Query Methods & Notifications

Query methods retrieve information from a clearnode, while notifications provide real-time updates about state changes.

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Overview

The Nitro RPC protocol provides two types of information retrieval:

Query Methods: Client-initiated requests to retrieve current state information (balances, channels, sessions, transactions).

Notifications: Server-initiated messages sent to all relevant active connections when events occur (balance changes, channel updates, incoming transfers).

:::tip Real-Time Updates Combine query methods for initial state retrieval with notifications for ongoing monitoring. This pattern ensures your application always reflects the latest state without constant polling. :::

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Query Methods Summary

Method	Authentication	Purpose	Pagination
get_config	Public	Retrieve clearnode configuration	No
get_assets	Public	List supported assets	No
get_app_definition	Public	Fetch the definition for a specific app session	No
get_channels	Public	List payment channels	Yes
get_app_sessions	Public	List app sessions	Yes
get_ledger_balances	Private	Query current balances	No
get_ledger_entries	Public	Detailed accounting entries	Yes
get_ledger_transactions	Public	User-facing transaction history	Yes
get_rpc_history	Private	Fetch recent RPC invocations	Yes
get_user_tag	Private	Retrieve user's alphanumeric tag	No
get_session_keys	Private	List active session keys	Yes
ping	Public	Connection health check	No

:::info Authentication Public methods can be called without authentication. Private methods require completing the authentication flow first. :::

:::note Pagination defaults Unless explicitly provided, paginated methods default to limit = 10 (maximum 100) and offset = 0, matching the broker’s ListOptions. :::

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get_config

Name

get_config

Usage

Retrieves the clearnode's configuration: broker address plus supported blockchains and their custody/adjudicator contracts.

Request

No parameters.

Response

Parameter	Type	Description	Example
broker_address	string	Clearnode's wallet address	"0xbbbb567890abcdef..."
networks	array<BlockchainInfo>	List of supported blockchain networks	See structure below

BlockchainInfo Structure

Field	Type	Description	Example
chain_id	uint32	Network identifier	137 (Polygon)
name	string	Human-readable blockchain name	"Polygon"
custody_address	string	Custody contract address on this chain	"0xCustodyContractAddress..."
adjudicator_address	string	Adjudicator contract address on this chain	"0xAdjudicatorAddress..."

Use Cases:

• Discover supported chains and contract addresses
• Verify clearnode wallet address

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get_assets

Name

get_assets

Usage

Retrieves all supported assets and their configurations across supported blockchains.

Request

Parameter	Type	Required	Description	Example	Notes
chain_id	uint32	No	Filter by specific chain	137	If omitted, returns assets for all chains

Response

Parameter	Type	Description	Example
assets	array<Asset>	List of supported assets	See structure below

Asset Structure

Field	Type	Description	Example
token	string	Token contract address	"0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174"
chain_id	uint32	Blockchain network identifier	137
symbol	string	Token symbol	"usdc"
decimals	uint8	Number of decimal places	6

Use Cases:

• Display supported assets in UI
• Validate asset identifiers before transfers
• Get contract addresses for specific chains

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get_app_definition

Name

get_app_definition

Usage

Retrieves the immutable definition for a given app session so clients can verify governance parameters and participants.

Request

Parameter	Type	Required	Description	Example
app_session_id	string	Yes	Target app session identifier	"0x9876543210fedcba..."

Response

Returns the AppDefinition structure:

Field	Type	Description
protocol	string	Protocol version ("NitroRPC/0.2" or "NitroRPC/0.4")
participants	array<address>	Wallet addresses authorized for this session
weights	array<int64>	Voting weight per participant (aligned with participants order)
quorum	uint64	Minimum combined weight required for updates
challenge	uint64	Dispute timeout (seconds)
nonce	uint64	Unique instance identifier

Use Cases:

• Validate session metadata before signing states
• Display governance rules in UI
• Confirm protocol version compatibility

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get_channels

Name

get_channels

Usage

Lists all channels for a specific participant address across all supported chains.

