rsp
Introduction: A Java library for building real-time user interfaces and UI components.
Tags:
Welcome! This is a server-side Java UI toolkit for admin panels, internal tools, and live web applications. Components keep state and run event handlers on the server; the browser receives initial HTML and small DOM updates over WebSocket.
- plain Java with constructor injection and no annotation-driven lifecycle;
- typed component state, intents, context, and events;
- no third-party runtime dependencies in the framework modules;
- optional compositions, schema, authorization, telemetry, dashboard, and agent modules.
Smallest Interactive Application
import rsp.component.ComponentView;
import rsp.component.definitions.LocalStateComponent;
import rsp.http.WebServer;
import static rsp.dsl.Html.*;
public final class Counter {
private enum CounterIntent { INCREMENT }
static void main(String[] args) {
ComponentView<Integer, CounterIntent> view = intents -> state ->
html(body(
h1("Current count: " + state),
button(on("click", _ -> intents.dispatch(CounterIntent.INCREMENT)),
text("Increment"))));
WebServer server = new WebServer(8080, _ ->
new LocalStateComponent<>((_, _) -> 0, view,
(state, intent) -> state + 1));
server.start();
server.join();
}
}
The server renders the first page, the browser opens a WebSocket, and subsequent events run Java handlers that produce targeted DOM patches. Application state does not need to be duplicated in a JavaScript frontend.
Try The Repository
Requirements: Java 25 and Maven 3.8.7 or newer.
git clone https://github.com/vadimv/server-components.git
cd server-components
mvn clean install
mvn exec:java -pl examples -Dexec.mainClass=rsp.app.posts.CrudApp
Open http://localhost:8085 and select Sign in. The default agent is a deterministic local stub and requires no API key.
