Block Node Types and Tiers
Overview
Block Nodes can offer many services and features. The core system encompasses a wide array of flexible options made possible by composing relatively small and focused "plug-ins" within a framework designed to support very low latency processing of high volume block stream data. There are many "types" of block nodes discussed in various places, each of which is actually the same core block node, with different combinations of "plug-ins" deployed. This demonstrates the flexibility of the block node system to meet a specific set of needs, but the many names and terms also leads to much confusion. This document seeks to better define the various terms and names, as well as provide a visual representation of where different block node instances might fit into an example network.
This document is intended for a general audience, and does not describe the technical details of operation, access, internal "plug-ins" deployed, facilities or any other internal detail. This document, instead, focuses on services offered and operating intent.
Block Node Types and Tiers Visualized
Definitions
Block StreamA continuous stream of consensus network data organized into blocks. Blocks are independent, self-contained, chained, and cryptographically verifiable units of data.Block NodeA software system that enables processing of block stream data for a wide variety of purposes and in myriad ways. A Block Node may be deployed with any, or many, set or subset of service plugins built to provide specific capabilities within the context of processing the block stream.Mirror NodeA service available in Hiero networks that provides extensive history and query capabilities for that network. A Mirror Node is a client of one or more Block Nodes, which deliver the block stream to the Mirror Node for indexing, storage, and related purposes.Consensus NodeOne node in the consensus network of an Hiero network. Consensus Nodes perform the critical work of executing the network consensus algorithm, executing transactions in consensus order, maintaining a current network state, and producing the Block Stream.Private SphereAn Hiero network operated on behalf of a private entity. Also a commercial service offered by Hashgraph Foundry Inc.Block Node ServicesFull HistoryA service provided by some block nodes that choose to make available the entire history of the associated Hiero network, from genesis (or general availability in the case of the Hedera network).Partial HistoryA service provided by some block nodes that choose to make available a subset of the history of the associated Hiero network, starting from a particular block, or for a particular duration, or based on other criteria.Private ArchiveA service provided by some block nodes that receive the block stream and store the data in an archive for the benefit of a particular entity, rather than the network as a whole. Examples include cloud buckets, long-term tape, or replicated local disks. Private archives are often intended for disaster recovery or offline analysis.Custom AnalysisA theoretical service provided by a block node specialized to perform some form of data analysis in, or near, real time.General Interledger BridgeA theoretical service provided by a block node specialized to bridge an Hiero network to another general-purpose network, such as Cardano, Base, Ethereum, etc...Dapp SupportA theoretical service provided by a block node specialized to support only the requirements of a specific distributed application.Defined FilterA theoretical service provided by a block node specialized to filter the block stream according to well-defined criteria, producing a modified block stream with un-desired or private data removed. Critically, the filtered stream is _still verifiable_ using the Block Proof for each block.Block Node TypesRolling-HistoryA type of node that chooses to manage only "recent" history. May offer other services that do not require more than a day (or other limited duration) of locally stored history. Most Tier 2 nodes are expected to be this type of node. A "Private Archive" service could be provided by this type of node. Rolling-History provides a particular type of "Partial History" service.Full NodeA type of node that chooses to manage all history and state. Also offers state management, state proof, content proof, query, hiero-inter-ledger bridge, and other core services. This type of node may also offer almost any array of custom block node services.Light NodeAnother type of "Rolling-History" or other "Partial History" node. A Light Node is a good option for developing and testing new block stream based services, or providing services that do not require the full history of the network.Private-CloudAnother name for a block node that serves a Private Sphere. This type of node could provide almost any service, or only very few.Archive ServerA theoretical type of node that provides a client-only service. Reads blocks from an archival source and delivers them on demand. This type of Node does not stream data or provide state management.Community NodeA Block Node operated by any entity other than a network council member or an entity contracted by the network council to operate block nodes.Block Node TiersTier 1A Block Node that receives its Block Stream data directly from Consensus Nodes. Tier 1 Block Nodes are critical to the operation of the Consensus Network, and it is expected that, eventually, each Consensus Node operator will need to run their own Tier 1 Block Node in a "Full Node" configuration.Tier 2A Block Node that receives its Block Stream data from another Block Node (often a Tier 1 Block Node). The data may be received via direct stream, network gossip, file transfer, or any other mechanism desired. Tier 2 Block Nodes are still required to verify the Block Stream received, but are not required to store the full history of the network or provide a Full Node configuration. Some Tier 2 nodes may, nonetheless, _choose_ to operate a Full Node configuration and offer Full History services.
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