What is Polkadot’s Join-Accumulate Machine?

In its current form, the Polkadot ecosystem and its parachains are built around the “layer 0” known as the Relay Chain, but the JAM Upgrade proposes a modern alternative which will be more similar to a traditional smart contract chain.

JAM, short for Join-Accumulate Machine, was unveiled by Polkadot co-founder Gavin Wood in April at Token2049 in Dubai with the introduction of its Graypaper, which acts as JAM’s litepaper.

JAM aims to provide Polkadot with scalability similar to that of a Layer 2 (L2) network, but without the need for rollups, through a simplistic and modular design that features enhanced smart contract capabilities.

By combining Polkadot’s parachain architecture with smart contract functionality, the JAM upgrade will result in a comprehensive, decentralized network that acts similarly to a blend between Polkadot as we know it and Ethereum with the addition of ZK-Rollups.

Unlike other smart contract chains, JAM will operate without transactions, and instead, all of the actions on the chain are completely permissionless through its “Refine” stage, which makes the chain functionality more efficient.

Through the Refine process, actions and their input data are interpreted into “work reports” and their corresponding results; these results are then transferred directly onto the chain, as opposed to the process taking place directly on JAM.

JAM presents a more simplistic approach through its non-upgradable design, compared to the Relay Chain, which bears complex functions and their predecessors. The Relay Chain’s reliance on complex functions can result in unnecessary complications for developers, and with a more simplistic design, upgrades can be implemented easily.

The upgrade also looks to improve Polkadot’s transactions per second (TPS) count by up to 180 times to nearly 270,000, compared to its current maximum rate of just 1,500, according to Chainspect.

The upgrades will be gradual, could take as long as five years to be fully completed, and are expected to have minimal impact on individual parachain ecosystems, but may enable innovative use cases and opportunities for both new and existing parachains.