RESI

RESI is the Redundant Energy Services Interface project. The RESI project is an experimental repository has two contributions:

1. Gives a path toward a protocol specification for an ESI which allows extensions

2. A demonstration of an extension to the ESI which allows for redundant transports.

Extendable ESI

This repository proposes to design the ESI protocol such that it allows for future extension. The RESI uses SCTP1 as inspiration. To better allow future extensions to the ESI, RESI proposes that a special RPC is included in the ESI, called Modify:

service Esi {
  // ..
  rpc Modify (ModifyRequest) returns (ModifyResponse) {}
  // ..
}
message Extension {
  uint32 id = 1;
  bool pass = 2;
  bytes data = 3;
}
message ModifyRequest {
  Extension ext = 1;
}
message ModifyResponse {
  Extension ext = 1;
}

The Extension message can contain any bytes encoded message which may be implemented by an extending protocol. The id value is used to identify which extension the message belongs to, while the pass value indicates whether unrecognized extension messages should be passed to other ESI servers.

Redundant ESI

RESI allows for redundant transport connections between ESI gateways. The ideal method to achieve redundancy using RESI is to deploy two RESI gateways: one in front of end nodes, and another in front of users of the ESI.

At the moment, two transport protocols are aimed to be supported by the RESI extension: TCP and NKN2.

Configuring Redundancy

RESI supports three transportation methods:

1. ESI over TCP;
2. ESI over NKN;
3. ESI over a special RESI transport protocol

To configure the RESI gateway, pass in a -config flag which points to a TOML flavoured configuration file:

# At least one of [tcp] or [nkn] must be present for RESI to function correctly.

# If the [tcp] section is not configued, RESI will not attempt to use TCP.
[Tcp]
Address = "127.0.0.1:9000" # IPv4 or IPv6
Listen = "localhost:4001"

# If the [nkn] section is not configued, RESI will not attempt to use NKN.
[Nkn]
Address = "919c54b38f907e82f030068c2c4a06239a2941f712306d9409474ebade479208"
Seed = "039e481266e5a05168c1d834a94db512dbc235877f150c5a3cc1e3903662d673"
Subclients = 4 # See NKN documentation for more details.

# RESI specific configuration options
[Resi]
# RESI can operate in either 'strict' or 'permissive' mode. In the default
# strict mode, identical data must be observed on all transports before it
# is passed through the gateway. This is considered the most reliable mode,
# although is not always beneficial and necessarily implies that the transport
# will be as slow as the slowest underlying protocol.
#
# In permissive mode, the RESI gateway will wait for the data to arrive on one
# of the transports and disregard any duplicate data that arrives in the
# future.
Mode = "strict"