01: /*
02: * <copyright>
03: *
04: * Copyright 1997-2004 BBNT Solutions, LLC
05: * under sponsorship of the Defense Advanced Research Projects
06: * Agency (DARPA).
07: *
08: * You can redistribute this software and/or modify it under the
09: * terms of the Cougaar Open Source License as published on the
10: * Cougaar Open Source Website (www.cougaar.org).
11: *
12: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
13: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
14: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
15: * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
16: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
17: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
18: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
22: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: *
24: * </copyright>
25: */
26:
27: package org.cougaar.core.blackboard;
28:
29: /**
30: * An object "claimed" by a single actor, typically a plugin
31: * instance.
32: * <p>
33: * For example, a Claimable object would likely be "claimed" by a
34: * plugin when that plugin creates the object or the object is
35: * added into the blackboard.
36: * <p>
37: * Claiming of objects is done by the infrastruture *only* - plugins
38: * should *never* call claim().
39: */
40: public interface Claimable {
41: /** @return true IFF this object been claimed. */
42: boolean isClaimed();
43:
44: /** @return the current claim holder, or null if there is none. */
45: Object getClaim();
46:
47: /**
48: * Stake a Claim on the object.
49: * @exception IllegalArgumentException If there is already a Claim
50: * on the object which is not == the putativeClaimHolder.
51: */
52: void setClaim(Object putativeClaimHolder);
53:
54: /**
55: * Try to stake a Claim on the object.
56: * @return true IFF success.
57: */
58: boolean tryClaim(Object putativeClaimHolder);
59:
60: /**
61: * Release a Claim on the object.
62: * @exception IllegalArgumentExcpeiton If the object is not
63: * currently claimed, or is claimed by someone else.
64: */
65: void resetClaim(Object oldClaimHolder);
66: }
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