An Evaluation of Dynamic Web Service Composition

Approaches

Ravi Khadka

and Brahmananda Sapkota

Faculty of Electrical Engineering, Mathematics and Computer Science

University of Twente, Enschede, The Netherlands

Information System Group, University of Twente, Enschede, The Netherlands

Abstract. Web Services composition has received much interest from both the

academic researchers and industry to support cross-enterprise application inte-

gration. Promising research projects and their prototypes are being developed. At

the same time the web service environment is getting more dynamic as numerous

web services are being published by the service providers in the Internet. To meet

the users requirements regarding on-demand delivery of customized services, dy-

namic web service composition approaches have emerged. But still many com-

positional issues have to be overcome like dynamic discovery of services, com-

positional correctness, transactional supports etc. In this paper we discuss some

of these issues and then investigate some of the representative dynamic web ser-

vice composition approaches. We evaluate those approaches on the basis of the

issues and present how the future research can beneﬁt by addressing those issues

of dynamic web service composition.

1 Introduction

In recent years Web services have received much interest as an emerging technology

for Business-to-Business Integration (B2Bi) of heterogeneous applications over the In-

ternet [1]. Many enterprises are transforming their business model in Internet with web

services because web services technology enables integration of heterogeneous appli-

cations regardless of implementation platforms. The full potential of web services as

a means for B2Bi solutions will only be realized when existing services and business

processes are able to integrate into a value-added composite service. A composite ser-

vice [2] is a service developed by aggregating the existing services to realize a new

value-added functionality. The aggregating process is called (web) service composition.

There are two approaches of web service composition: static and dynamic composition.

In static compositions, the aggregation of the services is done at design time. The

composition of all the necessary components is determined, bound together and then

deployed. This type of composition is more suitable if the business partners involved in

the process are ﬁxed and their offered functionalities or the requirements are unlikely to

change in short term. Static web service composition is not ﬂexible in the sense that it is

not adaptive to the runtime changes when it is in execution and is too restrictive to un-

avoidable changes in the service requirements [3]. Dynamic web service composition

The work is done in the context of DySCoTec Project.

Khadka R. and Sapkota B. (2010).

An Evaluation of Dynamic Web Service Composition Approaches.

In Proceedings of the 4th International Workshop on Architectures, Concepts and Technologies for Service Oriented Computing, pages 29-41

DOI: 10.5220/0003045100290041

 SciTePress

aims at overcoming the problems which are apparent in static web service composi-

tion. A dynamic service composition provides ﬂexibility for modifying, extending and

adapting changes at runtime [4].

The web service environment is highly dynamic in nature. The number of web ser-

vice providers is constantly increasing leading to the availability of new services in daily

basis [5]. In such a dynamic environment, realizing dynamic web service composition

is not so easy because of the following reasons:

– composition process should discover the appropriate components in a composition

that is able to transparently adapt the environmental changes.

– composition process should adapt to the customer requirements with minimal user

intervention.

– composition process should have transactional support.

– composition process should guarantee composition correctness.

– composition process should also consider Quality of Service (QoS) properties.

With some of above stated issues of dynamic web service composition, we aim at

evaluating available approaches of dynamic web service composition with respect to the

issues like transaction support, compositional correctness, and QoS support etc. Based

on the evaluation we believe that understanding those issues and their importance will

pave way for future research directions in dynamic web service composition. A signif-

icant number of evaluation papers have been published in literatures for web service

composition approaches. The survey of [5] extensively evaluates the various available

web service composition approaches based on classiﬁcations and compositional issues.

In [1], the paper focuses more on web service composition languages like WS-BPEL

with WSDL, OWL-S with Golog/Planning. In [6], the authors evaluate the web service

composition frameworks based on the level of automation of the service composition

process. [7] discusses Web Service Composition and Execution (WSCE). The frame-

work are categorized as interleaved, Monolithic, Staged, and Template-based service

composition and execution. We beleive there is no evaluation paper speciﬁcally on dy-

namic service composition. So, the paper summarizes the currently available dynamic

web service composition approaches, evaluate the approach according to the framework

and then gives an outlook to essential future research works.