Request

Parameter	Type	Required	Description	Default	Example
participant	string	No	Participant wallet address to query	(empty = all channels)	"0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb"
status	string	No	Filter by status	-	"open"
offset	number	No	Pagination offset	0	42
limit	number	No	Number of channels to return	10 (max 100)	10
sort	string	No	Sort order by created_at	"desc"	"desc"

Allowed status values: "open" | "closed" | "challenged" | "resizing"

Response

Parameter	Type	Description	Example
channels	array<Channel>	List of channels	See structure below

Channel Structure

Field	Type	Description	Example
channel_id	string	Unique channel identifier	"0xabcdef..."
participant	string	User's wallet address	"0x742d35Cc..."
status	string	Channel status	"open"
token	string	Asset contract address	"0x2791Bca1..."
wallet	string	Participant's wallet address	"0x742d35Cc..."
amount	string	Total channel capacity (human-readable)	"100.0"
chain_id	uint32	Blockchain network identifier	137
adjudicator	string	Dispute resolution contract address	"0xAdjudicator..."
challenge	uint64	Dispute timeout period (seconds)	3600
nonce	uint64	Unique nonce ensuring channel uniqueness	1699123456789
version	uint64	Current state version	5
created_at	string	Channel creation timestamp (ISO 8601)	"2023-05-01T12:00:00Z"
updated_at	string	Last modification timestamp (ISO 8601)	"2023-05-01T14:30:00Z"

Use Cases:

• Display user's open channels
• Check channel status before operations
• Monitor multi-chain channel distribution

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get_app_sessions

Name

get_app_sessions

Usage

Lists all app sessions for a participant, sorted by creation date (newest first by default). Optionally filter by status (open/closed). Returns complete session information including participants, voting weights, quorum, protocol version, and current state. Supports pagination for large result sets.

Request

Parameter	Type	Required	Description	Default	Allowed Values	Example
participant	string (address)	No	Filter by participant wallet address	(empty = all sessions)	"0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb"
status	string	No	Filter by status	-	"open"
offset	number	No	Pagination offset	0	-	42
limit	number	No	Number of sessions to return	10 (max 100)	-	10
sort	string	No	Sort order by created_at	"desc"	"desc"

Allowed status values: "open" | "closed"

Response

Parameter	Type	Description	See Also
app_sessions	array<AppSessionInfo>	List of app sessions	See structure below

AppSessionInfo

Field	Type	Description	Example
app_session_id	string	Unique identifier	"0x9876543210fedcba..."
application	string	Application identifier	"VirtualAppChess"
status	string	Current status	"open" | "closed"
participants	array<address>	All participant wallet addresses	["0x742d35Cc...", "0x8B3192f2..."]
weights	array<int64>	Voting weights per participant	[50, 50, 100]
quorum	uint64	Required weight for state updates	100
protocol	string	Protocol version	"NitroRPC/0.4"
challenge	uint64	Challenge period in seconds	86400
version	number	Current state version	5
nonce	uint64	Unique session identifier	1699123456789
session_data	string	Current application state	"{\"gameType\":\"chess\",\"turn\":\"white\"}"
created_at	string (timestamp)	Creation timestamp	"2023-05-01T12:00:00Z"
updated_at	string (timestamp)	Last update timestamp	"2023-05-01T14:30:00Z"

Use Cases:

• Display user's active games or escrows
• Monitor session history
• Paginate through large session lists

:::tip Pagination Best Practice When dealing with users who have many app sessions, use pagination with reasonable limit values (10-50) to improve performance and user experience. :::

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get_ledger_balances

Name

get_ledger_balances

Usage

Retrieves the ledger balances for an account. If no parameters are provided, returns the authenticated user's unified balance across all assets. Can also query balance within a specific app session by providing the app_session_id. Returns all tracked assets (including those that currently evaluate to zero).

Request

Parameter	Type	Required	Description	Format	Example
account_id	string	No	Account or app session identifier	0x-prefixed hex string or wallet address	"0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb"

:::info App Session Balances To query balance within a specific app session, provide the app_session_id as the account_id. :::

Response

Parameter	Type	Description	Example
ledger_balances	array<Balance>	Balance per asset	See structure below

Balance Structure

Field	Type	Description	Example
asset	string	Asset identifier	"usdc"
amount	string	Balance in human-readable format	"100.0"

Use Cases:

• Display user's current balances
• Check available funds before operations
• Monitor balance changes in real-time

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get_ledger_entries

Name

get_ledger_entries

Usage

Retrieves detailed ledger entries for an account, providing a complete audit trail of all debits and credits. Each entry represents one side of a double-entry bookkeeping transaction. Used for detailed financial reconciliation and accounting. Supports filtering by account, asset, and pagination. Sorted by creation date (newest first by default).

