A UNIFIED FRAMEWORK FOR APPLICATION INTEGRATION

An Ontology-Driven Service-Oriented Approach

Saïd Izza, Lucien Vincent, Patrick Burlat

Laboratoire G2I, Ecole des Mines de Saint-Etienne, 158 Cours Fauriel, Saint-Etienne, France

Keywords: Enterprise application, integration, web service, ontology, mediation.

Abstract: The crucial problem of Enterprise Application Integra

tion (EAI) is the semantic integration problem. This

latter is not correctly addressed by today's EAI solutions that focus mainly on the technical and syntactical

integration. Addressing the semantic aspect will promote EAI by providing it more consistency and robust-

ness. Some efforts are suggested to solve the semantic problem, but they are still not mature. This article

will propose an approach that combines both ontologies and web services in order to overcome some issues

related to the semantic integration problem.

1 INTRODUCTION

Over the last decade, a new technology typically

known as Enterprise Application Integration (EAI),

have emerged. In essence, EAI technologies provide

tools to interconnect multiple and heterogeneous

enterprise application systems (EAS) such as ERP

(Enterprise Resource Planning), CRM (Customer

Relationship Management), SCM (Supply Chain

Management), and legacy systems. The most diffi-

culty of these interconnections is that the integrated

systems were never designed to work together.

More recently, Web Services (WS) have

erged with the advent and the evolution of the

Internet and they provide a set of standards for EAI.

Even if WSs are not fully mature, they seem to be-

come the linga franca of EAI. This will notably

make integration simpler and easier through using

web protocols and standards.

Despite the whole range of available tools and

despread standards adoption, the main goal of

EAI, which is the semantically correct integration of

EASs, is not yet achieved. Indeed, EAI still provides

technical and syntactical solutions but does not ad-

dress correctly the semantic problem, which consti-

tutes the real integration problem.

Semantic integration becomes very important in

rder to overcame semantic heterogeneities within

EAI, and which mainly concern both data and be-

havior of EASs. Although there is some related

works, which concern semantic integration, but there

has been no mature solution that deals correctly with

integration problem.

In this paper, we will focus on the semantic

roblem in the context of EAI. Our approach is

based on an extension of service-oriented architec-

ture (SOA), called ODSOI (Ontology-Driven Ser-

vice-Oriented Integration) and which is mainly

based on WSs and ontologies. The rest of this paper

is organized as follows. Firstly, we will present the

integration problem. Secondly, we will briefly re-

view the current state-of-the-art in EAI through pre-

senting two major kinds of solutions: traditional and

Web-Services-based EAI systems. Finally and be-

fore concluding, we will describe some aspects of

our work which attempts to provide a solution for

the integration problem.

2 THE INTEGRATION PROBLEM

Enterprise application systems (EAS) can take many

different types including batch applications, tradi-

tional applications, client/server applications, web

applications, application packages (Izza, 2004).

These systems are often materialized in enterprise

reality in form of ERP, CRM, SCM, and legacy sys-

tems.

An appropriate characterization of EASs in the

conte

xt of EAI is that EASs are HAD (heterogene-

ous, autonomous and distributed) systems (Bussler,

2003):

- Het

erogeneous systems mean that each EAS

implements its own data and process model.

- Aut

onomous systems refer to the fact that each

165

Izza S., Vincent L. and Burlat P. (2005).

A UNIFIED FRAMEWORK FOR APPLICATION INTEGRATION - An Ontology-Driven Service-Oriented Approach.

In Proceedings of the Seventh International Conference on Enterprise Information Systems, pages 165-170

DOI: 10.5220/0002521601650170

 SciTePress

EAS runs independently of any other EAS.

- Distributed systems mean that each EAS locally

implements its data model, which it generally do

not share with other EAS.

The consequence of these characteristics is that

EASs are generally standalone software entities,

which form what we often call islands of informa-

tion and automation. In this case, any form of inte-

gration of the EASs must happen outside of the in-

volved EASs, by using integration systems such as

EAI systems. This integration consists in intercon-

necting the interfaces of each EAS using technolo-

gies supported by the integration systems such as

queuing systems, databases or remote invocations.

