RMI WebSocket provides a library for remote method invocations between a browser and a Jetty Web Server using the HTML5 WebSocket. The idea is to enable tight method-level integration between the user interface and the server so that patterns such as MVP (Model-View-Presenter) can be applied in a Web environment. The method-level communications between the browser code and the server code allows the developer to think about the Web page and server-side components as objects in a UML world. Details such as the over-the-wire protocols in WebSockets are abstracted away in the process.
msg-rpc provides bidirectional RPC support over a simple message interface such as WebSocket. Tere are WebSocket examples based on socket.io and sockjs. It just has a simple sendMessage/onMessage interface, with no other dependencies. It supports not only normal RPC, but also RPC Service, which makes RPC pushable (i.e. the server can also send a request to the client and expect some kind of response).
MyRPC is a remote procedure call framework designed to easily connect heterogeneous systems. It features IDL-based client/server stub generation, multi-platform capability, binary protocol (no need for escaping of binary data, less overhead), support for various data types (like string, binary, signed and unsigned integer, float, list, struct, and enum), and exception support. It has no external dependencies.