/*
* @(#)file Descriptor.java
* @(#)author IBM Corp.
* @(#)version 1.39
* @(#)lastedit 06/03/15
*/
/*
* Copyright IBM Corp. 1999-2000. All rights reserved.
*
* The program is provided "as is" without any warranty express or implied,
* including the warranty of non-infringement and the implied warranties of
* merchantibility and fitness for a particular purpose. IBM will not be
* liable for any damages suffered by you or any third party claim against
* you regarding the Program.
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* This software is the proprietary information of Sun Microsystems, Inc.
* Use is subject to license terms.
*
* Copyright 2006 Sun Microsystems, Inc. Tous droits reserves.
* Ce logiciel est propriete de Sun Microsystems, Inc.
* Distribue par des licences qui en restreignent l'utilisation.
*
*/
package javax.management;
import java.io.Serializable;
// Javadoc imports:
import java.lang.management.MemoryUsage;
import java.util.Arrays;
import java.util.ResourceBundle;
import javax.management.openmbean.CompositeData;
import javax.management.openmbean.OpenMBeanAttributeInfoSupport;
import javax.management.openmbean.OpenMBeanOperationInfoSupport;
import javax.management.openmbean.OpenMBeanParameterInfoSupport;
import javax.management.openmbean.OpenType;
/**
* <p>Additional metadata for a JMX element. A {@code Descriptor}
* is associated with a {@link MBeanInfo}, {@link MBeanAttributeInfo}, etc.
* It consists of a collection of fields. A field is a name and an
* associated value.</p>
*
* <p>Field names are not case-sensitive. The names {@code descriptorType},
* {@code descriptortype}, and {@code DESCRIPTORTYPE} are all equivalent.
* However, the case that was used when the field was first set is preserved
* in the result of the {@link #getFields} and {@link #getFieldNames}
* methods.</p>
*
* <p>Not all field names and values are predefined.
* New fields can be defined and added by any program.</p>
*
* <p>A descriptor can be mutable or immutable.
* An immutable descriptor, once created, never changes.
* The <code>Descriptor</code> methods that could modify the contents
* of the descriptor will throw an exception
* for an immutable descriptor. Immutable descriptors are usually
* instances of {@link ImmutableDescriptor} or a subclass. Mutable
* descriptors are usually instances of
* {@link javax.management.modelmbean.DescriptorSupport} or a subclass.
*
* <p>Certain fields are used by the JMX implementation. This means
* either that the presence of the field may change the behavior of
* the JMX API or that the field may be set in descriptors returned by
* the JMX API. These fields appear in <i>italics</i> in the table
* below, and each one has a corresponding constant in the {@link JMX}
* class. For example, the field {@code defaultValue} is represented
* by the constant {@link JMX#DEFAULT_VALUE_FIELD}.</p>
*
* <p>Certain other fields have conventional meanings described in the
* table below but they are not required to be understood or set by
* the JMX implementation.</p>
*
* <p>Field names defined by the JMX specification in this and all
* future versions will never contain a period (.). Users can safely
* create their own fields by including a period in the name and be
* sure that these names will not collide with any future version of
* the JMX API. It is recommended to follow the Java package naming
* convention to avoid collisions between field names from different
* origins. For example, a field created by {@code example.com} might
* have the name {@code com.example.interestLevel}.</p>
*
* <p>Note that the values in the {@code defaultValue}, {@code
* legalValues}, {@code maxValue}, and {@code minValue} fields should
* be consistent with the type returned by the {@code getType()}
* method for the associated {@code MBeanAttributeInfo} or {@code
* MBeanParameterInfo}. For MXBeans, this means that they should be
* of the mapped Java type, called <em>opendata</em>(J) in the <a
* href="MXBean.html#mapping-rules">MXBean type mapping rules</a>.</p>
*
* <table border="1" cellpadding="5">
*
* <tr><th>Name</th><th>Type</th><th>Used in</th><th>Meaning</th></tr>
*
* <tr><td><a name="defaultValue"><i>defaultValue</i></a><td>Object</td>
* <td>MBeanAttributeInfo<br>MBeanParameterInfo</td>
*
* <td>Default value for an attribute or parameter. See
* {@link javax.management.openmbean}.</td>
*
* <tr><td>deprecated</td><td>String</td><td>Any</td>
*
* <td>An indication that this element of the information model is no
* longer recommended for use. A set of MBeans defined by an
* application is collectively called an <em>information model</em>.
