What is Koios?

Koios Java Client Library is based on Koios Elastic Query Layer for Cardano Node by Cardano Community Guild Operators.
Koios is best described as a Decentralized and Elastic RESTful query layer for exploring data on Cardano blockchain to consume within applications/wallets/explorers/etc.
Resource and maintenance requirements for Cardano blockchain components (e.g. cardano-node, cardano-db-sync) are ever-growing. Along with that, every builder needs to identify how to query complex information from the chain.

Overview

Koios Java Client is a Java REST Client library which allows interacting with Koios Server Instances using Java Objects.

Features

• Synchronous REST messaging using java objects
• Structured Java Objects logging
• Pagination (Limit and Offset) Supported
• Horizontal Filtering Supported
• Sorting Supported
• API Token Supported
• Inner Retry Mechanism upon Timeouts
• HTTP GZIP Compression Supported

Supported REST Services

Service	Endpoint	Description
Network	Chain Tip	Get the tip info about the latest block seen by chain
	Genesis Info	Get the Genesis parameters used to start specific era on chain
	Historical tokenomic stats	Get the circulating utxo, treasury, rewards, supply and reserves in lovelace for specified epoch, all epochs if empty
	Param Update Proposals	Get all parameter update proposals submitted to the chain starting Shelley era
	Reserve Withdrawals	List of all withdrawals from reserves against stake accounts
	Treasury Withdrawals	List of all withdrawals from treasury against stake accounts
Epoch	Epoch Information	Get the epoch information, all epochs if no epoch specified
	Epoch's Protocol Parameters	Get the protocol parameters for specific epoch, returns information about all epochs if no epoch specified
	Epoch's Block Protocols	Get the information about block protocol distribution in epoch
Block	Block List	Get summarised details about all blocks (paginated - latest first)
	Block Information	Get detailed information about a specific block
	Block Transactions	Get a list of all transactions included in a provided block
	Block Transactions (Detailed Info)	Get detailed information about transaction(s) for requested blocks
Transactions	UTxO Info	Get UTxO set for requested UTxO references
	Raw Transaction (CBOR)	Get raw transaction(s) in CBOR format
	Transaction Information	Get detailed information about transaction(s)
	Transaction Metadata	Get metadata information (if any) for given transaction(s)
	Transaction Metadata Labels	Get a list of all transaction metalabels
	Submit Transaction	Submit an already serialized transaction to the network.
	Transaction Status (Block Confirmations)	Get the number of block confirmations for a given transaction hash list
Address	Address Information	Get address info - balance, associated stake address (if any) and UTxO set
	Address UTxOs	Get UTxO set for given addresses
	UTxOs from payment credentials	Get UTxO details for requested payment credentials
	Address Transactions	Get the transaction hash list of input address array, optionally filtering after specified block height (inclusive)
	Transactions from payment credentials	Get the transaction hash list of input payment credential array, optionally filtering after specified block height (inclusive)
	Address Assets	Get the list of all the assets (policy, name and quantity) for a given address
Stake Account	Account List	Get a list of all accounts
	Account Information	Get the account info of any (payment or staking) address
	Account Information (Cached)	Get the cached account information for given stake addresses (accounts)
	Account UTxOs	Get a list of all UTxOs for given stake addresses (account)s
	Account Txs	Get a list of all Txs for a given stake address (account)
	Account Rewards	Get the full rewards history (including MIR) for a stake address, or certain epoch if specified
	Account Updates	Get the account updates (registration, deregistration, delegation and withdrawals)
	Account Addresses	Get all addresses associated with an account
	Account Assets	Get the native asset balance of an account
	Account History	Get the staking history of an account
Asset	Asset List	Get the list of all native assets (paginated)
	Policy Asset List	Get the list of asset under the given policy (including balances)
	Asset Token Registry	Get a list of assets registered via token registry on github
	Asset Information	Get the information of an asset including first minting & token registry metadata
	Asset Information (Bulk)	Get the information of a list of assets including first minting & token registry metadata
	Asset UTxOs	Get the UTXO information of a list of assets including
	Asset History	Get the mint/burn history of an asset
	Asset Addresses	Get the list of all addresses holding a given asset
	NFT Address	Get the address where specified NFT currently reside on
	Policy Asset Address List	Get the list of addresses with quantity for each asset on the given policy.
	Policy Asset Information	Get the information for all assets under the same policy
	Policy Asset Mints	Get a list of mint or burn count details for all assets minted under a policy
	Asset Summary	Get the summary of an asset (total transactions exclude minting/total wallets include only wallets with asset balance)
	Asset Transactions	Get the list of all asset transaction hashes (newest first)
Governance	DReps Epoch Summary	Summary of voting power and DRep count for each epoch
	DReps List	List of all active delegated representatives (DReps)
	DReps Info	Get detailed information about requested delegated representatives (DReps)
	DReps Metadata	List metadata for requested delegated representatives (DReps)
	DReps Updates	List of updates for requested (or all) delegated representatives (DReps)
	DReps Votes	List of all votes casted by requested delegated representative (DRep)
	DReps Delegators	List of all delegators to requested delegated representative (DRep).
	Committee Information	Information about active committee and its members
	Committee Votes	List of all votes casted by given committee member or collective
	Proposals List	List of all governance proposals
	Voter's Proposal List	List of all governance proposals for specified DRep, SPO or Committee credential
	Proposal Voting Summary	Summary of votes for given proposal
	Proposal Votes	List of all votes cast on specified governance action
	Pool Votes	List of all votes casted by a pool
Pool	Pool List	A list of all currently registered/retiring (not retired) pools
	Pool Information	Current pool statuses and details for a specified list of pool ids
	Pool Stake Snapshot	Returns Mark, Set and Go stake snapshots for the selected pool, useful for leaderlog calculation
	Pool Delegators List	Return information about live delegators for a given pool.
	Pool Delegators History	Return information about active delegators (incl. history) for a given pool and epoch number - current epoch if not provided.
	Pool Blocks	Return information about blocks minted by a given pool in current epoch (or _epoch_no if provided)
	Pool Stake, Block and Reward History	Return information about pool stake, block and reward history in a given epoch _epoch_no (or all epochs that pool existed for, in descending order if no _epoch_no was provided)
	Pool Updates (History)	Return all pool updates for all pools or only updates for specific pool if specified
	Pool Registrations	Return all pool registrations initiated in the requested epoch
	Pool Retirements	Return all pool retirements initiated in the requested epoch
	Pool Relays	A list of registered relays for all currently registered/retiring (not retired) pools
	Pool Metadata	Metadata (on & off-chain) for all currently registered/retiring (not retired) pools
Script	Script Information	List of script information for given script hashes
	Native Script List	List of all existing native script hashes along with their creation transaction hashes
	Plutus Script List	List of all existing Plutus script hashes along with their creation transaction hashes
	Script Redeemers	List of all redeemers for a given script hash
	Script UTxOs	List of all UTXOs for a given script hash
	Datum Information	List of datum information for given datum hashes

