corda / net.corda.core.node / ServiceHub

ServiceHub

interface ServiceHub : ServicesForResolution

A service hub is the starting point for most operations you can do inside the node. You are provided with one when a class annotated with CordaService is constructed, and you have access to one inside flows. Most RPCs simply forward to the services found here after some access checking.

The APIs are organised roughly by category, with a few very important top level APIs available on the ServiceHub itself. Inside a flow, it's safe to keep a reference to services found here on the stack: checkpointing will do the right thing (it won't try to serialise the internals of the service).

In unit test environments, some of those services may be missing or mocked out.

Properties

clock	`abstract val clock: Clock` A Clock representing the node's current time. This should be used in preference to directly accessing the clock so the current time can be controlled during unit testing.
contractUpgradeService	`abstract val contractUpgradeService: ContractUpgradeService` The ContractUpgradeService is responsible for securely upgrading contract state objects according to a specified and mutually agreed (amongst participants) contract version.
diagnosticsService	`abstract val diagnosticsService: DiagnosticsService` The DiagnosticsService provides diagnostic level information about the node, including the current version of the node, and the CorDapps currently installed on the node. Note that this information should be used to provide diagnostics only, and no functional decisions should be made based on this.
keyManagementService	`abstract val keyManagementService: KeyManagementService` The key management service is responsible for storing and using private keys to sign things. An implementation of this may, for example, call out to a hardware security module that enforces various auditing and frequency-of-use requirements.
myInfo	`abstract val myInfo: NodeInfo` The NodeInfo object corresponding to our own entry in the network map.
networkMapCache	`abstract val networkMapCache: NetworkMapCache` A network map contains lists of nodes on the network along with information about their identity keys, services they provide and host names or IP addresses where they can be connected to. The cache wraps around a map fetched from an authoritative service, and adds easy lookup of the data stored within it. Generally it would be initialised with a specified network map service, which it fetches data from and then subscribes to updates of.
validatedTransactions	`abstract val validatedTransactions: TransactionStorage` A map of hash->tx where tx has been signature/contract validated and the states are known to be correct. The signatures aren't technically needed after that point, but we keep them around so that we can relay the transaction data to other nodes that need it.
vaultService	`abstract val vaultService: VaultService` The vault service lets you observe, soft lock and add notes to states that involve you or are relevant to your node in some way. Additionally you may query and track states that correspond to various criteria.

Inherited Properties

attachments	`abstract val attachments: AttachmentStorage` Provides access to storage of arbitrary JAR files (which may contain only data, no code).
cordappProvider	`abstract val cordappProvider: CordappProvider` Provides access to anything relating to cordapps including contract attachment resolution and app context
identityService	`abstract val identityService: IdentityService` An identity service maintains a directory of parties by their associated distinguished name/public keys and thus supports lookup of a party given its key, or name. The service also manages the certificates linking confidential identities back to the well known identity (i.e. the identity in the network map) of a party.
networkParameters	`abstract val networkParameters: NetworkParameters` Returns the network parameters the node is operating under.
networkParametersService	`abstract val networkParametersService: NetworkParametersService` Provides access to historical network parameters that are used in transaction resolution.