* The convention is for the value of this field to contain a string
* that is the version of the model in which the element was first
* deprecated, followed by a space, followed by an explanation of the
* deprecation, for example {@code "1.3 Replaced by the Capacity
* attribute"}.</td>
*
* <tr><td>descriptionResource<br>BundleBaseName</td><td>String</td><td>Any</td>
*
* <td>The base name for the {@link ResourceBundle} in which the key given in
* the {@code descriptionResourceKey} field can be found, for example
* {@code "com.example.myapp.MBeanResources"}. The meaning of this
* field is defined by this specification but the field is not set or
* used by the JMX API itself.</td>
*
* <tr><td>descriptionResourceKey</td><td>String</td><td>Any</td>
*
* <td>A resource key for the description of this element. In
* conjunction with the {@code descriptionResourceBundleBaseName},
* this can be used to find a localized version of the description.
* The meaning of this field is defined by this specification but the
* field is not set or used by the JMX API itself.</td>
*
* <tr><td>enabled</td><td>String</td>
* <td>MBeanAttributeInfo<br>MBeanNotificationInfo<br>MBeanOperationInfo</td>
*
* <td>The string {@code "true"} or {@code "false"} according as this
* item is enabled. When an attribute or operation is not enabled, it
* exists but cannot currently be accessed. A user interface might
* present it as a greyed-out item. For example, an attribute might
* only be meaningful after the {@code start()} method of an MBean has
* been called, and is otherwise disabled. Likewise, a notification
* might be disabled if it cannot currently be emitted but could be in
* other circumstances.</td>
*
* <tr><td><a name="immutableInfo"><i>immutableInfo</i></a><td>String</td>
* <td>MBeanInfo</td>
*
* <td>The string {@code "true"} or {@code "false"} according as this
* MBean's MBeanInfo is <em>immutable</em>. When this field is true,
* the MBeanInfo for the given MBean is guaranteed not to change over
* the lifetime of the MBean. Hence, a client can read it once and
* cache the read value. When this field is false or absent, there is
* no such guarantee, although that does not mean that the MBeanInfo
* will necessarily change.</td>
*
* <tr><td>infoTimeout</td><td>String<br>Long</td><td>MBeanInfo</td>
*
* <td>The time in milli-seconds that the MBeanInfo can reasonably be
* expected to be unchanged. The value can be a {@code Long} or a
* decimal string. This provides a hint from a DynamicMBean or any
* MBean that does not define {@code immutableInfo} as {@code true}
* that the MBeanInfo is not likely to change within this period and
* therefore can be cached. When this field is missing or has the
* value zero, it is not recommended to cache the MBeanInfo unless it
* has the {@code immutableInfo} set to {@code true}.</td></tr>
*
* <tr><td><a name="interfaceClassName"><i>interfaceClassName</i></a></td>
* <td>String</td><td>MBeanInfo</td>
*
* <td>The Java interface name for a Standard MBean or MXBean, as
* returned by {@link Class#getName()}. A Standard MBean or MXBean
* registered directly in the MBean Server or created using the {@link
* StandardMBean} class will have this field in its MBeanInfo
* Descriptor.</td>
*
* <tr><td><a name="legalValues"><i>legalValues</i></a></td>
* <td>{@literal Set<?>}</td><td>MBeanAttributeInfo<br>MBeanParameterInfo</td>
*
* <td>Legal values for an attribute or parameter. See
* {@link javax.management.openmbean}.</td>
*
* <tr><td><a name="maxValue"><i>maxValue</i></a><td>Object</td>
* <td>MBeanAttributeInfo<br>MBeanParameterInfo</td>
*
* <td>Maximum legal value for an attribute or parameter. See
* {@link javax.management.openmbean}.</td>
*
* <tr><td><a name="metricType">metricType</a><td>String</td>
* <td>MBeanAttributeInfo<br>MBeanOperationInfo</td>
*
* <td>The type of a metric, one of the strings "counter" or "gauge".
* A metric is a measurement exported by an MBean, usually an
* attribute but sometimes the result of an operation. A metric that
* is a <em>counter</em> has a value that never decreases except by
* being reset to a starting value. Counter metrics are almost always
* non-negative integers. An example might be the number of requests
* received. A metric that is a <em>gauge</em> has a numeric value
* that can increase or decrease. Examples might be the number of
* open connections or a cache hit rate or a temperature reading.
