Interface IEventSourcingAggregate<C, S, E, V, CM, EM>

Event sourcing aggregate interface is using/delegating a decider of type IDecider<C, S, E> to handle commands and produce events. In order to handle the command, aggregate needs to fetch the current state (represented as a list of events) via IEventRepository.fetchEvents function, and then delegate the command to the decider which can produce new event(s) as a result.

Produced events are then stored via IEventRepository.save function.

Author

Иван Дугалић / Ivan Dugalic /

Idugalic

interface IEventSourcingAggregate<C, S, E, V, CM, EM> {
    decide: ((command, state) => readonly E[]);
    evolve: ((state, event) => S);
    fetch: ((command) => Promise<readonly (E & V & EM)[]>);
    handle: ((command) => Promise<readonly (E & V & EM)[]>);
    initialState: S;
    save: ((events, commandMetadata, versionProvider) => Promise<readonly (E & V & EM)[]>);
    versionProvider: ((event) => Promise<null | V>);
}

Type Parameters

  • C

    Commands of type C that this aggregate can handle

  • S

    Aggregate state of type S

  • E

    Events of type E that this aggregate can publish

  • V

    Version

  • CM

    Command Metadata

  • EM

    Event Metadata

Hierarchy (view full)

Implemented by

Properties

decide evolve fetch handle initialState save versionProvider

Properties

Readonly decide

decide: ((command, state) => readonly E[])

Type declaration

    • (command, state): readonly E[]

    • Parameters

      • command: C
      • state: S

      Returns readonly E[]

Readonly evolve

evolve: ((state, event) => S)

Type declaration

    • (state, event): S

    • Parameters

      • state: S
      • event: E

      Returns S

Readonly fetch

fetch: ((command) => Promise<readonly (E & V & EM)[]>)

Fetch events

Type declaration

    • (command): Promise<readonly (E & V & EM)[]>

    • Parameters

      • command: C & CM

        Command of type C with metadata of type CM

      Returns Promise<readonly (E & V & EM)[]>

Returns

list of Events with Version and Event Metadata

Readonly handle

handle: ((command) => Promise<readonly (E & V & EM)[]>)

Handles the command of type C, and returns new persisted list of pairs of event and its version.

Type declaration

    • (command): Promise<readonly (E & V & EM)[]>

    • Parameters

      • command: C & CM

        Command of type C with Command Metadata

      Returns Promise<readonly (E & V & EM)[]>

Returns

list of persisted events with Version and Event Metadata

Readonly initialState

initialState: S

Readonly save

save: ((events, commandMetadata, versionProvider) => Promise<readonly (E & V & EM)[]>)

Save events

Type declaration

    • (events, commandMetadata, versionProvider): Promise<readonly (E & V & EM)[]>

    • Parameters

      • events: readonly E[]

        list of Events

      • commandMetadata: CM

        Command Metadata of the command that initiated events

      • versionProvider: ((e) => Promise<null | V>)

        A provider for the Latest Event in this stream and its Version/Sequence

          • (e): Promise<null | V>

          • Parameters

            Returns Promise<null | V>

      Returns Promise<readonly (E & V & EM)[]>

Returns

a list of newly saved Event(s) of type E with Version of type V and with Event Metadata of type EM

Readonly versionProvider

versionProvider: ((event) => Promise<null | V>)

Get the latest event stream version / sequence

Type declaration

    • (event): Promise<null | V>

    • Parameters

      • event: E

        Event of type E

      Returns Promise<null | V>

Returns

the latest version / sequence of the event stream that this event belongs to.

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