Functions

addSignature	`open fun addSignature(signedTransaction: SignedTransaction, publicKey: PublicKey): SignedTransaction` Helper method to append an additional signature to an existing (partially) SignedTransaction. `open fun addSignature(signedTransaction: SignedTransaction): SignedTransaction` Helper method to append an additional signature for an existing (partially) SignedTransaction using the default identity signing key of the node.
cordaService	`abstract fun <T : SerializeAsToken> cordaService(type: Class<T>): T` Return the singleton instance of the given Corda service type. This is a class that is annotated with CordaService and will have automatically been registered by the node.
createSignature	`open fun createSignature(signedTransaction: SignedTransaction, publicKey: PublicKey): TransactionSignature` Helper method to create an additional signature for an existing (partially) SignedTransaction. Additional SignatureMetadata, including the platform version used during signing and the cryptographic signature scheme use, is added to the signature. `open fun createSignature(signedTransaction: SignedTransaction): TransactionSignature` Helper method to create a signature for an existing (partially) SignedTransaction using the default identity signing key of the node. The legal identity key is used to sign. Additional SignatureMetadata, including the platform version used during signing and the cryptographic signature scheme use, is added to the signature. `open fun createSignature(filteredTransaction: FilteredTransaction, publicKey: PublicKey): TransactionSignature` Helper method to create a signature for a FilteredTransaction. Additional SignatureMetadata, including the platform version used during signing and the cryptographic signature scheme use, is added to the signature. `open fun createSignature(filteredTransaction: FilteredTransaction): TransactionSignature` Helper method to create a signature for a FilteredTransaction using the default identity signing key of the node. The legal identity key is used to sign. Additional SignatureMetadata, including the platform version used during signing and the cryptographic signature scheme use, is added to the signature.
getAppContext	`open fun getAppContext(): CordappContext` See CordappProvider.getAppContext
jdbcSession	`abstract fun jdbcSession(): Connection` Exposes a JDBC connection (session) object using the currently configured database. Applications can use this to execute arbitrary SQL queries (native, direct, prepared, callable) against its Node database tables (including custom contract tables defined by extending net.corda.core.schemas.QueryableState).
recordTransactions	`open fun recordTransactions(notifyVault: Boolean, txs: Iterable<SignedTransaction>): Unit` `open fun recordTransactions(notifyVault: Boolean, first: SignedTransaction, vararg remaining: SignedTransaction): Unit` Stores the given SignedTransactions in the local transaction storage and then sends them to the vault for further processing if notifyVault is true. This is expected to be run within a database transaction. `abstract fun recordTransactions(statesToRecord: StatesToRecord, txs: Iterable<SignedTransaction>): Unit` Stores the given SignedTransactions in the local transaction storage and then sends them to the vault for further processing if statesToRecord is not StatesToRecord.NONE. This is expected to be run within a database transaction. `open fun recordTransactions(first: SignedTransaction, vararg remaining: SignedTransaction): Unit` `open fun recordTransactions(txs: Iterable<SignedTransaction>): Unit` Stores the given SignedTransactions in the local transaction storage and then sends them to the vault for further processing. This is expected to be run within a database transaction.
registerUnloadHandler	`abstract fun registerUnloadHandler(runOnStop: () -> Unit): Unit` Allows the registration of a callback that may inform services when the app is shutting down.
signInitialTransaction	`open fun signInitialTransaction(builder: TransactionBuilder, publicKey: PublicKey): SignedTransaction` Helper method to construct an initial partially signed transaction from a TransactionBuilder using keys stored inside the node. Signature metadata is added automatically. `open fun signInitialTransaction(builder: TransactionBuilder): SignedTransaction` Helper method to construct an initial partially signed transaction from a TransactionBuilder using the default identity key contained in the node. The legal identity key is used to sign. `open fun signInitialTransaction(builder: TransactionBuilder, signingPubKeys: Iterable<PublicKey>): SignedTransaction` Helper method to construct an initial partially signed transaction from a TransactionBuilder using a set of keys all held in this node.
toStateAndRef	`open fun <T : ContractState> toStateAndRef(stateRef: StateRef): StateAndRef<T>` Converts the given StateRef into a StateAndRef object.
withEntityManager	`abstract fun <T> withEntityManager(block: <ERROR CLASS>.() -> T): T` `abstract fun withEntityManager(block: Consumer<<ERROR CLASS>>): Unit` Exposes the Java Persistence API (JPA) to flows via a restricted EntityManager. This method can be used to persist and query entities which inherit from MappedSchema. This is particularly useful if off-ledger data needs to be kept in conjunction with on-ledger state data.

Inherited Functions

loadContractAttachment	`abstract fun loadContractAttachment(stateRef: StateRef): Attachment` Returns the Attachment that defines the given StateRef, which must be in the visible subset of the ledger.
loadState	`abstract fun loadState(stateRef: StateRef): TransactionState<*>` Given a StateRef loads the referenced transaction and looks up the specified output ContractState.
loadStates	`abstract fun loadStates(stateRefs: Set<StateRef>): Set<StateAndRef<ContractState>>` Given a Set of StateRef's loads the referenced transaction and looks up the specified output ContractState.
specialise	`open fun specialise(ltx: LedgerTransaction): LedgerTransaction` Provides a callback for the Node to customise the LedgerTransaction.

Extension Functions

contextLogger	`fun Any.contextLogger(): <ERROR CLASS>` When called from a companion object, returns the logger for the enclosing class.
getCashBalance	`fun ServiceHub.getCashBalance(currency: Currency): Amount<Currency>`
getCashBalances	`fun ServiceHub.getCashBalances(): Map<Currency, Amount<Currency>>`
ledger	`fun ServiceHub.ledger(notary: Party = TestIdentity.fresh("ledger notary").party, script: LedgerDSL<TestTransactionDSLInterpreter, TestLedgerDSLInterpreter>.() -> Unit): LedgerDSL<TestTransactionDSLInterpreter, TestLedgerDSLInterpreter>` Creates and tests a ledger built by the passed in dsl.
transaction	`fun ServiceHub.transaction(notary: Party = TestIdentity.fresh("transaction notary").party, script: TransactionDSL<TransactionDSLInterpreter>.() -> EnforceVerifyOrFail): LedgerDSL<TestTransactionDSLInterpreter, TestLedgerDSLInterpreter>` Creates a ledger with a single transaction, built by the passed in dsl.

Inheritors

AppServiceHub

interface AppServiceHub : ServiceHub

A net.corda.core.node.services.CordaService annotated class requires a constructor taking a single parameter of type AppServiceHub. With the AppServiceHub parameter a net.corda.core.node.services.CordaService is able to access to privileged operations. In particular such a net.corda.core.node.services.CordaService can initiate and track flows marked with net.corda.core.flows.StartableByService.

MockServices

open class MockServices : ServiceHub

An implementation of ServiceHub that is designed for in-memory unit tests of contract validation logic. It has enough functionality to do tests of code that queries the vault, inserts to the vault, and constructs/checks transactions. However it isn't enough to test flows and other aspects of an app that require a network. For that you should investigate MockNetwork.