∃ao∈AO makes st = ao.s i → ao.s j .

RES is a set of necessary resources of se; QoS is a set of quality parameters that are attached to se. In the beginning of service modeling process, some service business can not be directly described as a service behavior, and only can be described as a sub-process. In the subsequent service modeling process, the sub-processes are gradually refined, until all the sub-processes are transformed into the service behavior that can be implemented by service component (e.g. web service).

In service value space, the four kinds of value models are used in the iterative and interactive service modeling process. They are value proposition model (VPM), participant oriented value network (POVN), value dependency model (VDM) and value annotation model (VAM).

VPM is used to identify various end-customers and end-providers in the top service that will be designed and implemented, and identify which service values they expected to obtain from the top service.

It is denoted as VPM=(TS, EPA, TV), where TS is the top service composed of the attribute name and the attribute description, TS would be decomposed into a series of sequential sub-services and service behaviors during service modeling; EPA is the set of end-participants composed of the end-customers set EC and the end-providers set EP; TV is the set of the top value, ∀v i ∈ TV, service value v i can be denoted as CON is the value profit constraint. ∀q j ∈CON, q j can be used to evaluate the a specific characteristic of the service in which v i 's receiver is participating. CA is the set of constraint attributes of v i , CA={e(B), e(C), e(E) ,e(CON)}, where e(B)={ B best , min(B)}, B best is the value of B during v i 's receiver accepts the best service, min(B) is the worst value of B that v i 's receiver can accept; (C), e(E) are similar to e(B); ∀econ∈ e(CON), econ is the constraint set of some quality parameter q j , econ include basic constraint, comparative constraint and conditional constraint.

v i =(BA,
POVN is used to identify which enablers that are needed to import so as to realize service. POVN is also used to describe how the various values are exchanged among the participants (customers, providers, enablers).

POVN is denoted as POVN={N, E}, where N is the node set in POVN, ∀node ∈N, node is a participant. N=C∪P∪EN, where C is the customer subset, P is the provider subset and EN is the enabler subset. E is the edge set in POVN, ∀edge∈E, edge=(se, v), ∃participant i , participant j ∈N, participant i , participant j are two endpoints of edge, se is the service functional elements that participant i and participant j refer to, and v is the corresponding value of se.

VDM is used to describe the relationships among the various edges in POVN. The relationships are the dependency relationships among the various service values in POVN. VDM is denoted as VDM = (N, SN, E D , E I ), where:

N={node 1 , node 2 ,…, node n }, ∀node i ∈N, ∃edge i ∈POVN.E, node i =edge i =(se j , v i ); SN={super_node 1 , super_node 2 ,…, super_node m }, super_node k ⊆N, | super_node k |>1
, where super_node k is a set of edges in POVN, and its constitutive rules: 1) to take the set of edges {(se j , v p ),…, (se l , v q )} as super_node k , and the participants of any two edges are same; 2) to take the set of edges {(se j , v p ),…, (se j , v q )} as super_node k , and the service functional element of any two edges is same;

∀e D ∈E D ,
d=DiffProducer(v 1 ,v 2 ,…,v n ), ∀d∈SPDE, d=SameProducer(v 1 ,v 2 ,…,v n ), and let pset={v 1 ,v 2 ,…,v n }.
VAM is used to describe the corresponding relationships between service values and service functional elements. It is denoted as VAM= (SM, VAT, R(se, vat)), where VAT is the set of value annotation tables, ∀vat k ∈VAT, vat k is a set of values, and their corresponding service functional element is same; R(se, vat) is the set of the corresponding relationships between se and vat. ∀ v i ∈vat k , v i = (BA, CA, DA), where DA is the set of impendency attributes of v i , DA= E D ∪E I .

For more details of value models please refer to the references [18][19] .

Detailed modeling process

The detailed value-oriented iterative service modeling process is shown in figure 2. This modeling process include 13 phases, and each phase is composed of serval steps. Step3. To initialize TV=∅, n=|EC|+|EP|, and add n service values into TV;

Step4. ∀c i ∈EC, to assign values to BA of service value v i that end-customer c i expects to obtain according to IDoSV and the domain knowledge;

Step5. ∀p j ∈EP, to assign values to BA of service value v j that end-provider p j expects to obtain according to IDoSV and the domain knowledge;

Step6. ∀c i ∈EC, end-customer c i would consult with the corresponding endproviders, and then to assign values to CA of service value v i ;

Step7. ∀p j ∈EP, end-provider p j would consult with the corresponding endcustomers, and then to assign values to CA of service value v j ; Phase3: To build service model, denoted as SM i = (SE, R); SM i would be gradually transformed layer by layer by means of MDA;

Step1. If i=0, to initialize SM i = (SE, R), let SM i = (IDoSF,∅); Step2. To judge whether or not all the service elements se i j belonging to SM i .SE can be realized by service components (e.g. web service);

Step3. If it can be, then go to Phase13; Step4: ∀se i j ∈ SM i .SE, if se i j can not be realized, to decompose se i j into (se i+1 j1 , se i+1 j2 ,…, se i+1 jn ), and then SM i is transformed into SM i+1 ; Phase4: To build POVN i+1 corresponding to SM i+1 , denoted as POVN i+1 = (N, E);