This paper is structured as follows: In Section 2, we deﬁne a framework used in

the evaluation of the different dynamic service composition approaches. In Section 3,

we present some of the most relevant dynamic service composition approaches on the

basis of a evaluation framework. In Section 4 we evaluate the approaches against the

evaluation framework. Finally, we conclude the paper in Section 5.

2 Evaluation Framework

We propose an evaluation framework for the dynamic service composition approaches

that are discussed in Section 3. The evaluation framework includes some of the key

composition issues and requirements that are identiﬁed based on the analysis of [5]

and [8]. We do not guarantee the completeness of all the necessary requirements and

issues in this evaluation framework. However, we have included some of the important

ones in the evaluation framework.

2.1 Transaction Support

Traditional transaction is based on Atomicity, Consistency, Isolation, and Durability

(ACID) properties and implicitly assumes closely coupled environment with short-

duration activities. But web services often involve loosely coupled systems with long

run transactional activities. Using ACID-based transactions in such long running trans-

actional activities could result in undesirable effects like locking of resources for longer

time. So, in web service composition it is necessary to provide a ﬂexible transactional

supports for the long-running activities in order to guarantee consistency and reliable

execution of composite web services that can support coordination, recovery and com-

pensation [9, 10]. WS-Transaction standard, WS-TXM standards are examples of trans-

actional feature support in web service environment. In this paper, we identify whether

the transaction support is available in a composition approach being evaluated.

2.2 Compositional Correctness

An important aspect of web service composition is to maintain the correctness of be-

havior of the composite service. We consider two ways of exploiting compositional

correctness of a service composition to preserve the behavioral properties like dead-

lock free, liveliness, safety etc. The ﬁrst way is to design the composition algorithm

in such a way that it preserves the behavioral properties. The other way is to formal-

ize the composite service and then verify the behavioral properties formally i.e. using

some formalization like pi-calculus, petri-nets e.t.c and verify the properties. We be-

lieve the later mechanism can be more useful in those cases where the business goal is

already achieved but the workﬂow still might have deadlocks in the path that are yet to

be traversed. Using the later mechanism, we can reason about the preservation of the

behavioral properties in all possible paths of the workﬂow of the composite logic. So,

formalizing the compositional logic enables us to verify the behavior of the composite

service completely. Recently, a variety of concrete proposals from the formal methods

community have emerged in order to verify the correctness of the web service compo-

sition which is based on state action models or process models [11]. In this paper, we

identify whether the approach supports the veriﬁcation of compositional correctness. In

case if it supports, we also identify by which mechanism does it support.

2.3 QoS Support

QoS is used for expressing non-functional properties like performance, reusability,

maintainability, security, reliability and availability [12]. In case of loosely coupled

environment of web services, the QoS properties can vary greatly because web ser-

vices can be provided by various third parties and invoked dynamically over the inter-

net [13]. Therefore service compositions must be QoS-aware in terms of understanding

and respecting one another’s policies, performance levels, security requirements [14].

To support QoS in dynamic service composition, a web service description language

that supports QoS description, QoS estimation approach of the composite web service

and QoS monitoring is required [15]. In this paper, we identify whether the QoS support

is available or if there is partial support in a composition approach being evaluated.

2.4 Automated Composition

We deﬁne automated composition as a process of generating an executable process that

communicates and binds with a set of existing web services for web service composi-

tion and publish itself as a web service with higher level of functionalities. One of the

main aims of web service composition approaches is to achieve automated service com-

position because it enables faster application development and reuse [8]. In absence of

automated web service composition, the end user/agent will have to specify the business

goal and manually select the available services after the discovery of services match-

ing the requirements and then compose them. In this paper, we identify whether the

automated composition feature is available in a composition approach being evaluated.

