Resolvers (How to become a resolver)

This guide explains how to become a resolver (Market Maker) in the Omniston protocol and integrate with its gRPC API.

Overview

A resolver is a service that provides token exchange rates and executes trades. To become a resolver, you need to:

1. Register by obtaining a Soul-Bound Token (SBT)

2. Connect to the gRPC API

3. Handle quote requests and trades

Registration Process

Step 1: Generate Keys

First, generate one or more Ed25519 key pairs that will be used for authentication:

JavaScript implementation

Rust implementation

For other languages, you can use any standard Ed25519 implementation library available in your preferred programming language

Step 2: Prepare Metadata

Create a JSON document containing:

• Your resolver name

• Your public key(s)

Example:

{
  "name": "MyResolver",
  "publicKeys": [
    "b951254b184fae6906a61ab01e37296fbb28961494cacf7befac9f638fcfe40c",
    "9397ddd52a0d6033da4a32e654b4afbddcc5d832575e396c0a6f5b213faa199f"
  ]
}

Step 3: Submit Registration

Link to google form

1. Your metadata will be stored in an SBT NFT collection

2. You'll receive your SBT stake address for API authentication

Connecting to the API

Authentication

1. Create a connection payload:

message ConnectPayload {
  uint64 connect_timestamp = 1;  // Current timestamp in milliseconds
  string stake_address = 2;      // Your SBT stake address
}

1. Sign the payload:

• Serialize the ConnectPayload to bytes

• Sign using your Ed25519 private key

• Base64 encode the signature

1. Send a ConnectRequest:

message ConnectRequest {
  bytes payload = 1;    // Serialized ConnectPayload
  bytes public_key = 2; // Your Ed25519 public key
  bytes signature = 3;  // Signature of the payload
}

Example connection request:

{
  "connect": {
    "payload": "CPKnlt2xYxIwRVFDWFNzMnhaMmRoazlUQXh6R3pYcmEyRWJHX1MyU3F5TjhUZmk2Zko4MkVZaVZq",
    "public_key": "TAPsnPvWhlOvxEK19rONv4sueMeQzOzlrrIFUOKsi34=",
    "signature": "us7nMd9wmUOkuPk0otg6dvUojZwj8VcyXU6HD13BDQhVrzV8sKgyXtKze+9+j9FC1Ghxkx7Jo5FIDeE8ljbADQjyp5bdsWMSMEVRQ1hTczJ4WjJkaGs5VEF4ekd6WHJhMkViR19TMlNxeU44VGZpNmZKODJFWWlWag=="
  },
  "seqno": 1
}

Message Flow

The resolver API uses a bidirectional gRPC stream. After connecting:

1. Incoming Events

You'll receive these events from the server:

message ResolverEvent {
  oneof mux {
    uint64 seqno = 1;    // Server-generated event ID
    uint64 reply_to = 2;  // References your request seqno
  }

  oneof event {
    QuoteRequestedEvent quote_requested = 10;
    QuoteRequestCancelledEvent quote_request_cancelled = 11;
    QuoteAcceptedEvent quote_accepted = 20;
    QuoteRejectedEvent quote_rejected = 21;
    QuoteInvalidatedEvent quote_invalidated = 22;
    KeepAlive keep_alive = 100;
  }
}

Key events:

• QuoteRequestedEvent: New quote request from a trader

• QuoteRequestCancelledEvent: Trader cancelled their request

• QuoteAcceptedEvent: Your quote was accepted

• QuoteRejectedEvent: Your quote was rejected

• QuoteInvalidatedEvent: Confirmation of quote invalidation

2. Outgoing Requests

You can send these requests to the server:

message ResolverRequest {
  oneof mux {
    uint64 seqno = 1;    // Your request ID
    uint64 reply_to = 2;  // References server event seqno
  }

  oneof request {
    ConnectRequest connect = 10;
    UpdateQuoteRequest update_quote = 11;
    InvalidateQuoteRequest invalidate_quote = 12;
  }
}

Key requests:

• UpdateQuoteRequest: Provide or update a quote

• InvalidateQuoteRequest: Cancel a previously provided quote

Quote Flow

1. Receiving Quote Requests

When you receive a QuoteRequestedEvent:

message QuoteRequestedEvent {
  string rfq_id = 1;                      // Quote request ID
  QuoteRequest quote_request = 2;         // The actual request
  uint32 protocol_fee_bps = 3;           // Protocol fee in basis points
  sint64 request_timestamp = 4;          // When request was made
  sint64 quote_validity_timeout = 5;     // How long quote should be valid
  sint64 deposit_settling_delay = 6;     // Min delay before settlement
  sint64 resolve_timeout = 7;            // Max time to complete trade
}

2. Providing Quotes

Respond with an UpdateQuoteRequest:

message UpdateQuoteRequest {
  string rfq_id = 1;                    // From QuoteRequestedEvent
  string offer_units = 2;               // Amount trader pays
  string ask_units = 3;                 // Amount trader receives
  uint64 trade_start_deadline = 4;      // Quote expiration time

  oneof params {
    ResolverSwapParams swap = 20;       // For swap settlement
    ResolverEscrowParams escrow = 21;   // For escrow settlement
    ResolverHtlcParams htlc = 22;       // For HTLC settlement
  }
}

For swap settlement, include route information:

message ResolverSwapParams {
  repeated SwapRoute routes = 1;  // Possible swap paths
}

3. Quote Lifecycle

1. You receive QuoteRequestedEvent

2. You send UpdateQuoteRequest

3. The server validates your quote and responds with:

   • QuoteAcceptedEvent: Your quote was validated and accepted, includes quote_id.

   • QuoteRejectedEvent: Your quote was rejected. The event includes a code field from the QuoteRejectedCode enum. Possible reasons include:

     • UNDEFINED (0) - Uncategorized error

     • INVALID_PARAMETERS (1) - Invalid value of a parameter

     • INVALID_AMOUNTS (2) - Asset amount restrictions don't pass RFQ requirements

     • ROUTE_PROHIBITED (3) - Route uses a prohibited intermediate asset

     • POOL_PROHIBITED (4) - Route uses a unverified or prohibited liquidity pool

     • EMULATION_RESULT_MISMATCH (5) - Transaction emulation produced a result different from the quote

     • INTERNAL_ERROR (101) - Server errors

4. At any time, you can:

   • Send new UpdateQuoteRequest to update the quote

   • Send InvalidateQuoteRequest to cancel the quote

Best Practices

1. Sequence Numbers

   • Use monotonically increasing seqno for your requests

   • Match reply_to with event seqno when responding

   • Track request/response correlation using seqno

2. Quote Management

   • Honor your quotes until trade_start_deadline

   • Invalidate quotes you can't fulfill

   • Include all fees in your quoted amounts

3. Error Handling

   • Reconnect on connection loss

   • Handle all event types

   • Log rejected quotes for monitoring

4. Performance

   • Maintain a single gRPC connection

   • Process events asynchronously

   • Buffer outgoing requests

API Endpoint

Connect to: https://omni-grpc.ston.fi

See Also

• Swap Protocol Documentation