Request

Parameter	Type	Required	Description	Default	Allowed Values	Example
account_id	string	No	Filter by account identifier	-	-	"0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb"
wallet	string (address)	No	Filter by wallet address	-	-	"0x742d35Cc..."
asset	string	No	Filter by asset	-	-	"usdc"
offset	number	No	Pagination offset	0	-	-
limit	number	No	Number of entries to return	10 (max 100)	-	-
sort	string	No	Sort order by created_at	"desc"	"asc" | "desc"	-

Response

Parameter	Type	Description	Structure	Example
ledger_entries	array<LedgerEntry>	List of ledger entries	See structure below

LedgerEntry Structure

Field	Type	Description	Example
id	number	Unique entry identifier	123
account_id	string	Account this entry belongs to	"0x742d35Cc..."
account_type	number	Ledger account classification (1000=asset, 2000=liability, etc.)	1000
asset	string	Asset symbol	"usdc"
participant	string	Participant wallet address	"0x742d35Cc..."
credit	string	Credit amount (incoming funds, "0.0" if debit)	"100.0"
debit	string	Debit amount (outgoing funds, "0.0" if credit)	"25.0"
created_at	string	Entry creation timestamp (ISO 8601)	"2023-05-01T12:00:00Z"

Account types follow the broker’s GAAP-style codes: 1000 series for assets, 2000 liabilities, 3000 equity, 4000 revenue, and 5000 expenses.

Double-Entry Bookkeeping

Every transaction creates two entries:

Transfer: Alice sends 50 USDC to Bob

Entry 1 (Alice's ledger):
  account_id: Alice's address
  asset: usdc
  credit: 0.0
  debit: 50.0
  
Entry 2 (Bob's ledger):
  account_id: Bob's address
  asset: usdc
  credit: 50.0
  debit: 0.0

:::info Accounting Principle The double-entry system ensures that the total of all debits always equals the total of all credits, providing mathematical proof of accounting accuracy. This is the same principle used by traditional financial institutions. :::

Use Cases:

• Detailed financial reconciliation
• Audit trail generation
• Accounting system integration
• Verify balance calculations

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get_ledger_transactions

Name

get_ledger_transactions

Usage

Retrieves user-facing transaction history showing transfers, deposits, withdrawals, and app session operations. Unlike ledger entries (which show accounting details), this provides a simplified view of financial activity with sender, receiver, amount, and transaction type. Supports filtering by asset and transaction type. Sorted by creation date (newest first by default).

Request

Parameter	Type	Required	Description	Default	Allowed Values	Example
account_id	string	No	Filter by account identifier	-	-	"0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb"
asset	string	No	Filter by asset	-	-	"usdc"
tx_type	string	No	Filter by transaction type	-	"transfer" | "deposit" | "withdrawal" | "app_deposit" | "app_withdrawal" | "escrow_lock" | "escrow_unlock"	"transfer"
offset	number	No	Pagination offset	0	-	-
limit	number	No	Number of transactions to return	10 (max 100)	-	-
sort	string	No	Sort order by created_at	"desc"	"asc" | "desc"	-

Response

Parameter	Type	Description	Example
ledger_transactions	array<LedgerTransaction>	List of transactions	See structure below

LedgerTransaction Structure

Field	Type	Description	Example
id	number	Unique transaction identifier	1
tx_type	string	Transaction type	"transfer"
from_account	string	Sender account identifier (wallet, channel, or app session)	"0x742d35Cc..."
from_account_tag	string	Sender's user tag (empty if none)	"NQKO7C"
to_account	string	Receiver account identifier (wallet, channel, or app session)	"0x8B3192f2..."
to_account_tag	string	Receiver's user tag (empty if none)	"UX123D"
asset	string	Asset symbol	"usdc"
amount	string	Transaction amount	"50.0"
created_at	string	Transaction timestamp (ISO 8601)	"2023-05-01T12:00:00Z"

from_account and to_account mirror the broker’s internal AccountID values, so they can reference wallets, app session escrow accounts, or channel escrows.

Transaction Types

Type	Description	Direction
transfer	Direct transfer between unified balances	Off-chain ↔ Off-chain
deposit	Funds deposited from channel to unified balance	On-chain → Off-chain
withdrawal	Funds withdrawn from unified balance to channel	Off-chain → On-chain
app_deposit	Funds moved from unified balance into app session	Unified → App Session
app_withdrawal	Funds released from app session to unified balance	App Session → Unified
escrow_lock	Funds temporarily locked for blockchain operations	Unified → Escrow
escrow_unlock	Funds released from escrow after blockchain confirmation	Escrow → Unified

Use Cases:

• Display transaction history in UI
• Export transaction records
• Monitor specific transaction types
• Track payment flows

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get_rpc_history

Name

get_rpc_history

Usage

Returns the authenticated user's recent RPC invocations, including signed request and response payloads. Useful for audit trails and debugging client integrations.

