Database Reference
In-Depth Information
integrating object components over the Internet. They enable a development environment where
it is no longer necessary to build complete and monolithic applications for every project. Instead,
the core components can be combined from other standard components available on the Web to
build the complete applications that run as services to the core applications.
Some of the past approaches for enabling program-to-program communications included
combinations of program-to-program protocols such as Remote Procedure Call (RPC) and
Application Program Interfaces (APIs) coupled with the architecture such as Common Object
Model (COM), the Distributed Common Object Model (DCOM), and the Common Object
Request Broker Architecture (CORBA). But without a common underlying network, common
protocols for program-to-program communication, and a common architecture to help applica-
tions to declare their availability and services, it has proven difficult to implement cross platform
program-to-program communication between application modules. These previous attempts to
set up standards for accomplishing these objectives were not very successful because
◾
They were not functionally rich enough and are difficult to maintain as
best of breed.
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They were vendor specific as opposed to using open and cross vendor standards.
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They were too complex to deploy and use.
The use of Web Service standards holds the potential of correcting each of these deficiencies. This
new approach presents applications as services to each other and enables applications to be rapidly
assembled by linking application objects together.
With the advent of the Internet and its protocols, most vendors and enterprises have gradu-
ated to a common communication and network protocol—the Internet's TCP/IP. And with the
availability of web standards such as Extended Markup Language (XML), Simple Object Access
Protocol (SOAP), Universal Description, Discovery and Integration (UDDI), and Web Services
Definition Language (WSDL), vendors enable customers to
1. Publish specifications about application modules via WSDL
2. Discover those modules (either on the internal intranet or on the Internet) via the UDDI
3. Bind the applications together to work seamlessly and cooperatively and deliver the holistic
functionality of composite application via SOAP and XML
Figure 10.2 shows the schematic of the interaction between the Web Service Provider, Discovery
Service Provider (Service Registry), and Web Service Consumer (Service Client).
Major hardware vendors and certain key software vendors are looking at these new
Web standards for providing solutions for program-to-program communication.
IBM's WebSphere Server environment, Sun Microsystems' Open Network
Environment (ONE) constituting of various Sun technologies and third-party prod-
ucts, and Microsoft's .NET initiatives deliver Web-Service-based solutions.
The significance of Web Services for the future is by reason of the following:
◾
Web Services will enable enterprises to reduce development costs and expand application
functionality at the fraction of costs per traditional application development and deploy-
ment methods.
