External services description

Jerome's proposal

Database table should only contain data that can be manage by administrator
All the web services description should be in a array into each external.php file
a cron job browse all external file, check the description and update the database (if functions/services disappeared or are created)

external_functions table

List of external functions. Created automatically by parsing of external files.

Field	Type	Default	Description
id	int(10)	auto-incrementing
name	varchar(150)		Name of function - Appears on the admin page
enabled	int(1)		function enabled, function might be disabled for security reasons - The only field editable by administrator !
phpfile	varchar(255)		location where function defined - Needed for identifying

external_services table

Service is defined as a group of functions.

Field	Type	Default	Description
id	int(10)	auto-incrementing
name	varchar(150)		Name of service (gradeexport_xml_export, mod_chat_export) - appears on the admin page
enabled	int(1)		service enabled, for security reasons some services may be disabled - The only editable field by the admin
custom	int(1)	0	Custom local service, created manually by admin or some other way (CAN BE updated automatically during the cron job => function not existing get removed). This field is useful if we want to implement an admin page where the admin selects some functions from a list of all external functions. Note: we probably need a button to desactivate all services in once.

external_services_functions table

Specifies functions used by services.

Field	Type	Default	Description
id	int(10)	auto-incrementing
externalserviceid	int(10)		foreign key, reference external_services.id
externalfunctionid	int(10)		foreign key, reference external_functions.id

PHP array description

$this->descriptions['function_name'] = array( 'params' => array('params_name'=> PARAM_STRING),

                                      'optionalparams' => array( ),
                                      'return' => array('list:param_1' => 
                                                           array('attribut_1' => PARAM_INT, 
                                                                 'attribut_2' => PARAM_STRING, 
                                                                 'attribut_3' => PARAM_INT)));

Explanation:

base is:

$this->descriptions['function_name'] = array( 'params' => array(),

                                                           'optionalparams' => array( ),
                                                           'return' => array());

when a param/return is a list so it should be called 'list:param_name'
when a param/return is not a list so it's either a primary type (e.g. PARAM_STRING), either a object (e.g. array)
params and optionalparams have to follow the exact order of the function
PARAM_RAW has to be replaced by the correct type (cannot be array)

Way to fill the database tables

Fill the external_functions, external_services and external_services_functions tables from a XML file like xmldb install.

Return values are filtered by the servers

External function should be able to return whatever they want. Each server should be looking at the web services description and return the expected values.

Documentation