Definition
The Job Declarator is the moving part of Stratum V2 that actually carries a miner's transaction choices to the pool and gets them approved. It exists as two halves: the Job Declarator Client (JDC), which runs on the miner's side, and the Job Declarator Server (JDS), which runs on the pool's side. Together they implement the negotiation that lets a miner build its own block while still being paid through a shared pool.
The client (JDC)
The JDC sits between the local Template Provider and the pool. It pulls candidate templates from the node, declares the chosen transaction set to the pool, distributes the resulting jobs to downstream hashing devices, manages share submission, and broadcasts any block it finds. Because it runs locally, the operator, not the pool, controls which transactions are mined.
The server (JDS)
The JDS lives at the pool. It issues mining job tokens, acknowledges declarations, keeps an internal mempool so it can independently check the declared transactions, asks for any transactions it lacks, and publishes valid block submissions to the network. If the pool's JDS rejects shares that are demonstrably valid, the honest move for the miner is to fail over to another pool, which is exactly the incentive Stratum V2 is designed to create.
The Job Declarator is the enforcement layer of the broader Job Declaration Protocol, and it depends on a local Template Provider to supply the templates it negotiates over.
In Simple Terms
The Job Declarator is the moving part of Stratum V2 that actually carries a miner’s transaction choices to the pool and gets them approved. It…