Message Types

Message	Message Type	Purpose
HELLO	hello	The Hello message is the first message sent between the Gateway and a relay. The Hello message is used to inform a peer of the sender’s protocol version, network number, buffer, and node ID.
ACK	ack	The Ack Message is sent to acknowledge the receipt of a hello message.
PING	ping	A Keep-alive message that should expect a Pong Message response with the provided nonce.
PONG	pong	Response to the Ping Message that should include the nonce provided in the Ping message.
BROADCAST	broadcast	Message used to broadcast a new block to the BDN.
TRANSACTION	tx	Message to propagate a transaction across the BDN.
GET TRANSACTIONS	gettxs	Message used to request information about services with specified short IDs.
TRANSACTIONS	txs	Message with tx details send in response to GET TRANSACTIONS Message.
GET TRANSACTION CONTENTS	getcontents	Message used to request transaction contents with specified network number and short id.
TRANSACTION CONTENTS	txcontents	Message with tx details. Reply to GET TRANSACTION CONTENTS Message.
KEY	key	A key message includes the encryption key used to encrypt a block when encryption is used for blocks sent over the BDN.
BLOCK HOLDING	blockhold	Request for other Gateways to hold onto the block for a timeout to avoid encrypted block duplication.
DISCONNECT RELAY PEER	droprelay	Request for the Gateway to disconnect from its Relay peers.
BLOCK CONFIRMATION	blkcnfrm	Message with confirmed blck details and transaction short IDs marked for cleanup.
TRANSACTION CLEANUP	txclnup	Expired transactions to remove from Gateway memory.
NOTIFICATION	notify	Notification message that includes updates like account quota status and account expiration information.
BDN PERFORMANCE STATS	bdnstats	Message that contains gateway statistics on BDN performance, such as number of blocks/transactions received from BDN and number of blocks/transactions received from blockchain node.
REFRESH BLOCKCHAIN NETWORK	blkntwrk	Message used to request BDN to refresh blockchain network configuration.
GET COMPRESSED BLOCK TRANSACTIONS	getblocktxs	Message used to request details of transactions included in a compressed block.
COMPRESSED BLOCK TRANSACTIONS	blocktxs	Message with compressed block transaction details. Reply to GET COMPRESSED BLOCK TRANSACTIONS Message.

Message Type Details

Hello Message

The Hello message is the first message sent between the Gateway and a relay. The Hello message is used to inform a peer of the sender’s protocol version, network number, buffer and node ID.

Hello Message	Payload Length	Description
Protocol Version	4 bytes	The version of the BLXR protocol used by the sender of the message.
Network Number	4 bytes	The blockchain network used by the Gateway.
Node ID	16 bytes	The Node ID is a unique identifier provided to the Gateway by the SDN.

ACK Message

The ACK Message is sent to acknowledge the receipt of a hello message. The ACK message does not include a payload.

Ping Message

A Keep-alive message that should expect a Pong Message response with the provided nonce.

Ping Message	Payload Length	Description
Nonce	8 bytes	A counter provided and managed by the connection.

Pong Message

Response to the Ping Message that should include the nonce provided in the Ping message.

Pong Message	Payload Length	Description
Nonce	8 bytes	A counter provided and managed by the connection.

Broadcast Message

Message used to broadcast a new block to the BDN.

Broadcast Message	Payload Length	Description
Hash	32 bytes	Hash of the new block.
Network Number	4 bytes	The blockchain network of the block.
Source ID	16 byte	Indicates the first Relay to broadcast the message. This field is not of interest to Gateways.
Block Encrypted Flag	1 byte	A flag that is set to true if the block is encrypted.
Blob	variable size	The contents of the new block. If the Block Encrypted flag is true, the contents are encrypted.

Transaction Message

Message to propagate a transaction across the BDN.

Transaction Message	Payload Length	Description
Hash	32 bytes	Hash of the transaction.
Network Number	4 bytes	The blockchain network of the transaction.
Source ID	16 bytes	Indicates the first Relay to broadcast the message. This field is not of interest to Gateways.
SID	4 bytes	The short ID of the transaction. When a Gateway is sending a transaction to a Relay, it lists the SID as 0 to indicate that the short ID has not yet been assigned.
TX VAL	variable length	The contents of the transaction. When a Gateway sends a transaction message to a Relay, the Relay may respond with a transaction message including the assigned SID and leave this field empty.
Quota Type	1 byte	Type of quota used for the transaction, it can either be the limited free daily quota or the paid quota.
Timestamp	4 bytes	The time the transaction message was sent.

Get Transactions Message

Message used to request information about services with specified short IDs.

Get Transactions Message Payload	Payload Length	Description
Number of short IDs	4 bytes	Number of short IDs in payload.
List of Short IDs	variable length	A list of short IDs, each short ID is 4 bytes in length.

Transactions Message

Message with tx details send in response to GET_TRANSACTIONS Message.

Transactions Message Payload	Payload Length	Description
Length	4 bytes	Length of the list of TransactionInfo objects
List of Transaction Info	variable length	list of Transaction Info objects. The structure of Transaction Info objects is described below.

Transaction Info Objects

A transaction info object is a part of the Transactions Message that describes a single transaction and its associated short ID.

Transaction Info objects	Payload Length	Description
SID	4 bytes	Short ID of the transaction.
Hash	32 bytes	Hash of the transaction.
TX Len	4 bytes	The length of the transaction.
TX	variable length	The contents of the transaction.

Key Message

A key message includes the encryption key used to encrypt a block when encryption is used for blocks sent over the BDN.

Key Message Payload	Payload Length	Description
Hash	32 bytes	Hash of the block encrypted using the key.
Network Number	4 bytes	The blockchain network of the encrypted block.
Source ID	16 bytes	Indicates the first relay to broadcast the message. This field is not of interest to Gateways.
Key	32 bytes	Encryption key to decrypt the encrypted block having the hash provided.

Block Holding Message

Request for other Gateways to hold onto the block for a timeout to avoid encrypted block duplication.

Block Holding Message Payload	Payload Length	Description
Hash	32 bytes	Hash of the block to hold.
Network Number	4 bytes	The blockchain network of the block.

Disconnect Relay Peer Message

Request for the Gateway to disconnect from it’s Relay peers. This message does not have a payload.

Transaction Cleanup Message

Provides expired transactions for removal from Gateway memory. The expired transactions may be provided as a list of short IDs or as a list of transaction hashes. Since Gateways are not validating nodes, over time they will collect transactions that have been discarded by blockchain network full nodes. This may occur because, for example, the transaction was invalid, double spent, or provided insufficient fees. The bloXroute BDN will occasionally poll its internal blockchain nodes for a list of valid transactions and compare it to its list of tracked transactions. Transactions not found in internal blockchain nodes will be broadcast to the network with the Transaction Cleanup message to permit Gateways to remove these transactions from their memory.

Transaction Cleanup Message Payload	Payload Length	Description
Message Hash	32 bytes	hash of the contents of the Transaction Cleanup message (used as a message identifier).
Network Number	4 bytes	The blockchain network of the block.
Source ID	16 bytes	indicates the first relay to broadcast the message. This field is not of interest to Gateways.
List of SIDs	variable length	list of short IDs. Each short ID is 4 bytes in length
List of Transaction Hashes	variable length	list of transaction hashes of expired transactions. Each transaction hash is 32 bytes in length.