Chapter 4. XML and Web Services Fundamentals

Part I of this book introduced St. Matthews (our business case), the key concepts and objectives for Service-Oriented Architecture, the industry standards, and the Oracle product portfolio for implementing SOA. At the end of Chapter 3, we installed the SOA Suite and got our first SOA application running by publishing the obligatory HelloWorld Web Service.

Before we start developing much more complex SOA applications, we need to establish a little foundation, consisting of XML, XSD, and WSDL. Of course, XML is the lingua franca for all messages and most contracts, definitions, configurations, and even programs in our service-oriented world. XSD (XML Schema Definition) is the data-modeling language for describing the structure of XML documents, and WSDL (Web Service Definition Language) is the language for describing service interfaces. This chapter provides only a quick introduction to these three key languages. You may want to check out some of the resources mentioned on the wiki to get a little more background on XML, XSD, and WSDL.