Descriptor JDK 1.6)

Description

public interface Descriptor

Additional metadata for a JMX element.

Additional metadata for a JMX element. A Descriptor is associated with a MBeanInfo, MBeanAttributeInfo, etc. It consists of a collection of fields. A field is a name and an associated value.

Field names are not case-sensitive. The names descriptorType, descriptortype, and DESCRIPTORTYPE are all equivalent. However, the case that was used when the field was first set is preserved in the result of the Descriptor.getFields() and Descriptor.getFieldNames() methods.

Not all field names and values are predefined. New fields can be defined and added by any program.

A descriptor can be mutable or immutable. An immutable descriptor, once created, never changes. The Descriptor methods that could modify the contents of the descriptor will throw an exception for an immutable descriptor. Immutable descriptors are usually instances of ImmutableDescriptor or a subclass. Mutable descriptors are usually instances of DescriptorSupport or a subclass.

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 italics in the table below, and each one has a corresponding constant in the JMX class. For example, the field defaultValue is represented by the constant JMX.DEFAULT_VALUE_FIELD.

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.

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 example.com might have the name com.example.interestLevel.

Note that the values in the defaultValue, legalValues, maxValue, and minValue fields should be consistent with the type returned by the getType() method for the associated MBeanAttributeInfo or MBeanParameterInfo. For MXBeans, this means that they should be of the mapped Java type, called opendata(J) in the MXBean type mapping rules.

Name	Type	Used in	Meaning
defaultValue	Object	MBeanAttributeInfo MBeanParameterInfo	Default value for an attribute or parameter. See `javax.management.openmbean`.
deprecated	String	Any	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 information model. 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 `"1.3 Replaced by the Capacity attribute"`.
descriptionResource BundleBaseName	String	Any	The base name for the `ResourceBundle` in which the key given in the `descriptionResourceKey` field can be found, for example `"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.
descriptionResourceKey	String	Any	A resource key for the description of this element. In conjunction with the `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.
enabled	String	MBeanAttributeInfo MBeanNotificationInfo MBeanOperationInfo	The string `"true"` or `"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 `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.
immutableInfo	String	MBeanInfo	The string `"true"` or `"false"` according as this MBean's MBeanInfo is immutable. 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.
infoTimeout	String Long	MBeanInfo	The time in milli-seconds that the MBeanInfo can reasonably be expected to be unchanged. The value can be a `Long` or a decimal string. This provides a hint from a DynamicMBean or any MBean that does not define `immutableInfo` as `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 `immutableInfo` set to `true`.
interfaceClassName	String	MBeanInfo	The Java interface name for a Standard MBean or MXBean, as returned by `Class.getName()`. A Standard MBean or MXBean registered directly in the MBean Server or created using the `StandardMBean` class will have this field in its MBeanInfo Descriptor.
legalValues	Set<?>	MBeanAttributeInfo MBeanParameterInfo	Legal values for an attribute or parameter. See `javax.management.openmbean`.
maxValue	Object	MBeanAttributeInfo MBeanParameterInfo	Maximum legal value for an attribute or parameter. See `javax.management.openmbean`.
metricType	String	MBeanAttributeInfo MBeanOperationInfo	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 counter 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 gauge 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.
minValue	Object	MBeanAttributeInfo MBeanParameterInfo	Minimum legal value for an attribute or parameter. See `javax.management.openmbean`.
mxbean	String	MBeanInfo	The string `"true"` or `"false"` according as this MBean is an `MXBean`. A Standard MBean or MXBean registered directly with the MBean Server or created using the `StandardMBean` class will have this field in its MBeanInfo Descriptor.
openType	`OpenType`	MBeanAttributeInfo MBeanOperationInfo MBeanParameterInfo	The Open Type of this element. In the case of `MBeanAttributeInfo` and `MBeanParameterInfo`, this is the Open Type of the attribute or parameter. In the case of `MBeanOperationInfo`, it is the Open Type of the return value. This field is set in the Descriptor for all instances of `OpenMBeanAttributeInfoSupport`, `OpenMBeanOperationInfoSupport`, and `OpenMBeanParameterInfoSupport`. It is also set for attributes, operations, and parameters of MXBeans. This field can be set for an `MBeanNotificationInfo`, in which case it indicates the Open Type that the `user data` will have.
originalType	String	MBeanAttributeInfo MBeanOperationInfo MBeanParameterInfo	The original Java type of this element as it appeared in the `MXBean` interface method that produced this `MBeanAttributeInfo` (etc). For example, a method `public` `MemoryUsage` `getHeapMemoryUsage();` in an MXBean interface defines an attribute called `HeapMemoryUsage` of type `CompositeData`. The `originalType` field in the Descriptor for this attribute will have the value `"java.lang.management.MemoryUsage"`. The format of this string is described in the section Type Names of the MXBean specification.
severity	String Integer	MBeanNotificationInfo	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 `Integer`.
since	String	Any	The version of the information model in which this element was introduced. A set of MBeans defined by an application is collectively called an information model. The application may also define versions of this model, and use the `"since"` field to record the version in which an element first appeared.
units	String	MBeanAttributeInfo MBeanParameterInfo MBeanOperationInfo	The units in which an attribute, parameter, or operation return value is measured, for example `"bytes"` or `"seconds"`.

Some additional fields are defined by Model MBeans. See ModelMBeanInfo and related classes and the chapter "Model MBeans" of the JMX Specification.

See also:

Methods

Hide/Show inherited methods

public Object clone () throws RuntimeOperationsException

Returns a descriptor which is equal to this descriptor.

public boolean equals (Object obj)

Compares this descriptor to the given object.

public String getFieldNames ()

Returns all the field names in the descriptor.

public String getFields ()

Returns all of the fields contained in this descriptor as a string array.

public Object getFieldValue (String fieldName) throws RuntimeOperationsException

Returns the value for a specific field name, or null if no value is present for that name.

public Object getFieldValues (String fieldNames)

Returns all the field values in the descriptor as an array of Objects.

Returns all the field values in the descriptor as an array of Objects. The
returned values are in the same order as the fieldNames String array parameter.
Returns: Object array of field values. If the list of {@code fieldNames} is empty, you will get an empty array.
Parameters:
- 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.

public int hashCode ()

Returns the hash code value for this descriptor.

public boolean isValid () throws RuntimeOperationsException

Returns true if all of the fields have legal values given their names.

public void removeField (String fieldName)

Removes a field from the descriptor.

public void setField (String fieldName, Object fieldValue) throws RuntimeOperationsException

Sets the value for a specific field name.

public void setFields (String fieldNames, Object fieldValues) throws RuntimeOperationsException

Sets all fields in the field names array to the new value with the same index in the field values array.