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# 4 Discovery of JMX objects

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#### Overview

It is possible to [discover](/manual/discovery/low_level_discovery) all
JMX MBeans or MBean attributes or to specify a pattern for the discovery
of these objects.

It is mandatory to understand the difference between Mbean and Mbean
attributes for discovery rule configuration. An MBean is an object which
can represent a device, an application, or any resource that needs to be
managed. For example, there is an Mbean which represents a web-server.
Its attributes are connection count, thread count, request timeout, http
file cache, memory usage, etc. Expressing this thought in human
comprehensive language we can define a coffee machine as an Mbean which
has the following attributes to be monitored: water amount per cup,
average consumption of water for a certain period of time, number of
coffee beans required per cup, coffee beans and water refill time, etc.

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#### Item key

In [discovery
rule](/manual/discovery/low_level_discovery#discovery_rule)
configuration, select **JMX agent** in the *Type* field.

The item key to use is

    jmx.discovery[<discovery mode>,<object name>]

where

-   discovery mode - one of the following: *attributes* (retrieve JMX
    MBean attributes, default) or *beans* (retrieve JMX MBeans)
-   object name - object name pattern identifying the MBean names to be
    retrieved (empty by default, retrieving all registered beans).

You may consult ObjectName
[documentation](https://docs.oracle.com/javase/7/docs/api/javax/management/ObjectName.html)
for the options of specifying object name pattern.

If no parameters are passed, all MBean attributes from JMX are
requested.

::: noteimportant
Not specifying parameters for JMX discovery or
trying to receive all attributes for a wide range like `*:type=*,name=*`
may lead to potential performance problems.
:::

This item key is supported since Zabbix Java gateway 3.4.

Item key examples:

    jmx.discovery  #Retrieve all JMX MBean attributes
    jmx.discovery[beans]  #Retrieve all JMX MBeans
    jmx.discovery[attributes,"*:type=GarbageCollector,name=*"]  #Retrieve all garbage collector attributes
    jmx.discovery[beans,"*:type=GarbageCollector,name=*"]  #Retrieve all garbage collectors

This item returns a JSON object. For example, in the discovery of MBean
attributes (reformatted for clarity):

``` {.javascript}
{
   "data":[
      {
         "{#JMXVALUE}":"0",
         "{#JMXTYPE}":"java.lang.Long",
         "{#JMXOBJ}":"java.lang:type=GarbageCollector,name=PS Scavenge",
         "{#JMXDESC}":"java.lang:type=GarbageCollector,name=PS Scavenge,CollectionCount",
         "{#JMXATTR}":"CollectionCount"
      },
      {
         "{#JMXVALUE}":"0",
         "{#JMXTYPE}":"java.lang.Long",
         "{#JMXOBJ}":"java.lang:type=GarbageCollector,name=PS Scavenge",
         "{#JMXDESC}":"java.lang:type=GarbageCollector,name=PS Scavenge,CollectionTime",
         "{#JMXATTR}":"CollectionTime"
      },
      {
         "{#JMXVALUE}":"true",
         "{#JMXTYPE}":"java.lang.Boolean",
         "{#JMXOBJ}":"java.lang:type=GarbageCollector,name=PS Scavenge",
         "{#JMXDESC}":"java.lang:type=GarbageCollector,name=PS Scavenge,Valid",
         "{#JMXATTR}":"Valid"
      },
      {
         "{#JMXVALUE}":"PS Scavenge",
         "{#JMXTYPE}":"java.lang.String",
         "{#JMXOBJ}":"java.lang:type=GarbageCollector,name=PS Scavenge",
         "{#JMXDESC}":"java.lang:type=GarbageCollector,name=PS Scavenge,Name",
         "{#JMXATTR}":"Name"
      },
      {
         "{#JMXVALUE}":"java.lang:type=GarbageCollector,name=PS Scavenge",
         "{#JMXTYPE}":"javax.management.ObjectName",
         "{#JMXOBJ}":"java.lang:type=GarbageCollector,name=PS Scavenge",
         "{#JMXDESC}":"java.lang:type=GarbageCollector,name=PS Scavenge,ObjectName",
         "{#JMXATTR}":"ObjectName"
      }
   ]
}
```

In the discovery of MBeans (reformatted for clarity):

``` {.javascript}
{
   "data":[
      {  
         "{#JMXDOMAIN}":"java.lang",
         "{#JMXTYPE}":"GarbageCollector",
         "{#JMXOBJ}":"java.lang:type=GarbageCollector,name=PS Scavenge",
         "{#JMXNAME}":"PS Scavenge"
      }
   ]
}
```

