from ERP systems.” Pointing to the little green boxes, Sedgewick continues. “Each  of  these  little  applications  are  Web  services,  written  in  Java  or C/C++—it really doesn’t matter. In addition to the main application func- tionality, which is simply to get inventory records from the ERP system or database, they have some eXtensible Markup Language (XML) code added to them.” At the mention of these acronyms, Dunston’s face brightens because he has read about XML and Web services in the Harvard Business Review, so at least he understands some of it. Dunston quipped, “You mean, expen- sive markup language, don’t you?” “Yeah,  right,”  chuckles  Sedgewick  as  he  proceeds.  “The  XML  code that I am referring to does two simple things: It has a SOAP protocol layer, which is Simple Object Access Protocol. The SOAP protocol is a messaging standard to format messages between Web services consumers and produc- ers.  SOAP  specifies  the  message  envelope,  the  header,  and  the  message body—all in XML. This is how a consumer or user of a Web service and the  producer  of  a  Web  service  communicate  via  Internet  protocols,  typi- cally HTTP.” Dunston furiously scribbles notes as Sedgewick describes these primary Web services standards for messaging. Sedgewick watches Dunston’s facial expression as he continues, making sure that there is no confusion or bore- dom in his eyes. “The other piece of XML code that is added is known as Web  Services  Description  Language  (WSDL).  This  XML-based  standard describes how a Web service is accessed and what its inputs and outputs are. WSDL provides the interface to the Web service so it can be used pro- grammatically  by  other  Web  services  without  ever  needing  human  inter- vention.” “What this all means,” says Sedgewick, “is that these software compo- nents are designed to work together, over the Internet, or in this specific case  over  our  corporate  intranet,  to  gather  inventory  information  from three different systems and aggregate it in the inventory portal. Using Web services  in  this  way  can  help  us  integrate  legacy  information  systems  by exposing  important  business  information  using  standards  such  as  XML, SOAP, and WSDL—as opposed to often expensive EAI tools and propri- etary and inflexible integration techniques.” “Will our integration expenses go down with Web services?” Dunston asks. His inquiry draws a quick grin from Sedgewick. “It’s conceivable that over time, the effort and expense associated with internal  systems  integration  will  be  reduced  significantly  as  Web  services are used to expose information from proprietary business systems for use by other business applications. Web services could reduce or eliminate the need  for  EAI  tools  because  Web  services  are  based  on  standard  Internet protocols and XML. As more and more Web services are made available, 6 EXECUTIVE’S GUIDE TO WEB SERVICES 74188_WY_Marks_01  2/5/2003  4:08 PM  Page 6