2.5 Composition Logic Formulation

We deﬁne composition logic as the way how the interactions among the participating

services take place in the composition process. Under this requirement we investigate

how the control ﬂow and the data ﬂow of the composition mechanism are represented.

The classiﬁcation will be either process-driven or rule-driven or hybrid. In process-

driven mechanism, the composition uses process deﬁnitions where business logic is

expressed as a process model to specify possible interactions among the participating

web services [16, 17]. In rule-driven approach, business rules are used as composition

logic. A business rule

is deﬁned as a statement that deﬁnes or constrains some aspect

of the business. The main features of rule-driven composition approach are that it is

purely declarative, highly adaptive and integrated in a truly service oriented approach

to business rule management [18]. In the hybrid approach [19], the composition logic

is broken down into core part (business processes) and independently evolving, well

modularized business rules. In this paper we investigate if the composition approach

being evaluated is process-driven, rule-driven or hybrid approach.

3 Dynamic Service Composition Approaches

This section presents a brief overview of some of the prominent dynamic service com-

position approaches namely: eFlow [20, 21], METEOR-S [22], WebTransact [23, 24],

DynamiCoS [25, 26] and SeGSeC [27]. We choose these approaches on the basis of

high references in literatures for dynamic service composition. These approaches are

then evaluated based on the framework presented in Section 2. Through this evaluation,

we identify which of the features are supported by these approaches.

3.1 eFlow

eFlow [20, 21] is a system that supports the speciﬁcation, enactment, monitoring and

management of composite e-services where the composite e-services are modeled as

business processes. E-services and web services share commonalities [28] so we inter-

changeably use those terms in this paper. eFlow runs on the top of E-services Platforms

www.businessrulesgroup.org

(ESPs), such as HP e-speak or Sun Jini which allow the development, deployment and

secure delivery of e-services to business and customers.The eFlow model and the over-

all system provide a ﬂexible, conﬁgurable and an open approach to the service composi-

tion [29]. The adaptive and dynamic eFlow process model allows processes to adapt the

changes in the running environment, perform necessary service execution according to

the need of the customer. E-service composition is modeled by a graph that deﬁnes the

order of execution among the nodes in the process. The graph is created manually but it

can be updated dynamically. The graph may include services (represent the invocation

of WS), decisions (specify the alternatives and rules controlling the execution ﬂow) and

event nodes (enable service processes to send and receive several types of events). Arcs

in the graph denote the execution dependency among the nodes.

eFlow includes the notion of transactional region and supports ACID service-level

transaction. A transactional region enforces to maintain service level of atomicity. Ac-

cording to the deﬁnition of transaction support in Section 2, only preserving the ACID

property of transaction is not sufﬁcient to maintain transaction support in web services

environment. Hence, transactional feature is not supported in eFLow. eFlow supports

the modiﬁcation of the process for dynamic service composition, but it can not guar-

antee the correctness of the output. eFlow does not provide QoS modeling capabilities.

Service processes in eFlow are able to transparently adapt to environmental changes and

dynamically conﬁgure at runtime. However, the limitation of the eFlow is that it needs

too much manual participation to concretize the generic service nodes (a node in eFlow

that supports dynamic process deﬁnition for composite services) at execution phase and

it does not support the automatic generation of composition for the generic nodes [30].

So, there is no support for the automatic composition. In eFlow, the composite ser-

vices are modeled as processes that are enacted by a service process engine [29].So, the

composition logic is process-driven and a composite service is described as a process

schema that composes other basic or composite services.