Step1. ∀se i+1 j ∈ SM i+1 .SE, to identify the customer set C, the provider set P and the enabler set EN from se i+1 j .PA, and to let POVN i+1 .N= C ∪P ∪ EN; Step2. ∀(se i j , v i h )∈POVN i .E (if i=0, ∀v i h ∈VPM.TV), according to the decomposition relationships between se i j and the corresponding service elements of SM i+1 , by utilizing some decomposition method of service value, to decompose Step5. To judge whether or not all the consistency between SDE, TSDE, SPDE, DPDE of VDM i+1 and the corresponding ones of VDM i is maintained;

v i h into v i+1 h1 , v i+1 h2 ,…, v i+1 hm ,
Step6. If it is, then go to Phase6;

Step7. If it is not, then go back to Phase5_Step 4; Phase6: To build VAM i+1 , denoted as VAM i+1 = (SM i+1 , VAT, R(se i+1 j , vat)); Step1. ∀(se i+1 j , v i+1 h )∈POVN i+1 .E, according to the corresponding relationship between v i+1 h and se i+1 j , to divide all the service values of POVN i+1 into a group of subsets {subV 1 , subV 2 ,…, subV m }, the corresponding service element of any two service values in each subset is same; each subset is related to one vat;

Step2.

∀subV k ∈{subV 1 , subV 2 ,…, subV m }, ∀v i+1 h ∈ subV k , ∀d∈SDE∪TSDE, if v i+1 h ∈cons(d), then add d into v i+1 h .DA; ∀d∈SPDE ∪DPDE, if v i+1 h ∈pset(d), then add d into v i+1 h .DA; ∀d∈CDE ∪ADE, if v i+1 h ∈ ante(d), then add d into v i+1 h
.DA; Phase7: To carry on the local analysis of VAM i+1 [START_REF] Ma | A Process Algebra based Method for Value Analysis on Service Process Model[END_REF] ;

Step1. ∀v i+1 h ∈VAM i+1 , to calculate v i+1 h based on the Qos of the corresponding service functional elements;

Step2. To judge whether or not the implementation of all the values can meet the constraints;

Step3. If there are the constraints of some values (represented by UnmetVset) that can not be met, then go to Phase8;

Step4. If the constraints of all the values can be met, then go to Phase10; Phase8: To optimize SM i+1 ;

Step1. To modify the QoS of the corresponding service functional elements of the values belonging to UnmetVset by utilizing some heuristic optimization method;

Step2. If the gaps between the implementation and the constraints of the values belonging to UnmetVset can be eliminated, then go to Phase10;

Step3. If the gaps can not be, then go to Phase9; Phase9: To eliminate the gaps by relaxing the constraints of the values of POVN i+1 ;

Step1. To relax the constraints of the values belonging to UnmetVset; Step2. To judge whether or not the gaps can be eliminated;

Step3. If the gaps can be, then go to Phase10;

Step4. If the gaps can not be, then let i=i-1:

Step4.1. If i==0, to relax the constraints of the values in VPM which are the father value of the values belonging to UnmetVset, then go back to phase2;

Step4.2. If i≠0, to relax the constraints of the values in POVN i+1 which are the father value of the values belonging to UnmetVset, and then go back to phase4; Phase10: To carry on the global analysis of VAM i+1 ;

Step1. FV i+1 is the set of the Fv of all the values in VAM i+1 , ∀v i k ∈FV i+1 , to calculate all the values of FV i+1 ;

Step2. To judge whether or not the implementation of all the values can meet the constraints;

Step3. If there are the constraints of some values (represented by UnmetFVset) that can not be met, then go to Phase12;

Step4. If the constraints of all the values can be met, then i=i+1, and go to Phase3; Phase11: To optimize SM i+1 ;

Step1. To modify the QoS of the corresponding service functional elements of the values decomposed from the values belonging to UnmetFVset by utilizing some heuristic optimization method;

Step2. If the gaps between the implementation and the constraints of the values belonging to UnmetFVset can be eliminated, then i=i+1, and go to Phase3;

Step3. If the gaps can not be, then go to Phase12; Phase12: To eliminate the gaps by relaxing the constraints of the values of POVN i+1 ;

Step1. To relax the constraints of the values decomposed from the values belonging to UnmetFVset;

Step2. To judge whether or not the gaps can be eliminated;

Step3. If the gaps can be, then i=i+1, and go to Phase3;

Step4. If the gaps can not be, then let i=i-1;

Step4.1. If i==0, to relax the constraints of the values belonging to UnmetFVset in VPM, and then go back to phase2;

Step4.2. If i≠0, to relax the constraints of the values belonging to UnmetFVset in POVN i+1 , and then go back to phase4; Phase13: To realize service system by utilizing service composition approach;

Step1: To carry on the quantitative evaluation on the value-oriented priority of service functional elements in SM n [START_REF] Ma | The Quantitative Evaluation on the Value-Oriented Priority of Service Elements[END_REF] ;