The characteristics of EASs form the main rea-

sons of the existence of the integration problem, and

the more these characteristics are extremes, the more

the integration become hard and complex. Despite

the importance of the problems described above, we

will focus, in this paper, only on the heterogeneity

problem, precisely the semantic heterogeneity prob-

lem, which is the hard problem of enterprise integra-

tion in general, and EAI in particular (Bussler,

2003).

Since EASs are HAD, a semantic mediation is

needed in order to achieve their integration. Its aim

is to resolve all the semantic conflicts that can arise

between the exchanged data, and also between in-

voked behavior interfaces. Indeed, data semantic

mediation provides mechanisms to preserve the

meaning of the data during the flow exchanges be-

tween EASs (adressing ), whereas behavior semantic

integration provides mechanisms to resolve the se-

mantic behavior interface heterogeneity when EASs

invoke each other.

Furthermore, the integration problem is more

complicated by our industrial context concerned by a

complex enterprise in the multidisciplinary microe-

lectronics area. This particular context is mainly

characterized by several and heterogeneous knowl-

edge domains that needs sophisticated semantic me-

diation in order to achieve the integration process.

3 INTEGRATION SOLUTIONS

In this section, we will describe the major existing

EAI solutions, which will be followed by some per-

tinent related works about EAI.

3.1 Today's EAI Solutions

In this paper, we will consider only two main impor-

tant solutions in the context of EAI: traditional EAI

systems and WSs. These solutions can fulfill major

integration requirements such as data synchroniza-

tion, business process execution, reconciliation of

technical and syntactic differences, fast deployment

of new applications and so on.

3.1.1 Traditional EAI Systems

Currently, EAI systems are based on a lot of tech-

nologies such as: message brokers, process brokers,

message-oriented middleware, etc. Even if EAI sys-

tems may differ from a technological point of view,

the main functionalities remain the same and we can

mainly distinguish five components, which provide

respectively transport services, connectivity ser-

vices, transformation services, distribution services

and process management services (Erasala, 2003).

The principle of EAI systems is based on using

interfaces (connectors) to integrate EASs. The inter-

faces convert all traffic to canonical formats and

protocols. These interfaces constitute the only mean

to access EASs, and they can occur in different lev-

els: user-interface level, business logic level and

data level (Linthicum, 1999).

Although EAI systems address technical and

syntactical integration, nevertheless they must ad-

dress the semantic level which is more difficult and

which can provide more added value. Today, no

traditional EAI system can provide mechanism that

correctly supports semantics. In best cases, data is

passed between EASs by-value, and in general no

shared semantic concepts are explicitly used to de-

fine semantics through different messages or to se-

mantically describe the behavior that is provided.

3.1.2 Web Services

WSs are considered as a result of convergence of

Web with distributed object technologies. They are

defined as an application providing data and services

to other applications through the Internet (Kadima,

2003). WSs promote an SOA (Service-Oriented Ar-

chitecture) that is based fundamentally on three

roles: service provider, service requestor and service

broker; and three basic operations: publish, find and

bind, and any particular EAS can play any or all

these roles (Kontogiannis, 2002).

WSs constitute the most important concretization

of the SOA model. They can be deployed inside

(EAI) or outside (B2B) the enterprise. In all cases,

WSs are published with appropriate URLs by WS

providers over the Internet or Intranet. Once pub-

lished, these WSs are accessible by WS consumers

via standards Web such as HTTP, SOAP, WSDL

and UDDI. In addition to this, WSs can be used for

integrating EASs via standards such as BPEL or

WSFL.

WSs are very promising in solving the integra-

ICEIS 2005 - DATABASES AND INFORMATION SYSTEMS INTEGRATION

166

tion problem. Today, some new integration products

based on WSs standards exist and will certainly re-

place in the near future the proprietary solutions that

are the traditional EAI systems (BIJOnline, 2004).

