D-LAN

h1. Protocol core-core

This page describes the protocol used by D-LAN for network communication between cores.

See source:application/Protos/core_protocol.proto for message details.

!network_protocol.png!

h2. Parameters

Most parameters will be stored as constants in their component. The given values below are just for illustrate with an example, they will be defined in a empiric manner later.

|_.Name|_.Value |_.Unit|_.Explanation/Comments|

| _ChunkSize_ | 67108864 | [Byte] | (64 MB) |

| _LanSpeed_ | 52428800 | [Byte/s] | (50 MB/s) |

| _TimeRecheckChunkFactor_ | 4 | - | If the time to download a chunk exceeds _TimeRecheckChunkFactor_ * _ChunkSize_ / _LanSpeed_ the peers are rescanned to choose a better one (better download rate). For example : 4 * 64 / 50 = 5 second |

| _SwitchToAnotherPeerFactor_ | 1.5 | - | During the recheck of the peers to choose a better one the download rate of the candidate must be above the current * 1.5. |

| _DownloadRateValidTime_ | 1500 / _LanSpeed_ = 30 s | [s] | The download rate of a peer is only valid during this time after its last update. After that its rate is set to the maximum. | 

| _IMAliveFrequency_ | 10 s | [s] | The message _IMAlive_ is sent each 10s. |

| _NbDownloadThread_ | 3 | - | Number of concurrent downloading thread. |

| _BufferSize_ | 65535 | [Byte] | (64 KiB). This buffer is used when reading or writing a file. |

| _TCPSocketBufferSize_ | 65535 | [Byte] | (64 KiB). Used when data are received. See _QAbstractSocket::setReadBufferSize_. |

| _TCPPeerConnectionKeepAlive_ | 60 | [s] | (1 min). There's can be one or more connection to a certain peer, these connections are kept alive for a period of time. For each known peer there is a pool of connection.  |