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A Comparison Between Traditional and Context-Aware Semantic Web services
Semantic Web Services or Context aware Web Services is very rapidly growing technology in present time. Semantic web services are the source of detecting context about the service requester and the type of service that is being requested. We have performed some comparative study between traditional and semantic web services to better understand and reveal the fact about the high efficiency that can be achieved if the technological development continues to advance with this speed. This review paper has tried to show some of the basic differences cum advancements that reside in Semantic Web Services than traditional web services.
Keywords-component; Web, Web Services, Semantic Web, Semantic Webe Services, Intelligent web service
Web services [XI] are the most important part of the Service Oriented Architectures (SOA's) [XII]. These provide us with the ability to develop and use some software as a service, and incorporate and real sense of re-usability. As it allows applications to be converted into web applications and they can be used over the internet, everyone who requires the same sort of functionality. It is mostly like a concept of software as a service. Involvement of SOA's and web services in the field of software has once again revolutionized the paradigm of software computing, as it has satisfied the needs of not only question of re-usability but also the problem of interoperability has been satisfied. These are the two main reasons that the Web Services and SOA's have taken the internet and the facility to the next level and due to this all the advancements made are so rapid and robust.
But software revolution is continuous and still in way of making these services better and more efficient. Keeping this in mind the concept of Semantic Web Services has been originated and in recent times, efforts are being made in this direction. The purpose is to make web services more intelligent that they their selves will be able to know what they are doing and will return the results in more efficient and reliable way. The concept of semantic web services has come long after the idea of making web intelligent. As a result an infrastructure was introduced, in which all the autonomous software entities and applications will be intelligent enough to do their tasks efficiently and will leave less work for the other system who will be requesting the web service.
This review paper we discussed about the Web Services and their new and advanced form i.e. Semantic Web Services (SWS). Section II will be about literature survey, Section III compares the traditional web services and semantic web services and Section IV tells about the conclusion and suggestions.
A. Web Services
Web services are concept of providing software as services. Previously the web was the collection of text and images but now the time has evolved towards service oriented computing and web services have played an important and vital role in taking this concept to existence.
Web services are normally application programming interfaces (API) or web APIs that can be accessed over a network, and executed on a remote system hosting the requested services [XI].
B. Semantic Web Services
Like traditional web services, semantic web services have the same concept. But the difference comes in the intelligence and the involvement of the semantics in the Web Services
Semantic Web Services, like conventional web services, are the server side part of the client server architecture, but additionally semantic web services are the component of the semantic web as well. They introduce intelligence in the web services. Semantic Web Service processes or displays data/information in more systematic and user readable format. That is more intelligently processed and produced.
The main problem answered by semantic web services is, they semantically try to solve a problem not syntactically. Semantic web services are built more or less like universal standards for the exchange of semantic data, which makes it easy for programmers to combine data from different sources and services without losing their meaning. Web services can be activated "behind the scenes" when a web browser makes a request to a web server, which then uses various web services to construct a more sophisticated reply than it would have been able to do on its own. Semantic web services can also be used by automatic programs that run without any connection to a web browser [I].
[II] shows how a Semantic web service works in the traditional web workflow architecture. Semantic Web Services (SWS) introduces a complete component of intelligence in the present web architecture.
As it is quite pertinent, the working of web services has different parts in it. Firstly there is a client application module that is requiring a particular application/service to fulfill its business requirements, for this the client application contacts with the Web Services directory for finding a particular service that is published for this particular task, for this purpose the mechanism that is being used is soap messaging. SOAP is basically xml bound with http protocol. Then there is Web Service directory which contains paths and information about all the registered web services and acknowledges user according to nature of the request.
The figure 2 shows typical high level semantic web service architecture. Figure clearly denotes that there is a distinct aspect of intelligence in concepts of ontology and semantic web.
If viewed critically, we will see that there are mostly the same components as are in the traditional web services, but the basic and the most distinct component in the architecture of the semantic web services is the increment of the intelligence in the architecture. This basic thing, that differentiate traditional web services with SWS. This increment introduces lots of other changes in the composition, discovery and invocation mechanisms. For this many languages, artifacts and frameworks have been introduced in this regard, and still many advancements are on their way.
II. Literature Survey
Context can be used for further processing, and systems that do so are said to be "context-aware" [III]. With the passage of time the technology is moving towards better and intelligent Service Oriented Architecture (SOA), and Web Services are the core part of the SOA world. Many efforts are being made and ideas are being originated to bring this useful idea into existence but still a lot of work has to be done.
Semantic Web Services (SWS) are technology that enables dynamic-ism, execution time discovery, composition and invocation of services [X]. The emerging concept of Semantic Web Services aims at more sophisticated Web Service technologies: on basis of semantic description frameworks, intelligent mechanisms are envisioned for discovery, composition, and contracting of Web Services [IV].
Many architectures and techniques have been proposed in order to create stable form of SWS. One of the basic description and architecture of SWS has been discussed in [V]; the paper describes a brief introduction of SWS in a very simple and easy format and discusses its various layers that can be used in creating a stable architecture. In [VI], a folksonomy based web service modeling approach has been mentioned in which the emphasis on the input and output that can be generated by the web services according to the their model, web service operations are described by the kinds of messages they require as input and the kinds of messages they produce as output [VI].
While there are intelligent web services there should also be some proper way of discovering the web services in an autonomous way. So, for this purpose, work has been done in the direction of web service discovery mechanisms as well in which a completely autonomous system that is capable of searching the relevant service and perform their tasks. On the other hand, web services by themselves are capable of exposing their functionality to the outer world as well as the organization itself. So the future of the web services and specifically context-aware web services is going to be a fascinating one, and indeed it will be equally beneficial for the users and other systems as well.
