XINS is a technology used to define, create, and invoke remote APIs. XINS is specification-oriented. When API specifications are written (in XML), XINS will transform them to HTML-based documentation and Java code for both the client-side and the server-side. The communication is based on HTTP. XINS competes with the complex SOAP technology. Main design goals include simplicity, scalability, and testability. XINS is not only a specification technology, but also an application development framework. It offers transaction logging, unique log documentation, and active code generation.
Restlet is a REST framework for Java. It supports all REST concepts (Resource, Representation, Connector, Component, etc.) and is suitable for both client and server Web applications. It supports major Web standards like HTTP, SMTP, XML, JSON, WADL, and Atom. Many extensions are also available to integrate with Servlet, Spring, Jetty, Grizzly, Simple, JAXB, JAX-RS, JiBX, Velocity, or FreeMarker. A GWT version is also available.