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package eu.unicore.uas.util;
/**
* The State interface encapsulates two notions:
*
* - a target object is transitioned from the current state to the
* next using the next() method
* - when errors occur, recovery actions can be taken, or simply a retry
* can occur, as handled by the onError() method
*
*
* @author schuller
*/
public interface State {
/**
* transition to the next state
* @param target - the target object
* @return next State, or null if there is no next state
* @throws Exception
*/
public State next(T target) throws Exception;
/**
* decide how to handle an error which occurred while processing next()
*
* @param target - the target object
* @param exception - the error that occurred
* @return next State, or null if there is no next state
* @throws Exception
*/
public State onError(T target, Exception exception) throws Exception;
/**
* get this state's name, unique for the state machine, which is both
* useful for humans, and which can be used as e.g. hash map key
*/
public String getName();
/**
* whether the state machine can pause after this state:
* if false the state machine must always process the
* next state
*/
public boolean isPausable();
/**
* if this is larger than zero, failed state transitions will be re-tried
* (at most the given number of times)
*/
public int getNumberOfRetries();
/**
* if this is larger than zero, it is used to delay a retry by the given number
* of milliseconds
*/
public int getRetryDelay();
}