Database Reference
In-Depth Information
independent of the underlying protocol and encoding requirements. In general, WSDL provides
an abstract language for defining the published operations of a service with their respective param-
eters and data types. The language also addresses the definition of the locations and binding
details of the service.
10.3.1.2 Accessing Web Services: Simple Object Access Protocol (SOAP)
Simple Object Access Protocol is an XML-based lightweight protocol for the exchange of infor-
mation in a decentralized distributed environment. SOAP is a means by which different systems
can communicate, based on the HTTP Web standard. It specifies how to encode an hypertext
transfer protocol (HTTP) header and XML file so that different applications, running on differ-
ent systems, can share data. SOAP defines a messaging protocol between requestor and provider
objects, such that the requesting objects can perform a remote method invocation on the providing
objects in an object-oriented programming fashion. The SOAP specification was coauthored by
Microsoft, IBM, Lotus, UserLand, and DevelopMentor. The specification subsequently spawned
the creation of W3C XML Protocol Workgroup, which is constituted of over 30 participating
companies.
In most vendor implementations of SOA, SOAP forms the basis for distributed object commu-
nication. Although SOA does not define a messaging protocol, SOAP has recently been referred
to as the Service-Oriented Architecture protocol due to its common use in SOA implementations.
The beauty of SOAP is that it is completely vendor neutral, allowing for independent imple-
mentations relative to platform, operating system, object model, and programming language.
Additionally, transport and language bindings as well as data-encoding preferences are all imple-
mentation dependent.
10.3.1.3 Finding Web Services: Universal Description,
Discovery, and Integration (UDDI)
The Universal Description, Discovery and Integration is an XML-based registry that enables orga-
nizations in a global business-to-business (B2B) environment to locate each other. UDDI specifi-
cation provides a common set of SOAP APIs that enable the implementation of a service broker.
The UDDI specification was outlined by IBM, Microsoft, and Ariba to help facilitate the creation,
description, discovery, and integration of Web-based services.
UDDI is like a telephone directory that additionally also
◾
Indicates the suitability of a potential partner
◾
Describes the access mechanism by which an enterprise can be interfaced with
The motivation behind UDDI.org, a partnership and cooperation between more than 70 industry
and business leaders, is to define a standard for B2B interoperability.
10.3.2 Enterprise Services
Enterprise Services are based on the same technology as Web Services. SAP recognized early the
potential of Web Services as the basic theme to enable provisioning of flexible and innovative func-
tionality on an ongoing basis in a fast, flexible, and efficient manner. SAP enlarged the concept of
Web Services to Embrace Enterprise Services.
