a) Describe what is meant by a web service and the role of WSDL in such services. Explain in your answer how this differs from sites offering a website through the use of HTML pages only.

b) What are the goals of a messaging protocol such as SOAP? How does such a protocol enable the provision of web services?

c) Explain what the difference is between stateful and stateless web services.

d) Consider a social media messaging platform such as Twitter. Explain whether this is a stateful or stateless service, and then discuss the advantages and drawbacks of implementing such a service with SOAP.