Shaflo/P2P-Client

P2P-Client

• Protocol: TCP
• Port: 3333
• Type: Unstructed Network
• Join network over Lead Peer
• Peer list with max 4 Peers
• sending Messages in Byte Array
• Heartbeat (min. 1 per minute to leader)
• unique IDs for every Peer (1-25)

Messages

Join Network

new Client → Leader (EntryMSG):    
Tag: 1 (1 byte)  
Version: 0 (1 byte)  
IPv4+Port (6 byte)  

Leader → new Client (EntryResponseMsg):   
Tag: 2 (1 byte)  
Version: 1 (1 byte)  
ID (2 byte / Leader give IDs from 1-25)  
4 * IPv4+Port+ID (4 * 8 byte)  

Know other Peers

Peer1 → Peer2 (NodeRequestMsg):  
Tag: 3 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port+ID (8 byte)  

Peer2 → Peer1 (NodeResponseMsg):  
Tag: 4 (1 byte)  
Version: 1 (1 byte)  
4 * IPv4+Port+ID (4 * 8 byte)  

Heartbeat

Peer → Server (IAmAliveMsg):  
Tag: 5 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port+ID (8 byte)  

Search ID

Peer1 → Peer2 (NodeSearchMsg):  
Tag: 6 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port (6 byte)  
SourceID (2 byte / Peer who start search)  
SearchID (2 byte / given by Peer who start search)  
DestinationID (2 byte / PeerID who is searched)  

DestinationPeer → AskingPeer (IAmFoundMsg):  
Tag: 7 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port+ID (8 byte)    
SearchID (2 byte / copy from Tag 6 message)  

Message

Peer → Peer (TextMsg):   
Tag: 8 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port+ID (8 byte)  
LengthMsg (2byte / length from xbytes)  
Msg (xbyte)  

Leader Election

Peer → Peer (AreYouAliveMsg):  
Tag: 9 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port+ID (8 byte)  

Peer → Peer (IAmLeaderMsg):  
Tag: 10 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port+ID (8 byte)  

Time Synchronization

Leader → Peer (TellMeYourTimeMSG):  
Tag: 11 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port+ID (8 byte)  

Peer → Leader (HereIsMyTimeMSG):  
Tag: 12 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port+ID (8 byte)
Time (8 byte)  

Leader → Peer (HereIsYourNewTimeMSG):  
Tag: 13 (1 byte)  
Version: 1 (1 byte)  
IPv4+Port+ID (8 byte)
Time (8 byte)

Search Algorithm

• Peer fragt die Nachbarn
• Fall 1: Nachbar hat SearchID bekommen
• Fall 2: Nachbar hat SearchID nicht bekommen
  2.1 bin ich der Knoten?
  → Antwort an Suchenden
  2.2 Bin ich nicht der Knoten
  → Nachricht an alle meine Nachbarn, außer SuchendenListe

Leader Election (Bully Algorithm)

2 ways of starting leader election:

• we want (manually)
• we get Tag 9 message and answer with Tag 5

1. The Peer asks all higher IDs with Tag 9
2. If a higher ID answer with Tag 5, this peer will take the leader election. we are finish
3. We are leader, when we cannot find a peer with higher ID. We send Tag10 (IAmLeaderMessage) to all Peers

Time Synchronization

1. Leader asks every Peer for the time
2. Peers answer the Leader
3. Leader calculate the Time and tell tell the all Peers

Dictionary

SourceID: ID des suchenden Knoten
DestinationID: ID des zu suchenden Knoten
SearchID: eindeutige ID der jeweiligen Suche