diff --git a/.gitignore b/.gitignore
index cf2b89c..ed0d000 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,4 @@ ReEncrypt.py
 src/temp_message_file
 src/temp_key_file
 src/client.db
+src/server.db
diff --git a/src/server.py b/src/server.py
index 5a25696..30481fe 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():
+    nothing = 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')
+        time.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