Abstract
The advent of Web Services (WS) has signaled a true revolution in the way service-oriented computing and remote procedure invocation over the Web are conducted. Web Services comprise of a set of loosely coupled specifications to coordinate process execution from distance, based on common and widely accepted Web protocols such as HTTP, FTP, and XML, and therefore, providing increased development flexibility. Since the WS Framework was built on top of those protocols, Web Services have been widely acclaimed by the Web development community and paradoxically; they have marked one of the few examples in the history of computer protocols where a global consensus has been reached. The Web Service framework consists of essentially three basic components: 1. The Web Service Description Language (WSDL), a language that allows formal functional characterization of the provided functionalities; 2. The Simple Object Access Protocol (simply SOAP from its version 1.2), a protocol that defines the format of the information interchange; and 3. The UDDI (Universal Description, Discovery and Integration) is a catalog of Web Service descriptions. All three of these components are specified using XML markup. The elegance of the WS architecture lies in the fact that every WS transaction is taking place over established Web protocols such as HTTP and FTP. As remarked in Ballinger (2003, p. 5): “A Web Service is an application logic that is accessible using Internet standards.” This very fact has accounted for the rapid and universal adoption of Web Services. This work is organized as follows: First, a review of underlying technologies and tools is presented. Consequently, existing techniques for design methodologies are described. Next, an overview of storage and retrieval techniques for Web Services is given followed by real-world applications of Web Services. We conclude with open issues and discussion.
TopIntroduction
The advent of Web Services (WS) has signaled a true revolution in the way service-oriented computing and remote procedure invocation over the Web are conducted. Web Services comprise of a set of loosely coupled specifications to coordinate process execution from distance, based on common and widely accepted Web protocols such as HTTP, FTP, and XML, and therefore, providing increased development flexibility. Since the WS Framework was built on top of those protocols, Web Services have been widely acclaimed by the Web development community and paradoxically; they have marked one of the few examples in the history of computer protocols where a global consensus has been reached.
The Web Service framework consists of essentially three basic components:
- 1.
The Web Service Description Language (WSDL), a language that allows formal functional characterization of the provided functionalities;
- 2.
The Simple Object Access Protocol (simply SOAP from its version 1.2), a protocol that defines the format of the information interchange; and
- 3.
The UDDI (Universal Description, Discovery and Integration) is a catalog of Web Service descriptions.
All three of these components are specified using XML markup. The elegance of the WS architecture lies in the fact that every WS transaction is taking place over established Web protocols such as HTTP and FTP. As remarked in Ballinger (2003, p. 5): “A Web Service is an application logic that is accessible using Internet standards.” This very fact has accounted for the rapid and universal adoption of Web Services.
This work is organized as follows: First, a review of underlying technologies and tools is presented. Consequently, existing techniques for design methodologies are described. Next, an overview of storage and retrieval techniques for Web Services is given followed by real-world applications of Web Services. We conclude with open issues and discussion.
TopThis section deals with the state-of-the-art in the technologies supporting the development of Web Services.
Key Terms in this Chapter
World Wide Web: Computer network consisting of a collection of Internet sites that offer text and sound and animation resources through the hypertext transfer protocol.
XML: Short for Extensible Markup Language, a specification developed by the W3C. XML is a pared-down version of SGML, designed especially for Web documents. It allows designers to create their own customized tags, enabling the definition, transmission, validation, and interpretation of data between applications and between organizations.
Information Retrieval: Information Retrieval (IR) deals with the representation, storage, organization of, and access to information items. The representation and organization of the information items should provide the user with easy access to the information in which he is interested.
Web Engineering: A branch of software engineering, addressing the specific issues relating to design and development of large-scale Web applications. It focuses on the methodologies, techniques, and tools that are the foundation of complex Web application development and which support their design, development, evolution, and evaluation.
Web Services: A family of standards promoted by the W3C for working with other businesses, developers, and programs, through open protocols, languages, and APIs, including XML, SOAP, WSDL, and UDDI.
Information Technology: Information technology (IT) or information and communication technology (ICT) is the technology required for information processing. In particular the use of electronic computers and computer software to convert, store, protect, process, transmit, and retrieve information from anywhere, anytime.
Distributed Application Development: A programming paradigm focusing on designing distributed, open, transparent, scalable, fault tolerant systems. This paradigm is a natural result of computer internetworking.