Understanding Web Services

Web Services is the term used to describe a set of technologies that facilitate distributed computing. Using Web Services, it is possible to create applications that invoke remote code optionally passing structured data and obtaining results back.

Web Services are gaining popularity because:

• They are supported by all major industry hardware and software vendors.

• They are built on readily available open and nonproprietary technologies.

• They are highly portable, allowing applications to be shared despite differences in hardware, platforms, and operating systems.

• The technology is inexpensive.

ColdFusion fully supports Web Servicesboth consuming (using) Web Services hosted locally or elsewhere and creating Web Services for use by other servers and applications.

The Technology

Web Services are built on top of several important technologies and protocols:

• XML

• HTTP

• SOAP (Simple Object Access Protocol)

• UDDI (Universal Description, Discovery, and Integration)

WSDL

Web Services are documented via an XML format named WSDL (Web Services Description Language). Every Web Service has a corresponding WSDL that describes what methods the Web Service exposes, what arguments those methods expect, what they return, the URL to each, and so on.

Consuming Web Services requires the URL to the Web Service WSDL, as well as knowledge about the Web Services' methods (information gleaned from the WSDL).

Creating Web Services requires that a WSDL document be created to describe the Web Service, and that the URL to it is made available.