3.2 METEOR-S

METEOR for Semantic web services (METEOR-S) is a dynamic web service compo-

sition framework developed at the University of Georgia which incorporates workﬂow

management for semantic web services. METEOR-S is the follow-up research of Man-

aging End-To-End OpeRations (METEOR). METEOR-S uses semantics for the com-

plete life-cycle of the semantic web services. Its annotation framework is an approach

to add semantics to current industry standards such as WSDL. METEOR-S uses tech-

niques from the semantic Web, semantic Web services and the METEOR project to

deal with the problems of semantic Web service description, discovery and composi-

tion. The Figure 1 depicts the architecture of METEOR-S which has two parts: front

end and back end. The front end of METEOR-S is related with annotation and pub-

lication of service speciﬁcations. The abstract process designer which is related with

dynamic composition is a component present at the back end of the METEOR-S. The

composition process is initiated by creating the ﬂow of process using the control ﬂow

constructs provided by WS-BPEL. The requirements of each service in the process is

represented by specifying the service template, which allow to either specify semantic

description of the web services or a binding to a known web services. Then, the process



Back‐End

Front‐End

Service

Template(s)

Discovery

Engine 5

Execution

Engine 7

Constraint

Analyzer 6

Abstract

Process

Service

Template(s)

Abstract

Process

Desi

Advertisement

Annotated Source

Code (Java)

Enhanced

UDDI

Semantic

Web

Services

Designer

Publishing Interface

Annotated

WSDL1.1

OWL-S

WSDL-S

Semantic

Description

Generator

Query

RankedResponse

Fig. 1. METEOR-S architecture [22].

constraints for optimization is speciﬁed. The details of dynamic service composition in

METEOR-S is available on [31].

In METEOR-S architecture, the The constraint analyzer deals with correctness of

the process based on QoS constraints. The support for state machine based veriﬁcation

of WS-BPEL process also contributes on the existence of compositional correctness.

METEOR-S uses an extensible ontology to represent the generic QoS metrics and do-

main speciﬁc QoS metrics. The cost estimation module of constraint analyzer represents

the QoS support. There composition process is not fully automated. The METEOR-S

uses process-driven approach for composition. The coordination of the composite ser-

vice is based on a BPEL-like centralized process engine.

3.3 WebTransact

WebTransact [23] provides necessary infrastructure for building reliable, maintainable,

and scalable web service composition. It is composed of a multilayered architecture,

an XML-based language named Web Service Transactional Language and a Transac-

tion model. The multi-layered architecture containing a Service Composition Layer, a

Service Aggregation Layer, an Integration layer, and a Description Layer are depicted

in Figure 2. Based on [24], we provide a brief explanation of web service composition

in WebTransact. Application programs interact with the composite mediator services

written by composition developers. Such compositions are deﬁned through transaction

interaction patterns of mediator services. Mediator services provide a homogenized in-

terface of semantically equivalent remote services. Mediator services also integrate web

services providing the necessary mapping information to convert messages from the

particular format of the web service to the mediator format.

In WebTransact, an XML-based language named Web Service Transaction Lan-

guage (WSTL), is used for describing the transaction support. The transaction model

Application Programs

WEBTRANSACT

Composite Mediator

Service

Composition Layer

Mediator service

Mediator Service Layer

Remote

Service

Remote

Service

Remote

Service

Remote Service

Layer

WSDL WSDL

Web Service

WSDL WSDL

Web Service

WSDL WSDL

Web Service

Web Service Provider at site 1 Web Service Provider at site 2

Fig. 2. WebTransact Architecture [24].

of WebTransact provides an adequate level of correctness guarantees when executing

the web services composition built with WSTL. Hence, there is transaction support

in WebTransact. The transactional model of the WebTransact exploits the dissimilar

transaction behavior of web services and guarantees the correct and safe execution of

mediator compositions. The notion of correctness of composition execution is based

on both the user needs (composition speciﬁcation) and the 2L-guaranteed-termination

criterion (a weaker notion of atomicity that considers the needs of web service environ-

ments). Hence, WebTransact has compositional correctness feature. WebTransact does

not provide QoS modeling. The WebTransact approach does not support the dynamic

discovery and integration of web services. The Web Services are statically integrated

in WebTransact by a developer who plays the role of Web service integrator [24]. So

automatic composition is not supported. In WebTransact, web service composition is

modeled as composite task by WSTL where a composite task is the combination of

atomic task or another composite task. Tasks are identiﬁed by its signature, execution

dependencies, links and rules. Here rules specify the conditions under which certain

event will happen and can be associated with dependencies or to data links and ﬁnally

evaluating either true or false based on execution [23]. Hence, WebTransact follows the

rule-based logic formulation.

