self describing values
making types self describing. flexible protocols for entities to agree
Mutliaddr is a set of rules for building and parsing self-describing network addresses which are simple, human readable, composable and efficient to parse and generate.
Each protocol is well defined and has a protocol code. There are interfaces
and primitives for developers to generate and parse
multiaddr addresses per protocol, which include transcoding from and to byte
and string.
The multistream protocol makes data streams - e.g. files, tcp streams, etc, .. - self described by prefixing the stream with the encoding type. The protocol is very well described here.
Based on the multistream representation and protocol, the multistream-select
makes it easy for two entities to agree which codec to use during the
communication. An example use case is when two hosts start a TCP and want to
agree in which format to encode the data stream. The protocol allows the hosts
to exchange the information about which codecs they support and agree upon one
to proceed with the data communication.
This flexible interface allows software to evolve without breaking changes and gives developers the interfaces to change and agree upon data stream encoding according to the cases and peers.
The multistream-select protocol is very simple and consist of 4 different
stages: greeting, in which one node claims using the multistream protocol
and its version; list, when a node requires the list of codecs supported by
the other entity; select and communication: the peers exchange data using a
codec which both know. The codec type is prepended to the data stream so that
the destination knows how to decode the data stream.