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Web services are here to stay—they are simply too useful and solve too many existing
problems to go away. That said,
there are times when they aren't yet ready for prime time. Unresolved issues relating to
interoperability, discoverability,
error handling, and versioning often must be addressed. Nonetheless, developers are still
using Web services in their current
immature state to solve architectural issues related to distributed software projects. For
this reason, developers are forced
to address weaknesses in the Web services standards. Take, for example, problems in version
control; you can use the Web
Services Description Language (WSDL) to create a model for versioning a Web service
implementation, based on the method used
by Microsoft's COM/DCOM registry.
WSDL is an XML-based description language for describing the end-points, services, and
specific methods or operations
provided by a given web service. While languages like WSDL might be explicitly enhanced to
support multiple versions of a
service interface, you don't necessarily need to wait for this to happen. Even in cases where
explicit versioning is built
into a technology, the system still relies on the discipline of users to be reliable. For
example, source-code control systems
let users modify and track changes in versions of a given software application. For this to
work, users must not check in code
that is solid and tested or the entire system breaks. Ultimately the release of a single
"version" of a product will be
"marked/tagged/stamped" across the entire source code base to recreate that version of the
product. Luckily, WSDL can be used
in a disciplined manner to version a Web service.
First, you can add multiple services to WSDL service descriptions for major releases of
the web interface. This makes
possible a clean separation of different versions of the interface with the specification of
different physical locations; see
Listing One. However, Listing One still has a problem—it
automatically forces Web service clients to
a specific version even if your interface permits backwards compatibility: Existing clients
can't benefit from the new
version.
Extending Enterprise Value with Web 2.0 In this webcast we will talk about how to simply build and quickly remix Web 2.0 applications and the role of the IT department and how they support mashups. We will discuss how IBM can help IT teams adapt existing enterprise systems as well as develop unique ones that can support end user driven mashups in a reliable, scalable and secure way. We will highlight a simple scenario adapting an enterprise information source for mashups and how to test it. We will also cover how IBM can help you build agile, fast and simple web applications based on dynamic scripting languages that dramatically reduces development time. Wednesday, September 24, 2008 - 12pm PT / 3pm ET
2008 International Mathematica Conference Dr. Dobb's interviews Wolfram Research's Theo Gray, co-founder and Director of User Interfaces, and Roger Germundsson, Director of Research and Development, about the upcoming 2008 International
Mathematica Conference.
In this volume of Best of BYTE, we explore the emergence of some heuristic algorithms. Although we have only scratched the surface of this intriguing subject, we hope we've suggested the potential of the synthesis of heuristics and algorithms.