*
* <tr><td><a name="minValue"><i>minValue</i></a><td>Object</td>
* <td>MBeanAttributeInfo<br>MBeanParameterInfo</td>
*
* <td>Minimum legal value for an attribute or parameter. See
* {@link javax.management.openmbean}.</td>
*
* <tr><td><a name="mxbean"><i>mxbean</i></a><td>String</td>
* <td>MBeanInfo</td>
*
* <td>The string {@code "true"} or {@code "false"} according as this
* MBean is an {@link MXBean}. A Standard MBean or MXBean registered
* directly with the MBean Server or created using the {@link
* StandardMBean} class will have this field in its MBeanInfo
* Descriptor.</td>
*
* <tr><td><a name="openType"><i>openType</i></a><td>{@link OpenType}</td>
* <td>MBeanAttributeInfo<br>MBeanOperationInfo<br>MBeanParameterInfo</td>
*
* <td><p>The Open Type of this element. In the case of {@code
* MBeanAttributeInfo} and {@code MBeanParameterInfo}, this is the
* Open Type of the attribute or parameter. In the case of {@code
* MBeanOperationInfo}, it is the Open Type of the return value. This
* field is set in the Descriptor for all instances of {@link
* OpenMBeanAttributeInfoSupport}, {@link
* OpenMBeanOperationInfoSupport}, and {@link
* OpenMBeanParameterInfoSupport}. It is also set for attributes,
* operations, and parameters of MXBeans.</p>
*
* <p>This field can be set for an {@code MBeanNotificationInfo}, in
* which case it indicates the Open Type that the {@link
* Notification#getUserData() user data} will have.</td>
*
* <tr><td><a name="originalType"><i>originalType</i></a><td>String</td>
* <td>MBeanAttributeInfo<br>MBeanOperationInfo<br>MBeanParameterInfo</td>
*
* <td><p>The original Java type of this element as it appeared in the
* {@link MXBean} interface method that produced this {@code
* MBeanAttributeInfo} (etc). For example, a method<br> <code>public
* </code> {@link MemoryUsage}<code> getHeapMemoryUsage();</code><br>
* in an MXBean interface defines an attribute called {@code
* HeapMemoryUsage} of type {@link CompositeData}. The {@code
* originalType} field in the Descriptor for this attribute will have
* the value {@code "java.lang.management.MemoryUsage"}.
*
* <p>The format of this string is described in the section <a
* href="MXBean.html#type-names">Type Names</a> of the MXBean
* specification.</p>
*
* <tr><td>severity</td><td>String<br>Integer</td>
* <td>MBeanNotificationInfo</td>
*
* <td>The severity of this notification. It can be 0 to mean
* unknown severity or a value from 1 to 6 representing decreasing
* levels of severity. It can be represented as a decimal string or
* an {@code Integer}.</td>
*
* <tr><td>since</td><td>String</td><td>Any</td>
*
* <td>The version of the information model in which this element
* was introduced. A set of MBeans defined by an application is
* collectively called an <em>information model</em>. The
* application may also define versions of this model, and use the
* {@code "since"} field to record the version in which an element
* first appeared.</td>
*
* <tr><td>units</td><td>String</td>
* <td>MBeanAttributeInfo<br>MBeanParameterInfo<br>MBeanOperationInfo</td>
*
* <td>The units in which an attribute, parameter, or operation return
* value is measured, for example {@code "bytes"} or {@code
* "seconds"}.</td>
*
* </table>
*
* <p>Some additional fields are defined by Model MBeans. See
* {@link javax.management.modelmbean.ModelMBeanInfo ModelMBeanInfo}
* and related classes and the chapter "Model MBeans" of the
* <a href="http://java.sun.com/products/JavaManagement/download.html">
* JMX Specification</a>.</p>
*
* @since 1.5
*/
public interface Descriptor extends Serializable, Cloneable
{
/**
* Returns the value for a specific field name, or null if no value
* is present for that name.
*
* @param fieldName the field name.
*
* @return the corresponding value, or null if the field is not present.
*
* @exception RuntimeOperationsException if the field name is illegal.
*/
public Object getFieldValue(String fieldName)
throws RuntimeOperationsException;
/**
* <p>Sets the value for a specific field name. This will
* modify an existing field or add a new field.</p>
*
* <p>The field value will be validated before it is set.
* If it is not valid, then an exception will be thrown.
* The meaning of validity is dependent on the descriptor
* implementation.</p>
*
* @param fieldName The field name to be set. Cannot be null or empty.
* @param fieldValue The field value to be set for the field
* name. Can be null if that is a valid value for the field.
*
* @exception RuntimeOperationsException if the field name or field value
* is illegal (wrapped exception is {@link IllegalArgumentException}); or
* if the descriptor is immutable (wrapped exception is
* {@link UnsupportedOperationException}).
*/
public void setField(String fieldName, Object fieldValue)
throws RuntimeOperationsException;
/**
* Returns all of the fields contained in this descriptor as a string array.
*
* @return String array of fields in the format <i>fieldName=fieldValue</i>
* <br>If the value of a field is not a String, then the toString() method
* will be called on it and the returned value, enclosed in parentheses,
* used as the value for the field in the returned array. If the value
* of a field is null, then the value of the field in the returned array
* will be empty. If the descriptor is empty, you will get
* an empty array.
