Common Concepts

Defining Terms

When discussing CDL we need to define some common terms.

  • State: A class or object which complies with ContractState interface in net.corda.core.contracts. In the training materials, this is what is referred to as a State.
  • Ledger state: This is the sum total of all the unconsumed ContractStates
  • Status: (of a State) A snap shot of the potential values of the properties of a State.
  • Contract: A class or object which inherits from Contract in net.corda.core.contracts. This defines the set of constraints which operate over the States in a Transaction.
  • Transaction: A Corda transaction, the mechanism by which the Ledger state is changed.

Representing States

Many views in CDL show representation of a Corda State. For the latest version of CDL we have standardised the representation of a Corda State across all the various views. The base representation of a Corda State is as follows:

../../_images/CMN2_State.png
  1. State Class and Status
The Class of State and the Status of the State, this effectively defines the scope of the box, ie. if the State Class or Status is different, it’s a different box. Note all Corda States comply with the ContractState Interface.
  1. Properties
These are the properties of the State whilst in the particular status. Not all properties need to be shown, just the ones salient to the behaviour of the State in this Status.
  1. Participants
These are the participants in the state, this corresponds to the parties who the Transaction containing the State will be sent to. Note, if the Transaction contains multiple States the Transaction will be sent to the union of all the States’ participants.

The State representation no longer contains any Contract constraints, these are all shown externally to the State itself. See the State Machine view for details on constraints.

The representation of a State can degrade to show less detail For example, if you don’t need to show participants or properties they can be omitted.

../../_images/CMN2_Degraded_state.png