Even if WSs are promising, they do not correctly

address the semantic aspect that is currently some-

what supported by UDDI registries with the help of

some standard taxonomies such as NAICS,

UN/SPSC and ISO 3166 (Dogac, 2004). In addition,

WSs do not provide neither data nor behavior me-

diation (Cordoso, 2002) (Fensel, 2002) (Bussler,

2004). These drawbacks are due mainly to the lack

of service ontology and mediation support in current

WSs. This lack penalizes the efficiency of current

WS integration in the context of EAI.

3.2 Related works

Recently, the importance of WSs has been recog-

nized and widely accepted both by industry and aca-

demic research. This section will review some im-

portant related works about enterprise integration,

mainly those that concerns WS-based integration

and ontology-based integration.

In the context of data integration, there are many

general works which use ontology-based approaches

such as COIN project (Goh, 1994), OBSERVER

project (Mena, 1996), INFOSLEUTH project

(Woelk, 1994), BUSTER project (Stuckenschmidt,

2000) and so on. These works are ontology based

but they are not concerned about the mediation in

the context of SOA.

In addition to the listed related works above,

there are some other works that are addressing the

WS viewpoint such as Active XML from GEMO

project (Abiteboul, 2002) and SODIA from IBHIS

project (Turner, 2004). Active XML extends XML

language by allowing embedding of calls to WSs.

SODIA is an implementation of Federated Database

System in the context of WSs. These works do not

support any mediation services.

In the context of application and process integra-

tion, some important initiatives and works exist

around the semantic web service concept (Dogac,

2004) (McIlraith, 2001) that aim to bridge the cur-

rent WS gap such as OWL-S (W3C, 2004), BPEL

(EBPML, 2004), WSMF (Fensel, 2002], SWSI

(SWSI, 2004), METEOR-S (METEOR-S, 2004).

OWL-S provides an ontology markup language in

order to semantically describe capabilities and pro-

prieties of WSs. BPEL is a standard providing a lan-

guage to define business processes that can be used

in application integration. WSMF and SWSI are

initiatives that provide frameworks in order to sup-

port the concept of semantic web service.

METEOR-S is an effort, which provide semantic

web services through the extension of WS standards

(WSDL, UDDI). But, most of these efforts do not

provide mature concepts for mediation, particularly

in the context of EAI.

4 ODSOI APPROACH

This section will succinctly describe the important

characteristics of our approach called ODSOI that

aims to extend the state-of-the-art in EAI in order to

address the semantic problem.

4.1 Global Architecture

First of all, ODSOI approach is a solution to the in-

formation system integration problem. This means

that our approach addresses the heterogeneity prob-

lem by providing a mediation-based solution using

ontology concept. Indeed, our approach is based on

service-oriented since it uses WSs for integrating

EASs. The architecture integration that we suggest is

called ODSOA (ODSO Architecture). This latter

extends SOA with a semantic layer that aims to en-

hance service mediation in the context of EAI.

The ODSOA concept provides a unified frame-

work in order to integrate EASs. In this framework,

three main types of services (Fundamental-Services)

are defined: Data-Services, Functional-Services and

Business-Services. This different types can respec-

tively address data, application and process integra-

tion.

Figure 1: Global View of ODSOA Architecture.

Data-Services (DS) are services that expose data

sources as a service. Functional-Services (FS) are

services that expose application systems, fundamen-

tally functional systems (software that can perform

enterprise functions such as administrative and tech-

nical ones). Business-Services (BS) are defined as

the combination of the above services in order to

expose business processes. Our service typology can

be seen as an extension of the one proposed by

(Turner, 2004) which distinguishes two concepts:

A UNIFIED FRAMEWORK FOR APPLICATION INTEGRATION - An Ontology-Driven Service-Oriented Approach

167

SaaS (Software-as-a-Service) and DaaS (Data-as-a-

Service).

Figure 1, which is a particular SOA, recapitu-

lates these important types of services. Indeed, there

are of course some other important technical ser-

vices that are mainly Brokering-Services, Descrip-

tion-Services, Mediation-Services, Publication-

Services, Discovery-Services and Execution-

Services. Some of them will be described below.

