Popular understanding of TCP 3-time handshake

Read many articles about TCP Handshake articles , I don't know if it's a problem I understand , I felt I understood at that time , But then I forgot , Never form a deep impression in your head , So I decided to use the examples of my daily life to deepen my understanding of TCP The memory of shaking hands , I call it the takeout principle （ Hey , Self created ）.

Take-away little elder brother , Corresponding client
customer , Corresponding server

The first handshake ：
The delivery boy called to tell the customer that the order will be in 30 Minute service , Ask the customer if they can accept ？

The second handshake ：
The customer replied that he had time to pick up the takeout .

The third handshake ：
The delivery boy called to tell the customer that he had arrived at the designated place , Invite the customer to pick up the meal .

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I wrote the above several years ago , Now I found something wrong , Because in the example, if you make a phone call , So the two have established communication , So it doesn't conform to TCP Handshake mechanism of , It is suggested to change to sending text messages , I also think it's quite reasonable , Revised as follows

The first handshake ：
The delivery boy sends a text message to tell the customer that the order will be in 30 Minute service , Ask the customer if they can accept ？

The second handshake ：
The customer replied by SMS that he had time to pick up the takeout .

The third handshake ：
The delivery boy sends a text message to tell the customer that he has arrived at the designated place , Invite the customer to pick up the meal .

3 The handshake is done , You can wait for the communication , Customers pick up food at the designated place , See the delivery boy , Say hello （ Start communicating ）, Take out , Communication complete