A web service is a network accessible interface to application functionality, built using standard Internet technologies.
The fundamental concept behind web services is the SOA (service-oriented architecture), where an application is no longer a large monolithic program, but is divided into smaller, loosely coupled programs, and provided services are loosely coupled together with standardized and well-defined interfaces. These loosely coupled programs make the architecture very extensible, as it acquires the ability to add or remove services with limited costs. Therefore, new services can be created by combining and reusing existing services.
Because of the abstraction provided by the standards-based interfaces, it does not matter whether the application services are written in Java and the browser written in C++, or the application services deployed on a UNIX box while the browser is deployed on Windows. Web services allow for cross-platform interoperability in a way that makes the platform irrelevant. Interoperability is one of the key benefits gained from implementing web services. See the basic web service architecture shown in figure A.
Figure 1. The web service architecture
In the web services architecture, the service provider publishes a description of the service(s) it offers via the service registry. The service consumer searches the service registry to find a service that meets their needs. The service consumer could be a person or a program.
The service provider offers business processes in the form of services. The services offered by the provider are called by the consumer to achieve certain sets of business goals. The process of services being provided and consumed is achieved by using directory services that lie between the provider and the consumer, in the form of broker. The service to be made available to the consumer is published to the directory services in the broker. The consumer wanting to achieve the set of business goal(s) will discover the service from the broker. If the service is found, it will bind to the service and execute the processing logic.
Apache CXF is an open source framework that provides a robust infrastructure for conveniently building and developing web services. It lets you create high-performance and extensible services, which you can deploy in the Tomcat and Spring-based lightweight containers as well as on a more advanced server infrastructure, such as JBoss, IBM® WebSphere®, or Oracle WebLogic.
CXF provides you with many options to build services. CXF support all three major types of services:
- SOAP - this page summarizes the options for creating SOAP services.
- REST-ful - REST support