Chapter 8 -- Building a Web Service with SOAP

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Chapter 8

SOAP, the Simple Object Access Protocol, relies on two open standards: HTTP and XML. The SOAP XML syntax is straightforward, containing only a handful of elements and attributes. SOAP defines an envelope into which you can put data. The SOAP: namespace prefix defines the SOAP elements.

In this chapter, we will build an example that is broken into two parts. First we'll use JScript and the XMLHTTP object to create a SOAP client by hand. I want to start with the XMLHTTP object so that you can see exactly what goes on inside a SOAP client. The XMLHTTP object provides an interface between your application, which is a Web page containing JScript, and any other site over HTTP. We will use this page to post an XML document to a server. The big advantage to using HTTP is that posted data travels through firewalls without any modification. That means you can get information from your trading partners by using XML just as easily as through traditional HTML forms.

In the second part of our example, we will create a SOAP server and a Web service using a non-Microsoft product, OmniMark. OmniMark runs on Microsoft Windows platforms, but it also runs on many flavors of UNIX, including Linux. The point of including this product is to show you that a Web service is accessible through multiple platform/language combinations over the Web.