3.4 DynamiCoS

In [26, 25], an approach for automated and dynamic service composition named Dy-

namic Composition of Services (DynamicCoS) is proposed primarily to alleviate the

complexity of service composition from the end-users. Upon specifying the service

speciﬁcations by the users as per their requirements, automatic discovery, matching and

the composition of set of services that together fulﬁll the user’s requirement is done by

DynamiCoS. The results are then presented to the user who can selects the best suited

composition. DynamiCoS represents services in language neutral formalism. A service

is represented as a seven-tuple S =<ID,I,O,P,E,G,NF>, where ID is the service identi-

ﬁer, I is the set of service inputs, O is the set of service outputs, P is the set of service

preconditions, E is the set of service effects, G is the set of goals the service realises,

NF is the set of service non-functional properties and constraint values. DynamiCoS

approach consists of following modules: service creation, service publication, service

request, service discovery and service composition. Figure 3 depicts the service com-

position framework of DynamiCoS. To perform composition, it ﬁrst organizes the set

of services discovered in service discovery phase in a Casual Link Matrix (CLM). The

CLM stores all possible semantic connections, or causal links, between the discovered

services input and output concepts. Then the graph-based algorithm approach [26] ﬁnds

a composition of services that fulﬁl the service request.

Fig. 3. DynamiCoS Architecture [25].

The main aim of DynamiCoS is to develop dynamic service composition mecha-

nism to support the end-users requirements. Considerable interest is not given in trans-

action support in DynamiCoS. The service composition module of DynamiCoS builds

compositions from service requests and the compositions are correct-by-construction.

The algorithm for composition checks for deadlock and also verify if the composition

is in accordance with the goals. In DynamiCoS some simple QoS characteristics can

be represented and considered in service compositions. Among four ontologies, Non-

Functional.owl in DynamiCoS deﬁnes non-functional properties for services and hence

partially supports QoS modeling. DynamiCoS enbles service creation and publication

by service developers at design-time, and automatic service composition by end-users

at runtime.The composition is based on semantic graph based composition algorithm,

so the composition logic formulation is process-driven.

3.5 SeGSeC

In [27, 32], the authors present a semantic-based dynamic service composition archi-

tecture named Semantic Graph-Based Service Composition (SeGSeC) in which the

user requests the service in a natural language and the request is then converted into

machine-understandable format, i.e. a semantic graph. Based on this semantic graph,

SeGSeC composes services. In order to achieve semantic-based dynamic service com-

position, modeling of the service components and the service composition mechanism

itself must support semantics. To satisfy this requirement, SeGSeC is supported by

Component Service Model with Semantics (CoSMoS) and Component Runtime En-

vironment (CoRE). The semantic support in the component modeling is achieved by

CoSMoS which integrates the semantic and functional information into semantic graph

representation. CoRE functions as middleware and provides functionality to discover

and convert different component implementations into a single semantic graph repre-

sentation. Figure 4 depicts the architecture of SeGSeC.

CoRE

SeGSeC

CoSMoS

Various other technologies

Fig. 4. SeGSeC Architecture [27].

Upon receiving the service request from a user in a natural language, SeGSeC gen-

erates the execution path or workﬂow. The execution path represents the order plan

specifying which operations of which component should be accessed in what order.

Additionally, SeGSeC also performs the semantic matching to conﬁrm the semantics of

the execution plan matches the semantic of the user request.

SeGSeC does not provide transactional support and does not guarantee the com-

positional correctness. Given the user requirements in the natural language the overall

approach generates the workﬂow such that it satisﬁes the semantics of the requested

services. Starting from the service request from the user to the ﬁnal composition the

process is automated. SeGSeC does not provide QoS modeling capabilities. Upon re-

ceiving the user request in the form of semantic graph from CoSMoS, the Service-

Composer component of SeGSeC discovers the components and creates the workﬂow.

