/**
* Copyright (c) 2011, SOCIETIES Consortium (WATERFORD INSTITUTE OF TECHNOLOGY (TSSG), HERIOT-WATT UNIVERSITY (HWU), SOLUTA.NET
* (SN), GERMAN AEROSPACE CENTRE (Deutsches Zentrum fuer Luft- und Raumfahrt e.V.) (DLR), Zavod za varnostne tehnologije
* informacijske družbe in elektronsko poslovanje (SETCCE), INSTITUTE OF COMMUNICATION AND COMPUTER SYSTEMS (ICCS), LAKE
* COMMUNICATIONS (LAKE), INTEL PERFORMANCE LEARNING SOLUTIONS LTD (INTEL), PORTUGAL TELECOM INOVAÇÃO, SA (PTIN), IBM Corp.,
* INSTITUT TELECOM (ITSUD), AMITEC DIACHYTI EFYIA PLIROFORIKI KAI EPIKINONIES ETERIA PERIORISMENIS EFTHINIS (AMITEC), TELECOM
* ITALIA S.p.a.(TI), TRIALOG (TRIALOG), Stiftelsen SINTEF (SINTEF), NEC EUROPE LTD (NEC))
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
* conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.societies.api.context.model;
import java.io.Serializable;
import java.util.Date;
/**
* This class is used to represent the quality characteristics of context
* attribute values. This information is known as Quality of Context (QoC) and
* contains the following properties:
* <ul>
* <li><b>Freshness</b>: Specifies the age of context information. This is
* derived from the time that particular piece of context information was last
* updated.</li>
* <li><b>Origin</b>: Denotes whether a context attribute value was
* {@link CtxOriginType#MANUALLY_SET manually set}, {@link CtxOriginType#SENSED
* sensed}, {@link CtxOriginType#INFERRED inferred}, or
* {@link CtxOriginType#INHERITED inherited}.</li>
* <li><b>Precision:</b> Denotes the quality of coherence or reproducibility of
* measured context attribute values. It is usually expressed in terms of the
* standard deviation of the extended set of measurement results from a well
* defined measurement process. The standard deviation of the conceptual
* population is approximated by the standard deviation of an extended set of
* actual context attribute value measurements. For directly sensed context
* information this parameter is identical to the precision of the sensor used,
* e.g. the precision of a GPS device.</li>
* <li><b>Update Frequency</b>: Defines how often a piece of context information
* is updated. For directly sensed context information this parameter is
* identical to the sample rate of the sensor used.</li>
* </ul>
*
* @author <a href="mailto:nicolas.liampotis@cn.ntua.gr">Nicolas Liampotis</a> (ICCS)
* @see CtxAttribute
* @see CtxOriginType
* @since 0.0.1
*/
public class CtxQuality implements Serializable {
private static final long serialVersionUID = 2596329083367854427L;
/** The context attribute this QoC information refers to. */
private final CtxAttribute attribute;
/** The time the current context attribute value was last updated. */
private Date lastUpdated;
/** The origin type of the current context attribute value. */
private CtxOriginType originType = CtxOriginType.MANUALLY_SET;
/** The precision of the current context attribute value. */
private Double precision;
/** The update frequency of the current context attribute value. */
private Double updateFrequency;
/**
* Constructs a <code>CtxQuality</code> object for the specified context
* attribute.
*
* @param attribute
* the context attribute to associate with this QoC information.
*/
CtxQuality(CtxAttribute attribute) {
this.attribute = attribute;
}
/**
* Returns the context attribute associated to this QoC information.
*
* @return the context attribute associated to this QoC information.
*/
public CtxAttribute getAttribute() {
return this.attribute;
}
/**
* Returns the time in milliseconds since the last update of the current
* context attribute value.
*
* @return the time in milliseconds since the last update of the current
* context attribute value.
* @see #getLastUpdated()
*/
public long getFreshness() {
return new Date().getTime() - this.getLastUpdated().getTime();
}
/**
* Returns the time when the current context attribute value was last updated.
*
* @return the time when the current context attribute value was last updated.
* @see #getFreshness()
*/
public Date getLastUpdated() {
return (this.lastUpdated != null)
? new Date(this.lastUpdated.getTime())
: new Date(this.attribute.getLastModified().getTime());
}
/**
* Sets the time when the current context attribute value was last updated.
*
* @param lastUpdated
* the time when the current context attribute value was last updated
*/
void setLastUpdated(Date lastUpdated) {
this.lastUpdated = new Date(lastUpdated.getTime());
}
/**
* Returns the origin type of the current context attribute value.
* <p>
* The method returns <code>null</code> if the origin type has not been set.
*
* @return the origin type of the current context attribute value.
* @see CtxOriginType
*/
public CtxOriginType getOriginType() {
return this.originType;
}
/**
* Sets the origin type of the current context attribute value.
*
* @param originType
* the origin type of the current context attribute value to set
* @see CtxOriginType
*/
public void setOriginType(CtxOriginType originType) {
this.originType = originType;
}
/**
* Returns the precision of the current context attribute value.
* <p>
* The method returns <code>null</code> if precision has not been set.
*
* @return the precision of the current context attribute value.
*/
public Double getPrecision() {
return (this.precision != null) ? new Double(this.precision) : null;
}
/**
* Sets the precision of the current context attribute value.
*
* @param precision
* the precision of the current context attribute value to set.
*/
public void setPrecision(Double precision){
this.precision = (precision != null) ? new Double(precision) : null;
}
/**
* Returns the update frequency of the current context attribute value.
* <p>
* The method returns <code>null</code> if the update frequency has not been
* set.
*
* @return the update frequency of the current context attribute value
*/
public Double getUpdateFrequency() {
return (this.updateFrequency != null) ? new Double(this.updateFrequency) : null;
}
/**
* Sets the update frequency of the current context attribute value.
*
* @param updateFrequency
* the update frequency of the current context attribute value to set.
*/
public void setUpdateFrequency(Double updateFrequency) {
this.updateFrequency = (updateFrequency != null) ? new Double(updateFrequency) : null;
}
/**
* TODO
* Returns a String representation of this QoC information.
*
* @return a String representation of this QoC information.
*
public String toString() {
}*/
/**
* @see java.lang.Object#hashCode()
* @since 0.0.2
*/
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result
+ ((this.attribute == null) ? 0 : this.attribute.hashCode());
return result;
}
/**
* @see java.lang.Object#equals(java.lang.Object)
* @since 0.0.2
*/
@Override
public boolean equals(Object that) {
if (this == that)
return true;
if (that == null)
return false;
if (this.getClass() != that.getClass())
return false;
CtxQuality other = (CtxQuality) that;
if (this.attribute == null) {
if (other.attribute != null)
return false;
} else if (!this.attribute.equals(other.attribute))
return false;
return true;
}
}