rpc.md

#rpc.js

rpc.js

This holds the network protocol for the Off System and many of the procedures are identical to those found in Kademlia. Procedures have three parts. The first is the external class function calls by which a procedure is invoked and forms the initial request to the netowrk. The Second is the response handler which forms the response to requests received over the network. The third is the request handler this handles responses received from the network and return the final results to the invoker through a callback.

handlers

Handlers are formed and defined in the class constructor of the RPC Object. There is one generic handler for responding to network events. This peels back the outer layer of the protbuf message and forwards it on to the correct handler for the type of procedure it is. It also maintains the routing table buckets when messages are received.

###invocation functions These are methods on the RPC Object itself. They create request objects on the initiating node and set up their automatic timeout responses when network requests fail. These request objects contain the tracking variables needed to forward the request through each stage of the rpc.

message

message RPC {
  required RPCType type =1;
  required Peer from = 2;
  required Direction comType = 3;
  required bytes id = 4;
  optional bytes payload= 5;
  optional Status status = 6;
}

##Procedures There are seven procedures involved in the rpc for the off system.

   enum RPCType {
       Ping = 1;
       Find_Node = 2;
       Find_Value= 3;
       Store= 4;
       Random = 5;
       Promotion = 6;
       Ping_Value = 7;
   }

ping

Pings are the means by which connection to the network is tested and maintained. This predominately used to maintain the quality of the routing table buckets.

find_node

Find nodes is the means by which the routing table bucket is filed. When a node comes online it connects to bootstrap nodes and gathers the closest nodes to their nodeids until it is filled .

find_value

Find value is the means by which the network searches for contents. It gathers the nodes that are closest in hamming distance to a value's key and tries to travel down network topology by ever decreasing distance to find the value with that key.

store

When new values are created by a node it will attempt to store those values at the node closest in hamming distance to the key of that value and will attempt to travel down network topology by ever decreasing distance to find a node that will succesfully accept and store that new value.

random

This is the first rpc call that diverges from the kademlia style of dht rpc. The random is a call exclusive to off system's functionality that allows a node automatically and atruistically gather content from other nodes. This helps nodes gather content to optomize usage of space as a whole on the network and increase the speed of lookups for values on the dht. Furthermore, it means that when a node is storing content the likelihood of it having enough blocks stored on the node to create a full representation of a file is increased. A list of held blocks is sent to be excluded is sent with each request to other nodes to avoid redundant responses. Responding nodes return values that are the most popular they have available

promotion

This is the second divergent rpc call. Promotion is the means by which blocks determine which values are the most popular on the network and help reduce the amount of network searches are needed to recover the full representations of a file. The node's block cache has a means of recording how popular a certain block is at being used on it. When a value reaches a certain threshold of hits it is promoted to a higher rank making it more likely to be selected for the representation of a newly stored file. When new ranks of popularity are created by the use of a block they a propagated through out the network. This causes nodes to search for this new popular content and draw it into the storage. This increases the likelihood of a cache hit when retrieving representation at all nodes.

ping_value

Ping value is primarily a method to judge the current state of a value's storage on the network. Nodes use this as a method of determining whether its safe to delete a value from their block cache.