| author | uvangapally |
| Tue, 01 Aug 2017 10:33:47 +0530 | |
| changeset 46050 | f51c14dc540f |
| parent 25859 | 3317bb8137f4 |
| permissions | -rw-r--r-- |
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<title>javax.management.relation package</title> |
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Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved. |
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DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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published by the Free Software Foundation. Oracle designates this |
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particular file as subject to the "Classpath" exception as provided |
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by Oracle in the LICENSE file that accompanied this code. |
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This code is distributed in the hope that it will be useful, but WITHOUT |
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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version 2 for more details (a copy is included in the LICENSE file that |
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accompanied this code). |
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You should have received a copy of the GNU General Public License version |
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Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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or visit www.oracle.com if you need additional information or have any |
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questions. |
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</head> |
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<body bgcolor="white"> |
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<p>Provides the definition of the Relation Service. The |
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Relation Service is used to record relationships between |
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MBeans in an MBean Server. The Relation Service is itself an |
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MBean. More than one instance of a {@link
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javax.management.relation.RelationService RelationService} |
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MBean can be registered in an MBean Server.</p> |
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<p>A <em>relation type</em> defines a relationship between MBeans. |
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It contains <em>roles</em> that the MBeans play in the |
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relationship. Usually there are at least two roles in a |
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relation type.</p> |
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<p>A <em>relation</em> is a named instance of a relation type, |
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where specific MBeans appear in the roles, represented by |
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their {@link javax.management.ObjectName ObjectName}s.</p>
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<p>For example, suppose there are <code>Module</code> MBeans, |
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representing modules within an application. A |
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<code>DependsOn</code> relation type could express the |
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relationship that some modules depend on others, which could |
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be used to determine the order in which the modules are |
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started or stopped. The <code>DependsOn</code> relation type |
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would have two roles, <code>dependent</code> and |
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<code>dependedOn</code>.</p> |
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<p>Every role is <em>typed</em>, meaning that an MBean that |
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appears in that role must be an instance of the role's type. |
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In the <code>DependsOn</code> example, both roles would be of |
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type <code>Module</code>.</p> |
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<p>Every role has a <em>cardinality</em>, which provides lower |
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and upper bounds on the number of MBeans that can appear in |
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that role in a given relation instance. Usually, the lower |
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and upper bounds are both 1, with exactly one MBean appearing |
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in the role. The cardinality only limits the number of MBeans |
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in the role per relation instance. The same MBean can appear |
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in the same role in any number of instances of a relation |
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type. In the <code>DependsOn</code> example, a given module |
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can depend on many other modules, and be depended on by many |
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others, but any given relation instance links exactly one |
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<code>dependent</code> module with exactly one |
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<code>dependedOn</code> module.</p> |
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<p>A relation type can be created explicitly, as an object |
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implementing the {@link javax.management.relation.RelationType
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RelationType} interface, typically a {@link
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javax.management.relation.RelationTypeSupport |
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RelationTypeSupport}. Alternatively, it can be created |
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implicitly using the Relation Service's {@link
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javax.management.relation.RelationServiceMBean#createRelationType(String, |
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RoleInfo[]) createRelationType} method.</p> |
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<p>A relation instance can be created explicitly, as an object |
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implementing the {@link javax.management.relation.Relation
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Relation} interface, typically a {@link
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javax.management.relation.RelationSupport RelationSupport}. |
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(A <code>RelationSupport</code> is itself a valid MBean, so it |
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can be registered in the MBean Server, though this is not |
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required.) Alternatively, a relation instance can be created |
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implicitly using the Relation Service's {@link
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javax.management.relation.RelationServiceMBean#createRelation(String, |
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String, RoleList) createRelation} method.</p> |
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<p>The <code>DependsOn</code> example might be coded as follows.</p> |
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<pre> |
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import java.util.*; |
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import javax.management.*; |
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import javax.management.relation.*; |
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// ... |
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MBeanServer mbs = ...; |
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// Create the Relation Service MBean |
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ObjectName relSvcName = new ObjectName(":type=RelationService");
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RelationService relSvcObject = new RelationService(true); |
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mbs.registerMBean(relSvcObject, relSvcName); |
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// Create an MBean proxy for easier access to the Relation Service |
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RelationServiceMBean relSvc = |
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MBeanServerInvocationHandler.newProxyInstance(mbs, relSvcName, |
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RelationServiceMBean.class, |
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false); |
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// Define the DependsOn relation type |
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RoleInfo[] dependsOnRoles = {
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new RoleInfo("dependent", Module.class.getName()),
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new RoleInfo("dependedOn", Module.class.getName())
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}; |
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relSvc.createRelationType("DependsOn", dependsOnRoles);
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// Now define a relation instance "moduleA DependsOn moduleB" |
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ObjectName moduleA = new ObjectName(":type=Module,name=A");
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ObjectName moduleB = new ObjectName(":type=Module,name=B");
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Role dependent = new Role("dependent", Collections.singletonList(moduleA));
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Role dependedOn = new Role("dependedOn", Collections.singletonList(moduleB));
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Role[] roleArray = {dependent, dependedOn};
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RoleList roles = new RoleList(Arrays.asList(roleArray)); |
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relSvc.createRelation("A-DependsOn-B", "DependsOn", roles);
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// Query the Relation Service to find what modules moduleA depends on |
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Map<ObjectName,List<String>> dependentAMap = |
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relSvc.findAssociatedMBeans(moduleA, "DependsOn", "dependent"); |
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Set<ObjectName> dependentASet = dependentAMap.keySet(); |
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// Set of ObjectName containing moduleB |
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</pre> |
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f51c14dc540f
8181895: javax management docs contain links to technotes
uvangapally
parents:
25859
diff
changeset
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@see <a href="https://jcp.org/aboutJava/communityprocess/mrel/jsr160/index2.html"> |
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JMX Specification, version 1.4</a> |
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@since 1.5 |
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