adding RPC client demo

Author: jkyberneees

src/main/java/samples/rpc/Client.java

@@ -0,0 +1,28 @@
+package samples.rpc;
+
+import realtime.pubsub.*;
+
+import java.util.logging.Logger;
+
+public class Client {
+
+    public static void main(String[] args) throws Exception {
+        var logger = Logger.getLogger(samples.ClientDemoMinimal.class.getName());
+
+        var accessToken = System.getenv("ACCESS_TOKEN");
+        var appId = System.getenv("APP_ID");
+
+        var config = new RealtimeClientConfig(()
+                -> String.format("wss://genesis.r7.21no.de/apps/%s?access_token=%s", appId, accessToken));
+        var client = new RealtimeClient(config);
+        client.connect();
+
+        client.waitFor("session.started").get();
+
+        var publishWaitFor = client.send("", "gettime");
+        var response = publishWaitFor.waitForReply().get()[0];
+        logger.info("Server Time: " + response);
+
+        client.disconnect();
+    }
+}