In later stage of composition the semantic retrieval rules are applied onto the seman-

tic graph such that the graph models the semantics of the workﬂow. Hence, SeGSeC

has hybrid compositional logic formulation because the workﬂow is process-driven and

later the rules are imposed in composition.

4 Summary and Evaluation

This section presents the overall summary of the comparison and evaluation of the

dynamic service composition approaches based on the evaluation framework presented

in Section 2. Table 1 presents the summary of the approaches evaluated according to

the evaluation framework.

4.1 Transaction Support

Due to the inherent autonomy and dissimilar capabilities of web services, maintaining

the transaction support is challenging but still the web service composition requires

Table 1. Summary of the dynamic web service composition approaches.

Approaches Transaction

Support

Compositional

correctness

QoS Support Automated

composition

Composition

logic

formulation

eFlow No No No No Process-driven

METEOR-S No yes Yes No Process-driven

WebTransact Yes Yes No No Rule-driven

DynamiCoS No Partial Partial Yes Process-driven

SeGSeC No No No Yes Hybrid

an advanced transactional management solution for reliable, consistent and recover-

able composition. In this aspect WebTransact approach appears to be better than others

since it is supported by a transactional model. The eFlow approach includes the notion

of transactional regions and ACID level transactional support which is insufﬁcient in

the loosely-coupled web service environment. The remaining three approaches do not

ensure the transaction support.

4.2 Compositional Correctness

The compositional correctness ensures the veriﬁcation of behavior of the composite

services. In order to preserve compositional correctness various formal methods tech-

niques can be integrated with the framework. METEOR-S has a support for state ma-

chine based veriﬁcation of WS-BPEL process. However, WebTransact provides another

approach to reason about the compositional correctness. It uses compositional speciﬁ-

cation provided by the user and 2L-guranteed-termination criterion to verify the com-

positional correctness [24]. With this feature WebTransact and METEOR-S appear to

be the promising one among the others.

4.3 QoS Support

From the evaluation it shows that most of the approaches do not include the QoS prop-

erties of the web service composition. Only METEOR-S provides the framework for

modeling QoS. There is partial support of QoS modeling in DynamiCoS which is done

by by extending the OWL-S. Even the industry based approach eFlow neglects such

an important aspect of the composition. In [12], the author mentions two ways to in-

clude QoS property namely developing a new language based on semantics like XL and

OWL-S and to extend web service description languages like WSDL to support more

QoS description. The later one seems to be promising to those approaches where QoS

modeling is not included because all of them are based on WSDL.

4.4 Automated Composition

Automated composition enables faster application development without the interven-

tion of the users. From the evaluation and comparison presented earlier, we conclude

that use of semantic descriptions or ontology can help in automating the composition

process as in DynamiCoS, METEOR-S, and SeGSeC. Including the semantic approach

and automating the composition in eFlow can be helpful to the industry.

4.5 Compositional Logic Formulation

Process-driven approach is more suitable for those collaborative businesses where there

are few changes in the requirements of business process workﬂow. It appears to be

more effective in terms of managing the workﬂow because seldom changes are re-

quired. But in those collaborative businesses where there are constant changes in the

requirements of the business then rule-based systems are advantageous. Hybrid compo-

sition approach has its own beneﬁts as it reduces the complexity and avoids monolithic

composition [19]. Each part of composition logic in hybrid approach is expressed in the

more suitable way either in a business rules or as a process activity providing higher

degree of ﬂexibility.

With this evaluation WebTransact and METEOR-S appear to be the most promis-

ing approaches. The WebTransact framework is a multidisciplinary work that is related

with many other areas such as e-service composition, transactional process coordina-

tion, workﬂow management system and distributed computing systems [24]. However,

WebTransact lacks semantic descriptions for automation of the composition process and

QoS support. The METEOR-S lacks transactional support and is semi-automated but

supports QoS modeling. eFlow is the industrial product and another promising frame-

work but it signiﬁcantly lacks the transactional support, semantic descriptions for au-

tomation and QoS support.