Request

Parameter	Type	Required	Description	Default	Example
offset	number	No	Pagination offset	0	20
limit	number	No	Maximum entries to return	10 (max 100)	25
sort	string	No	Sort order by timestamp	"desc"	"asc"

Response

Parameter	Type	Description	See Also
rpc_entries	array<RPCEntry>	Recorded invocations	See structure below

RPCEntry Structure

Field	Type	Description
id	number	Internal history identifier
sender	string	Wallet that issued the call
req_id	number	Request sequence number
method	string	RPC method name
params	string	JSON-encoded request parameters
timestamp	number	Unix timestamp (seconds)
req_sig	array<Signature>	Signatures attached to the request
response	string	JSON-encoded response payload
res_sig	array<Signature>	Response signatures

Use Cases:

• Debug client/server mismatches
• Provide user-facing audit logs
• Verify signed payloads during dispute resolution

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get_user_tag

Name

get_user_tag

Usage

Retrieves the authenticated user's unique alphanumeric tag. User tags provide a human-readable alternative to addresses for transfer operations, similar to username systems. Tags are automatically generated upon first interaction with a clearnode and remain constant. This is a convenience feature for improving user experience.

Request

No parameters.

Response

Parameter	Type	Description	Format	Example	Notes
tag	string	User's unique alphanumeric tag	6 uppercase alphanumeric characters	"UX123D"	Can be used in transfer operations as destination_user_tag

Usage in Transfers

Instead of using full address:

transfer({destination: "0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb", ...})

Users can use the tag:

transfer({destination_user_tag: "UX123D", ...})

:::note Human-Readable Addresses User tags make it easier for users to share their "address" verbally or in non-technical contexts, similar to payment apps like Venmo or Cash App usernames. :::

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get_session_keys

Name

get_session_keys

Usage

Retrieves all active (non-expired) session keys for the authenticated user. Shows each session key's address, application name, spending allowances, current usage, expiration, and permissions. Used for managing delegated keys and monitoring spending caps. Only returns session keys (not custody signers).

Authentication

Required (private method)

Request

Parameter	Type	Required	Description	Default	Example
offset	number	No	Pagination offset	0	20
limit	number	No	Results per page	10 (max 100)	25
sort	string	No	Sort order by created_at	"desc"	"asc"

Response

Parameter	Type	Description	See Also
session_keys	array<SessionKeyInfo>	List of active session keys	See structure below

SessionKeyInfo Structure

Field	Type	Description	Default	Notes
id	number	Internal identifier	—	—
session_key	string (address)	Session key address	—	—
application	string	Application name for this session	"clearnode"	—
allowances	array<AllowanceUsage>	Spending limits and usage	—	See structure below
scope	string	Permission scope	—	Future feature, not fully enforced yet
expires_at	string (timestamp)	Session expiration time (ISO 8601 format)	—	—
created_at	string (timestamp)	Session creation time (ISO 8601 format)	—	—

Example:

{
  "id": 1,
  "session_key": "0x9876543210fedcba...",
  "application": "Chess Game",
  "allowances": [
    {"asset": "usdc", "allowance": "100.0", "used": "45.0"}
  ],
  "scope": "app.create,transfer",
  "expires_at": "2023-05-02T12:00:00Z",
  "created_at": "2023-05-01T12:00:00Z"
}

AllowanceUsage

Field	Type	Description
asset	string	Asset identifier (e.g., "usdc")
allowance	string	Total spending limit
used	string	Amount already spent

Spending Tracking

The clearnode tracks session key spending by monitoring all ledger debit operations:

Initial: allowance = 100 USDC, used = 0 USDC
After transfer of 45 USDC: allowance = 100 USDC, used = 45 USDC
Remaining = 55 USDC available for future operations

When a session key reaches its spending cap, further operations are rejected:

Error: "operation denied: insufficient session key allowance: 60 required, 55 available"

:::tip Spending Caps Session key allowances provide important security: even if a session key is compromised, the maximum loss is limited to the allowance amount. :::

Use Cases:

• Display active sessions in UI
• Monitor spending against caps
• Manage session lifecycles
• Security auditing

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ping

Name

ping

Usage

Simple connectivity check to verify the clearnode is responsive and the RPC connection is alive. Returns immediately with success. Used for heartbeat, connection testing, and latency measurement.