A cross section of the integration bus (also called

ODESB – Ontology-Driven Enterprise Service Bus)

(figure 2) shows many concentric existing standard

layers such as Transport layer, Exchange layer, Reg-

istry layer and Transversal layer.

Figure 2: Cross Section of the ODESB Bus.

In addition to these standard and existing layers, we

suggest to adopt in a similar way as semantic web

services, another layer, called Semantic-Layer,

which includes two sub-layers that are Domain-

Layer and Integration-Layer. The Domain-Layer

aims to describe and publish the three fundamental

services described above using specific descriptions

such as DSD (Data Service Description) for DSs,

FSD (Functional Service Description) for FSs, and

BSD (Business Service Description) for BSs. All

these descriptions exploit some specific ontologies

and are the specialization of OWL-S (Web Ontology

Language-Services). Concerning the Integration-

Layer, it provides some technical services (men-

tioned above) in order to semantically discovery,

mediate and execute fundamental services that are

described and published by the layer above (domain

layer). In the next section, some important technical

services of the Semantic-Layer will be developed.

4.2 Semantic Layer Services

Semantic-Layer services are the main services that

address the semantic problem.

They are divided into Domain-Layer-Services

and Integration-Layer-Services. The most important

technical service of each layer (which are Descrip-

tion-Services and Mediation-Services) will be de-

scribed below.

4.2.1 Description Services

The principle of ODSOA is based on the use of

some knowledge registries that store some formal

ontologies, which are exploited by Description-

Services in order to define the semantic description

of services. According to Gruber, an ontology is

defined as an explicit and formal specification of a

conceptualization

(Gruber, 1993), and for our pur-

pose, we have defined three major types of ontolo-

gies: information or data-based ontologies, behavior

or functional–based ontologies and process or busi-

ness-based ontologies.

Data-based ontologies are the most basic ones.

They provide semantic description of the data. The-

ses ontologies are required in all cases, no matter if

we leverage functional-based or business-based on-

tologies.

Functional-based ontologies define semantic de-

scription around functions that are provided by the

multiple EASs (and then services) and that can be

remotely invoked. These ontologies are generally

required in order to provide a better reuse of func-

tionalities.

Business-based ontologies define semantic de-

scription around coordinating business processes.

These ontologies are generally required in order to

integrate both business processes and applications.

Furthermore, Description-Services are based on

the context of a service (Service-Context), which is

defined by a set of ontologies, related to the con-

cerned service and used for the annotation process.

This Service-Context is also called local ontology,

which means that there are several ontology levels.

For our purpose, three ontology levels have been

identified: local level, domain level and global level.

In essence, local ontologies concern services,

whereas domain ontologies concern the generaliza-

tion of local ones that belong to the same domain

(Production, Metrology, Packaging, etc.) and they

can serve in aligning the involved local ontologies.

At last, global ontology is considered as generaliza-

tion of domain ontologies, it is the root of the ontol-

ogy hierarchy, and they can serve both in aligning

domain ontologies and also in B2B integration that

constitutes a natural prospect of our present work.

Our ontology architecture is somewhat an exten-

ICEIS 2005 - DATABASES AND INFORMATION SYSTEMS INTEGRATION

168

sion of the hybrid ontology approach mentioned in

the case of information integration in (Wache,

2001). This extension is motivated by the fact that

none of the approaches proposed by (Wache, 2001)

(single ontology, multi-independent-ontologies and

hybrid-ontology approach) are appropriate to fully

capture and correctly structure semantics in our case.

This ontology clustering, which is firstly used in

a general fashion in (Visser, 1999), is a very impor-

tant concept in order to master the ontology evolu-

tion. We call this structuring Ontology Urbanization

and it is related to the concepts of city-planning

(zones, areas and islands) applied to EASs. It takes

an important role in our integration approach and it

will be more developed in future work.