5 Conclusions

Because of the growing trend of transforming existing business models to the Internet

with web services and the possibility of creating new web services dynamically, vari-

ous developments are on-going in the dynamic web service composition. The research

and development ranges industry-based products like eFlow to academic researches

like WebTransact, DynamiCoS to name a few. In all these developments, many dif-

ferent standards and mechanisms have been proposed but there is still a lack of an

overall agreement. In this paper, we presented different dynamic service composition

frameworks, ranging from industry based product to the academic research products

and compared them in terms of some important requirements and features.

The evaluation shows that transactional support is still missing in most of the ap-

proaches which, is one of the most important requirements. So, researches leading to

include transactional supports in those approaches and in currently ongoing research

approaches will be an important step. The veriﬁcation of the compositional correctness

is also missing in most of the approaches. It is an important aspect however, on the

other hand integrating formal techniques in such frameworks is not so easy. In order

to verify the correctness, compositional speciﬁcations have to be modeled into mathe-

matical formalisms like pi-calculus, process algebra such that the safety and liveliness

properties can be explored to detect deadlocks and data consistency in the composition

process. The easier way is to include compositional correctness features in the compo-

sition algorithm of the framework. QoS support is also the important requirement of

the web service composition. In most of the approaches QoS support is not available so

research on including QoS modeling is also an open research direction. The researches

on the features like especially automated composition of the web service composition

have gained some maturity by using semantics. The use of semantics and ontology in

composition has resulted in the automated composition but is still limited in academic

researches like DyanmiCoS, METEOR-S, and SeGSeC approaches. The use of seman-

tic descriptions in order to automate composition in industry approaches like eFlow is

still an awaiting result in web service composition ﬁeld.

The dynamic web service composition problem is likely to be around with some

open issues like supporting transactional support, veriﬁcation of compositional cor-

rectness etc. In future research, addressing such issues will surely be beneﬁcial and

is desirable.

References

1. Srivastava, B., Koehler, J.: Web Service Composition - Current Solutions and Open Prob-

lems. In: ICAPS 2003 Workshop on Planning for Web Services. (2003) 28–35

2. Alonso, G.: Web services: concepts, architectures and applications. Springer Verlag (2004)

3. Shen, L., Li, F., Ren, S., Mu, Y.: Dynamic composition of web service based on coordination

model. Advances in Web and Network Technologies, and Information Management (2007)

317–327

4. Tosic, V., Mennie, D., Pagurek, B.: Dynamic Service Composition and Its Applicability to

E-Business Software Systems–The ICARIS Experience. Advances in Business Solutions

(2002) 93–104

5. Dustdar, S., Schreiner, W.: A survey on web services composition. International Journal of

Web and Grid Services 1 (2005) 1–30

6. Rao, J., Su, X.: A survey of automated web service composition methods. Semantic Web

Services and Web Process Composition (2005) 43–54

7. Agarwal, V., Chaﬂe, G., Mittal, S., Srivastava, B.: Understanding approaches for web service

composition and execution. In: Proceedings of the 1st Bangalore annual Compute confer-

ence, ACM (2008) 1

8. Milanovic, N., Malek, M.: Current solutions for web service composition. IEEE Internet

Computing 8 (2004) 51–59

9. Papazoglou, M.: Web services: principles and technology. Addison-Wesley (2008)

10. Papazoglou, M.: Web services and business transactions. World Wide Web 6 (2003) 49–91

11. ter Beek, M., Bucchiarone, A., Gnesi, S.: A survey on service composition approaches:

From industrial standards to formal methods. Technical report, Technical Report 2006-TR-

15 (2006)