Version Compatability Chart

Koios Instance	Koios Java Client
1.3.0	1.20.1
1.2.0	1.19.3
1.1.2	1.18.2
1.0.10	1.17.3
1.0.9	1.16.3
1.0.8	1.15.2
1.0.7	1.14.1
1.0.6	1.13

Use as a library in a Java Project

Add dependency

• For Maven, add the following dependency to project's pom.xml

<dependency>
    <groupId>io.github.cardano-community</groupId>
    <artifactId>koios-java-client</artifactId>
    <version>1.20.1</version>
</dependency>

• For Gradle, add the following dependency to build.gradle

compile group: 'io.github.cardano-community', name: 'koios-java-client', version: '1.20.1'

Get Koios Backend Service (No API Token)

• Mainnet

BackendService backendService = BackendFactory.getKoiosMainnetService();

• Preview

BackendService backendService = BackendFactory.getKoiosPreviewService();

• Preprod

BackendService backendService = BackendFactory.getKoiosPreprodService();

• Guildnet

BackendService backendService = BackendFactory.getKoiosGuildService();

Get Koios Backend Service (with API Token)

Get Your API Token from Koios Website: https://www.koios.rest/

• Mainnet

String apiToken = "<API_TOKEN>";
BackendService backendService = BackendFactory.getKoiosMainnetService(apiToken);

Get Koios Backend Services

NetworkService networkService = backendService.getNetworkService();
EpochService epochService = backendService.getEpochService();
BlockService blockService = backendService.getBlockService();
TransactionsService transactionsService = backendService.getTransactionsService();
AddressService addressService = backendService.getAddressService();
AccountService accountService = backendService.getAccountService();
AssetService assetService = backendService.getAssetService();
PoolService poolService = backendService.getPoolService();
ScriptService scriptService = backendService.getScriptService();

Advanced Query Example (Preview)

Querying a Descending Order of All Address Transactions since Block No. #42248 to Block No. #69447 (inclusive), Limited to Maximum of 10 Results.

String address = "addr_test1qrvaadv0h7atv366u6966u4rft2svjlf5uajy8lkpsgdrc24rnskuetxz2u3m5ac22s3njvftxcl2fc8k8kjr088ge0qz98xmv";

Options options = Options.builder()
        .option(Limit.of(10))
        .option(Offset.of(0))
        .option(Order.by("block_height", SortType.DESC))
        .option(Filter.of("block_height", FilterType.GTE, "42248"))
        .option(Filter.of("block_height", FilterType.LTE, "69447")).build();

Result<List<TxHash>> transactionsResult = addressService.getAddressTransactions(List.of(address), options);

Supported Environment Variables

Variable	Type	Description	Default
KOIOS_JAVA_LIB_LOGGING	boolean	Toggle Logging	false
KOIOS_JAVA_LIB_RETRIES_COUNT	integer	Sets the max retry count upon request timeout	5
KOIOS_JAVA_LIB_READ_TIMEOUT_SEC	integer	Sets the default read timeout for new connections (seconds)	300
KOIOS_JAVA_LIB_CONNECT_TIMEOUT_SEC	integer	Sets the default connect timeout for new connections (seconds)	300
KOIOS_JAVA_LIB_RETRY_ON_TIMEOUT	boolean	Sets whether to retry upon request timeout	true
KOIOS_JAVA_LIB_GZIP_COMPRESSION	boolean	Sets whether to use GZIP Compression	true

Clone & Build with Maven

git clone https://github.com/cardano-community/koios-java-client.git
cd koios-java-client
mvn clean install

Used by

• Bloxbean - Cardano Client Library
• ISR - Israeli Cardano Community
• MusicBox - CNFT Project
• Adabox - Decentralized All in One Hub

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