Function Declarations

Before they can be used, all functions must be declared to Moodle, and their inputs and outputs must be defined.

• Functions are declared by noting them in the db/services.php file for a plugin.
• Functions are defined within their own class located within the \component\external namespace of a component.

Note that there is a strict naming convention for external service functions.

Function implementation classes consist of one class containing a number of functions, some of which are mandatory.

During a Moodle installation or upgrade, the service and function declarations are parsed by a service discovery process and stored within the database. An administrative UI may be used to change some configuration details of these declarations.

Service declarations

Each component wishing to create an external service function must declare that the function exists by describing it in the db/services.php file for that component.

This information is stored internally within Moodle, and collected as part of the service discovery during installation and upgrade.

local/groupmanager/db/services.php

$functions = [
    // The name of your web service function, as discussed above.
    'local_myplugin_create_groups' => [
        // The name of the namespaced class that the function is located in.
        'classname'   => 'local_groupmanager\external\create_groups',

        // A brief, human-readable, description of the web service function.
        'description' => 'Creates new groups.',

        // Options include read, and write.
        'type'        => 'write',

        // Whether the service is available for use in AJAX calls from the web.
        'ajax'        => true,

        // An optional list of services where the function will be included.
        'services'    => [
            // A standard Moodle install includes one default service:
            // - MOODLE_OFFICIAL_MOBILE_SERVICE.
            // Specifying this service means that your function will be available for
            // use in the Moodle Mobile App.
            MOODLE_OFFICIAL_MOBILE_SERVICE,
        ],
    ],
];

Advanced options

A number of advanced options are also available, as described below:

local/groupmanager/db/services.php

$functions = [
    // The name of your web service function, as discussed above.
    'local_myplugin_create_groups' => [
        // A comma-separated list of capabilities used by the function.
        // This is advisory only and used to indicate to the administrator
        // configuring a custom service definition.
        'capabilities' => 'moodle/course:creategroups,moodle/course:managegroups',

        // The following parameters are also available, but are no longer recommended.

        // The name of the external function name.
        // If not specified, this will default to 'execute'.
        'methodname'  => 'execute',

        // The file containing the class/external function.
        // Do not use if using namespaced auto-loading classes.
        'classpath'   => 'local/groupmanager/externallib.php',
    ],
];

The function name is arbitrary, but must follow the naming convention. This helps ensure that it is globally unique.