com.wassilak.emom.message.header.Header Maven / Gradle / Ivy
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package com.wassilak.emom.message.header;
import java.io.Serializable;
import java.util.Date;
/**
* The Header interface defines the behavior of the emom Header object, which
* represents the header of a Message. Headers contain metadata about it's
* Message, and as such are typically used to locate the desired message
* without having to load and inspect the Message's payload.
*
* Copyright (C) 2014 John Wassilak ([email protected])
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see http://www.gnu.org/licenses/.
*/
public interface Header extends Serializable, Comparable {
/**
* The MIN_TTL constant represents the minimum allowable value of a
* Header's timeToLive property.
*/
public static final Long MIN_TTL = 0L;
/**
* The MAX_TTL constant represents the maximum allowable value of a
* Header's timeToLive property.
*/
public static final Long MAX_TTL = Long.MAX_VALUE - 1;
/**
* The MIN_ID_LENGTH constant represents the minimum allowable length
* of a Header's id property.
*/
public static final Integer MIN_ID_LENGTH = 1;
/**
* The MAX_ID_LENGTH constant represents the maximum allowable length
* of a Header's id property.
*/
public static final Integer MAX_ID_LENGTH = 20;
/**
* The getID method returns the ID of the message.
*
* @return The ID of the message.
*/
public String getID();
/**
* The getTimeToLive method returns the time that the message can live
* before it expires, in milliseconds.
*
* @return The length of time before the message should expire.
*/
public Long getTimeToLive();
/**
* The getTimeStamp method returns the date/time that the message was sent.
* If the message hasn't been sent yet, this will typically be null.
*
* @return The date/time that the message was sent, null if it hasn't been
* sent.
*/
public Date getTimeStamp();
/**
* The setTimeStamp method sets the date/time that the message was sent.
*
* @param timeStamp The date/time to set the message's timestamp to.
*/
public void setTimeStamp(Date timeStamp);
/**
* The equals method indicates whether some other object is "equal to"
* this one.
*
* @param obj the reference object with which to compare.
* @return true if this object is the same as the obj argument;
* false otherwise.
*/
@Override
public boolean equals(Object obj);
/**
* The hashCode method returns a hash code value for the object.
*
* @return a hash code value for this object.
*/
@Override
public int hashCode();
/**
* The compareTo method compares this object with the specified object
* for order. Returns a negative integer, zero, or a positive integer as
* this object is less than, equal to, or greater than the specified
* object. The comparison is based on timeStamp, so Headers with a later
* timeStamp are placed later in a list. Null timeStamps are handled such
* that Headers with null timestamps are less than those with populated
* ones. Not that, per java spec, null Headers throw an exception.
*
* @param o the object to be compared.
* @return a negative integer, zero, or a positive integer as this object
* is less than, equal to, or greater than the specified object.
*/
@Override
public int compareTo(Header o);
}