A Web service usually uses HTTP to exchange data. Unlike a Web application, which is typically HTML over HTTP, a Web service is Extensible Markup Language (XML) over HTTP. A client sends a request in XML, and the server responds with an XML response. This XML can be Plain Old XML (POX), which is typically a nonstandard XML that only the client and server can make sense of, or it is standard Simple Object Access Protocol (SOAP).
A Representational State Transfer (REST) API is a service. A REST API differs from SOAP‑based Web services in the manner in which it is intended to be used. By using REST, the API tends to be lightweight and embraces HTTP. For example, a REST API leverages HTTP methods to present the actions a user would like to perform and the application entities would become resources these HTTP methods can act on. Although SOAP is not used, messages (requests and responses) are either in XML or JavaScript Object Notation (JSON).
The following sections contain information about the SOAP‑based and REST‑based Web services functionality that JADE provides.