The Canonical Text Services protocol defines interaction between a client and a server program using the HTTP protocol: clients submit requests, with parameters included as HTTP GET parameters; the CTS response is structured in XML validating against the CTS reply schemas.
hessian.caucho.com Hessian is a binary Web service protocol that makes Web services usable without requiring a large framework, and without learning a new set of protocols [weasel words]. Because it is a binary protocol, it is well-suited to sending binary data without any need to extend the protocol with attachments.
JSON-RPC works by sending a request to a server implementing this protocol. The client in that case is typically software intending to call a single method of a remote system. Multiple input parameters can be passed to the remote method as an array or object, whereas the method itself can return multiple output data as well.
Web services exist all over the web and many are open to the public. If you’re fortunate, you might find one that meets your data requirements. If not, you could always build and host one yourself. The advantage of web services is that they are focused on a particular set of data, so you don’t have to filter out information that is of no use to you. For example, say you wanted a weather forecast.
SOAP (Simple Object Access Protocol) is a messaging protocol that allows programs that run on disparate operating systems (such as Windows and Linux) to communicate using Hypertext Transfer Protocol (HTTP) and its Extensible Markup Language (XML).
UDDI (Universal Description, Discovery, and Integration) is an XML-based registry for businesses worldwide to list themselves on the Internet. Its ultimate goal is to streamline online transactions by enabling companies to find one another on the Web and make their systems interoperable for e-commerce.