Step2: To carry on VOP based service composition. In order to better explain the above modeling process, a simple example is given in figure 3. It is assumed that there is a service functional elements se in the layer i-1, its corresponding value is v, and the implementation of v can meet v's own constraints. In the layer i, firstly , se is transformed into <se 1 , se 2 , se 3 >; secondly, v is decomposed into {v 1 , v 2 , v 3 }, and there is a corresponding relationship between se 1 and v 1 ; the next phase is to analyze whether or not the constraints of v 1 can be met by v 1 's implementation that is under the support of se 1 . If the constraints of v 1 can not be met, the next phase is optimize se 1 by modifying its QoS; If the gaps between v 1 's implementation and v 1 's constraints can not be eliminated by optimizing se 1 or by relaxing v 1 's own constraints, the next phase is to go back to the layer i-1 to relax v's constraints. If all the constraints of se 1 , se 2 and se 3 can be met, then go to the layer i+1.

Rationality of modeling process

The iteration and interactive are two key characteristics of the modeling process. The rationality of them is respectively discussed below.

There are various stakeholders in service system, their requirements are different and their degree of the understanding for service system is also different. Each stakeholder only can understand service system from their own point of view, and then pursue their own goal. Therefore, the stakeholder that can understand service system from a global perspective is impossible to exist. During service system designing, it is necessary to interactively carry on modeling process among various stakeholders, and to combine those understandings for service system together, so as to make service system can meet the requirements of all the stakeholders. As is shown in figure 4, the different stakeholders have different perspectives, and their range of the cognition for service and service system is different, but there are the intersections among various cognitive ranges, it is rational to interactively carry on modeling process among various stakeholders. In this paper, the modeling process includes two perspectives: values perspective and business perspective. The modeling process is executed interactively between service model space and service value space. From business perspective, service functional model is gradually built; the model designers only focus on the functional and quality requirements, and ignore the expected values. From value perspective, several corresponding value models is built along with service functional model, the value designers focus on the expected values, and did not understand much service business. But the value designers and the model designers can know what relationship between the expected values and service functional elements. Therefore, it is rational to interactively carry on modeling process between the value designers and the model designers.

The people's cognition for new things is progressive. The same goes for the cognition of the stakeholders for service systems. At the beginning of modeling, the stakeholders' degree of the understanding for service system is not high because their perspectives are local and the information obtained is few. As the stakeholders obtain some new information from others, their degree of the understanding for service system become higher, they may found some previous understanding for service system is wrong, so it is necessary to go back to adjust. It is similar to the backtracking method in software engineering.

In this paper, at the beginning of modeling, the cognition of the value designers and the model designers for service systems is limited. The cognition is constantly deepened by carrying on iteratively modeling process. For example, the model designers built SM i , but it is founded that SM i can not support the sufficient implementation of the expected values by model analysis, so it is necessary to go back to modify SM i . For another example, the value designers set the constraints of the expected values in POVN i , but the gaps can not be eliminated by utilizing model optimization or relaxing the constraints of the expected values in POVN i , so it is necessary to go back to relax the constraints of the corresponding values in POVN i-1 . Therefore, it is rational to iteratively carry on modeling process among different layers.

Conclusion

This paper presents a value-oriented iterative service modeling process. On the one hand, it combines the service business perspective and service value perspective together. The expected values are taken as constraints for service models. The value characteristic of service system is focused on. On the other hand, it makes service models can support the implementation of the expected values to a great extent by carrying on interactively between service model space and service value space and by carrying on iteratively among different layers. The modeling process can be used to help service designers to build the high-quality service model, and the service system that is built based on this service model can deliver the service values to providers and customers to a great extent.

Fig. 1 .

 1 Fig. 1. Schematics of the service modeling process

  e D is a directed super edge, it is denoted as e D =(a(e D ), c(e D )), where a(e D ), c(e D ) may be the super node, and may also be node. E D = CDE ∪ ADE ∪ SDE ∪ TSDE, where CDE is the set of composition dependency edges, ADE is the set of aggregation dependency edges, SDE is the set of support dependency edges, TSDE is the set of timing sequence dependency edges; ∀e I ∈E I , e I is an undirected super edge, e I ⊆N, |e I |>1. E I = DPDE ∪ SPDE, where ∀d∈DPDE,

Fig 3 .

 3 Fig 3. An example of the modeling process

Fig 4 .

 4 Fig 4. Different perspectives of the different stakeholders

  ∈POVN i+1 .E, according to v i+1 h .Fv, to divide all the service values of POVN i+1 into a group of subsets {subV 1 , subV 2 ,…, subV n }, Fv of any two service values in each subset is same; Step5. ∀subV k ∈{subV 1 , subV 2 ,…, subV n }, ∀v i+1 h ∈subV k , according to CA of v i+1 h .Fv, by utilizing some decomposition method of service values constraint, to assign values to CA of v i+1 h ; Phase5: To build VDM i+1 corresponding to POVN i+1 , denoted as VDM i+1 = (N, SN, E D , E I ); CDE and ADE, and then add CDE and ADE into E D ; Step4. To identify SDE, TSDE, SPDE and DPDE between various service values of VDM i+1 , and to add SDE, TSDE into E D , to add SPDE, DPDE into E I ;

