Sequencing

Sequencing is the essential first step for handling your transactions. Think of it as an organizer that takes all incoming transactions, puts them in a clear order, and then groups them into batches. This process is vital for keeping everything consistent and making the chain run. Evolve uses a "Sequencing Interface" with key functions like submitting, retrieving, and verifying these transaction batches, ensuring smooth communication between the chain and the sequencing mechanism, which often acts as a bridge to the underlying network.

Sequencing Interface

Sequencing Interface defines a sequencing interface for communicating between any sequencing network and Evolve. The key functions of the interface are defined as shown below.

// Sequencer is a generic interface for a sequencer
type Sequencer interface {
 // SubmitBatchTxs submits a batch of transactions  to sequencer
 // Id is the unique identifier for the target chain
 // Batch is the batch of transactions to submit
 // returns an error if any from the sequencer
 SubmitBatchTxs(ctx context.Context, req SubmitBatchTxsRequest) (*SubmitBatchTxsResponse, error)

 // GetNextBatch returns the next batch of transactions from sequencer to
 // Id is the unique identifier for the target chain
 // LastBatchHash is the cryptographic hash of the last batch received by the
 // MaxBytes is the maximum number of bytes to return in the batch
 // returns the next batch of transactions and an error if any from the sequencer
 GetNextBatch(ctx context.Context, req GetNextBatchRequest) (*GetNextBatchResponse, error)

 // VerifyBatch verifies a batch of transactions received from the sequencer
 // Id is the unique identifier for the target chain
 // BatchHash is the cryptographic hash of the batch to verify
 // returns a boolean indicating if the batch is valid and an error if any from the sequencer
 VerifyBatch(ctx context.Context, req VerifyBatchResponse) (*VerifyBatchResponse, error)
}

It mainly consists of:

• SubmitBatchTxs relays the chain transactions from Evolve chain to the sequencing network
• GetNextBatch returns the next batch of transactions along with a deterministic timestamp
• VerifyBatch validates the sequenced batch

Sequencing Implementations

An implementation of the sequencing interface mainly acts as a middleware that connects Evolve chain and the sequencing layer. It implements the sequencing interface functions described above. There are several implementations of the sequencer available in Evolve:

• single-sequencer - The simplest and most widely used sequencing model, where a single node (the sequencer) is responsible for ordering transactions and producing blocks.
• based-sequencer - A decentralized sequencing model where transaction ordering is determined by the base layer, and every full node acts as its own proposer.