net.jini.core.constraint

Class DelegationRelativeTime

java.lang.Object

net.jini.core.constraint.DelegationRelativeTime

All Implemented Interfaces:

Serializable, InvocationConstraint, RelativeTimeConstraint

public final class DelegationRelativeTime
extends Object
implements RelativeTimeConstraint, Serializable

Represents a constraint on delegation, such that if delegation is permitted, it be permitted only for a range of time measured relative to the start of the remote call. The mechanisms and credentials used to support this are not specified by this constraint. Each end of the range is itself specified as a range, yielding four durations, all specified in milliseconds. If t represents the current time at the start of a remote call, then the four durations have the following semantics:

• minStart - delegation must not be permitted any earlier than time t + minStart
• maxStart - delegation must be permitted from time t + maxStart onwards
• minStop - delegation must be permitted up until at least time t + minStop
• maxStop - delegation must not be permitted after time t + maxStop

The durations are translated into absolute end times at the point of a remote call by adding the caller's current time. To accommodate clock skew between systems, it is permitted (and may be desirable) to specify negative values for the minimum and maximum start durations, to include start times that are earlier than the current time.

The use of an instance of this class does not directly imply a ClientAuthentication.YES constraint or a Delegation.YES constraint; those must be specified separately to ensure that the client actually authenticates itself and that delegation is actually used. Because this constraint is conditional on delegation, it does not conflict with ClientAuthentication.NO or Delegation.NO.

Since:

2.0

Author:

Sun Microsystems, Inc.

See Also:

ClientAuthentication, Delegation, DelegationAbsoluteTime, Serialized Form

Constructor Summary

Constructors

Constructor and Description
DelegationRelativeTime(long minStart, long maxStart, long minStop, long maxStop) Creates a constraint with the specified durations.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(Object obj) Two instances of this class are equal if both have the same minimum start, the same maximum start, the same minimum stop, and the same maximum stop.
long	getMaxStart() Returns the maximum start duration in milliseconds.
long	getMaxStop() Returns the maximum stop duration in milliseconds.
long	getMinStart() Returns the minimum start duration in milliseconds.
long	getMinStop() Returns the minimum stop duration in milliseconds.
int	hashCode() Returns a hash code value for this object.
InvocationConstraint	makeAbsolute(long baseTime) Returns a DelegationAbsoluteTime instance with times obtained by adding the specified base time argument to the duration values from this instance.
String	toString() Returns a string representation of this object.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

DelegationRelativeTime

public DelegationRelativeTime(long minStart,
                      long maxStart,
                      long minStop,
                      long maxStop)

Creates a constraint with the specified durations.

Parameters:

minStart - the minimum start duration in milliseconds

maxStart - the maximum start duration in milliseconds

minStop - the minimum stop duration in milliseconds

maxStop - the maximum stop duration in milliseconds

Throws:

IllegalArgumentException - if minStart is greater than maxStart, or maxStart is greater than minStop, or minStop is greater than maxStop, or minStop is less than zero

Method Detail

getMinStart

public long getMinStart()

Returns the minimum start duration in milliseconds.

Returns:

the minimum start duration in milliseconds

getMaxStart

public long getMaxStart()

Returns the maximum start duration in milliseconds.

Returns:

the maximum start duration in milliseconds

getMinStop

public long getMinStop()

Returns the minimum stop duration in milliseconds.

Returns:

the minimum stop duration in milliseconds

getMaxStop

public long getMaxStop()

Returns the maximum stop duration in milliseconds.

Returns:

the maximum stop duration in milliseconds

makeAbsolute

public InvocationConstraint makeAbsolute(long baseTime)

Returns a DelegationAbsoluteTime instance with times obtained by adding the specified base time argument to the duration values from this instance. If an addition results in underflow or overflow, a time value of Long.MIN_VALUE or Long.MAX_VALUE is used, respectively.

Specified by:

makeAbsolute in interface RelativeTimeConstraint

Parameters:

baseTime - an absolute time, specified in milliseconds from midnight, January 1, 1970 UTC

Returns:

a constraint that has the relative times converted to absolute times by adding the specified absolute time to each relative time

hashCode

public int hashCode()

Returns a hash code value for this object.

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Two instances of this class are equal if both have the same minimum start, the same maximum start, the same minimum stop, and the same maximum stop.

Overrides:

equals in class Object

toString

public String toString()

Returns a string representation of this object.

Overrides:

toString in class Object