Information Technology Reference
In-Depth Information
The further standards that complement the core specification are often
aggregated under the acronym “WS-* standards”. They have been developed
by standardization bodies such as the W3C
9
and OASIS.
10
Without claiming
completeness, or discussing them extensively, we shall mention some of them
here:
•
WS-Security [97] standardizes a SOAP extension to encode security-
related information.
•
WS-Policy [8] is a standard that enables the description of supported prop-
erties of a service, such as security level, and language.
•
WS-PolicyAttachment [7] allows one to link policy descriptions with
WSDL descriptions.
•
WS-Trust [3] can describe trust relationships between business partners.
4.4 Web Services in Reality
It is hard to assess the total spread of this technology. First, it is at present
mainly used within or between companies, and second, there is no reliable
way to count the publicly available Web services. However, if one considers the
behavior of software vendors as an indicator for the adoption of the technology,
it is a tremendous success. There are numerous different platforms that allow
the easy publication of software components as Web services. The technology
is an integral part of the Microsoft .NET environment and of various platforms
for Java-based solutions. Even script languages such as PHP provide libraries
for easy publication and consumption of Web services. The support is not
limited to the technology providers; application vendors such as SAP and
Oracle have made Web services an integral part of their products.
This indicates that the technology has indeed been widely adopted; how-
ever, of these many services, relatively few are made publicly available. The
big public UDDI-based repositories from IBM, Microsoft, and SAP have re-
cently been shut down. The majority of registered services have been toy
examples or simple tests by technology enthusiasts. Currently, several portal
sites have begun to fill this void by providing a central point of registration.
One such portal is StrikeIron,
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which not only allows the registration of Web
services, but also serves as a reseller of Web service usage contracts. Having
contracts with multiple smaller providers allows StrikeIron to offer compa-
nies the ease of aggregated invoicing and contract management. The services
available range from currency conversion services, and various forms of SMS
or fax services (many available without charge), to commercial offers, such as
address validation and services that perform printing and mailing of electronic
letters via surface mail delivery.
9
http://www.w3.org
.
10
http://www.oasis.org
.
11
http://strikeiron.com
.
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