diff --git a/.gitignore b/.gitignore
index 1e6c292..ed0d000 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,3 +8,5 @@ example.py
 ReEncrypt.py
 src/temp_message_file
 src/temp_key_file
+src/client.db
+src/server.db
diff --git a/src/client.ini b/src/client.ini
new file mode 100644
index 0000000..04c5027
--- /dev/null
+++ b/src/client.ini
@@ -0,0 +1,3 @@
+[settings]
+server_address = "127.0.0.1:8000"
+version = 1.0
diff --git a/src/client.py b/src/client.py
index e69de29..7044b5f 100644
--- a/src/client.py
+++ b/src/client.py
@@ -0,0 +1,275 @@
+from fastapi import FastAPI, HTTPException
+import requests
+import os
+from typing import Tuple
+from tpre import *
+import sqlite3
+from contextlib import asynccontextmanager
+from pydantic import BaseModel
+import socket
+import random
+import time
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    init()
+    yield
+    clean_env()
+
+
+app = FastAPI(lifespan=lifespan)
+
+pk = point
+sk = int
+server_address = str
+node_response = False
+message = bytes
+
+
+def init():
+    global pk, sk, server_address
+    init_db()
+    pk, sk = GenerateKeyPair()
+    init_config()
+    # get_node_list(6, server_address)  # type: ignore
+
+
+def init_db():
+    with sqlite3.connect("client.db") as db:
+        # message table
+        db.execute(
+            """
+            CREATE TABLE IF NOT EXISTS message (
+                id INTEGER PRIMARY KEY,
+                capsule TEXT,
+                ct TEXT,
+                senderip TEXT
+            );
+        """
+        )
+
+        # node ip table
+        db.execute(
+            """
+            CREATE TABLE IF NOT EXISTS node (
+                id INTEGER PRIMARY KEY,
+                nodeip TEXT
+            );
+        """
+        )
+
+        # sender info table
+        db.execute(
+            """
+            CREATE TABLE IF NOT EXISTS senderinfo (
+                id INTEGER PRIMARY KEY,
+                ip TEXT,
+                publickey TEXT,
+                threshold INTEGER
+            )
+            """
+        )
+        db.commit()
+        print("Init Database Successful")
+
+
+# load config from config file
+def init_config():
+    import configparser
+
+    global server_address
+    config = configparser.ConfigParser()
+    config.read("client.ini")
+
+    server_address = config["settings"]["server_address"]
+
+
+# execute on exit
+def clean_env():
+    print("Exit app")
+
+
+# main page
+@app.get("/")
+async def read_root():
+    return {"message": "Hello, World!"}
+
+
+class C(BaseModel):
+    Tuple: Tuple[capsule, int]
+    ip: str
+
+
+# receive messages from node
+@app.post("/receive_messages")
+async def receive_messages(message: C):
+    """
+    receive capsule and ip from nodes
+    params:
+    C: capsule and ct
+    ip: sender ip
+    return:
+    status_code
+    """
+    C_tuple = message.Tuple
+
+    ip = message.ip
+    if not C_tuple or not ip:
+        raise HTTPException(status_code=400, detail="Invalid input data")
+
+    C_capsule = C_tuple[0]
+    C_ct = C_tuple[1]
+
+    if not Checkcapsule(C_capsule):
+        raise HTTPException(status_code=400, detail="Invalid capsule")
+
+    # insert record into database
+    with sqlite3.connect("message.db") as db:
+        try:
+            db.execute(
+                """
+                INSERT INTO message 
+                (capsule_column, ct_column, ip_column) 
+                VALUES 
+                (?, ?, ?)
+                """,
+                (C_capsule, C_ct, ip),
+            )
+            db.commit()
+            await check_merge(db, C_ct, ip)
+            return HTTPException(status_code=200, detail="Message received")
+        except Exception as e:
+            print(f"Error occurred: {e}")
+            db.rollback()
+            return HTTPException(status_code=400, detail="Database error")
+
+
+# check record count
+async def check_merge(db, ct: int, ip: str):
+    global sk, pk, node_response, message
+    # Check if the combination of ct_column and ip_column appears more than once.
+    cursor = db.execute(
+        """
+    SELECT capsule, ct 
+    FROM message  
+    WHERE ct = ? AND senderip = ?
+    """,
+        (ct, ip),
+    )
+    # [(capsule, ct), ...]
+    cfrag_cts = cursor.fetchall()
+
+    # get N
+    cursor = db.execute(
+        """
+    SELECT publickey, threshold 
+    FROM senderinfo
+    WHERE senderip = ?
