With this sample you can connect and control LEDs and Electrical valves by ESP8266 (NodeMCU - Arduino) via Wi-Fi in your Android devices.
Android application can created by NIO as simple applets.
Get NIO from this link: http://niomatic.com
Implement web socket server in an ESP8266. Command send from NIO to ESP in the JSON structure via Websocket.
Parse Json:
JsonObject &root = jsonBuffer.parseObject(payload);
bool led_mod = root["led"];
bool water_mode = root["water"];
Download esp8266 greenhouse.nio and open in your tablet.