NodeManager.md

Node Manager

Database

---

Active Node Database

CREATE TABLE nodes (
    ip VARCHAR(255) NOT NULL, 
    port VARCHAR(255) NOT NULL, 
    status VARCHAR(255) NOT NULL, 
    user VARCHAR(255) NOT NULL, 
    PRIMARY KEY(ip,port)
)

---

Working

Interaction With Deployer

• List of Active Nodes

  def get_active_node_list(message_content):
      if message_content == "node_list":
          active_node_list = fetch_active_nodes()
          send_message = "{};{}".format('multiple', form_string(active_node_list))

  def fetch_active_nodes():
      mycursor.execute("select ip, port, user from nodes where status='active'")
      active_nodes = mycursor.fetchall()
  
      return active_nodes

• Asking For new Node to run Application

  def get_active_node_list(message_content):
      elif message_content == "new_node":
  
          new_node = create_new_node()
          set_active(new_node)

  #create and send the new node. <ip and port>
  def create_new_node():
  		
      mycursor.execute("select ip, port, user from nodes where status='free' limit 1;")
      free_node = mycursor.fetchall()
      
      return free_node

  def set_active(ip, port,user):
  
      Q = "update nodes set status = 'active' " + \
  				"where ip = '{}' and port = '{}' " + \
  				"and user = '{}';".format(ip,port,user)
  		
      mycursor.execute(Q)

---

Interaction With Node

• Insert New Node to Database

  def insert_free_node(ip, port, user):
  
     if Node_Exists:
          Q = "update nodes set status = 'active'" + \
              " where ip = '{}' and port = '{}' " + \ 
              "and user = '{}';".format(ip,port,user)
  
          mycursor.execute(Q)
  
      else:
          Q = "insert into nodes " + \
              "values('{}', '{}', '{}', '{}');".format(ip,port, "free", user)
  
          mycursor.execute(Q)
  		

---

Interaction With Fault Tollerance

• Delete Node from Database

  def set_deleted(ip, port):
      Q = "update nodes set status = 'deleted' " + \
          "where ip = '{}' and port = '{}';".format(ip,port)
  
      mycursor.execute(Q)