Accessing node services

Within FlowLogic.call, the flow developer has access to the node’s ServiceHub, which provides access to the various services the node provides. The services offered by the ServiceHub are split into the following categories:

• ServiceHub.networkMapCache

  • Provides information on other nodes on the network (e.g. notaries…)

• ServiceHub.identityService

  • Allows you to resolve anonymous identities to well-known identities if you have the required certificates

• ServiceHub.attachments

  • Gives you access to the node’s attachments

• ServiceHub.validatedTransactions

  • Gives you access to the transactions stored in the node

• ServiceHub.vaultService

  • Stores the node’s current and historic states

• ServiceHub.keyManagementService

  • Manages signing transactions and generating fresh public keys

• ServiceHub.myInfo

  • Other information about the node

• ServiceHub.clock

  • Provides access to the node’s internal time and date

• ServiceHub.diagnosticsService

  • Provides diagnostic information about the node, including the node version and currently running apps. Note that this data should be used for diagnostic purposes ONLY

• ServiceHub.contractUpgradeService

  • Provides functionality for secure contract upgrades

Additional, ServiceHub exposes the following properties:

• ServiceHub.loadState and ServiceHub.toStateAndRef to resolve a StateRef into a TransactionState or a StateAndRef
• ServiceHub.signInitialTransaction to sign a TransactionBuilder and convert it into a SignedTransaction
• ServiceHub.createSignature and ServiceHub.addSignature to create and add signatures to a SignedTransaction