4.2.2 Mediation Services

Mediation-Services are generally invoked by Bro-

kering-Services (technical services that aim to pro-

vide global mechanism to integration process) in

order to perform matching or resolution of semantic

heterogeneity between Fundamental-Services. They

exploit the description provided by the Description-

Services described above.

Since we use an hybrid ontology approach, this

requires the integration (mediation) of ontologies

which are performed by Ontology-Mediation-

Services (OMS) and that are based on ontology

mapping (Kalfoglou, 2003). This latter is the process

whereby two or more ontologies are semantically

related at conceptual level. According to the seman-

tic relations defined in the mappings (e.g. equiva-

lence, subsumption), source ontology instances can

then be transformed (or matched with) into target

ones (Noy, 2004).

In addition to OMS and according to the above

different fundamental types of services, we can

mainly distinguish three other types of mediation

services: Data Mediation Service (DMS), Functional

Mediation Service (FMS), Business Mediation Ser-

vice (BMS). These mediation services aim to medi-

ate respectively between DSs, FSs, BSs and they are

based on OMS that match and mediate between dif-

ferent ontologies. To be performed, Mediation-

Services can exploit two particular utility services

that are Inference-Service and Matching-Service.

These particular services can be respectively

supported by academic or commercial inference

engine and matching tool. For the initial prototype

that is ongoing, we decide to use Racer engine

(Racer, 2004) and OLA (OWL Lite Alignment)

matcher (OLA, 2004) that seems be appropriate to

our approach.

4.3 The initial Prototype

The initial prototype (also called ODSODI - Ontol-

ogy-Driven Service-Oriented Data Integration),

which is ongoing, aims to provide a first implemen-

tation of some functionalities of our architecture. We

have restricted this first prototype to data integra-

tion. Further versions of the prototype will address

application and process integration.

The underlying architecture of this first proto-

type is based around a fusion of WS concepts with

the concepts of data mediation, especially the media-

tors concepts like those defined by (Wiederhold,

1992).

Figure 3: Principles of the initial prototype (ODSODI).

Figure 3 illustrates the principle of the ODSODI

prototype. As shown, this prototype implements a

local-centric approach (aka local-as-view approach)

(Calvanese, 2001). In this approach, the query is

done over the global ontology and the Mediation-

Services access the data sets by a series of mappings:

from global to domain (which are done by global

mediation service), and then from domain to local

(which are done by local mediation services). This

choice is appropriate in the context of EAI in general

and in the context of our microelectronics society in

particular. It is motivated by the fact that users and

EASs are autonomous and have a limited knowledge

about DSs.

5 CONCLUSION

The semantic integration of enterprise application

systems is a hard problem that can concern data,

applications and processes. This problem needs on-

tology-based semantic mediation and, in our opin-

ion, is best resolved in the context of service-

oriented architectures.

A UNIFIED FRAMEWORK FOR APPLICATION INTEGRATION - An Ontology-Driven Service-Oriented Approach

169

This paper has proposed a unified approach for

Enterprise Application Integration that exploits both

ontology mediation and Web services. This ap-

proach called ODSOI (Ontology-Driven Service-

Oriented Integration) aims to extend the current web

services stack technology by a semantic layer offer-

ing some specific services that can mainly define the

service semantics and also perform semantic media-

tion in the context of EAI. Typologies of services

and also of ontologies have been suggested, and the

initial prototype is described. This latter is of course

limited, and its extensions, which may increase the

field of use and the usefulness of our approach, will

no doubt constitute important prospects in the future.

REFERENCES

Abiteboul S., Benjelloum O., Milo T., 2002. Web Services

and Data Integration. INRIA report.

Amjad U., 2004. The Emerging Role of the Web for En-

terprise, Proceedings of the IEEE, 92(9), pp. 1420-

1438.

BIJOnline, 2004. www.bijonline.com.

Bussler C., 2003. The Role of Semantic Web Technology

in EAI. In the Bulletin of the IEEE Computer Society

Technical Committee on Data Engineering.

Bussler C., 2004. Semantic Web Services. ICWE'04.

Munich.