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#### Supported macros

The following macros are supported for use in the discovery rule
[filter](/manual/discovery/low_level_discovery#discovery_rule_filter)
and prototypes of items, triggers and graphs:

|Macro|Description|
|-----|-----------|
|Discovery of MBean attributes|<|
|{\#JMXVALUE}|Attribute value.|
|{\#JMXTYPE}|Attribute type.|
|{\#JMXOBJ}|Object name.|
|{\#JMXDESC}|Object name including attribute name.|
|{\#JMXATTR}|Attribute name.|
|Discovery of MBeans|<|
|{\#JMXDOMAIN}|MBean domain. (*Zabbix reserved name*)|
|{\#JMXOBJ}|Object name. (*Zabbix reserved name*)|
|{\#JMX<key property>}|MBean properties (like {\#JMXTYPE}, {\#JMXNAME}). Some important notes to pay attention to when defining MBean attribute name that is created from MBean property name by the following algorithm:<br><br>\* attribute name case is changed to uppercase;<br>\* attribute name case is ignored (no LLD macro is generated) in case it consists of not supported characters. Supported characters can be described by the following regular expression: "A-Z0-9\_\\.";<br>\* if an attribute name is called "*obj*" or "*domain*" it will be replaced with the values of Zabbix properties {\#JMXOBJ} and {\#JMXDOMAIN} (supported since Zabbix 3.4.3.).|

Please consider this jmx.discovery (with "beans" mode) example. MBean
has the following properties defined:

    name=test
    тип=Type
    attributes []=1,2,3
    Name=NameOfTheTest
    domAin=some

As a result of JMX discovery, the following LLD macros will be
generated:

-   {\#JMXDOMAIN} - Zabbix internal, describing the domain of MBean
-   {\#JMXOBJ} - Zabbix internal, describing MBean object
-   {\#JMXNAME} - created from "name" property

Ignored properties are:

-   тип : its name contains unsupported characters (non-ASCII)
-   attributes\[\] : its name contains unsupported characters (square
    brackets are not supported)
-   Name : it's already defined (name=test)
-   domAin : it's a Zabbix reserved name

Let’s review two more practical examples of a LLD rule creation with the
use of Mbean. To understand the difference between a LLD rule collecting
Mbeans and a LLD rule collecting Mbean attributes better please take a
look at following table:

|   |   |   |
|---|---|---|
|**MBean1**|**MBean2**|**MBean3**|
|MBean1Attribute1|MBean2Attribute1|MBean3Attribute1|
|MBean1Attribute2|MBean2Attribute2|MBean3Attribute2|
|MBean1Attribute3|MBean2Attribute3|MBean3Attribute3|

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#### LLD rule collecting Mbeans

This rule will return 3 objects: the top row of the column: MBean1,
MBean2, MBean3.

For more information about objects please refer to [supported
macros](/fr/manual/discovery/low_level_discovery/jmx#supported_macros)
table, *Discovery of MBeans* section.

Discovery rule configuration collecting Mbeans (without the attributes)
looks like the following:

![discovery\_rule\_mbean\_1.png](../../../../assets/en/manual/discovery/low_level_discovery/discovery_rule_mbean_1.png)

Key used:

    jmx.discovery[beans,"*:type=GarbageCollector,name=*"]

All the garbage collectors without attributes will be discovered. As
Garbage collectors have the same attribute set, we can use desired
attributes in item prototypes the following way:

![discovery\_rule\_mbean\_2.png](../../../../assets/en/manual/discovery/low_level_discovery/discovery_rule_mbean_2.png)

Keys used:

    jmx[{#JMXOBJ},CollectionCount] 
    jmx[{#JMXOBJ},CollectionTime] 
    jmx[{#JMXOBJ},Valid] 

LLD discovery rule will result in something close to this (items are
discovered for two Garbage collectors):

![discovery\_rule\_mbean\_3.png](../../../../assets/en/manual/discovery/low_level_discovery/discovery_rule_mbean_3.png)

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#### LLD rule collecting Mbean attributes

This rule will return 9 objects with the following fields:
MBean1Attribute1, MBean2Attribute1,
Mbean3Attribute1,MBean1Attribute2,MBean2Attribute2, Mbean3Attribute2,
MBean1Attribute3, MBean2Attribute3, Mbean3Attribute3.

For more information about objects please refer to [supported
macros](/fr/manual/discovery/low_level_discovery/jmx#supported_macros)
table, *Discovery of MBean attributes* section.

Discovery rule configuration collecting Mbean attributes looks like the
following:

![discovery\_rule\_mbean\_attributes\_1.png](../../../../assets/en/manual/discovery/low_level_discovery/discovery_rule_mbean_attributes_1.png)

Key used:

    jmx.discovery[attributes,"*:type=GarbageCollector,name=*"]

All the garbage collectors with a single item attribute will be
discovered.

![discovery\_rule\_mbean\_attributes\_2.png](../../../../assets/en/manual/discovery/low_level_discovery/discovery_rule_mbean_attributes_2.png)

In this particular case an item will be created from prototype for every
MBean attribute. The main drawback of this configuration is that trigger
creation from trigger prototypes is impossible as there is only one item
prototype for all attributes. So this setup can be used for data
collection, but is not recommended for automatic monitoring.

