Web services allow you to use preexisting components (available on the Internet or on a local network) instead of writing new business logic to perform common tasks invoked by the applications that you develop. Web services originated when the Simple Object Access Protocol (SOAP) was introduced. SOAP leverages Extensible Markup Language (XML) and usually employs Hypertext Transfer Protocol (HTTP) as the transport. Invoking Web services through SOAP requires serialization and deserialization of datatypes, and the building and parsing of SOAP messages.
Part of the value of Web services comes from the Web Services Description Language (WSDL), which enables a service to be self-describing. WSDL defines an XML grammar for describing Web services as collections of communication endpoints capable of exchanging messages. WSDL service definitions provide documentation for distributed systems and serve as a recipe for automating the details involved in applications communication.
With SOAP and WSDL, using third-party components is easier because interfaces between applications become standardized across disparate platforms.
PowerBuilder supports the following Web services standards:
SOAP 1.1 or later
WSDL 1.1 or later
HTTP or HTTPS
XSD (XML Schema Document) 1.0
Producing a Web service
PowerBuilder
provides tools for developing custom class (nonvisual) user objects
and deploying them as EAServer components
and exposing them as Web services. You can deploy a component to
an EAServer host running on Windows
and UNIX operating systems. For more information, see Chapter 23, “Building an EAServer Component.”