+    """,
+        (ip),
+    )
+    result = cursor.fetchall()
+    pk_sender, T = result[0]
+    if len(cfrag_cts) >= T:
+        cfrags = mergecfrag(cfrag_cts)
+        message = DecryptFrags(sk, pk, pk_sender, cfrags)  # type: ignore
+        node_response = True
+
+
+# send message to node
+def send_message(ip: tuple[str, ...]):
+    return 0
+
+
+class IP_Message(BaseModel):
+    dest_ip: str
+    message_name: str
+    source_ip: str
+
+
+# request message from others
+@app.post("/request_message")
+async def request_message(i_m: IP_Message):
+    global message, node_response
+    dest_ip = i_m.dest_ip
+    message_name = i_m.message_name
+    source_ip = get_own_ip()
+    dest_port = "8003"
+    url = "http://" + dest_ip + dest_port + "/recieve_request"
+    payload = {"dest_ip": dest_ip, "message_name": message_name, "source_ip": source_ip}
+    response = requests.post(url, json=payload)
+    if response.status_code == 200:
+        data = response.json()
+        public_key = int(data["public_key"])
+        threshold = int(data["threshold"])
+        with sqlite3.connect("client.db") as db:
+            db.execute(
+                """
+        INSERT INTO senderinfo
+        (public_key, threshold)
+        VALUES
+        (?, ?)
+        """,
+                (public_key, threshold),
+            )
+
+    # wait to recieve message from nodes
+    for _ in range(10):
+        if node_response:
+            data = message
+            message = b""
+            # return message to frontend
+            return {"message": data}
+        time.sleep(1)
+
+
+# recieve request from others
+@app.post("/recieve_request")
+async def recieve_request(i_m: IP_Message):
+    global pk
+    source_ip = get_own_ip()
+    if source_ip != i_m.dest_ip:
+        return HTTPException(status_code=400, detail="Wrong ip")
+    dest_ip = i_m.source_ip
+    threshold = random.randrange(1, 6)
+    public_key = pk
+    response = {"threshold": threshold,"public_key": public_key}
+    return response
+
+
+def get_own_ip() -> str:
+    hostname = socket.gethostname()
+    ip = socket.gethostbyname(hostname)
+    return ip
+
+
+# get node list from central server
+def get_node_list(count: int, server_addr: str):
+    url = "http://" + server_addr + "/server/send_nodes_list"
+    payload = {"count": count}
+    response = requests.post(url, json=payload)
+    # Checking the response
+    if response.status_code == 200:
+        print("Success get node list")
+        node_ip = response.text
+        # insert node ip to database
+        with sqlite3.connect("client.db") as db:
+            db.executemany(
+                """
+                INSERT INTO node 
+                nodeip 
+                VALUE (?)
+                """,
+                node_ip,
+            )
+            db.commit()
+        print("Success add node ip")
+    else:
+        print("Failed:", response.status_code, response.text)
+
+
+if __name__ == "__main__":
+    import uvicorn  # pylint: disable=e0401
+
+    uvicorn.run("client:app", host="0.0.0.0", port=8003, reload="True")
diff --git a/src/node.py b/src/node.py
index 1f08167..c69be47 100644
--- a/src/node.py
+++ b/src/node.py
@@ -68,3 +68,52 @@ async def send_message(message: str):
     data = {"message": processed_message}
     response = requests.post(url, data=data)
     return response.json()
+
+
+import requests
+
+def send_heartbeat(url: str) -> bool:
+    try:
+        response = requests.get(url, timeout=5)  # 使用 GET 方法作为心跳请求
+        response.raise_for_status()  # 检查响应是否为 200 OK
+
+        # 可选：根据响应内容进行进一步验证
+        # if response.json() != expected_response:
+        #     return False
+
+        return True
+    except requests.RequestException:
+        return False
+
+# 使用方式
+url = "https://your-service-url.com/heartbeat"
+if send_heartbeat(url):
+    print("Service is alive!")
+else:
+    print("Service might be down or unreachable.")
+
+
+import asyncio
+from contextlib import asynccontextmanager
+from fastapi import FastAPI
+
+async def receive_heartbeat_internal() -> int:
+    while True:
+        print('successful delete1')
+        timeout = 10
+        # 删除超时的节点（假设你有一个异步的数据库操作函数）
+        await async_cursor_execute("DELETE FROM nodes WHERE last_heartbeat < ?", (time.time() - timeout,))
+        await async_conn_commit()
+        print('successful delete')
+        await asyncio.sleep(timeout)
+
+    return 1
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    task = asyncio.create_task(receive_heartbeat_internal())
+    yield
+    task.cancel()  # 取消我们之前创建的任务
+    await clean_env()  # 假设这是一个异步函数
+
+# 其他FastAPI应用的代码...
