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| {{Moodle_2.0}}
| | #REDIRECT [[Adding_a_web_service_to_a_plugin]] |
| WORK IN PROGRESS
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| In this document you will learn how to create a web service function.
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| This document expect that you first read the administration manual [[Setting_up_a_web_service]].<br/>
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| To explain how to write a new web service function, we will write a web service function '''create_groups($groups)'''. This function create a group into a Moodle course.
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| This function will take a list of group object as parameters and it will return the same groups with their newly created id. If ever one group creation fails, the function will throw an exception, and no creation will happen.
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| We'll finally add the web service function to a core web service.
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| == Preparation ==
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| We need to identify:
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| * '''the core functions''': for our case we will use ''groups_create_group()'' from [http://cvs.moodle.org/moodle/group/ /group/lib.php]. Of course not every core function exists and in some other cases you could have to write them.
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| * '''the parameter types''': for our case we'll send a list of object. This object are groups, with id/name/courseid.
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| * '''the returned value types''': for our case we want to send back a list of group object with their id.
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| * '''the user capabilities''': for our case the user will need the ''moodle/course:managegroups'' capability.
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| == declare the web service function ==
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| Web service functions are declared into ''db/services.php'' of each component. In our case ''create_groups()'' is a core external function, so we will add the function to [http://cvs.moodle.org/moodle/lib/db/ /lib/db/services.php].
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| <code php>
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| $functions = array(
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| 'moodle_group_create_groups' => array( //web service function name
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| 'classname' => 'moodle_group_external', //class containing the external function
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| 'methodname' => 'create_groups', //external function name
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| 'classpath' => 'group/externallib.php', //file containing the class/external function
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| 'description' => 'Creates new groups.', //human readable description of the web service function
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| 'type' => 'write', //database rights of the web service function (read, write)
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| ),
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| );
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| </code>
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| Here you should ask yourself what is the difference between a web service function and an external function. Web service function could be considered as a redirection to the external function. The web service function name is the name that is served by web service server to the client. By this way the client doesn't know about the external functions.
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| The web service function name is arbitrary, but it must be globally unique so we highly recommend using the component name as prefix (and "moodle" for core functions).
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| == define the web service function description ==
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| This example includes param/return value descriptions. It has been extracted from the group/externallib.php. This file is a good example of externallib.php files.
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| <code php>
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| class moodle_group_external extends external_api { //see following chapter 'function implementation' to have a look to the external_api class
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| public static function add_member_parameters() {
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| return new external_function_parameters(
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| array(
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| 'groupid' => new external_value(PARAM_INT, 'some group id'),
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| 'userid' => new external_value(PARAM_INT, 'some user id')
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| )
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| );
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| }
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| public static function add_member(...) {
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| ...
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| }
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| public static function add_member_returns() {
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| return null;
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| }
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| }
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| </code>
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| == define the external function ==
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| This example include a function implementation. It has been extracted from the group/externallib.php. This file is a good example of externallib.php files.
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| <code php>
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| class moodle_group_external extends external_api { //see following chapter 'function implementation' to have a look to the external_api class
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| ...
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| public static function add_member($groupid, $userid) {
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| $params = self::validate_parameters(self::add_member_parameters(), array('groupid'=>$groupid, 'userid'=>$userid));
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| // all the parameter/behavioural checks and security constrainsts go here,
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| // throwing exceptions if neeeded and and calling low level (grouplib)
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| // add_member() function that will be one in charge of the functionality without
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| // further checks.
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| }
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| ...
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| }
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| </code>
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| == Add the web service function into a service ==
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| == test the web service function ==
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| There is a central test client that can be accessed into [http://cvs.moodle.org/moodle/webservice/ webservice/testclient.php]<br/>
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| In order to add new function to be supported you will need to add a form into webservice/testclient_forms.php. Take example from the other implemented forms.
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| == create your own client ==
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| ==See also==
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| * [[Web services]]
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| * [[External services security]]
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| * [[External services description]]
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| * [[Setting_up_a_web_service]]
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| [[Category:Web Services]]
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