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.
Web services that are described in WSDL files can be registered on a Universal Description, Discovery, and Integration (UDDI) Web site. You can search UDDI registry sites from PowerBuilder at design time and find the services you need for your application.
With SOAP, WSDL, and UDDI, 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
You can access Web services from a PowerScript target or a JSP target. For information on accessing Web services in JSP applications that you create with PowerBuilder, see the chapter on JSP targets in the Working with JSP Targets book or the JSP page authoring topic in the online Help.
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 24, “Building an EAServer Component.”