Besides this there are many other challenges regarding SWS orientation, design, development, composition, and discovery etc. The realization of semantic web and web services is underway with the development of AI-inspired content markup language [II]. The emphasis is that the composition and discovery of the web service should be business logic driven and the functionality of the service should be intelligent enough to meet and analyze the business requirement according to the context and then should perform the operation underway. In [VII] another effort is quite visible in direction of making context aware web services using DAML (DARPA Agent Markup Language) [VIII] and OIL (Ontology Interchange Language) [IX].
Keeping all these efforts in mind, we should see that whether our all these efforts are going in right directions or not, either we are trying to achieve a thing that is or will be beneficial or not, for this we have tried to compare the traditional web services and the web services of the new era that we are trying to achieve i.e. (Context-aware or Semantic Web Services). The following discussion and studies will try to uncover the details while comparing these two generations of Web Services.
III. The Comparitive Study
By digging all the parameters, and after reviewing the technologies and advancements that have been introduced we have cut down, and selected few of the parameters to compare the two different technologies.
We have extracted some of the feature that can help us easily in distinguishing between the basic feature and capabilities of traditional web services and semantic web services. We will discuss the above factors one by one so that we can clearly how these affect any service efficiency.
Reasoning is a process of finding logical and cognitive reasons for any particular problem or to find a solution. Semantic web services are advance than the simple web services in this way that they try to find out the logical reasoning for every request they receive and in this way they tend to find a proper accurate and much near to required result.
A system or service is said to be robust if it has the capability of coping with the varying functionalities of the user. SWS can also provide you with the functionality of tackling different kinds of user requirements as they have the intelligence factor they use it to dynamically analyze, evaluate and then response accordingly.
C. Fault Tolerant
Fault tolerance is the key and a basic feature for any emerging system. This property enables the system to reduce the fail-time of the system. It makes system to work and continue to perform (might be with some reduced level or functionality) rather than failing the system completely. The SWS are designed to their top to increase the functionality of the system and continue to provide services to the users rather than failing down completely. Simple web services are not yet quite capable of fault tolerance.
D. Automatic Discovery
Automatic discovery of services is an interesting concept that helps in user in finding the service that could fulfill his requirements. This is an automated way of searching for the suitable service required by the process; it introduces extent of easiness in the process as the user does not have to remember the service name that he will need during the course. This mechanism identifies the requirement nature and searches web service repositories automatically for matching service that is published to fulfill the requested process.
E. Automatic Composition
Traditional web services do not have the ability of automatic composition. SWS are also enriched with this functionality as they can compose themselves dynamically upon request. So the services have now the ability to construct complex services if solely one service is not able to perform a required task, it then composes and constructs various web services to make one and then it performs the functionality. This feature lacks in the traditional web services.
F. Service Level Agreements
Service level agreements are important in both levels of services i.e. traditional or SWS but service level agreements are more important in the fields of SWS because the companies providing the web services dynamically so it is very important to have really what you want. Because selection of a wrong service while u are in production level.
We have tried to give a brief comparative study in this paper about the functionality and the features. These inform us about the capabilities of the semantic web services that how much flexible and robust they can be. Still there is a lot of work that can be done in this field of work. SWS can be one more addition in the field of technology and can lead the way of computing to a new step.
We have tried to sort out simply, the difference, between the two different technological levels of Web services. We have also tried to carve out that how the introduction of semantics into web services can help in increasing the efficiency of the services that have been provided for the use. Following are the simple steps that could be followed to convert any traditional web service to semantic web service:
- Determine the domain of the web service
- Determine all the terminologies in the service or domain
- Create the ontology of the terms that have been identified
- Introduce the ontology to the targeted services using already developed frameworks
- Publish your web service along with the new introduced technologies
So that it can now perform with more efficient way and you want it to be.
[I] Wikipedia - The Free Encylopedia, http://en.wikipedia.org/wiki/Semantic_Web_Services, Semantic Web Services
[II] Sheila A. McIlraith, "Semantic Web Services", Tran Cao Son, and Honglei Zeng, Stanford University
[III] M. Baldauf, S. Dustdar, and F. Rosenberg, "A Survey on Context Aware Systems", J. AdHoc and Ubiquitous Computing, 2007, vol. 2, no. 4, pp. 263-277.
[IV] Michael Stollberg, Armin Haller, "Semantic Web Services Tutorial", Proceedings of the 2005 IEEE International Conference on Services Computing (SCC'05)
[V] Iman Keivanloo, Hassan Abolhassani, "An Architecture for Context-aware Semantic Web Services", International Conference on Web Services 2008
[VI] Eric Bouillet, Mark Feblowitz, Hanhua Feng, Zhen Liu, Anand Ranganathan, Anton Riabov, "A Folksonomy-Based Model ofWeb Services for Discovery and Automatic Composition", 978-0-7695-3283-7/08 $25.00 © 2008 IEEE
[VII] R. Cost. "ITtalks: A Case Study in the Semantic Web and DAML+OIL". University of Maryland, Baltimore County, 2002.
[VIII] DARPA Agent Markup Language, http://www.daml.org/
[IX] Ontology Interchange Language, http://xml.coverpages.org/oil.html
[X] Seppo T¨orm¨a, Jukka Villstedt, Ville Lehtinen, Ian Oliver, Vesa Luukkala, "Semantic Web Services - A Survey", Helsinki University of Technology, Laboratory of Software Technology
[XI] Web Services - Wikipedia The Free Encyclopedia http://en.wikipedia.org/wiki/Web_service
[XII] Service-Oriented-Architecture, SOA Definition http://www.service-architecture.com/web-services/articles/service-oriented_architecture_soa_definition.html