diff --git a/src/server.py b/src/server.py
index 5a25696..d030e2c 100644
--- a/src/server.py
+++ b/src/server.py
@@ -1,44 +1,137 @@
 from fastapi import FastAPI
 from fastapi.encoders import jsonable_encoder
 from fastapi.responses import JSONResponse
+from contextlib import asynccontextmanager
 from typing import Tuple, Callable
+import sqlite3
+import asyncio
+import time
+import random
 
-app = FastAPI()
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    init()
+    yield
+    clean_env()
+
+app = FastAPI(lifespan = lifespan)
+
+# 连接到数据库（如果数据库不存在，则会自动创建）
+conn = sqlite3.connect('server.db')
+# 创建游标对象，用于执行SQL语句
+cursor = conn.cursor()
+# 创建表: id: int; ip: TEXT
+cursor.execute('''CREATE TABLE IF NOT EXISTS nodes (
+                   id INTEGER PRIMARY KEY AUTOINCREMENT,
+                   ip TEXT NOT NULL,
+                   last_heartbeat INTEGER
+               )''')
+
+def init():
+    task = asyncio.create_task(receive_heartbeat_internal())
+
+def clean_env():
+    # 关闭游标和连接
+    cursor.close()
+    conn.close()
+
+@app.get("/server/show_nodes")
+async def show_nodes() -> list:
+    nodes_list = []
+    # 查询数据
+    cursor.execute("SELECT * FROM nodes")
+    rows = cursor.fetchall()
+    for row in rows:
+        nodes_list.append(row)
+    return nodes_list
 
 @app.get("/server/get_node")
 async def get_node(ip: str) -> int:
     '''
-    中心服务器与节点交互, 节点发送ip, 中心服务器接收ip存入数据库并将ip转换为int作为节点id返回给节点
-    params:
-    ip: node ip
-    return:
-    id: ip按点分割成四部分, 每部分转二进制后拼接再转十进制作为节点id
+    中心服务器与节点交互, 节点发送ip, 中心服务器接收ip存入数据库并将ip转换为int作为节点id返回给节点  
+    params:  
+    ip: node ip  
+    return:  
+    id: ip按点分割成四部分, 每部分转二进制后拼接再转十进制作为节点id  
     '''
-    # ip存入数据库, id = hash(int(ip))
-
     ip_parts = ip.split(".")
     ip_int = 0
     for i in range(4):
         ip_int += int(ip_parts[i]) << (24 - (8 * i))
+    
+    # 获取当前时间
+    current_time = int(time.time())
+
+    # 插入数据
+    cursor.execute("INSERT INTO nodes (id, ip, last_heartbeat) VALUES (?, ?, ?)", (ip_int, ip, current_time))
+    conn.commit()
+
     return ip_int
 
 @app.get("/server/delete_node")
 async def delete_node(ip: str) -> None:
-    # 按照节点ip遍历数据库, 删除该行数据
+    '''
+    param:
+    ip: 待删除节点的ip地址
+    return:
+    None
+    '''
+    # 查询要删除的节点
+    cursor.execute("SELECT * FROM nodes WHERE ip=?", (ip,))
+    row = cursor.fetchone()
+    if row is not None:
+        # 执行删除操作
+        cursor.execute("DELETE FROM nodes WHERE ip=?", (ip,))
+        conn.commit()
+        print(f"Node with IP {ip} deleted successfully.")
+    else:
+        print(f"Node with IP {ip} not found.")
 
-@app.post("/server/send_nodes_list")
+# 接收节点心跳包
+@app.post("/server/heartbeat")
+async def receive_heartbeat(ip: str):
+        cursor.execute("UPDATE nodes SET last_heartbeat = ? WHERE ip = ?", (time.time(), ip))
+        return {"status": "received"}     
+    
+async def receive_heartbeat_internal() -> int:
+    while 1:
+        print('successful delete1')
+        timeout = 10
+        # 删除超时的节点
+        cursor.execute("DELETE FROM nodes WHERE last_heartbeat < ?", (time.time() - timeout,))
+        conn.commit()
+        print('successful delete')
+        await asyncio.sleep(timeout)
+    return 1
+
+@app.get("/server/send_nodes_list")
 async def send_nodes_list(count: int) -> JSONResponse:
     '''
     中心服务器与客户端交互, 客户端发送所需节点个数, 中心服务器从数据库中顺序取出节点封装成json格式返回给客户端
-    params:
-    count: 所需节点个数
-    return:
-    JSONResponse: {id: ip,...}
+    params:  
+    count: 所需节点个数  
+    return:  
+    JSONResponse: {id: ip,...}  
     '''
     nodes_list = {}
-    for i in range(count):
-        # 访问数据库取出节点数据
-        node = (id, ip)
-        nodes_list[node[0]] = node[1]
+
+    # 查询数据库中的节点数据
+    cursor.execute("SELECT * FROM nodes LIMIT ?", (count,))
+    rows = cursor.fetchall()
+
+    for row in rows:
+        id, ip, last_heartbeat = row
+        nodes_list[id] = ip
+
     json_result = jsonable_encoder(nodes_list)
-    return JSONResponse(content=json_result)
\ No newline at end of file
+    return JSONResponse(content=json_result)
+
+@app.get("/server/clear_database")
+async def clear_database() -> None:
+    cursor.execute("DELETE FROM nodes")
+    conn.commit()
+
+if __name__ == "__main__":
+    import uvicorn  # pylint: disable=e0401
+
+    uvicorn.run("server:app", host="0.0.0.0", port=8000, reload=True)
\ No newline at end of file
diff --git a/test.py b/test.py
deleted file mode 100644
index 3b4e363..0000000
--- a/test.py
+++ /dev/null
@@ -1,6 +0,0 @@
-from gmssl import * #pylint: disable = e0401 
-
-sm3 = Sm3() #pylint: disable = e0602
-sm3.update(b'abc')
-dgst = sm3.digest()
-print("sm3('abc') : " + dgst.hex())
\ No newline at end of file