Hello world

This tutorial shows you how to build a simple plugin that adds a new page and prints the text “Hello world” on it.

In this tutorial we will use the address http://www.mysite.com/ as an example. While developing the plugin you should use the address of your own site instead of the example address.

Required files

First of all you need a directory that will hold all the files required by the plugin. Go to the mod directory of your Elgg site and create there a directory with the name hello_world.

Go to the hello_world directory and create these two files inside it:
  • start.php
  • manifest.xml

Copy this to the manifest.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">
    <name>Hello world</name>
    <author>Your name here</author>
    <description>Adds a page that prints "Hello world".</description>


Add your name to the <author></author> element.

The plugin has now the minimum requirements for your site to recognize it. Log in to your site as an administrator and access the plugins page at the administration panel. By default the plugin is at the bottom of the plugins list. Click the “Activate” button to start it.


The Hello world plugin has appeared to the bottom of the plugin list

Initializing the plugin

The next step is to add some actual features. Open the start.php and copy this to it:


elgg_register_event_handler('init', 'system', 'hello_world_init');

function hello_world_init() {


This piece of code tells Elgg that it should call the function hello_world_init() when the Elgg core system is initiated.

Registering a page handler

The next step is to register a page handler which has the purpose of handling request that users make to the URL http://www.mysite.com/hello/.

Update the start.php to look like this:


elgg_register_event_handler('init', 'system', 'hello_world_init');

function hello_world_init() {
    elgg_register_page_handler('hello', 'hello_world_page_handler');

function hello_world_page_handler() {
    $params = array(
        'title' => 'Hello world!',
        'content' => 'This is my first plugin.',
        'filter' => '',

    $body = elgg_view_layout('content', $params);

    echo elgg_view_page('Hello', $body);

The call to elgg_register_page_handler() tells Elgg that it should call the function hello_world_page_handler() when user goes to your site and has “hello” at the end of the URL.

The hello_world_page_handler() makes it possible for the users to access the actual page. Inside the function we first give an array of parameters to the elgg_view_layout() function.

The parameters include:
  • The title of the page
  • The contents of the page
  • Filter which is left empty because there’s currently nothing to filter

This creates the basic layout for the page. The layout is then run through elgg_view_page() which assembles and outputs the full page.

You can now go to the address http://www.mysite.com/hello/ and you should see the page.


Elgg is now routing the URL http://www.mysite.com/hello/ to the page you created.