	and then to identify all the corresponding relationships
	(se i+1 jk , v i+1 Step3.∀(se i+1 hk ), and add (se i+1 jk , v i+1 hk ) into POVN i+1 .E; j , v i+1 h ) ∈POVN i+1 .E, according to se i+1 j , to assign values to BA of service value v i+1 h ; Step4. ∀(se i+1 j , v i+1 h ) Step1. ∀edge i+1 h ∈POVN i+1 .E, to let VDM i+1 .node i+1 h = edge i+1 h =(se i+1 j , v i+1 h ); Step2. ∀subE⊂POVN i+1 .E, to let VDM i+1 .super_node i+1 k =subE, and subE ={(se i+1 j , v i+1 p ),…, (se i+1 j , v i+1 q )} , or subE={(se i+1 j , v i+1 p ),…, (se i+1 l , v i+1 q )}; Step3. If i=0, to skip this step; ∀node i+1 h ∈VDM i+1 .N, according to v i+1 h .Fv, to
	identify

Acknowledgment

Research works in this paper are supported by the National Natural Science Foundation (NSF) of China (No. 61033005, 70971029).


Ariyan Fazlollahi
email: ariyan@kth.se

Ulrik Franke

Johan Ullberg
email: johanu@ics.kth.se

Benefits of Enterprise Integration: Review, Classification, and Suggestions for Future Research

Keywords: Enterprise Integration, Enterprise Systems, Benefits, Classification, Literature Review

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Large multinational enterprises operating in global markets, continuous development of computing technologies, and the extended, dispersed and continuously interconnected enterprise information systems, has caused a fundamental transformation of the economy [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF]. Moreover, the migration of organizations toward greater complexity with global presence, sever economic pressures, the need for enhanced innovation and more participative and learningoriented management practices call for change in organizational life regarding the technology-organizational relationship [START_REF] Fulk | Electronic communication and changing organizational forms[END_REF]. Considering such forces, studies in organizational sciences generally agree on the evolution of organizational forms towards decentralized and more flexible approaches and structures [START_REF] Fulk | Electronic communication and changing organizational forms[END_REF].

In order to evolve, survive and thrive in these competitive markets, enterprises must find a way to cope with rapid changes in both internal and external environments. As a strategy to be able to rapidly respond to a changing environment, business functions can be integrated in order to efficiently utilize information technology, and share data with third-party actors in the marketplace [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF].

It is believed that the cost advantages of enterprise integration systems are significant [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF]. The authors in [START_REF] Mukhopadhyay | Business Value of Information Technology: A Study of Electronic Data Interchange[END_REF] have estimated the benefits of improved information exchanges using electronic data interchange (EDI) between Chrysler and its suppliers to an annual amount of 220 million US$. In another study in the health care industry, Walker et al. [START_REF] Walker | The value of health care information exchange and interoperability[END_REF] assessed the net value of a fully implemented electronic health care information exchange and interoperability as $77.8 billion per year. However, it should be considered that enterprise integration is expensive and time-consuming [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF]. Gartner [START_REF] Lheureux | Taxonomy, Definitions and the Vendor Landscape for Application Integration Solutions[END_REF] estimates the total revenue of application integration infrastructure as $5 billion per year in 2011.

The scientific literature has touched upon the topic of benefits and effects of enterprise integration on organizations from different viewpoints. However, there has been no effort to date to comprehensively evaluate these benefits. This paper outlines how enterprise integration can be useful to organizations, and provides guidelines for how future research might be conducted. In short, the purpose of this paper is to review the current state of research on the benefits of Enterprise Integration, thus providing a useful baseline for future research. This paper presents the literature review from a master thesis project [START_REF] Fazlollahi | Benefits of Enterprise Integration Systems[END_REF] with the goal of developing a method capable of measuring the benefits of EI in quantitative terms.

Defining Enterprise Integration

A variety of terms are presented in the literature to denote the integration area. Examples of such terms are enterprise integration (EI) [START_REF] Chen | Architectures for enterprise integration and interoperability: Past, present and future[END_REF][START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF], application integration (AI) [START_REF] Themistocleous | Novel taxonomy for application integration[END_REF], systems integration [START_REF] Markus | Paradigm shifts-E-business and business/systems integration[END_REF], and enterprise application integration (EAI) [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF].

Vernadat [START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF] contrasts Enterprise Integration (EI) with systems interoperability, designating EI by a "strong organizational dimension" while considering interoperability more of a technical nature. From a pure technical perspective, EI is considered to denote connecting computer systems and IT applications to support business process operations [START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF]. On the other hand, from an organizational perspective, EI facilitates information, control, and material flows across organization by connecting all the necessary functions and functional entities to improve communication, cooperation, and coordination within the enterprise [START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF].

Adopting application integration (AI) term as the umbrella term for integration, the authors in [START_REF] Themistocleous | Novel taxonomy for application integration[END_REF] introduce three main subcategories, namely (1) intra-organizational AI, (2) inter-organizational AI, and (3) hybrid AI. They thus differentiate the integration of internal applications from cross-enterprise business processes and systems. The term hybrid is used to denote that in some cases, these applications function as intra-organizational AI and in others as inter-organizational applications.

