Messages

Register Interchain Query

MsgRegisterInterchainQuery can be submitted by smart-contract only via MsgRegisterInterchainQuery transaction:

message MsgRegisterInterchainQuery {
  // defines a query type: `kv` or `tx` now
  string query_type = 1;

  // is used to define KV-storage keys for which we want to get values from remote chain
  repeated KVKey keys = 2;

  // is used to define a filter for transaction search ICQ
  string transactions_filter = 3;

  // is IBC connection ID for getting ConsensusState to verify proofs
  string connection_id = 4;

  // is used to specify how often (in neutron blocks) the query must be updated
  uint64 update_period = 5;

  // is the signer of the message
  string sender = 6;
}

message KVKey {
  // Path (storage prefix) to the storage where you want to read value by key
  // (usually name of cosmos-sdk module: 'staking', 'bank', etc.)
  string path = 1;
  // Key you want to read from the storage
  bytes key = 2;
}

Note: the maximum allowed number of KVKey values for a single InterchainQuery is defined by a module's param MaxKvQueryKeysCount, default value is 32.

Currently query_type can take the following values:

• kv - query values from Cosmos-SDK KV-storage on remote chain which are stored under some keys. In this case kv_keys must be filled in.

• tx - query to search for transactions on remote chain. transactions_filter describes a filter by which the ICQ relayer will perform the transactions search. The transaction filter is described in more detail in the overview:

MsgRegisterInterchainQuery returns MsgRegisterInterchainQueryResponse where id is unique identifier of newly registered interchain query on success:

message MsgRegisterInterchainQueryResponse { 
  uint64 id = 1; 
}

State modifications

• increments last registered query id;
• generates new RegisteredQuery;
• save the record in storage under incremented query id;

Events

Emits EventTypeNeutonMessage with action equals query_updated.

Update Interchain Query

Note: as well as for query registration, for query updates the maximum allowed number of KVKey values for a single InterchainQuery equals to 32.

MsgUpdateInterchainQueryRequest can be submitted only by the owner of corresponding Interchain Query:

message MsgUpdateInterchainQueryRequest {
  uint64 query_id = 1;
  repeated KVKey new_keys = 2;
  uint64 new_update_period = 3;
  string new_transactions_filter = 4;
  string sender = 5; // is the signer of the message
}

Returns just an empty MsgUpdateInterchainQueryResponse on success:

message MsgUpdateInterchainQueryResponse {
}

State modifications

• Updates a corresponding RegisteredQuery structure.

Events

Emits EventTypeNeutonMessage with action equals query_updated.

Remove Interchain Query

MsgRemoveInterchainQueryRequest can be submitted only by the owner of corresponding Interchain Query within the query's service period or by anyone beyond it. Read more about this message permissions here.

message MsgRemoveInterchainQueryRequest {
  uint64 query_id = 1;
  string sender = 2; // is the signer of the message and the owner of corresponding ICQ
}

Returns just an empty MsgRemoveInterchainQueryResponse on success:

message MsgRemoveInterchainQueryResponse {
}

State modifications

• Removes a corresponding RegisteredQuery structure.
• Also removes the query results (immediately for a KV query, deferred in the ICQ module EndBlock for a TX query).

Events

Emits EventTypeNeutonMessage with action equals query_removed.

Submit Query Result

MsgSubmitQueryResult can be submitted by any Neutron account via MsgSubmitQueryResult transaction:

message MsgSubmitQueryResult {
  uint64 query_id = 1;
  string sender = 2;

  // is the IBC client ID for an IBC connection between Neutron chain and target chain (where the result was obtained from)
  string client_id = 3;
  QueryResult result = 4;
}

message QueryResult {
  repeated StorageValue kv_results = 1;
  Block block = 2;
  uint64 height = 3;
  uint64 revision = 4;
  bool allow_kv_callbacks = 5;
}

message StorageValue {
  // is the substore name (acc, staking, etc.)
  string storage_prefix = 1;

  // is the key in IAVL store
  bytes key = 2;

  // is the value in IAVL store
  bytes value = 3;

  // is the Merkle Proof which proves existence of key-value pair in IAVL storage
  tendermint.crypto.ProofOps Proof = 4;
}

message Block {
  // We need to know block X+1 to verify response of transaction for block X
  // since LastResultsHash is root hash of all results from the txs from the previous block
  google.protobuf.Any next_block_header = 1;

  // We need to know block X to verify inclusion of transaction for block X
  google.protobuf.Any header = 2;

  TxValue tx = 3;
}

message TxValue {
  tendermint.abci.ResponseDeliverTx response = 1;

  // is the Merkle Proof which proves existence of response in block with height next_block_header.Height
  tendermint.crypto.Proof delivery_proof = 2;

  // is the Merkle Proof which proves existence of data in block with height header.Height
  tendermint.crypto.Proof inclusion_proof = 3;

  // is body of the transaction
  bytes data = 4;
}

Returns just an empty MsgSubmitQueryResultResponse on success:

message MsgSubmitQueryResultResponse {
}

State modifications

• get registered interchain query info by MsgSubmitQueryResult.query_id;
• for every result in MsgSubmitQueryResult.result.kv_results:
  • read IBC connection consensus state from IBC keeper storage with registered_query.ConnectionID, MsgSubmitQueryResult.result.revision, MsgSubmitQueryResult.result.height+1;
  • verify result.Proof with Merkle Root Hash from consensus state;
• save MsgSubmitQueryResult.result.kv_results to the storage:
  • clear MsgSubmitQueryResult.result from the proofs, Neutron doesn't need them anymore;
  • save cleared result to storage with key registered_query.id;
  • set registered_query.last_submitted_result_remote_height to result.height;
  • set registered_query.last_submitted_result_local_height to the current Neutron height;
• callback MsgSubmitQueryResult.result.kv_results to thr appropriate smart-contract if needed;
• for every block in MsgSubmitQueryResult.result.blocks:
  • verify block.next_block_header and block.header by calling clientKeeper.UpdateClient(header);
  • verify block.txs with verified headers;
• process every transaction in every block from MsgSubmitQueryResult.result.blocks:
  • check transaction was not processed previously to avoid double submitting
  • save generated record to the storage with composite key bigEndianBytes(registered_query.id) + bigEndianBytes(last_submitted_transaction_id prefixed by SubmittedTxKey;
  • callback transaction to the appropriate smart-contract;
  • save transaction's hash to the storage to approach double-submission preventing mechanics.