Authentication

Not required (public method)

Request

No parameters required (empty object {}).

Response

The response method should be "pong".

Parameter	Type	Description	Value/Example	Notes
(empty)	object	Empty object or confirmation data	{}	Response indicates successful connection

Use Cases

Heartbeat: Periodic ping to keep RPC connection alive

setInterval(() => clearnode.call("ping"), 30000)  // Every 30 seconds

Latency Measurement: Measure round-trip time

const start = Date.now()
await clearnode.call("ping")
const latency = Date.now() - start
console.log(`Latency: ${latency}ms`)

Health Check: Verify connection before critical operations

try {
  await clearnode.call("ping")
  // Connection healthy, proceed with operation
} catch (error) {
  // Connection lost, reconnect
}

Authentication Status: Test if session is still valid

const response = await clearnode.call("ping")
// If no auth error, session is active

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Notifications (Server-to-Client)

The clearnode sends unsolicited notifications to clients via RPC when certain events occur. These are not responses to requests, but asynchronous messages initiated by the server.

Notification Types

Method	Description	Data Structure
bu	Balance update	balance_updates array with updated balances
cu	Channel update	Full Channel object
tr	Transfer (incoming/outgoing)	transactions array with transfer details
asu	App session update	app_session object and participant_allocations

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bu (Balance Update)

Method

bu

When Sent

Whenever account balances change due to transfers, app session operations, or channel operations.

Structure

Field	Type	Description	Example
balance_updates	array<LedgerBalance>	Updated balances for affected accounts	See structure below

LedgerBalance Structure

Field	Type	Description	Example
asset	string	Asset symbol	"usdc"
amount	string	New balance amount	"150.0"

Use Cases:

• Update balance display in real-time
• Trigger UI animations for balance changes
• Log balance history for analytics

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cu (Channel Update)

Method

cu

When Sent

When a channel's state changes (opened, resized, challenged, closed).

Structure

The notification contains the complete updated Channel object. See Channel Structure in the get_channels section for the full field list.

Use Cases:

• Update channel status in UI
• Alert user when channel becomes active
• Monitor for unexpected channel closures

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tr (Transfer)

Method

tr

When Sent

When a transfer affects the user's account (both incoming and outgoing transfers).

Structure

Field	Type	Description	Example
transactions	array<LedgerTransaction>	Array of transaction objects for the transfer	See structure below

The LedgerTransaction structure is identical to the one returned by get_ledger_transactions. See LedgerTransaction Structure for the full field list.

Use Cases:

• Display incoming/outgoing payment notifications
• Play sound/show toast for transfers
• Update transaction history in real-time

:::success Real-Time Payments Combine tr notifications with bu (balance update) to provide immediate feedback when users send or receive funds. :::

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asu (App Session Update)

Method

asu

When Sent

When an app session state changes (new state submitted, session closed, deposits/withdrawals).

Structure

Field	Type	Description	Example
app_session	AppSession	Complete app session object	See get_app_sessions for structure
participant_allocations	array<AppAllocation>	Current allocations for each participant	See structure below

AppAllocation Structure

Field	Type	Description	Example
participant	string	Participant wallet address	"0x742d35Cc..."
asset	string	Asset symbol	"usdc"
amount	string	Allocated amount	"50.0"

Use Cases:

• Update game UI when opponent makes a move
• Refresh session state in real-time
• Alert when session is closed
• Sync multi-participant applications

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Implementation Notes

Connection Management:

• Maintain persistent connection for notifications
• Implement automatic reconnection on disconnect
• Re-fetch current state after reconnection

Notification Handling:

• All notifications are asynchronous
• No response required from client
• Multiple notifications may arrive rapidly (batch if needed)

Best Practices:

• Use query methods for initial state retrieval
• Use notifications for ongoing monitoring
• Don't rely solely on notifications (could be missed during disconnect)
• Implement periodic state refresh as backup

Pagination:

• For methods with pagination, use reasonable limit values

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Next Steps

Explore other protocol features:

• App Sessions - Create and manage multi-party applications
• Transfers - Send funds between users
• Channel Methods - Manage payment channels

For protocol fundamentals:

• Authentication - Manage session keys
• Message Format - Understand request/response structure