Markus [START_REF] Markus | Paradigm shifts-E-business and business/systems integration[END_REF] defines systems integration as establishment of "tighter linkages between different computer-based information systems and databases". By this definition, the author views systems integration as a requirement to achieve business integration. In this context, enterprise application integration (EAI) is defined as an systems integration strategy to achieve data and process integration [START_REF] Markus | Paradigm shifts-E-business and business/systems integration[END_REF].

Lee et al. [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF] uses enterprise integration and systems integration synonymously as "the capability to integrate a variety of different system functionalities". Similar to [START_REF] Markus | Paradigm shifts-E-business and business/systems integration[END_REF], Lee et al. [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF] considers EAI as an approach to systems integration.

In this article enterprise integration (EI) is adopted to refer to the entire integration area. Most importantly, this definition of EI encompasses various perspectives and levels of integration, namely systems integration (interconnection of devices via computer networks), application integration (integration of software applications and database systems), and business integration (co-ordination of functions that manage, control and monitor business processes) [START_REF] Chen | Architectures for enterprise integration and interoperability: Past, present and future[END_REF]. Moreover, the term itself possess the required comprehensiveness to be considered as the umbrella term incorporating other related terms mentioned for integration.

Benefits of Enterprise Integration

The authors in [START_REF] Themistocleous | Towards a novel framework for the assessment of enterprise application integration packages[END_REF] propose a framework as a decision-making tool regarding the adoption of EI. The proposed framework considers four integration layers, namely the connectivity layer, transportation layer, translation layer, and the process automation layer. In the connectivity layer, integration elements like data and objects are extracted from source systems and are transferred to the integration infrastructure by the transportation layer. Transported elements are translated and reformatted for target systems using the translation layer. The process automation layer is responsible for routing the translated elements to target systems.

Based on the classification of ERP benefits proposed by [START_REF] Shang | A comprehensive framework for classifying the benefits of ERP systems[END_REF], Themistocleous [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF] classifies the benefits of EI in five different types; organizational (e.g. more organized business processes), managerial (e.g. ROI), strategic (e.g. increase collaboration among partners), technical (e.g. achieve data, object and process integration), and operational (e.g. reduce cost). However, it could be argued that such scheme imposes a subjective classification rather than an objective one, i.e. the decision to classify one benefit in a category depends on the researcher rather than the characteristics of the benefit itself. In this sense, these types could overlap, which makes it is difficult in practice to make a distinction between them.

Enterprise Integration Council suggests flexibility and agility, defined as the ability to rapidly respond to new business opportunities, as the ultimate goals of EI [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF]. Moreover, it proposes cycle time reductions, cost reductions, and cost containment as benefits of enterprise integration systems [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF]. In acclaiming such benefits, Chari and Seshadri state that "adopting standards-based integration solutions is the most promising way to reduce the long-term costs of integration and facilitate a flexible infrastructure" [START_REF] Chari | Demystifying integration[END_REF].

Themistocleous and Irani [START_REF] Themistocleous | Benchmarking the benefits and barriers of application integration[END_REF] view the benefits of EI as reduced integration time, more flexible and maintainable solutions, and the easing of migration to new technologies due to conformance of EI systems to common standards [START_REF] Themistocleous | Benchmarking the benefits and barriers of application integration[END_REF]. They argue that these benefits ultimately result in reduction of overall integration costs due to the reduction of both integration time and maintenance costs.

Ruh et al. [START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF] face the challenge of determining the effects of EI from the organizational perspective. The authors claim that an integrated infrastructure allows companies to improve their performance, increase their productivity and increase the quality of services offered to their customers. Similarly, Themistocleous and Irani assert that EI strengthens supply chains [START_REF] Themistocleous | Benchmarking the benefits and barriers of application integration[END_REF]. Manouvrier and Menard [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF] also stress improvements in quality of service as the most significant benefit of integration systems.

From another point of view, Shin [START_REF] Shin | Adoption of Enterprise Application Software and Firm Performance[END_REF] claims that EI is generally effective for large firms, with size above some critical point. They stress that in order to rationalize the initial fixed cost of EI systems, companies shall have conditions such as a mass of complicated information systems.

In addition to increasing reactivity, adaptability and the ability to manage external exchanges optimally, Manouvrier and Menard [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF] suggest accelerating time-to-market as another effect of EI.

Tackling the problem of determining the effects of EI, Themistocleous and Irani in [START_REF] Puschmann | Enterprise application integration-the case of the Robert Bosch Group[END_REF] and [START_REF] Themistocleous | Application Integration of Information Technology: Classification of Benefits and Barriers[END_REF] propose that Information systems that benefit from integration with others can arguably be viewed as no longer having a definitive start and end. The authors claim that such systems are evolving entities that grow and develop over time, in tune with the business environment.

Analyzing the benefits of enterprise integration on the data level, the authors in [START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF] suggest business benefits such as improved productivity, improved data accuracy, greater agility and flexibility, and system replacement/organizational mergers.

