Terminology

Glossary

Term	Description
Node Users	Business Layer Systems that communicate with one or more Nodes to send and receive messages to other Jurisdictions.
Node API	A set of APIs used to send and receive messages over channels.
Node	Service that provides the Node API, sends messages (after validating them) to a channel on behalf of a jurisdiction, and recieves then disburses messages sent to the jurisdiction over the channels. The Node is authorised (Node Accreditation) to send and recieve messages messages on behalf of the Jurisdiction. The node validates each messages to to ensure compliance with the channel policy (from the juridictional context). In other words, nodes are trusted by the accrediting body to apply local knowledge to the interpretation of channel policy in that jurisdiction. The Node is also a router. It decides which channel (Node Routing Policy) each valid message should be used to sent the message to the recipient Jurisdiction. Nodes also receive inbound messages, retrieves the associated document (object) and store these for Node Users, as well as notifying the appropriate Node when new messages have been received. Nodes act on behalf of jurisdictions and are authorised to do so by the jurisdiction (Node Accreditation). Messages are addressed to jurisdictions, not nodes. Node Users use the node to send a message to another jurisdiction, not nodes or channels. Node Operators may use trustbridge/intergov software (reference implementation) or they may create their own systems that comply with the open standards.
Channel	Implementation of an agreement between jurisdictions to exchange particular types of messages. Node Users should understand that all nodes on a channel can potentially see all messages posted to If there are multiple nodes acting on behalf of a jurisdiction, and subscribed to a particular channel, all of those nodes will receive all messages addressed to that jurisdiction that are posted to that channel. The “side-tree” protocol bundles multiple messages in a single message on the wire. It is up to the Node to unpackage these bundles. Other nodes, who are not the recipient (Nodes from other Jurisdictions) will NOT be able to access and unbundle these messages. The channel implementation MAY validate some aspects of the message, but the Node MUST send only valid messages to the channel. For example, a Channel Endpoint may reject messages with invalid sender or recipient juridisctions, or invalid message predicates.
Channel Policy	Rules, expressed in a common business language, that describe the acceptable use of the channel.
Channel Media	Append-only database where channel messages are written. Presumably a distributed database. Channel media are pan-jurisdictional (not owned or controlled by any one jurisdictions) and shared by all the nodes. Candidate technologies for Channel Media include public blockchaim and private blockchain (when each Jurisdiction has appropriate access for Channel Management and Operations. Channel media MAY convey cryptographic protocol characteristics to the channel e.g. non-repudiation Channel media technology is generally unspecified, to ensure Jurisdictions are free to negotiate the most appropriate technology for a given channel.
Channel Endpoint	Deployed system that can read and write to the channel media.
Channel API	Abstraction over channel media. Feature of the Channel Endpoint used by the IGL Node to send messages.
Channel Keys	Notional mechanism for restricting access (in particular write access) to legitimate channel endpoints.
Channel Operator	Party with access to the Channel Keys, who provides the Channel Endpoint.
Channel Manager	Party responsible for the channel. May have the ability to grant/revoke Channel Keys.
Channel Authentication	Mechanism to restrict access to the Channel API, So authorised Nodes can access the Channel Endpoint. Not to be confused with Node Authentication (restricting access to the Node to Node Users), Channel Keys (used to restrict access to Channel Media, to Channel Operators) or document issuer / verification mechanisms.

Notes