Homework 2 - SUB-POST PROTOCOL

HEADER

* CLIENT ID - String that identifies a client
* SYNC - BYTE value - representing the subject of the packet
* DATA_TYPE - BYTE value - representing message type
* TOPIC_LEN - BYTE value - representing the lenght of the topic which will be transmited after the header
* MSG_LEN - TWO BYTE value - representing lenght of the message

PAYLOAD

Can be empty or of varied lenghts depending on the SYNC field of the header

PACKET SUBJECT

* SEND_MSG
	Sent by the server when sending a message
	Format: | Header | UDP_CLIENT_ADDR | TOPIC | MESSAGE |
* START_CONN
	Send by the client after the TCP connection is established
	Format: | Header |
* SUBSCRIBE
	Send by the client to subscribe to a topic without Store and Forward
	Format: | Header | Topic
* SUBSCRIBE_SF
	Send by the client to subscribe to a topic with Store and Forward
	Format: | Header | Topic
* UNSUBSCRIBE
	Send by the client to unsubscribe from a topic
	Format: | Header | Topic
* REFUSE_CONN
	Send by the server when a second client tries to start a connection with the same id of a already connected client
	Format: | Header |