RAP reorients for remote platforms with version 2.0

The RAP project at Eclipse has completed a change of name and focus with the release of version 2.0. Formerly known as the "Rich Ajax Platform", the RAP developers considered that what they wanted to be delivering had a wider scope. Thus the project has transitioned from being a platform for browser applications to being "Remote Application Platform", a universal platform for remote objects based on the concept of half-objects split between server and client. That change sees the available remote targets expand from just the browser to include Tabris with native clients for iOS and Android.

Functionally, RAP splits its widgets between the client and server as half-objects. The server manipulates its object-graph of half-object widgets and those manipulations are transmitted to the client half of the object over HTTP and the JSON-based RAP protocol. The client takes responsibility for rendering its object-graph of the other half of the half-objects and rendering the transmitted changes, and, similarly transmits changes at the
The "Half Objects" model of RAP 2.0 client end back to the server.

The RAP Protocol was introduced in RAP 1.5 for communication between server and client; previously the connection was based on ad-hoc HTTP requests. In RAP 2.0 the protocol is now used between client and server. Because the platform now handles more than just browsers, the developers have expanded the client API to allow specific services to be accessed on the client. These include a JavaScript executor and loader, client information, URL launching, browser navigation and application exit confirmation. Communications have also moved to a server push model which allows for more responsive clients.

The developers have also made it easier to create custom widgets with new Java and JavaScript APIs which allow the server-side Java code to create a RemoteObject and the client-side JavaScript to access it via a rap object. The widget set has also been enhanced with support for touch-scrolling trees and tables on mobile devices, search field icons, enhanced theming and a reworked event system. For an overview of available UI components, consult the RAP Examples Demo and the Developers Guide.

Details of all the functional changes made are available on the RAP 2.0 New and Noteworthy page and a migration guide details changes, deprecations and deletions for existing RAP users. Five blog entries, created in the run up to RAP 2.0's release, cover the remote principles, API fundamentals, clients in 2.0, server push in 2.0 and custom widgets. The EPL-licensed platform is available to download as target components, tools and as an Eclipse IDE plugin. RAP 2.1 is currently planned for June 2013.

(djwm)