ServiceHub - corda

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 | 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. `abstract val clock: Clock`
#### contractUpgradeService | The ContractUpgradeService is responsible for securely upgrading contract state objects according to a specified and mutually agreed (amongst participants) contract version. `abstract val contractUpgradeService: ContractUpgradeService`
#### 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. `abstract val diagnosticsService: DiagnosticsService`
#### 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. `abstract val keyManagementService: KeyManagementService`
#### myInfo | The NodeInfo object corresponding to our own entry in the network map. `abstract val myInfo: NodeInfo`
#### 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. `abstract val networkMapCache: NetworkMapCache`
#### telemetryService | Provides operations to support telemetry and telemetry data between nodes. `abstract val telemetryService: TelemetryService`
#### validatedTransactions | 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. `abstract val validatedTransactions: TransactionStorage`
#### 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. `abstract val vaultService: VaultService`

### Functions

#### addSignature | Helper method to append an additional signature to an existing (partially) SignedTransaction. `open fun addSignature(signedTransaction: SignedTransaction, publicKey: PublicKey): SignedTransaction` Helper method to append an additional signature for an existing (partially) SignedTransaction using the default identity signing key of the node. `open fun addSignature(signedTransaction: SignedTransaction): SignedTransaction`
#### cordaService | 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. `abstract fun <T : SerializeAsToken> cordaService(type: Class<T>): T`
#### cordaTelemetryComponent | Return the singleton instance of the given Corda telemetry component type. This is a class that implements TelemetryComponent and will have automatically been registered by the node. `abstract fun <T : TelemetryComponent> cordaTelemetryComponent(type: Class<T>): T`
#### createSignature | 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, publicKey: PublicKey): 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(signedTransaction: SignedTransaction): 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, publicKey: PublicKey): 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. `open fun createSignature(filteredTransaction: FilteredTransaction): TransactionSignature`
#### getAppContext | See CordappProvider.getAppContext `open fun getAppContext(): CordappContext`
#### jdbcSession | 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). `abstract fun jdbcSession(): Connection`
#### recordTransactions | 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. `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 statesToRecord is not StatesToRecord.NONE. 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. 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`
#### registerUnloadHandler | Allows the registration of a callback that may inform services when the app is shutting down. `abstract fun registerUnloadHandler(runOnStop: () -> Unit): Unit`
#### signInitialTransaction | 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, publicKey: PublicKey): 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): SignedTransaction` Helper method to construct an initial partially signed transaction from a TransactionBuilder using a set of keys all held in this node. `open fun signInitialTransaction(builder: TransactionBuilder, signingPubKeys: Iterable<PublicKey>): SignedTransaction`
#### toStateAndRef | Converts the given StateRef into a StateAndRef object. `open fun <T : ContractState> toStateAndRef(stateRef: StateRef): StateAndRef<T>`
#### withEntityManager | 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. `abstract fun <T> withEntityManager(block: EntityManager.() -> T): T` `abstract fun withEntityManager(block: Consumer<EntityManager>): Unit`

### Extension Functions

#### getCashBalance | `fun ServiceHub.getCashBalance(currency: Currency): Amount<Currency>`
#### getCashBalances | `fun ServiceHub.getCashBalances(): Map<Currency, Amount<Currency>>`
#### ledger | Creates and tests a ledger built by the passed in dsl. `fun ServiceHub.ledger(notary: Party = TestIdentity.fresh("ledger notary").party, script: LedgerDSL<TestTransactionDSLInterpreter, TestLedgerDSLInterpreter>.() -> Unit): LedgerDSL<TestTransactionDSLInterpreter, TestLedgerDSLInterpreter>`
#### transaction | Creates a ledger with a single transaction, built by the passed in dsl. `fun ServiceHub.transaction(notary: Party = TestIdentity.fresh("transaction notary").party, script: TransactionDSL<TransactionDSLInterpreter>.() -> EnforceVerifyOrFail): LedgerDSL<TestTransactionDSLInterpreter, TestLedgerDSLInterpreter>`

### Inheritors

#### AppServiceHub | 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. `interface AppServiceHub : ServiceHub`
#### MockServices | 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. `open class MockServices : ServiceHub`