Exercise 11: XML introduction

1. Conduct research on the Internet to find out what tools can be used to parse an XML document and ensure that the document is well formed and valid.
2. XML schema is a forthcoming development of the technology. Visit the W3C website and search for information on schema. What are the benefits of adopting a schema standardized for a business sector?
3. What are DOMs and why were they developed?
4. Why are some developers using SAX instead of DOM for document processing?
5. SMIL is an application of XML. What is the purpose of this technology? Where does it apply?
6. The current recommendation of W3C is to use XHTML as an alternative to HTML.
7. Do you think adopting XHTML is a wise move?

Dynamic Discovery of Web Services (UDDI) and Describing Them (WSDL)
We can define a Web Service with Web Services Definition Language (WSDL). WSDL is an XML language used to describe what SOAP systems offer and is similar in concept to writing interfaces with IDL – as the WSDL file can be stored in the registry and discovered by clients, and help with workflow automation. In Topic 6 you can learn more about RMI and CORBA, which SOAP complements and improves. WSDL is used to mark-up, advertise and automate Web services for client businesses using UDDI in Topic 7. The Universal Description Discovery Integration (UDDI) – is seen as the phonebook-style register for e-commerce, where small businesses can describe themselves, discover other businesses and look at integration of services.
It is here that we conclude Topic 5 with firm evidence of XML as a core technology for e-commerce and business applications development of Web services – storing data, and transporting data and messages to objects. Topic 5 also gives an introduction to SOAP and its practical uses in accessing resources beyond the firewall, such as Database servers, CORBA, RMI and EJB systems, as well as in exposing a web application as a stand-alone application in Web services.
SOAP is a god for developing lightweight distributed component applications – by wrapping existing applications, and in automated business processes.
No wonder SOAP is the lightweight challenger for the distributed objects crown – and a good way to introduce the other main distributed objects systems – RMI and CORBA, coming up next in Topic 6.