Lab 3.1 - Review the HelloWorld iControl LX Extension

iControl LX Extensions are provided as RPM (RedHat Package Manager) files. An RPM is similar to a .tar or .zip file for installing application files.

Let’s begin by reviewing the JavaScript contents of the HelloWorld RPM. In this module we will be reviewing the contents of an extension. In the next module we will be creating our own.

Overview of the HelloWorld Extension

To help us get started we’ve kept this extension very simple:

1. It only supports HTTP GET requests.
2. It only responds to GET requests with Hello World!.
3. There are only 13 lines of JavaScript (the rest are comments and documentation).

The JavaScript code for the HelloWorld extension is as follows:

/**
* A simple iControl LX Extension that handles only HTTP GET
*/
function HelloWorld() {}

HelloWorld.prototype.WORKER_URI_PATH = "ilxe_lab/hello_world";
HelloWorld.prototype.isPublic = true;

/**
* handle onGet HTTP request
*/
HelloWorld.prototype.onGet = function(restOperation) {
  restOperation.setBody(JSON.stringify( { value: "Hello World!" } ));
  this.completeRestOperation(restOperation);
};

/**
* handle /example HTTP request
*/
HelloWorld.prototype.getExampleState = function () {
  return {
    "value": "your_string"
  };
};

module.exports = HelloWorld;

Key Parts of the HelloWorld Extension

WORKER_URI_PATH

Note the following line:

HelloWorld.prototype.WORKER_URI_PATH = "ilxe_lab/hello_world";

This specifies where the iControl LX Extension will appear within iControl REST. Adding the /mgmt prefix, this would result in:

https://10.1.1.245/mgmt/ilxe_lab/hello_world

isPublic

By default, the WORKER_URI_PATH would only be accessible to other extensions. To make it accessible to remote devices/systems, you must specify that it should be publicly available using:

HelloWorld.prototype.isPublic = true;

Accepting an HTTP GET transaction

To process an HTTP GET sent to the WORKER_URI_PATH you must use onGet as follows:

HelloWorld.prototype.onGet = function(restOperation) {
  restOperation.setBody(JSON.stringify( { value: "Hello World!" } ));
  this.completeRestOperation(restOperation);
};

This function performs the following actions:

• Accepts the HTTP GET sent to our WORKER_URI_PATH (/mgmt/ilxe_lab/hello_world)
• Sets the body of the response to { value: "Hello World!" }
• Completes the transaction by sending the response back to the client

iControl LX Example Transaction

This is a special service that will come in handy in the next lab. If you have an iControl LX Extension that supports an HTTP POST, PATCH, or PUT, then the client will need to know what data to send and in what format.

The getExampleState function responds when the user appends /example to the end of the WORKER_URI_PATH (/mgmt/ilxe_lab/hello_world/example):

HelloWorld.prototype.getExampleState = function () {
  return {
  "value": "your_string"
  };
};

As our HelloWorld extension does not require any inputs we haven’t put in any data here.

Note

/example must always be used with an HTTP GET.