MultiChain Blockchain Development: Private Ledgers with Streams and Assets

The MultiChain blockchain platform creates private, permissioned networks. Coin Sciences maintains MultiChain, and the code derives from Bitcoin Core. This guide explains how a MultiChain blockchain works, what you can build with it, how it compares with other private ledgers, and what to check before you depend on it.

Three things called "multichain"

Search results mix three unrelated things under this name:

• MultiChain the platform. This guide covers the platform.
• Multi-chain applications. These dApps run on several public chains at once; see multichain NFT platforms, multichain launchpads and the article on interoperability and layer 2 networks.
• Multichain the bridge. This cross-chain bridge, formerly called Anyswap, collapsed in July 2023. Its CEO had been detained in China in May 2023, and more than $120 million then left the bridge's contracts in unexplained transfers. The bridge has no link to the MultiChain platform, but the collapse shows the risk of a bridge that a few keys control.

How the MultiChain blockchain works

A MultiChain network starts from a parameters file, written by the command multichain-util create, that sets the block time, the maximum block size, the permission rules, the native currency and the mining rules. The default target block time is 15 seconds.

The command multichaind starts the first node, and other nodes join after an administrator grants them the connect permission. Applications control the nodes through a JSON-RPC API in the style of Bitcoin, or through the multichain-cli tool.

Permissions

MultiChain grants permissions per address. The permissions are connect, send, receive, issue, create (for streams), mine, activate and admin.

Chain parameters can require several administrators to agree on a change. For example, the admin-consensus-upgrade parameter sets the share of administrators who must approve a protocol upgrade, with a default value of 0.5. With these settings, no single administrator can take over the network.

Consensus: mining diversity

MultiChain does not use proof of work; permitted miners take turns to sign blocks in a round-robin order. The mining-diversity parameter limits how many blocks in a row one miner may create, so one node cannot control the chain.

This model suits a consortium of known members, but it tolerates fewer faults than Byzantine fault tolerant protocols, such as QBFT on Besu or the SmartBFT orderer in Hyperledger Fabric.

Native assets

One command issues an asset, and the protocol tracks assets in the UTXO model, as Bitcoin tracks coins. Holders can transfer assets and swap them atomically, and if the issuer allowed more issuance when creating the asset, it can create more units later. A MultiChain network can hold many assets without any token contracts.

Streams

A stream is an append-only list of items, each with keys and a publisher. Developers use streams as a key-value store, a time series or a document log.

Each node subscribes only to the streams it needs and indexes those streams for queries. Many MultiChain deployments use streams more than assets, for audit trails, document notarization and shared reference data.

Smart filters

MultiChain 2.0 added smart filters, which are JavaScript rules that every node runs to accept or reject a transaction or a stream item. Transaction filters check transactions, and stream filters check stream items.

A filter can enforce a rule such as "a transfer of this asset needs a second signature." Another filter can require stream items to match a JSON schema. Filters only validate data, and MultiChain has no general smart contract environment.

Community and Enterprise editions

Coin Sciences offers two editions, and nodes of both can run on the same network.

The Enterprise demo unlocks all features for development and testing, but a chain built with the demo works for three months after creation. Read restrictions and data purging matter for personal data, because Community nodes store every stream item they subscribe to.

MultiChain compared with other private ledgers

See Hyperledger development services, Quorum development and private blockchain development for those platforms.

MultiChain development steps

1. Model the data as assets, streams or both, and decide who publishes to each stream and who reads it.
2. Set the chain parameters and the permission scheme, including administrator consensus for governance.
3. Write smart filters for business rules and test them against edge cases.
4. Build an application layer that talks to nodes over JSON-RPC, keeps keys in a wallet or HSM, and indexes data for the user interface.
5. Deploy nodes at each participating organization, with monitoring and backups.

A focused registry or notarization system can reach a working pilot in a few weeks with one or two engineers. The chain itself needs little code, and most of the time goes into the application, the integrations and the governance agreement between participants. These figures are estimates, not quotes.

Risks to weigh

MultiChain development has slowed. The download page lists version 2.3.3 of MultiChain Community, released on May 16, 2023, as the latest release. The public GitHub repository shows its last commits in July 2022, and the user community is small.

Before you commit, ask Coin Sciences about its release plans and support terms. Design the application so that another ledger could replace MultiChain later. As with any private chain, compare the plan with a shared database that keeps signed audit logs, which may meet the need at lower cost.

Frequently asked questions