messages.md

Messages and message envelope

Message

Message class is a base structure for all data streams inside the constellation.

Message structure:

• messsageType (Int32) - Message type discriminator.
• messageId (UInt64) - Message identifier. Message results refer to original messages using those identifiers.

Additional data depends on the message type.

MessageTypes

Message types and it's structures:

• 0 Hardbeat – a message to keep connection alive. Doesn't have any additional fields.
• 100 HandshakeInit - initiates connection handshake.
• 102 ResultMessage - operation result, containing original quantum and processing status.
• 105 LedgerUpdateNotification - message from an auditor to Alpha server that contains all Stellar payments included into the recent ledger obtained from the Horizon.
• 106 AuditorState - transmits auditor current state (the last snapshot and all quanta since the last snapshot).
• 110 SetApexCursor - message that sets auditor sequence counter to the specified position.
• 202 AlphaState - alpha state message, contains current Alpha state and last snapshot.

HandshakeInit structure:

• handshakeData (Array<byte>) - random 32 byte array sent by Alpha.

ResultMessage structure:

• originalMessage (Message) - original message.
• status (Int32) - result status code.
• effects (Array<Int32>) - message effects.

ResultStatusCodes

• 200 - Success.
• 401 - Unauthorized.
• 500 - Internal Error.
• 551 - Unexpected Message.

MessageEffects

• 0 - Undefined.
• 1 - Asset Sent.
• 2 - Asset Received.
• 10 - Order Placed.
• 11 - Order Removed.
• 12 - Trade.

LedgerUpdateNotification structure:

• ledger (UInt64) - ledger sequence number.
• payments (Array<Payment>) - list of payments witnessed by an auditor.

Payment structure:

• type (Int32) - payment type Deposit = 1 and Withdrawal = 2.
• asset (Int32) - asset id, unique within a constellation.
• amount (Int64) - payment amount.
• destination (Array<byte>) - destination account public key.
• transactionHash (Array<byte>) - Stellar transaction hash
• paymentResult (Int32) - Success = 0 and Failed = 1.

AlphaState structure:

• state (Int32) - current Alpha server state.
• lastSnapshot (Snapshot) - the most recent valid snapshot.

AuditorState structure:

• state (Int32) - current auditor state.
• lastSnapshot (Snapshot) - the most recent valid snapshot.
• pendingQuantums (Array<MessageEnvelope>) - quanta processed since the last snapshot.

ApplicationState

• 0 - Undefined.
• 1 - Waiting for init.
• 2 - Running.
• 4 - Ready.
• 5 - Rising.
• 10 - Failed.

SetApexCursor structure:

• apex (UInt64) - apex sequence to set.

Message envelope

Every message is wrapped with envelope, containing the message itself and alpha/auditor signatures.

MessageEnvelope structure:

• message (Message) - nested message.
• signatures (Array<Ed25519Signature>) - ed25519 message signatures.

Ed25519Signature structure:

• signer (Array<byte>) - signer public key.
• signature (Array<byte>) - signature itself.