A Classification of Benefits

In order to present the identified benefits of EI for an enterprise, a classification scheme is employed. This scheme is intended to unite different perspectives of enterprise integration benefits that can be found in the literature. The classification scheme is based on the conceptual model proposed for enterprise integration in [START_REF] Giachetti | A research framework for operationalizing measures of enterprise integration[END_REF]. The authors in [START_REF] Giachetti | A research framework for operationalizing measures of enterprise integration[END_REF] proposed a model in which an enterprise is seen as a layered framework of related activities sharing common goals, which as a whole, describe an organization. Each of these layers can be seen independently as a view of the enterprise. These layers are network, information, application, work processes and organization. The integration goal at the network layer is to provide connectivity, defined as the linkages between systems, applications, and modules. Thus the integration issue addressed at this layer is the physical heterogeneity of the hardware and their operating systems in a physical network. In our model, however the notion of the network layer is excluded (cf. figure 1). Such exclusion could be justified considering that the network layer is deemed to be too fundamental to give rise to benefits.

The information layer is the view incorporating data sharing issues, as it involves enabling organizational sub-units to understand and use data from other subunits. The application layer describes the systems used by the organization. The integration goal at this layer is application interoperability which is defined as "the ability of one software application to access/use data generated by another software system" [START_REF] Giachetti | A research framework for operationalizing measures of enterprise integration[END_REF]. Tasks and the manner and order in which they are conducted in order to produce an output are the core of the work processes layer. In the last layer, organization layer is where the different strategies including business strategy, organizational design strategy and information systems strategy must all be aligned with one another. The described scheme provides an abstraction mechanism in order to unite various perspectives of enterprise integration benefits in different literature. Moreover, it offers the possibility to picture the relation between various benefits related to the different layers.

The presented scheme differs essentially from both models proposed in [START_REF] Themistocleous | Towards a novel framework for the assessment of enterprise application integration packages[END_REF] and [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF]. By classifying the workflow of a typical integration scenario, the model proposed in [START_REF] Themistocleous | Towards a novel framework for the assessment of enterprise application integration packages[END_REF] provides a layered view over EI activities (how it is performed) rather than the benefits of EI (what is achieved). The scheme proposed in this paper, however, aims to describe an organization as a layered framework of related independent activities which share common goals. The classification presented in [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF] provides a classification model for the benefits of EI. On the other hand, the model limits its perspective to the point of view of an organization's senior management.

With the aim of providing a comprehensive view over the benefits of EI, each of the layers in the presented scheme (cf. figure 1) can independently be seen as a view of the enterprise. In this way, the proposed scheme covers all the layers of an enterprise. This can also be justified by the similarity of the proposed layers to the enterprise layers in the enterprise architecture (EA) literature. For instance, the three layers presented in Archimate [START_REF]The Open Group: ArchiMate® 2.0 Specification. The Open Group[END_REF] could be associated with the proposed scheme: ─ Archimate's technology layer could be associated with scheme's information layer;

─ application layers of both could be related to each other; ─ business layer of Archimate could be linked with the process and organization layers of the proposed scheme.

Information Layer

Benefits identified from the literature related to the information layer are data entry/processing automation and data quality improvements [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF], enhanced data accessibility and reusability [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF], and superior data standardization [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF].

Data Entry/Processing Automation and Data Quality. The authors in [START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF] discuss that enterprise integration minimizes data entry points, automates data entry, business rules execution against data, and data transformation. They argue that such automation minimizes the opportunity for human error, which in turn results in improvements in data accuracy. Moreover, according to [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF], EI results in data with increased reliability, which is defined as a data quality dimension indicating whether the data can be relied on to convey the right information [START_REF] Wand | Anchoring data quality dimensions in ontological foundations[END_REF]. To indicate the significance of data quality improvements by enterprise integration, the authors in [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF] discuss that such improvements supports the decision-making process, which in turn, improves performance and management of the organization.

Data Accessibility and Reusability.

Providing support for more efficient data sharing and more reusable data is mentioned as one of the results of employing enterprise integration in organizations [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF]. However, more emphasis has been placed on enhanced data accessibility, which is discussed to be achieved through information exchanges [START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF]. More specifically, it is argued that enterprise integration improves data accessibility by facilitating greater degree of communication [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF] by connecting all the necessary functions and heterogeneous functional entities [START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF]. Data Standardization. Considering automated data entry and execution of business rules against the data as a feature of enterprise integration, Lee et al. [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF] argues that this would lead to improved data standardization. The authors in [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF] posit that an implication of enterprise integration is reduced data redundancy, resulting in less data and application, and less maintenance effort.

Application Layer

The application layer contains the following benefits: applications switching costs decrease [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Themistocleous | Novel taxonomy for application integration[END_REF], data analysis capabilities improvements [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF], systems interoperability improvements [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF], systems modifiability improvements [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF][START_REF] Themistocleous | Novel taxonomy for application integration[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF][START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF], total cost of ownership (TCO) decrease [START_REF] Themistocleous | Novel taxonomy for application integration[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Themistocleous | Extending the information system lifecycle through enterprise application integration: a case study experience[END_REF][START_REF] Irani | The impact of enterprise application integration on information system lifecycles[END_REF], and systems reusability improvements [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Irani | The impact of enterprise application integration on information system lifecycles[END_REF].

Total Cost of Ownership (TCO).

