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JSON-RPC

Introduction

Gevulot devnet provides a minimalist JSON-RPC API for end user interfacing. It allows for the creation and observation of transactions.

Operations

sendTransaction

sendTransaction operations allow users to submit a transaction for execution. Currently the devnet supports Deploy and Run transaction types.

getTransaction

getTransaction operations allow users to fetch any transaction for a given hash. The return value contains all details of a transaction, excluding related file data.

getTransactionTree

getTransactionTree returns a full transaction tree for a given hash that is part of an execution of a Run transaction.
Run transactions contain a workflow that is executed to generate a proof and then verify it. Each step results in a new transaction referring to the parent transaction. The result of a whole execution is a tree of transactions.

Rust Client

The Gevulot node crate provides types for easily working with transactions and an RPC client to communicate with the servers.

Construct client

Client construction is simple:
use gevulot_node::rpc_client::RpcClient;
// ...
let url = "http://node.address.example.com:9944"
let client = RpcClient::new(url);

Build a transaction

Deployment

This section assumes you have built program images for prover & verifier as described in the Development section. In order to deploy them, files must be available from an HTTP server and a BLAKE3 checksum must be calculated for them.
Given those details, a deploy transaction can be built as follows:
use gevulot_node::{
types::{
transaction::{Payload, ProgramMetadata},
Hash, Transaction,
},
};
use libsecp256k1::SecretKey;
use std::path::Path;
fn compute_file_hash(path: &Path) -> Hash {
// First compute BLAKE3 hash for the program image file.
let mut hasher = blake3::Hasher::new();
let fd = std::fs::File::open(&img_file).expect("open");
hasher.update_reader(fd).expect("checksum");
hasher.finalize()
}
fn build_program_metadata(name: &str, img_path: &Path) -> ProgramMetadata {
let img_file_name = img_path.file_name().unwrap().to_str().unwrap().to_string();
// Then construct the program metadata struct.
let mut prover_program_metadata = ProgramMetadata {
name: "example-prover".to_string(),
hash: Hash::default(),
image_file_name,
image_file_url: format!("http://my.example.com/images/{}", img_file_name),
image_file_checksum: compute_file_hash(img_path),
};
// Compute the program hash.
program_metadata.update_hash();
program_metadata
}
fn construct_deployment_tx(private_key: &SecretKey, name: &str, prover_img_file: &Path, verifier_img_file: &Path) -> Transaction {
// Construct the transaction with deployment payload.
Transaction::new(Payload::Deployment{
name: name.to_string(),
prover: build_program_metadata(format!("{}-prover", name), prover_img_file),
verifier: build_program_metadata(format!("{}-verifier", name), verifier_img_file),
}, &private_key)
}

Run transaction

When a prover and a verifier have been deployed, they can be used to generate and verify proofs.
Run transaction can be created in the following way:
use gevulot_node::{
types::{
transaction::{Payload, ProgramData, Workflow, WorkflowStep},
Transaction,
},
};
// Assume prover_hash & verifier_hash are variables to deployed prover and verifier.
let proving_step = WorkflowStep {
program: *prover_hash,
args: vec!["--prover-arg".to_string(), "arg value".to_string()],
inputs: vec![ProgramData::Input {
file_name: "proof_inputs.dat".to_string(),
file_url: "http://rollup.example.com/proof/inputs/3212".to_string(),
file_checksum: "886ace0f0ea0ddd53fca7f733586226b6ddbee7bcb769be71633d06e61ba36bc".to_string(),
}],
};
let verifying_step = WorkflowStep {
program: *verifier_hash,
args: vec!["--nonce".to_string(), nonce.to_string()],
inputs: vec![ProgramData::Output {
source_program: *prover_hash,
file_name: "/workspace/proof.dat".to_string(),
}],
};
let tx = Transaction::new(
Payload::Run {
workflow: Workflow {
steps: vec![proving_step, verifying_step],
},
},
&private_key,
);

Send transaction

Sending transactions is also straightforward:
client
.send_transaction(&tx)
.await
.expect("send_transaction");

Get transaction

Fetching known transaction:
let tx_hash = Hash::from("706c739440cd10ff7f8b20c4da722437ef42873607d66c320e1cef4d956f3512");
let tx = client
.get_transaction(&tx_hash)
.await
.expect("get_transaction");
if tx.is_some() {
dbg!(tx);
}

Get transaction tree

Fetch a transaction tree and print each transaction:
fn print_tx_tree(tree: &TransactionTree, indentation: u16) {
match tree {
TransactionTree::Root{ children, hash } => {
println!("Root: {hash}");
children.iter().for_each(|x| print_tx_tree(&x, indentation+1));
},
TransactionTree::Node{ children, hash } => {
println!("{}Node: {hash}", (0..indentation).map(|_| "\t").collect::<String>());
children.iter().for_each(|x| print_tx_tree(&x, indentation+1));
},
TransactionTree::Leaf{ hash } => {
println!("{}Leaf: {hash}", (0..indentation).map(|_| "\t").collect::<String>());
},
}
}
fn fetch_and_print_tx_tree() {
let tx_hash = Hash::from("706c739440cd10ff7f8b20c4da722437ef42873607d66c320e1cef4d956f3512");
let tx_tree = client
.get_tx_tree(&tx_hash)
.await
.expect("get_tx_tree");
print_tx_tree(&tx_tree, 0);
}

Full E2E example

The Gevulot node repo contains test code for full e2e test of deploying a prover & verifier and then executing a Run transaction:
The E2E example also contains embedded HTTP server for serving the program image files, when testing in local development environment.