A web service is a software application on a network that has an interface through which other programs can gain access. Web services can be as simple as a mortgage calculator program or as complex as a Fortune 500 software application built from components from y all over the world. They are currently being used to help large and small businesses get the most from their Information Technology resources by allowing the integration of diverse software applications, from desktop programs to large enterprise-wide systems.
Not only are web services useful for day-to-day operations of a company, but they are especially helpful for post- merger or post-acquisition system merger. (Geerts,Paretta & White, 2004). XML, the root markup language and key ingredient for creating web services, is gaining in popularity, according to IDC, which has seen the growth in XML-based servers go up by 160% over the last year.
Forrester Research, Cambridge, Mass. , notes that $500 million has already been spent on early projects in the financial services sector, while Gartner-Group, Stamford, Conn. suggests that the web services software market will reach $1. 7 billion in the U. S. by next year and balloon up from there. ( Ismail, Ayman, Samir Patil, and Suneel Saigal, 2002)/ This paper will give an overview of web services technology, and talk about XML, WSDL, SOAP and UDDI and how they fit into the process. It will also briefly explain how Microsoft. NET fits into the Web Services architecture. The key to making web services work is data, process, and communication standards. The communication protocol standard is the same as the Internet, TCP/IP.
All computers can understand TCP/IP. Web services implement the client-server model over the World Wide Web). On the client side, for example, they manage the different creen shapes and sizes and the different connection speeds of desktop computers, mobile telephones, and PDAs. On the server side, the various programming languages and middleware technologies at work behind each application or data source become transparent to programmers, so it is a lot easier for them to develop applications.
The data standard for TCP/IP is XML, a set of syntax rules for adding meaning to data and for building other XML standards. The process standards are actually a set of evolving XML standards: SOAP (Simple Object Access Protocol), for packaging messages from one software application to another, A set of rules that facilitate XML exchange between applications. Along with WSDL, SOAP performs message transport functions. (“Putting Web Services in a “No Spin Zone”, 2004) WSDL (Web Services Description Language)A common framework for describing tasks performed by a Web service.
Suppliers, for example, could discover what kinds of information a company’s inventory system offered them-nothing more than a bare indication that inventory was approaching zero, for example, or possible due dates as well. UDDI (Universal Description, Discovery and IntegrationA set of specifications for creating XML-based directories of Web services offerings. Much as callers consult the Yellow Pages for the telephone numbers of businesses, users of and applications for Web services may find them through these directories.
Message transport The actual workings of web services can be described from a provider’s and a user’s perspective. From a provider’s perspective, a web service is created by using the data, process, and communication standards identified above to create a web interface to one or more software applications. Most of the web services described above provide data from a database in response to specific request parameters. In essence, a web service responds to a “get data” command by reading the data from a database and sending it back to a software application on the Internet.
To actually create such a web service, the provider uses WSDL to define the allowable read access “get data” commands that the database management software can understand. The web service also knows how to put the results in a SOAP envelope addressed to the requesting software application and how to send it via the Internet. From a user’s perspective, a software application must be able to issue the appropriate commands, put them in a SOAP envelope, and send them to the web service interface for processing. This usually requires downloading the WSDL and plugging it into a software application.
For example, to use the Xmethods delayed stock quote web service, users employ a web browser to access the WSDL, plug it into an Excel spreadsheet, click the “insert stock quotes” icon that gets added to the Excel tool bar, and fill in the necessary information in the po-pup window. Because the Excel spreadsheet knows how to process XML, it packages the commands in a SOAP envelope addressed to the web service and sends it. When the return SOAP envelope arrives from the web service, Excel knows how to process it and insert the requested data in the appropriate cells.
All current software packages, including Microsoft Office, Internet Explorer, and Quicken, can understand and process XML and can therefore interface with web services. General ledger and other accounting packages should soon become XML-enabled. A further objective is to fully automate the process of finding and using web services. Web service providers will publish the availability of their applications, using UDDI to describe their location and available services and WSDL to define how to use them.
When a user logs on to the Internet and launches a software application, it will be able to identify available web services by reading the UDDI. The software application will then know how to use the web services by accessing their WSDL definitions. When the desired web service is found, the user will simply tell the software application to access it by downloading its WSDL interface instructions. All of the complexity is hidden behind the interface. A competiitor to the XML standard is The Microsoft NET Framework. The Microsoft .
NET Framework– first announced in July 2000–represents a new and in many ways radically different development foundation for Windows and Web-based servicess. It will overshadow and functionally replace previous Microsoft technologies, including COM and Win32, and will become the focus of all future development efforts across the company’s many operating systems Users, in fact, cannot utilize Windows Messenger without signing up for “Passport,” a universal Internet log-in and identification card, that serves as the gateway to all of Microsoft’s Internet services.
Passport stores users’ credit card and password information for a host of new consumer services that Microsoft has named “Hailstorm. ” Combining instant messaging, digital music, and video, those services, for a monthly subscription fee, will allow users to purchase products online, receive e-mail at remote cellphones or other mobile devices, and make copies of digital music. The forecast for the future is that both XML and Microsoft Passport will pave the way for the implementation of every more sophisticated and complext web services, combining audio, visual, multimedia, and text applications.