JavaScript Client Library

Jolokia’s JavaScript client library allows for easy access to the Jolokia agent from within JavaScript scripts. It encapsulates the JSON/HTTP access within a simple object layer.

The JavaScript client binding provides the following features:

  • Synchronous and asynchronous operations

  • Support for JSONP for accessing servers other than the one serving the Javscript file

  • Support for all Jolokia features like bulk requests or JMX proxy calls

  • Simple access methods like getAttribute or execute in addition to a generic request method.

Documentation for the JavaScript library can be found in the reference manual in the chapter JavaScript Client Library.

Installation

The Jolokia JavaScript library can be downloaded from the download page. It is divided into two scripts: jolokia.js contains the basic Jolokia object definition which provides the generic request() method. jolokia-simple.js adds to this definition methods for a simplified access, which are easier to use but less powerful. In addition these libs require jQuery. A typical setup in an HTML page using the library looks like:

<head>
    <script type="text/javascript" src="jquery-3.7.1.js"></script>
    <script type="text/javascript" src="jolokia.js"></script>
    <script type="text/javascript" src="jolokia-simple.js"></script>
</head>

For production setup, the minified versions (e.g. jolokia-min.js) are recommended since the original are blown up with inline documentation.

Example

The following simple example shows how to fetch the used Heap Memory from a Jolokia agent:

// Create a new jolokia client accessing the agent on the same
// Host which serves this document:
var j4p = new Jolokia("/jolokia");

// Request the memory information asynchronously and print it on the console
j4p.request({
        type: "read",
        mbean: "java.lang:type=Memory",
        attribute: "HeapMemoryUsage"
    },
    {
        success: function(response) {
            console.log(JSON.stringify(response));
            console.log("Heap-Memory used: " + response.value["used"]);
        }
    });

// Same as above, but synchronously and with the simple API:
console.log("Heap-Memory used:" +
            j4p.getAttribute("java.lang:type=Memory","HeapMemoryUsage","used"));

Testing

Jolokia comes with a test web application for integration testing. It contains QUnit based tests that run within a browser. The submodule examples/client-javascript-test-app creates a WAR artifact which can be deployed in a servlet container. The Jolokia agent is contained and reachable under the URL /jolokia. The unit tests can be found at

jolokia-test.html

QUnit tests for the base library

jolokia-simple-test.html

QUnit tests for the simple API

jolokia-all-test.html

All the tests above combined

This Maven module is using jetty-maven-plugin, so we can run the application using:

$ mvn clean package jetty:run-war -f examples/client-javascript-test-app/

Jetty server will be started with the test application deployed.

In order to simplify development of unit tests, a shell script makeLinks.sh is included in examples/client-javascript-test-app module, which can be used in Linux like OS’es to create symbolic links to the JavaScript and HTML files in the source directories. A typical workflow looks like:

  • Initialize:

    $ cd examples/client-javascript-test-app/
$ mvn clean package jetty:run-war
$ ./makeLinks.sh # in separate terminal window

  • Edit and save the JavaScript files (e.g. jolokia.js or jolokia-test.js)

  • Reload the test HTML files in the browser