A Web service is a self-contained, modular application that can be accessed and used over a network connection using the Simple Object Access Protocol (SOAP), Web Services Description Language (WSDL), and Extensible Markup Language (XML) open standards. Regardless of the programming language in which it has been implemented, a Web service can be accessed from many different platforms and operating systems, thus greatly enhancing the ability for diverse applications to share data.

About seven years ago, Microsoft started adding support for COM (Component Object Model) in all their products. The developer tools from Microsoft facilitated easy creation and consumption of COM objects; various APIs were upgraded from standard Windows calls to COM object methods; the Microsoft Office Suite (Word, Excel, etc.) and Internet Explorer browser were made automation enabled; to that end that even SQL Server supported COM (remember sp_OACreate and SQL DMO?).

About seven years ago, Microsoft started adding support for COM (Component Object Model) in all their products. The developer tools from Microsoft facilitated easy creation and consumption of COM objects; various APIs were upgraded from standard Windows calls to COM object methods; the Microsoft Office Suite (Word, Excel, etc.) and Internet Explorer browser were made automation enabled; to that end that even SQL Server supported COM (remember sp_OACreate and SQL DMO?).

Web Services themselves are not offering authentication and security services. The WS-Security standards can solve this issue.

When you use the Wsdl.exe tool (WSDL) to generate a Web service proxy in a specific language by using the /l or /language switch, you cannot specify the language for Microsoft Visual J# .NET. The language option permits you to specify CS for Microsoft Visual C# .NET, VB for Microsoft Visual Basic .NET, and JS for Microsoft JScript .NET. However, no value is available for Visual J# .NET. Therefore, you cannot generate the proxy file in Visual J# .NET.

This is the second article in a series of articles that relate to a new approach to using WSDL and UDDI, described in a new OASIS UDDI Technical Note. This article describes the types of UDDI query that can be issued against a UDDI model built according to the Technical Note.

WS-I, the Web Services Interoperability Organization, was announced last February in a press release from IBM and Microsoft. The release actually had a byline of Armonk and Redmond, which are of course the corporate headquarters of the two companies. While there were nine founders, the shared byline reinforces the conventional wisdom identifying the original catalysts.

Unlike today's Web, web services can be viewed as a set of programs interacting cross a network with no explicit human interaction involved during the transaction. In order for programs to exchange data, it's necessary to define strictly the communications protocol, the data transfer syntax, and the location of the endpoint. For building large, complex systems, such service definitions must be done in a rigorous manner: ideally, a machine-readable language with well-defined semantics, as opposed to parochial and imprecise natural languages.

This article is the third and final part of the WSDL Tales from the Trenches series, and in it I concentrate on the data in web services. More specifically, I examine the type definitions and element declarations in the types element of a WSDL document. Such types and elements are for use in the abstract messages, the message elements in a WSD.

Our initial discussion of WSDL invocation tools focused on programming and command-line invocation tools. We now move on to even simpler tools that are entirely driven by a web-based interface.

Using a web service involves a sender and a receiver exchanging at least one XML message. The format of that message must be defined so that the sender can construct it and the receiver can process it. The format of a message includes the overall structure of the tree, the local name and namespace name of the elements and attributes used in the tree, and the types of those elements and attributes.

The goal for the model was to represent the data in a WSDL file in a way that would be natural to understand and query in RDF.

Unlike today's Web, web services can be viewed as a set of programs interacting cross a network with no explicit human interaction involved during the transaction. In order for programs to exchange data, it's necessary to define strictly the communications protocol, the data transfer syntax, and the location of the endpoint. For building large, complex systems, such service definitions must be done in a rigorous manner: ideally, a machine-readable language with well-defined semantics, as opposed to parochial and imprecise natural languages.

The WSDL object provides support for the Web Services Definition Language, an XML format used to specify web services. WSDL files contain information on both the structure of requests and responses, and how to invoke services via one or more transports. Using WSDL simplifies JavaScript code by streamlining the specification of Request objects.

Overloaded methods may or may not be what you need for the project you are working on. Additionally, there are those who argue that if a function is taking a different set of argument-types, then it should be noted by giving it a different name. But neither of these are the argument for learning how to express overloaded interfaces in WSDL. The reason is simple: languages, commercially in use today, support this feature. In order to correctly describe their interfaces using a description written in WSDL, it must be possible to describe an operation that has different calling syntaxes.

In a previous article ("WSDL Tales From the Trenches, Part 1"), I painted a big picture of web services design. As I said, Web Services Description Language (WSDL) only defines the syntax of how a web service may be invoked; it says nothing about its semantics. I will observe this distinction in what I say in this article about WSDL.

The Universal Description, Discovery & Integration (UDDI) specification provides a platform-independent way of describing and discovering Web services and Web service providers. The UDDI data structures provide a framework for the description of basic service information, and an extensible mechanism to specify detailed service access information using any standard description language.

The client in the section, A Simple Example: HelloWorld, used a static stub for the proxy. In contrast, the client example in this section calls a remote procedure through a dynamic proxy, a class that is created during runtime. Before creating the proxy class, the client gets information about the service by looking up its WSDL document.

A traditional Web application is designed to take input from a human user and display output to a human user, as illustrated below. The user's browser and the Web server that hosts the Web application act as intermediaries. The output of the application is typically in HTML, for convenient display to the human user sitting at a browser, and the input is typically provided through HTML forms.

The wscompile tool generates stubs, ties, serializers, and WSDL files used in JAX-RPC clients and services. The tool reads as input a configuration file and either a WSDL file or an RMI interface that defines the service.