As discussed, lower applications switching costs and enhanced systems interoperability decrease the lifecycle cost of the information systems within the organization. Additionally, improved systems modifiability results in reduced purchasing, maintaining and training efforts [START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF]. In overall, enterprise integration reduces the total cost of ownership for information systems in the organization, including cost of managing, running and maintaining the IT infrastructure, and the time required to conclude systems integration [START_REF] Themistocleous | Novel taxonomy for application integration[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF]. On the other hand, increased flexibility and software reuse extends the information systems lifecycle, which could significantly reduce the total cost of ownership for information systems within the organization [START_REF] Themistocleous | Extending the information system lifecycle through enterprise application integration: a case study experience[END_REF][START_REF] Irani | The impact of enterprise application integration on information system lifecycles[END_REF].

Systems Reusability. The authors in [START_REF] Irani | The impact of enterprise application integration on information system lifecycles[END_REF] state that the new integrated information system resulting from integrating multiple information systems offers software reuse through the adaptability provided by integration. In the results of multiple case studies, Themistocleous [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF] also supports this finding.

Process Layer

This layer includes Business-to-Business (B2B) processes improvement [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF][START_REF] Themistocleous | Towards a novel framework for the assessment of enterprise application integration packages[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF], decision making processes improvements [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF], processes flexibility/agility improvements [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF][START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF], and processes performance improvements [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Themistocleous | Benchmarking the benefits and barriers of application integration[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF][START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF].

Business-to-Business (B2B) Processes. The integrated IT-infrastructure enables sharing information between the partners of a supply chain [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF], which increases collaboration among trading partners [START_REF] Themistocleous | Towards a novel framework for the assessment of enterprise application integration packages[END_REF], and strengthens supply chains [START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF]. Moreover, internal and external supply chains are integrated, resulting in improvements in supply chain planning. From the perspective of organization's customers, this would yield in improvements in the quality of services offered to customers [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF]. Decision Making Processes. Enterprise integration mediates the flow of information from stovepipe applications to the common warehouse and supports the conversion of data from various applications' formats to a common format. This facilitates the construction of a data warehouse which could provide integrated information for decision support of the organization. [START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF] Processes Flexibility/Agility. As a consequence of enterprise integration, process scalability is increased [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF], delays in activities of value chain could be decreased [START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF], organization could quickly respond to changes in its environment by providing new products, services and information [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF], quickly modifying its business methods [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF], or bringing new business lines [START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF].

Processes Performance. The authors in [START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF] argue that by connecting all the necessary functions and heterogeneous functional entities (e.g. information systems, devices, applications, and people), enterprise integration facilitates information, control, and material flows across organization boundaries, aids data and information exchanges (i.e. interoperation between applications), which in turn improves timely orchestration of process steps within the enterprise. Moreover, business processes are optimized in terms of productivity by reducing manual tasks [START_REF] Themistocleous | Towards a novel framework for the assessment of enterprise application integration packages[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF], eliminating unnecessary or redundant tasks by letting systems share data across the enterprise [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF], providing employees with better access to the information they need to do their jobs [START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF], and reducing time and resource required for reworking tasks [START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF]. Additionally, if processes are reengineered during implementation of enterprise integration, business processes would become more organized, which would lead to increases in business processes understanding and control, resulting in increased performance [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF].

Organization Layer

The layer with highest abstraction level encompasses the following benefits: customer relationship improvements [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF], enterprise flexibility improvements [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF][START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF], facilitating organizational mergers [START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF], costs reduction [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF], revenue growth [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF], and supply chain improvements [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF][START_REF] Mentzer | Defining supply chain management[END_REF].

Customer Relationship. In an integrated IT infrastructure, all information relevant to a customer would be available in an integrated form, which provides a 360-degree view of customer relationships, resulting in improved services quality for customers and increased services/products value to customers [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF]. Such increased value could build customer loyalty, which in turn could generate profit for the organization [START_REF] Hallowell | The relationships of customer satisfaction, customer loyalty, and profitability: an empirical study[END_REF][START_REF] Edvardsson | The effects of satisfaction and loyalty on profits and growth: Products versus services[END_REF][START_REF] Heskett | Putting the service-profit chain to work[END_REF].

Enterprise Flexibility. Connecting all the necessary functions and heterogeneous functional entities allows for a greater degree of communication, coordination, and cooperation in human factors as well as information technologies. This enables organizations to continuously monitor market demand, quickly respond by providing new products, services, information, and application, and quickly introduce new technologies and modify business methods [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF]. Moreover, not only does EI reduce the time-to-market [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF], but also due to cross-department standardization to all domains of the enterprise, the resulting increased reactivity can manifest itself by a reduction in loss of revenues or an increase of quality of service [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF].

Organizational Mergers. In case of organizational mergers or acquisitions, when new business units enter the mix, enterprise integration facilitates incorporating new systems into the enterprise architecture [START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF].

understanding regarding the benefits of EI, not least for decision-makers running actual integration projects.

Although the study aimed to be highly inclusive regarding the studies available on the subject of benefits of EI, it might not have covered the entire span of available literature. To increase the comprehensiveness, additional studies could be conducted to consider additional studies in other languages than English (which was the focus of the search in this study), as well as the gray literature (e.g. organizational statistics, internal reports).

