|Author : DAOUDI Samir | Context : MSc Software Engineering – Internet Programming|
Recently, a new concept appeared in the web technologies, which opens doors for new kind of computing and solutions development. It is the upcoming of service-oriented computing, which is new computing paradigm based on services that help in the development of rapid and low-cost applications. The services are modules deployed in middleware platforms that can be published and used using XML based technologies(Papazoglou,2008). The web services are self-contained, modular applications published and used over internet. The W3C, which is the consortium of web standards and web technologies defined Web Services as Software Systems (Gurugé,2004).
Actually, many web solutions use web-services for specific tasks and processes, bellow are some examples of using web services :
– Requesting weather information to be displayed in a web site.
– Currency converter.
– E-Commerce and online payment sites
– Requesting information from 3rd parties’ web sites.
Figure 1: Example of web-services’ use.
In general, web services are being developed to be the entry point of a system, as shown in the diagram, the different processes and information systems are being accessed throw a web service. This approach allows the online exposure of systems while ensures a control over the type of inputs and outputs (Alonso.et.al, 1999). It is clear that the web development field has significantly evolved from the 90s years, where web sites were limited to a set of static pages linked together.
“Web application development will be dominated by Web Services, and we can envisage a time when most web application development will involve just the calling of existing Web Services”, this statement raises many questions:
– The web services are in general designed and developed as classes and methods that do not have any explicit user interfaces, so in order to build a web application completely based on web services, these last should be able to provide convivial user interfaces.
– The web services interfaces are the inputs/outputs that are used to communicate with, these interfaces and communication methods are in general described in what is known as WSDL. If different web services have to collaborate together, some standard and unification of inputs (types and names) should be thought.
– The security point also should be carefully discussed as web services open doors to entire information systems.
If all these and other considerations can be satisfied by the design and development of web services’ framework which applies the different rules of interoperability and co-existence of web services, web application can be entirely developed based on web services.
– Anura Gurugé (2004).Web Services, Theory and Practice. ISBN: 978-1-55558-282-1.
– Michael P. Papazoglou (2008). Web Services: Principles and Technology. ISBN: 978-0-321-15555-9
– Gustavo Alonso, Fabio Casati, Harumi Kuno, Vijay Machiraju (1998). Web Services: Concepts, Architectures and Applications. ISBN: 3-540-44008-9.