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• x Please comment your code so I can read it well.
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Steps involved:

1. 1. Initialization
2. 2.   Ping Mechanism
3. 3.   File Request
4. 4.   Peer Churn.

 

(Example shown in brackets).

 

Input and Initialization Specifications:

• Takes in 3 integer arguments. (e.g. java cdht 1 42 58)
• First argument ("1") is the identity of the peer to be initialized
• Second argument is successor1,
• Third argument is sucessor2 ("42" and "58") are the two successive peers.

Notes:

• Max 10 peers.
• Identities of peers in the range of [0, 255].
• Use local host as IP Adress ("127.0.0.1")
• Use UDP protocol at port 50,000 + x for x = peer number (First argument)

Ping Mechanism

• My understanding is that a peer regularly pings its successive peers (42 and 58) via their port numbers (50,042 and 50,058) and receives back a response.
• When receiving either a request or response please output a string:
  "A ping response/request was received from peer X" where X is the peer's identity (1, 42, 58)

File Request

• Assume peer 1 is looking for a file 59, he types the string: request 59.
• This forwards on to its successor1 (peer 42).
• Peer 42 checks if 59 < it's successor1 identity (58) --> No.
• Peer 42 then passes the request to Peer 58.
• Peer 58 checks 59 against it's successor1 identity (e.g. 63) --> Yes
• Peer 58 sends a response through its predecessors back to peer 1 saying he has the file.

Peer Churn
Ungraceful Exit

• o Timeout function required so that if no response is received after 1 second of ping, the program seeks the alive successor's immediate successor. (peer 42 is dead, peer 1 requests peer 58 for its next successor)
• o   Peer closes connection to dead peer then connects to this new successor and keeps pinging it.
  (I imagine it will have to reshuffle so that peer 58 = successor1 and the new peer = successor2)

Graceful Exit

• o   Peer types in: quit
• o   This sends a message to its peers with its successors so they can change accordingly