Atlas is a protocol i.e. a contract between two peers on how to transmit information. Atlas is meant to be used in creation of multi user environments and especially multi user role playing games. Atlas was developed to meet the protocol requirements of the WorldForge project.
Currently Atlas is transported over TCP/IP. Atlas is also used as storage file format in some WorldForge solutions.
When two peers begin communication with Atlas they first announce their type and then negotiate the atlas codec to use. See Atlas Handshake.
Codec is the way the in memory model of Atlas objects are encoded to byte stream which can be transmitted over the transport layer. See Atlas Codecs.
Protocol is the contract between the peers about what kind of message structure (object model) is used and what are the meanings of different messages and values. Atlas protocol consists of the type definitions defined in machine readable format at atlas.xml . See Atlas Protocol, Atlas Operations and Atlas Entities.