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##### Examples

Let’s review two more practical examples of a LLD rule creation with the
use of Mbean. To understand the difference between a LLD rule collecting
Mbeans and a LLD rule collecting Mbean attributes better please take a
look at following table:

|   |   |   |
|---|---|---|
|**MBean1**|**MBean2**|**MBean3**|
|MBean1Attribute1|MBean2Attribute1|MBean3Attribute1|
|MBean1Attribute2|MBean2Attribute2|MBean3Attribute2|
|MBean1Attribute3|MBean2Attribute3|MBean3Attribute3|

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##### Example 1: Discovering Mbeans

This rule will return 3 objects: the top row of the column: MBean1,
MBean2, MBean3.

For more information about objects please refer to [supported
macros](/manual/discovery/low_level_discovery/jmx#supported_macros)
table, *Discovery of MBeans* section.

Discovery rule configuration collecting Mbeans (without the attributes)
looks like the following:

![lld\_rule\_mbean0.png](../../../../assets/en/manual/discovery/low_level_discovery/lld_rule_mbean0.png)

Key used:

    jmx.discovery[beans,"*:type=GarbageCollector,name=*"]

All the garbage collectors without attributes will be discovered. As
Garbage collectors have the same attribute set, we can use desired
attributes in item prototypes the following way:

![discovery\_rule\_mbean\_2.png](../../../../assets/en/manual/discovery/low_level_discovery/discovery_rule_mbean_2.png){width="600"}

Keys used:

    jmx[{#JMXOBJ},CollectionCount] 
    jmx[{#JMXOBJ},CollectionTime] 
    jmx[{#JMXOBJ},Valid] 

LLD discovery rule will result in something close to this (items are
discovered for two Garbage collectors):

![discovery\_rule\_mbean\_3.png](../../../../assets/en/manual/discovery/low_level_discovery/discovery_rule_mbean_3.png){width="600"}

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##### Example 2: Discovering Mbean attributes

This rule will return 9 objects with the following fields:
MBean1Attribute1, MBean2Attribute1,
Mbean3Attribute1,MBean1Attribute2,MBean2Attribute2, Mbean3Attribute2,
MBean1Attribute3, MBean2Attribute3, Mbean3Attribute3.

For more information about objects please refer to [supported
macros](/manual/discovery/low_level_discovery/jmx#supported_macros)
table, *Discovery of MBean attributes* section.

Discovery rule configuration collecting Mbean attributes looks like the
following:

![lld\_rule\_mbean\_attr.png](../../../../assets/en/manual/discovery/low_level_discovery/lld_rule_mbean_attr.png)

Key used:

    jmx.discovery[attributes,"*:type=GarbageCollector,name=*"]

All the garbage collectors with a single item attribute will be
discovered.

![discovery\_rule\_mbean\_attributes\_2.png](../../../../assets/en/manual/discovery/low_level_discovery/discovery_rule_mbean_attributes_2.png){width="600"}

In this particular case an item will be created from prototype for every
MBean attribute. The main drawback of this configuration is that trigger
creation from trigger prototypes is impossible as there is only one item
prototype for all attributes. So this setup can be used for data
collection, but is not recommended for automatic monitoring.

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#### Using jmx.get

`jmx.get[]` is similar to the `jmx.discovery[]` item, but is does not
turn Java object properties into low-level discovery macro names and
therefore can return values without [limitations](#limitations) that are
associated with LLD macro name generation such as hyphens or non-ASCII
characters.

When using `jmx.get[]` for discovery, low-level discovery macros can be
defined separately in the custom [LLD
macro](/manual/discovery/low_level_discovery#discovery_rule) tab of the
discovery rule configuration, using JSONPath to point to the required
values.

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##### Discovering MBeans

Discovery item: `jmx.get[beans,"com.example:type=*,*"]`

Response:

``` {.json}
[
    {
        "object": "com.example:type=Hello,data-src=data-base,ключ=значение",
        "domain": "com.example",
        "properties": {
            "data-src": "data-base",
            "ключ": "значение",
            "type": "Hello"
        }
    },
    {
        "object": "com.example:type=Atomic",
        "domain": "com.example",
        "properties": {
            "type": "Atomic"
        }
    }
]
```

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##### Discovering MBean attributes

Discovery item: `jmx.get[attributes,"com.example:type=*,*"]`

Response:

``` {.json}
[
    {
        "object": "com.example:type=*",
        "domain": "com.example",
        "properties": {
            "type": "Simple"
        }
    },
    {
        "object": "com.zabbix:type=yes,domain=zabbix.com,data-source=/dev/rand,ключ=значение,obj=true",
        "domain": "com.zabbix",
        "properties": {
            "type": "Hello",
            "domain": "com.example",
            "data-source": "/dev/rand",
            "ключ": "значение",
            "obj": true
        }
    }
]
```

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