web3j-component.adoc

Web3j Ethereum Blockchain Component

Available as of Camel version 2.22

The Ethereum blockchain component uses the web3j client API and allows you to interact with Ethereum compatible nodes such as Geth, Parity, Quorum, Infura, etc.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-web3j</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI Format

web3j://<local/remote host:port or local IPC path>[?options]

Web3j Options

The Web3j Ethereum Blockchain component supports 2 options, which are listed below.

Name	Description	Default	Type
configuration (common)	Default configuration		Web3jConfiguration
resolveProperty Placeholders (advanced)	Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.	true	boolean

The Web3j Ethereum Blockchain endpoint is configured using URI syntax:

web3j:nodeAddress

with the following path and query parameters:

Path Parameters (1 parameters):

Name	Description	Default	Type
nodeAddress	Required Sets the node address used to communicate		String

Query Parameters (36 parameters):

Name	Description	Default	Type
addresses (common)	Contract address or a list of addresses.		List
fromAddress (common)	The address the transaction is send from		String
fromBlock (common)	The block number, or the string latest for the last mined block or pending, earliest for not yet mined transactions.	latest	DefaultBlockParameter
fullTransactionObjects (common)	If true it returns the full transaction objects, if false only the hashes of the transactions.	false	boolean
gasLimit (common)	The maximum gas allowed in this block.		BigInteger
toAddress (common)	The address the transaction is directed to.		String
toBlock (common)	The block number, or the string latest for the last mined block or pending, earliest for not yet mined transactions.	latest	DefaultBlockParameter
topics (common)	Topics are order-dependent. Each topic can also be a list of topics. Specify multiple topics separated by comma.		String
web3j (common)	The preconfigured Web3j object.		Web3j
bridgeErrorHandler (consumer)	Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.	false	boolean
exceptionHandler (consumer)	To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.		ExceptionHandler
exchangePattern (consumer)	Sets the exchange pattern when the consumer creates an exchange.		ExchangePattern
address (producer)	Contract address.		String
atBlock (producer)	The block number, or the string latest for the last mined block or pending, earliest for not yet mined transactions.	latest	DefaultBlockParameter
blockHash (producer)	Hash of the block where this transaction was in.		String
clientId (producer)	A random hexadecimal(32 bytes) ID identifying the client.		String
data (producer)	The compiled code of a contract OR the hash of the invoked method signature and encoded parameters.		String
databaseName (producer)	The local database name.		String
filterId (producer)	The filter id to use.		BigInteger
gasPrice (producer)	Gas price used for each paid gas.		BigInteger
hashrate (producer)	A hexadecimal string representation (32 bytes) of the hash rate.		String
headerPowHash (producer)	The header’s pow-hash (256 bits) used for submitting a proof-of-work solution.		String
index (producer)	The transactions/uncle index position in the block.		BigInteger
keyName (producer)	The key name in the database.		String
mixDigest (producer)	The mix digest (256 bits) used for submitting a proof-of-work solution.		String
nonce (producer)	The nonce found (64 bits) used for submitting a proof-of-work solution.		String
operation (producer)	Operation to use.	transaction	String
position (producer)	The transaction index position withing a block.		BigInteger
priority (producer)	The priority of a whisper message.		BigInteger
sha3HashOfDataToSign (producer)	Message to sign by calculating an Ethereum specific signature.		String
signedTransactionData (producer)	The signed transaction data for a new message call transaction or a contract creation for signed transactions.		String
sourceCode (producer)	The source code to compile.		String
transactionHash (producer)	The information about a transaction requested by transaction hash.		String
ttl (producer)	The time to live in seconds of a whisper message.		BigInteger
value (producer)	The value sent within a transaction.		BigInteger
synchronous (advanced)	Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).	false	boolean

You can append query options to the URI in the following format, ?options=value&option2=value&…​

Message Headers

Header	Description
All URI options	All URI options can also be set as exchange headers.

Samples

Listen for new mined blocks and send the block hash to a jms queue:

from("web3j://http://127.0.0.1:7545?operation=ETH_BLOCK_HASH_OBSERVABLE")
    .to("jms:queue:blocks");

Use the block hash code to retrieve the block and full transaction details:

from("jms:queue:blocks")
    .setHeader(BLOCK_HASH, body())
    .to("web3j://http://127.0.0.1:7545?operation=ETH_GET_BLOCK_BY_HASH&fullTransactionObjects=true");

Read the balance of an address at a specific block number:

from("direct:start")
    .to("web3j://http://127.0.0.1:7545?operation=ETH_GET_BALANCE&address=0xc8CDceCE5d006dAB638029EBCf6Dd666efF5A952&atBlock=10");