12. Chen, Y., Li, Z., Jin, Q., Wang, C.: Study on qos driven web services composition. (Frontiers

of WWW Research and Development-APWeb 2006) 702–707

13. Ran, S.: A model for web services discovery with QoS. ACM SIGecom Exchanges 4 (2003)

14. Papazoglou, M., Traverso, P., Dustdar, S., Leymann, F.: Service-oriented computing: State

of the art and research challenges. Computer-IEEE computer society- 40 (2007) 38

15. Sun, H., Wang, X., Zhou, B., Zou, P.: Research and implementation of dynamic web services

composition. Advanced Parallel Processing Technologies (2003) 457–466

16. Benatallah, B., Sheng, Q., Dumas, M.: The self-serv environment for web services compo-

sition. IEEE Internet Computing 7 (2003) 40–48

17. Zeng, L., Benatallah, B., Dumas, M., Kalagnanam, J., Sheng, Q.: Quality driven web services

composition. In: Proceedings of the 12th international conference on World Wide Web, ACM

(2003) 421

18. Weigand, H., van den Heuvel, W.J., Hiel, M.: Rule-based service composition and service-

oriented business rule management. In Vanthienen, J., Hoppenbrouwers, S., eds.: Proceed-

ings of the International Workshop on Regulations Modeling and Deployment (ReMoD’08),

ACM (2008) 1–12

19. Charﬁ, A., Mezini, M.: Hybrid web service composition: business processes meet business

rules. In: Proceedings of the 2nd international conference on Service oriented computing,

ACM (2004) 30–38

20. Casati, F., Ilnicki, S., Jin, L., Krishnamoorthy, V., Shan, M.: eFlow: a platform for developing

and managing composite e-services. Technical Report HPL-2000-36, HPL (2000)

21. Casati, F., Ilnicki, S., Jin, L., Krishnamoorthy, V., Shan, M.: Adaptive and dynamic service

composition in eFlow. In: Advanced Information Systems Engineering, Springer (2000)

13–31

22. Aggarwal, R., Verma, K., Miller, J., Milnor, J.: Dynamic Web Service Composition in

METEOR-S. Technical report, LSDIS Lab, Univeristy of Georgia, Athens (2004)

23. Pires, P., Benevides, M., Mattoso, M.: Building reliable web services compositions. Web,

Web-Services, and Database Systems (2002) 59–72

24. Pires, P.F.: WEBTRANSACT: A Framework for Specifying and coordinating reliable web

services compositions. Technical Report ES-578/02, Federal University of Rio De Janerio

(2002)

25. L

ecu

e, F., Silva, E., Ferreira Pires, L.: A framework for dynamic web services composition.

Emerging Web Services Technology II (2007) 59–75

26. Silva, E., Ferreira Pires, L., van Sinderen, M.J.: Supporting Dynamic Service Composition

at Runtime based on End-user Requirements. In: Workshop at the International Conference

on Service Oriented Computing (ICSOC) 2009, Stockhome, Sweden. (2009) 22–27

27. Fujii, K., Suda, T.: Semantics-based dynamic Web service composition. International Journal

of Cooperative Information Systems 15 (2006) 293–324

28. Tiwana, A., Ramesh, B.: E-services: Problems, opportunities, and digital platforms. In:

Proceedings of the 34th Annual Hawaii International Conference on System Sciences, 2001.

(2001) 8

29. Casati, F., Ilnicki, S., Jin, L.J., Krishnamoorthy, V., Shan, M.C.: An Open, Flexible, and Con-

ﬁgurable System for E-Service Composition. Technical Report HPL-2000-41, HPL (2000)

30. Li, G., Hai, H., Hu, Z.: A Flexible Framework for Semi-automatic Web Services Compo-

sition. In: IEEE Asia-Paciﬁc Services Computing Conference, 2008. APSCC’08. (2008)

1258–1262

31. Sivashanmugam, K., Miller, J., Sheth, A., Verma, K.: Framework for semantic web process

composition. International Journal of Electronic Commerce 9 (2005) 71–106

32. Fujii, K., Suda, T.: Dynamic service composition using semantic information. In: Proceed-

ings of the 2nd international conference on Service oriented computing, ACM (2004) 39–48