Enum Config.TopologyReliabilityMode

    • Enum Constant Detail

      • ATMOST_ONCE

        public static final Config.TopologyReliabilityMode ATMOST_ONCE
        Heron provides no guarantees wrt tuple delivery. Tuples emitted by components can get lost for any reason(network issues, component failures, overloaded downstream component, etc).
      • ATLEAST_ONCE

        public static final Config.TopologyReliabilityMode ATLEAST_ONCE
        Heron guarantees that each emitted tuple is seen by the downstream components atleast once. This is achieved via the anchoring process where emitted tuples are anchored based on input tuples. Note that in failure scenarios, downstream components can see the same tuple multiple times.
      • EFFECTIVELY_ONCE

        public static final Config.TopologyReliabilityMode EFFECTIVELY_ONCE
        Heron guarantees that each emitted tuple is seen by the downstream components effectively once. This is achieved via distributed snapshotting approach is described at https://docs.google.com/document/d/1pNuE77diSrYHb7vHPuPO3DZqYdcxrhywH_f7loVryCI/edit In this mode Heron will try to take the snapshots of all of the components of the topology every TOPOLOGY_STATEFUL_CHECKPOINT_INTERVAL_SECONDS seconds. Upon failure of any component or detection of any network failure, Heron will initiate a recovery mechanism to revert the topology to the last globally consistent checkpoint
    • Method Detail

      • values

        public static Config.TopologyReliabilityMode[] values()
        Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:
        for (Config.TopologyReliabilityMode c : Config.TopologyReliabilityMode.values())
            System.out.println(c);
        
        Returns:
        an array containing the constants of this enum type, in the order they are declared
      • valueOf

        public static Config.TopologyReliabilityMode valueOf​(String name)
        Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
        Parameters:
        name - the name of the enum constant to be returned.
        Returns:
        the enum constant with the specified name
        Throws:
        IllegalArgumentException - if this enum type has no constant with the specified name
        NullPointerException - if the argument is null