com.hazelcast.quorum

Interface QuorumService

All Known Implementing Classes:

QuorumServiceImpl

public interface QuorumService

Quorum service can be used to trigger cluster quorums at any time. Normally quorums are done when any change happens on the member list. IMPORTANT: The term "quorum" simply refers to the count of members in the cluster required for an operation to succeed. It does NOT refer to an implementation of Paxos or Raft protocols as used in many NoSQL and distributed systems. The mechanism it provides in Hazelcast protects the user in case the number of nodes in a cluster drops below the specified one.

Method Summary

Modifier and Type	Method and Description
void	ensureQuorumPresent(String quorumName, QuorumType requiredQuorumPermissionType) Ensures that the quorum with the given name is present.
Quorum	getQuorum(String quorumName) Returns the Quorum instance for a given quorum name.

Method Detail

getQuorum

Quorum getQuorum(String quorumName)
          throws IllegalArgumentException

Returns the Quorum instance for a given quorum name.

Parameters:

quorumName - name of the quorum

Returns:

Quorum

Throws:

IllegalArgumentException - if no quorum found for given name

NullPointerException - if quorumName is null

ensureQuorumPresent

void ensureQuorumPresent(String quorumName,
                         QuorumType requiredQuorumPermissionType)
                  throws QuorumException

Ensures that the quorum with the given name is present. Throws a QuorumException if quorum not present. Does not throw exception if quorumName null or quorum undefined. If (requiredQuorumPermissionType == READ) -> will check for presence of READ or READ_WRITE quorum
If (requiredQuorumPermissionType == WRITE) -> will check for presence of WRITE or READ_WRITE quorum
If (requiredQuorumPermissionType == READ_WRITE) -> will check for presence of READ_WRITE quorum

Parameters:

quorumName - quorum name to ensure, can be null or empty

requiredQuorumPermissionType - type of quorum required

Throws:

QuorumException - if quorum defined and not present