Moreover, based on the results of this research, one future study could be to perform more rigorously designed EI research on benefits of EI. This would lead to more reproducible results, a crucial need for the area.

Fig. 1 .

 1 Fig.1. Classification scheme; based on[START_REF] Giachetti | A research framework for operationalizing measures of enterprise integration[END_REF]

Table 1 .

 1 Classified benefits of enterperise integration

		─ Business-to-Business (B2B) processes improvement
	Process	─ decision making processes improvements ─ processes flexibility/agility improvements
		─ processes performance improvements
		─ applications switching costs decrease
		─ data analysis capabilities improvements
	Application	─ systems interoperability improvements ─ systems modifiability improvements
		─ total cost of ownership (TCO) decrease
		─ systems reusability improvements
		─ data entry/processing automation and data quality improvements
	Information	─ enhanced data accessibility and reusability
		─ superior data standardization

Organization

─ customer relationship improvements ─ enterprise flexibility improvements ─ facilitating organizational mergers ─ costs reduction ─ revenue growth ─ supply chain improvements

Applications Switching Costs. The authors in [START_REF] Themistocleous | Novel taxonomy for application integration[END_REF] and [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF] argue that by enabling organizations to conform to common standards, enterprise integration facilitates easier and quicker migration to new technologies and reduces switching costs of systems.

Systems Interoperability. The literature relates improvements in systems interoperability achieved by enterprise integration to the standardization of interfaces [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF], which allows greater degree of cooperation between different applications [START_REF] Lee | Enterprise integration with ERP and EAI[END_REF][START_REF] Vernadat | Enterprise Integration and Interoperability[END_REF]. Brunnermeier et al. [START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF] discuss that enterprise integration reduces problems caused by imperfect interoperability.

Systems Modifiability.

Providing a common integrated infrastructure, enterprise integration minimizes the changes to application code [START_REF] Themistocleous | Novel taxonomy for application integration[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF], and leads to more flexible, manageable and maintainable solutions [START_REF] Themistocleous | Novel taxonomy for application integration[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF] with higher scalability [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Gleghorn | Enterprise application integration: a manager's perspective[END_REF]. Moreover, mediation and transformation functionalities of enterprise integration and provided asynchronous communication results in higher degrees of loose coupling between applications [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF], which yields in increased information systems flexibility and reactivity [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF]. Additionally, enterprise integration makes it possible to position business rules outside the code for applications, thus rendering maintenance and adaptability of systems much simpler and faster. Furthermore, the authors in [START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF] discuss that the improvements in systems interoperability reduce related mitigation and reworking activities and corresponding time and resources, which could be discussed that increase systems modifiability.

Costs Reduction. Reengineering processes, during implementation of enterprise integration, results in more organized business processes and increases business processes understanding and control. This leads to business processes improvement, resulting in increased organizational performance.

Revenue Growth. Imperfect interoperability could lead to delays in key activities in value chain. Such delays yield to reduction in market share and the associated revenues. Another consequence could be delays in revenue [START_REF] Manouvrier | Application Integration: EAI, B2B, BPM and SOA[END_REF][START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF][START_REF] Brunnermeier | Interoperability costs in the US automotive supply chain[END_REF].

Supply Chain. By integrating internal and external supply chains, enterprise integration improves planning in supply chain management [START_REF] Themistocleous | Justifying the decisions for EAI implementations: a validated proposition of influential factors[END_REF], and therefore improves supply chains [START_REF] Ruh | Enterprise application integration: a Wiley tech brief[END_REF][START_REF] Mentzer | Defining supply chain management[END_REF].

Discussion

This research sought to reveal the current state of the scientific literature concerning the potential benefits of EI. Our research results provide a consolidated view of the scientifically established picture of such potential benefits.

The literature suggests benefits of EI, related to various aspects of an enterprise. However, the results of many studies are limited to specific cases due to the research methodologies adopted. Some studies also suffer from limited understandability and reusability, since they lack a classification scheme or proper taxonomy. Moreover, disperse backgrounds of the studies conducted regarding EI benefits causes an ambiguity with regard to the context where the perceived benefits are applicable. To address such voids, the presented research provides an account of the available research findings of EI benefits, classified using a conceptual model of the enterprise.

The results have several implications for both researchers and practitioners. First of all, the provided information on potential EI benefits and their applicability (enterprise layer) enhances the understanding of EI. Moreover, the list and classification of EI benefits provided can function as a source for defining relevant objectives for EI projects, which is useful in business cases. Additionally, the results could be used to define EI effectiveness metrics. Within a more ambitious research agenda, the classified benefits could be employed to develop methods or models capable of measuring such benefits in financial terms.

Certain benefits have been found to semantically overlap or to group more than one notion, while some might appear vague or of high-level abstraction. This reflects the different intentions of the original studies' authors. However, the affected benefits were incorporated without any modifications to avoid potential semantic inconsistencies.

In addition to the context within which certain benefits appear as results of EI, future studies are recommended to understand and report the causal mechanisms behind these benefits. Identifying the relations between different benefits of EI with the specific mechanisms that generate them provides insight on how the benefits were actually brought about. Such causal relationships could offer additional and critical