hop-sdk

Client SDK for the Polkadot HOP protocol — send and claim data through ephemeral off-chain storage on Polkadot.

HOP is an ephemeral off-chain data pool hosted by Bulletin Chain collators. The sender uploads data to a collator, signals the receiver through the statement store, and the receiver claims it directly — no on-chain transaction required.

Quick start

use hop_sdk::{HopClient, HopEnvironment};

let client = HopClient::connect(HopEnvironment::Previewnet)?;

// Send
let data = b"hello HOP".to_vec();
let tickets = client.send(data, 1)?;

// Claim
let ticket = tickets.into_iter().next().unwrap();
let received = client.claim(ticket)?;

assert_eq!(received, b"hello HOP");
client.destroy();

API overview

`HopClient`

Method	Description
`connect(env: HopEnvironment) -> Result<HopClient, HopError>`	Connect to a HOP network by environment name
`send(data: Vec<u8>, recipient_count: u32) -> Result<Vec<Arc<HopTicket>>, HopError>`	Send data into the pool (max 64 MiB). Returns one ticket per recipient.
`claim(ticket: Arc<HopTicket>) -> Result<Vec<u8>, HopError>`	Claim data from the pool using a ticket
`destroy(&self)`	Release resources held by this client

`HopTicket`

Method	Description
`encode(&self) -> Vec<u8>`	Serialize to raw bytes
`decode(data: Vec<u8>) -> Result<HopTicket, HopError>`	Deserialize from raw bytes

Environments

`HopEnvironment`	Network	Notes
`Local`	Local dev node	For development against a local omni-node
`Previewnet`	Polkadot Previewnet	For products

Node endpoints are hardcoded per SDK release.

Error handling

All errors are represented by the HopError enum:

Variant	When
`DataTooLarge`	Data is empty or exceeds 64 MiB
`PoolFull`	The pool has no remaining capacity
`NotFound`	The requested entry does not exist in the pool
`InvalidTicket`	Ticket bytes are malformed or have wrong length
`Network`	Transport-level failure (connection refused, timeout, etc.)
`QuotaExceeded`	Rate or usage quota exceeded

UniFFI (mobile bindings)

To generate Kotlin/Swift bindings via UniFFI, enable the uniffi feature:

hop-sdk = { version = "0.1", features = ["uniffi"] }

This is not needed for pure Rust consumers.

Examples

See the examples/ directory for complete runnable programs.

License

Apache-2.0

hop-sdk 0.1.0