com.atomikos.icatch.Participant Maven / Gradle / Ivy
/**
* Copyright (C) 2000-2020 Atomikos
*
* LICENSE CONDITIONS
*
* See http://www.atomikos.com/Main/WhichLicenseApplies for details.
*/
package com.atomikos.icatch;
import java.util.Map;
/**
* A participant for (distributed) two-phase commit of composite transactions.
*
* Implementations can be added as a 2PC participant in the icatch kernel.
*
* VERY IMPORTANT: implementations should also override the
* default equals
* and hashCode methods, in order for two-phase commit to work properly!
*
*/
public interface Participant
{
/**
* Indicates that no commit/rollback is needed after prepare.
*/
static final int READ_ONLY=0x00;
/**
* @return String The unique URI for this remote participant.
*/
String getURI();
/**
* For cascading 2PC, this method sets the information needed
* to cascade. This method is relevant only for
* transaction monitors; leave empty otherwise!
*
* @param allParticipants The information needed by
* the transaction monitor.
*
* @exception SysException
*/
void setCascadeList(Map allParticipants)
throws SysException;
/**
* Set by the root coordinator: the total no of siblings detected.
* This method is relevant only for
* transaction monitors; leave empty otherwise!
*
*@param count The global count.
*/
void setGlobalSiblingCount(int count);
/**
* Prepares the participant.
* Any locks for this participant's work should be
* recoverable (either saved to an external file OR be part
* of the instance's non-transient state so that they can be
* flushed into the transaction manager's log).
*
* @return int READ_ONLY if no second round is needed.
* Participants that return this value on prepare will not be
* called by commit or rollback afterwards.
*
* @exception RollbackException For a NO vote.
* This indicates that the participant has already rolled back
* (or marked for rollback) the work on behalf of this participant.
*
* @exception HeurHazardException On possible conflicts.
* This happens for remote participants instances, in case of
* communication failures.
*
* @exception HeurMixedException If some subordinate
* participants voted YES, timed out and committed heuristically
* whereas afterwards some NO votes where received.
*
* @exception SysException
*/
int prepare()
throws RollbackException,
HeurHazardException,
HeurMixedException,
SysException;
/**
* Commits the participant's work.
* NOTE: custom participant implementations should
* preferably be made for the server's local VM
* (e.g., it is better not to do this over RMI).
* Also, they should rely on the transaction manager
* for heuristic timeout (and NOT decide to terminate
* heuristically themselves).
* In that case, implementations never need to throw any of the heuristic exceptions
* of this method.
*
*
* @param onePhase If true, one-phase commit is being started.
* If the participant has received a prepare call earlier,
* then it should throw a SysException here.
*
* @exception HeuristicRollbackException If the participant has rolled back.
*
* @exception HeuristicMixedException If part of it was rolled back.
*
* @exception HeurHazardException On possible conflicts.
*
* @exception RollbackException In case of one-phase commit,
* and the transaction has been rolled back at the time
* commit is called.
*
* @exception SysException
*/
void commit ( boolean onePhase )
throws HeurRollbackException,
HeurHazardException,
HeurMixedException,
RollbackException,
SysException;
/**
* Rollback of the participant's work.
*
* NOTE: custom participant implementations should
* preferably be made for the server's local VM
* (e.g., it is better not to do this over RMI).
* Also, they should rely on the icatch transaction manager
* for heuristic timeout (and NOT decide to terminate
* heuristically themselves).
* In that case, implementations never need to throw any of the heuristic exceptions
* of this method.
*
* @exception HeurCommitException If the participant committed.
* @exception HeurHazardException If the participant's final state
* is unsure.
* @exception HeurMixedException If part of the work was rolled back.
*
* @exception SysException
*/
void rollback()
throws HeurCommitException,
HeurMixedException,
HeurHazardException,
SysException;
/**
* Indicates that a heuristic participant can forget about its work.
*
* If implementations rely on the transaction manager to
* decide when to do heuristics (rather then deciding
* in the participant implementation), then
* leave this method empty.
*/
void forget();
/**
* @return The (unique) name of the recoverable resource as known in the configuration. Null if not relevant.
*/
String getResourceName();
}