Web Services

Web services are becoming the standard method for inter-application communications. A key technology in a service-oriented architecture (SOA) technology stack, web services utilize HTTP communications, W3C standards and XML messaging to simplify interoperability between applications.

Rhapsody provides an easy-to-use interface for harnessing web services, regardless of whether the web service is hosted by Rhapsody, or whether Rhapsody uses an external web service. Vendors can exploit Rhapsody's easy-to-use, secure web services for application integration, and providers can develop SOA strategies to simplify the control and management of their networks. Refer to Web Services in Rhapsody for details on how to set up web services in Rhapsody.

What Are Web Services?

The term web services describes a standardized way of integrating Web-based applications using the XML, SOAP, WSDL and UDDI open standards.

XML is used to tag the data, SOAP is used to transfer the data, WSDL is used to describe the services available, and UDDI is used to list the services available. Used primarily as a means for businesses to communicate with each other and with clients, web services allow organizations to communicate data without intimate knowledge of each other's IT systems behind the firewall.

Terms Explained

SOAP

Simple Object Access Protocol. A lightweight XML-based messaging protocol used to encode the information in Web service request and response messages before sending them over a network. SOAP messages are independent of any operating system or protocol and may be transported using a variety of Internet protocols, including SMTP, MIME, and HTTP.

SOA

Service-oriented Architecture. The underlying structure supporting communications between services. SOA defines how two computing entities interact with one another, so as to enable one entity to perform a unit of work on behalf of the other entity. Service interactions are defined using a description language. Each interaction is self-contained and loosely coupled, so each interaction is independent of any other interaction. SOAP-based Web services are becoming the most common implementation of SOA.

Let us use the example of making an online purchase. You browse through a store's online catalog and select a number of items. You specify your order through one service, which communicates with an inventory service to find out if the items you have requested are available in the sizes and colors you want. Your order and shipping details are submitted to another service which calculates your total, tells you when your order should arrive and provides a tracking number that, through another service, will allow you to keep track of your order's status and location en route to your door. The entire process, from the initial order to its delivery, is managed by communications between the Web services, all made possible by the underlying framework that SOA provides.

WSDL

Web Services Description Language. An XML-formatted language used to describe a web service's capabilities as collections of communication endpoints capable of exchanging messages. WSDL is an integral part of UDDI, an XML-based worldwide business registry. WSDL is the language that UDDI uses.

UDDI

Universal Description, Discovery, and Integration. UDDI is a Web-based distributed directory that enables businesses to list themselves on the Internet and discover each other, similar to a traditional phone book's Yellow Pages and White Pages.

WS-Security

Web Services Security. Defines a standard set of SOAP extensions or message headers that can be used to implement integrity and confidentiality in web services applications.