Introduction to web services in DataStage

A web service describes:

  • An application that is published and made available through a network, such as the internet.
  • Recent and well-established protocols and standards that make access to the application possible.

A web service exposes one or more operations, which are functions that you call from another application, such as DataStage®. The operation accepts a request and returns a response. For example, an electronic brokerage might deploy a web service that returns portfolio information when you submit an account and password.

The following diagram illustrates the flow in a transaction between a web service and DataStage. The web service is a self-contained application, which can interface with other applications within a company.
A web service is a self-contained application, which interfaces with other applications

About Web Services technologies

The protocols and standards that are needed to invoke a web service are represented in the following technology stack. The roles of each layer are discussed in the sections that follow.

The web services stack

Publishing Web Service operations

Web services publish their operations and locations through a document that is written in an XML-based language called Web Services Description Language (WSDL).

WSDL documents specify:

  • Operations that the web service offers. The collection of operations is called a port type.
  • URL of the web service that IBM® DataStage invokes. This information is represented by the service element.
  • Structures for the web service request and response of each operation. These structures are called messages.
  • Transport protocol for communication between a web service client and the web service. For example, SOAP over HTTP. This information is part of a binding.
  • Mechanism for sending individual web service requests, such as RPCs. This is another part of a binding.

Accessing Web Services

A growing number of companies that host web services publish their services through a registry. Some of these registries comply with the Universal Description, Discovery, and Integration (UDDI) specification. The UDDI specification sets standards for describing businesses that host web services and for finding or discovering them through a network connection. Typically, a UDDI registry has a web interface that contains direct or indirect links to WSDL documents.

A UDDI Business Registry (UBR) is a public subscriber service. Any company can enroll in a UBR, and anyone can search this information. Private registries are often made available only through password access. Using the Web Service stage, you have direct access to several UBRs.

UBR data falls in these groups:

  • White pages, which contain contact and general information about a company.
  • Yellow pages, which include taxonomies such as product categories and North American Industry Classification System (NAICS) identifiers.
  • Green pages, which contain technical specifications of the web service.

The following diagram illustrates the relationship between DataStage, a web service, and web service registries.

The relationship between DataStage, a web service, and web service registries.