Calvanese D., De Giacomo G., Lenzerini M., 2001. On-

tology of integration and integration of ontologies. In

Proceedings of the 2001 International Description

Logics Workshop (DL2001), pp. 10-19.

Cordoso J., Bussler C., Sheth A., Fensel D., 2002. Seman-

tic Web Services and Processes. Tutorial at Federated

Conferences.

Dogac A., 2004. Semantic Web Services, ICWE'04, Mu-

nich.

EBPML, 2004. www.ebpml.Org.

Erasala N., Yen D. C., Rajkumar T. M., 2003. Enterprise

Application Integration in the electronic commerce

world. Computer Standards & Interfaces 25, pp. 69-

82. Elsevier.

Fensel D., Bussler C., 2002. The Web Service Modeling

Framework WSMF. In Electronic Commerce Re-

search and Applications, 1(2). Elsevier.

Goh C. H., 1997. Representing and Reasoning about Se-

mantic Conflicts in Heterogeneous Information

Sources. Phd Thesis, MIT. USA.

Gruber R. T., 1993. Towards Principles for the Design of

Ontologies Used for Knowledge Sharing. KSL, Stand-

ford University.

Izza S. et al., 2004. Intégration d'applications: Etat de l'art

et Perspectives. JIE 2' 04 - Algérie.

Kadima H., Monfort V., 2003. Les Web Services. Dunod.

Kalfoglou Y., Schorlemmer M., 2003. Ontology Mapping.

The Knowledge Engineering Review, Vol. 18(1), pp. 1-

31. Cambridge University Press.

Kontogiannis K., Smith D., O'Brien L., 2002. On the Role

of Services in EAI. In the Proceedings of the 10th In-

ternational Workshop on Software Technology and

Engineering.

Linthicum D. S., 2004. Next Generation Application Inte-

gration. Addison-Wesley.

Lithicum D. S., 1999. Enterprise Application Integration,

Addison-Wesley.

McIlraith S., Son T., Zeng H., 2001. Semantic Web Ser-

vices, IEEE Intelligent Systems, pp. 46-53.

Mena E., Kashyap V., Sheth A., Illarramendi A., 1996.

OBSERVER.

In Proceedings 1st IFCIS International

Conference on Cooperative Information Systems,

Brussels.

METEOR-S, 2004. http://lsdis.cs.uga.edu/Projects/

METEOR-S.

Noy N. F., 2004. Semantic Integration: A Survey Of On-

tology- Based Approaches. Standford Medical Infor-

matics. Standford.

OLA, 2004. www.iro.umontreal.ca/~owlola/alignment.

html.

OWL-S, 2004. www.daml.org/services/owl-s/1.0/.

Racer, 2004. http://www.racer-systems.info.

Stuckenschmidt H., Wache H., Vogele T., Visser U, 2000.

Enabling technologies for interoperability. Workshop

on the 14th ISCSEP, pp. 35-46. Germany.

SWSI. 2004. Semantic Web Services Initiative,

www.swsi.org.

Turner M., Zhu F., Kotsiopoulos I., Russel M., Bennett K.,

Brereton P., Keane J., Rigby M., 2004. Using Web

Service Technologies to Create an Information Broker.

26th International Conference on Software Engineer-

ing (ICSE'04). IEEE Computer Society. pp 552-561.

Visser P., Tamma V., 1999. An experience with ontology

clustering for information integration. In Proceedings

of the IJCAI-99 Workshop on Intelligent Information

Integration, Sweden.

W3C, 2004. www.w3.org.

Wache H. et al.., 2001. Ontology-Based Integration of

Information. In Proceedings of IJCAI-01 Workshop:

Ontologies and Information Sharing (2001) pp.108-

117.

Wiederhold G., 1992. Mediators in the Architecture of

Future Information Systems, IEEE Computer Society,

25(3), pp. 38-49.

Woelk D., Tomlinson C., 1994. The InfoSleuth project. In

Second World Wide Web Conference ’94: Mosaic and

the Web.

ICEIS 2005 - DATABASES AND INFORMATION SYSTEMS INTEGRATION

170