*
* @see #setFields
*/
public String[] getFields();
/**
* Returns all the field names in the descriptor.
*
* @return String array of field names. If the descriptor is empty,
* you will get an empty array.
*/
public String[] getFieldNames();
/**
* Returns all the field values in the descriptor as an array of Objects. The
* returned values are in the same order as the {@code fieldNames} String array parameter.
*
* @param fieldNames String array of the names of the fields that
* the values should be returned for. If the array is empty then
* an empty array will be returned. If the array is null then all
* values will be returned, as if the parameter were the array
* returned by {@link #getFieldNames()}. If a field name in the
* array does not exist, including the case where it is null or
* the empty string, then null is returned for the matching array
* element being returned.
*
* @return Object array of field values. If the list of {@code fieldNames}
* is empty, you will get an empty array.
*/
public Object[] getFieldValues(String... fieldNames);
/**
* Removes a field from the descriptor.
*
* @param fieldName String name of the field to be removed.
* If the field name is illegal or the field is not found,
* no exception is thrown.
*
* @exception RuntimeOperationsException if a field of the given name
* exists and the descriptor is immutable. The wrapped exception will
* be an {@link UnsupportedOperationException}.
*/
public void removeField(String fieldName);
/**
* <p>Sets all fields in the field names array to the new value with
* the same index in the field values array. Array sizes must match.</p>
*
* <p>The field value will be validated before it is set.
* If it is not valid, then an exception will be thrown.
* If the arrays are empty, then no change will take effect.</p>
*
* @param fieldNames String array of field names. The array and array
* elements cannot be null.
* @param fieldValues Object array of the corresponding field values.
* The array cannot be null. Elements of the array can be null.
*
* @throws RuntimeOperationsException if the change fails for any reason.
* Wrapped exception is {@link IllegalArgumentException} if
* {@code fieldNames} or {@code fieldValues} is null, or if
* the arrays are of different lengths, or if there is an
* illegal value in one of them.
* Wrapped exception is {@link UnsupportedOperationException}
* if the descriptor is immutable, and the call would change
* its contents.
*
* @see #getFields
*/
public void setFields(String[] fieldNames, Object[] fieldValues)
throws RuntimeOperationsException;
/**
* <p>Returns a descriptor which is equal to this descriptor.
* Changes to the returned descriptor will have no effect on this
* descriptor, and vice versa. If this descriptor is immutable,
* it may fulfill this condition by returning itself.</p>
* @exception RuntimeOperationsException for illegal value for field names
* or field values.
* If the descriptor construction fails for any reason, this exception will
* be thrown.
* @return A descriptor which is equal to this descriptor.
*/
public Object clone() throws RuntimeOperationsException;
/**
* Returns true if all of the fields have legal values given their
* names.
*
* @return true if the values are legal.
*
* @exception RuntimeOperationsException If the validity checking fails for
* any reason, this exception will be thrown.
* The method returns false if the descriptor is not valid, but throws
* this exception if the attempt to determine validity fails.
*/
public boolean isValid() throws RuntimeOperationsException;
/**
* Compares this descriptor to the given object. The objects are equal if
* the given object is also a Descriptor, and if the two Descriptors have
* the same field names (possibly differing in case) and the same
* associated values. The respective values for a field in the two
* Descriptors are equal if the following conditions hold:</p>
*
* <ul>
* <li>If one value is null then the other must be too.</li>
* <li>If one value is a primitive array then the other must be a primitive
* array of the same type with the same elements.</li>
* <li>If one value is an object array then the other must be too and
* {@link Arrays#deepEquals(Object[],Object[])} must return true.</li>
* <li>Otherwise {@link Object#equals(Object)} must return true.</li>
* </ul>
*
* @param obj the object to compare with.
*
* @return {@code true} if the objects are the same; {@code false}
* otherwise.
*
* @since 1.6
*/
public boolean equals(Object obj);
/**
* <p>Returns the hash code value for this descriptor. The hash
* code is computed as the sum of the hash codes for each field in
* the descriptor. The hash code of a field with name {@code n}
* and value {@code v} is {@code n.toLowerCase().hashCode() ^ h}.
* Here {@code h} is the hash code of {@code v}, computed as
* follows:</p>
*
* <ul>
* <li>If {@code v} is null then {@code h} is 0.</li>
* <li>If {@code v} is a primitive array then {@code h} is computed using
* the appropriate overloading of {@code java.util.Arrays.hashCode}.</li>
* <li>If {@code v} is an object array then {@code h} is computed using
* {@link Arrays#deepHashCode(Object[])}.</li>
* <li>Otherwise {@code h} is {@code v.hashCode()}.</li>
* </ul>
*
* @return A hash code value for this object.
*
* @since 1.6
*/
public int hashCode();
}
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