Untitled :: Jolokia

Executing JMX operations (exec)

With Jolokia we can also execute exposed JMX operations with optional arguments. Just as when writing attributes, Jolokia must be able to serialize the operation arguments. See Object serialization for details. Execution of overloaded methods is supported. The JMX specifications recommends to avoid overloaded methods when exposing them via JMX, though.

GET exec request

The format of an GET exec request is

<base url>/exec/<mbean name>/<operation name>/<arg1>/<arg2>/....

Table 1. GET Exec Request
Part	Description	Example
`<mbean name>`	MBean’s ObjectName	`java.lang:type=Threading`
`<operation name>`	Name of the operation to execute. If this is an overloaded method, it is mandatory to provide a method signature as well. A signature consist the fully qualified argument class names or native types, separated by commas and enclosed with parentheses. For calling a non-argument overloaded method use `()` as signature.	`loadUsers(java.lang.String, int)`
`<arg1>`, `<arg2>`, `…`	String representation for the arguments required to execute this operation. Only certain data types can be used here as described in Request parameter serialization.	`/true/true/`

The following request will trigger a garbage collection:

http://localhost:8080/jolokia/exec/java.lang:type=Memory/gc

POST exec request

Table 2. POST Exec Request
Key	Description	Example
`type`	`exec`
`mbean`	MBean’s ObjectName	`java.lang:type=Threading`
`operation`	The operation to execute, optionally with a signature as described above.	`dumpAllThreads`
`arguments`	An array of arguments for invoking this operation. The value must be serializable as described in Request parameter serialization.	`[true, true]`

The following request dumps all threads (along with locked monitors and locked synchronizers, thats what the boolean arguments are for):

{
  "type": "exec",
  "mbean": "java.lang:type=Threading",
  "operation": "dumpAllThreads(boolean, boolean)",
  "arguments": [ true, true ]
}

Exec response

For an exec operation, the response contains the return value of the operation. null is returned if either the operation returns a null value or the operation is declared as void. A typical response for an URL like (mind that double quote (") has to be encoded with %22):

http://localhost:8080/jolokia/exec/java.util.logging:type=Logging/setLoggerLevel/%22%22/INFO

looks like

{
  "request": {
    "mbean": "java.util.logging:type=Logging",
    "arguments": [
      "",
      "INFO"
    ],
    "type": "exec",
    "operation": "setLoggerLevel"
  },
  "value": null,
  "status": 200,
  "timestamp": 1702456520
}

The return value get serialized as described in Request parameter serialization.