diff --git a/OKexProviderPublic.cs b/OKexProviderPublic.cs
new file mode 100644
index 0000000..d1607b0
--- /dev/null
+++ b/OKexProviderPublic.cs
@@ -0,0 +1,132 @@
+using Neo;
+using Neo.SmartContract;
+using Neo.SmartContract.Framework;
+using Neo.SmartContract.Framework.Native;
+using Neo.SmartContract.Framework.Services;
+using System;
+
+namespace PriceFeedServicePublic
+{
+    [ManifestExtra("Description", "OKex Provider")]
+
+    public class OKexProviderPublic : SmartContract
+    {
+        public const string Prefix_Price_URL = "https://www.okex.com/api/v5/market/mark-price-candles?bar=1m&limit=1";
+        public const string Prefix_Price_InstId = "&instId=";
+        public const string Prefix_Price_Time = "&after=";
+        // { "code": "0", "msg": "", "data": [["1597026360000","11983.2","11988.5","11980.2","11988.2","26.43284234","316742.81553508"]]}
+        public const string filter = "$.data[0][4]";
+        public const long gasForResponse = Oracle.MinimumResponseFee; // TBD
+
+        private const byte Prefix_Symbol = 0x02;
+        private const byte Prefix_Block = 0x03;
+        private const byte Prefix_Price = 0x04;
+
+        [InitialValue("NUjRiSuVGYZAD9gJWFGn4tmCBHfyoWfrTF", ContractParameterType.Hash160)]
+        private static readonly UInt160 Owner = default; //  Replace it with your own address
+
+        private static StorageMap Symbols => new(Storage.CurrentContext, Prefix_Symbol);
+
+        public static void _deploy(object data, bool update)
+        {
+            if (update) return;
+            Symbols.Put("GAS-USDT", 0);
+            Storage.Put(Storage.CurrentContext, new byte[] { Prefix_Block }, 0);
+        }
+
+        public static uint GetPriceRequest(string symbol) // "BTC-USDT"
+        {
+            uint blockIndex = Ledger.CurrentIndex;
+            ulong timestamp = Ledger.GetBlock(blockIndex).Timestamp;
+            string symbolUrl = Prefix_Price_URL + Prefix_Price_InstId + symbol + Prefix_Price_Time + timestamp;
+            Oracle.Request(symbolUrl, filter, "getPriceCallback", blockIndex + "#" + symbol, 100000000);
+            return blockIndex;
+        }
+
+        public static void GetPriceCallback(string url, string userdata, OracleResponseCode code, string result)
+        {
+            if (Runtime.CallingScriptHash != Oracle.Hash) throw new Exception("No authorization");
+            if (code != OracleResponseCode.Success) throw new Exception("Oracle response failure with code " + (byte)code);
+
+            object[] arr = (object[])StdLib.JsonDeserialize(result); // ["11988.2"]
+            string value = (string)arr[0];  // string currentPrice
+            string[] data = StdLib.StringSplit(userdata, "#");  // string blockIndex, string symbol
+            UpdatePrice(data[0], data[1], value);
+        }
+
+        private static void UpdatePrice(string blockIndex, string symbol, string currentPrice)
+        {
+            if (Symbols[symbol] is null) throw new Exception("Symbol has not registered.");
+            Storage.Put(Storage.CurrentContext, new byte[] { Prefix_Block }, blockIndex);
+            byte[] key = Helper.Concat((byte[])GetKey(symbol), (byte[])GetKey(blockIndex));
+            StorageMap priceList = new(Storage.CurrentContext, Prefix_Price);
+            priceList.Put(key, currentPrice);
+        }
+
+        public static string GetPrice(string symbol, string blockIndex)
+        {
+            if (Symbols[symbol] is null) throw new Exception($"Symbol has not registered.");
+            byte[] recordKey = Helper.Concat((byte[])GetKey(symbol), (byte[])GetKey(blockIndex));
+            StorageMap priceList = new(Storage.CurrentContext, Prefix_Price);
+            if (priceList[recordKey] is null) throw new Exception("The price of the symbol and blockIndex does not exist");
+            return priceList[recordKey];
+        }
+        public static string GetPrice(string symbol)
+        {
+            if (Symbols[symbol] is null) throw new Exception($"Symbol has not registered.");
+            byte[] recordKey = Helper.Concat((byte[])GetKey(symbol), (byte[])GetKey(BestBlockIndex()));
+            StorageMap priceList = new(Storage.CurrentContext, Prefix_Price);
+            if (priceList[recordKey] is null) throw new Exception("The price of the symbol and blockIndex does not exist");
+            return priceList[recordKey];
+        }
+
+        public static void Update(ByteString nefFile, string manifest, object data)
+        {
+            if (!IsOwner()) throw new Exception("No authorization.");
+            ContractManagement.Update(nefFile, manifest, data);
+        }
+
+        public static void Destroy()
+        {
+            if (!IsOwner()) throw new Exception("No authorization.");
+            ContractManagement.Destroy();
+        }
+
+        private static ByteString GetKey(string data)
+        {
+            return CryptoLib.ripemd160(data);
+        }
+
+        private static bool IsOwner() => Runtime.CheckWitness(Owner);
+
+        public static string BestBlockIndex() => Storage.Get(Storage.CurrentContext, new byte[] { Prefix_Block });
+
+        public static bool AddSymbol(string symbol)
+        {
+            if (!IsOwner()) throw new Exception("No authorization");
+            if (Symbols[symbol] is not null) throw new InvalidOperationException("The symbol already exists.");
+            Symbols.Put(symbol, 0);
+            return true;
+        }
+
+        public static bool RemoveSymbol(string symbol)
+        {
+            if (!IsOwner()) throw new Exception("No authorization");
+            if (Symbols[symbol] is null) throw new InvalidOperationException("The symbol does not exist.");
+            Symbols.Delete(symbol);
+            return true;
+        }
+
+        public static string[] GetAvailableSymbols()
+        {
+            List<string> ret = new();
+            Iterator symbolList = Symbols.Find(FindOptions.RemovePrefix | FindOptions.KeysOnly);
+            while (symbolList.Next())
+            {
+                ret.Add((string)symbolList.Value);
+            }
+            return ret;
+        }
+
+    }
+}