Public interfaces & APIs
What is a public interface?
A public interface is a set of code that third-party developers can call, implement, or build as a plug-in. Magento guarantees that this code will not change in subsequent releases without a major version change.
Public interfaces for a module are marked with @api annotation.
Third-party developers should use only these interfaces, that is, interfaces with the @api annotation. You can use other interfaces but those may be modified or removed in subsequent Magento releases. For more information, see Backward compatibility.
Example of public interface annotation
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namespace Magento\CatalogRule\Api;
/**
* Interface CatalogRuleRepositoryInterface
* @api
* @since 100.1.0
*/
interface CatalogRuleRepositoryInterface
{
...
What is an API?
An application programming interface (API) is a set of interfaces and their implementations that a module provides to other modules.
Example of an API interface implementation
The Magento_CatalogRule module.
The Magento\CatalogRule\Api\CatalogRuleRepositoryInterface interface
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namespace Magento\CatalogRule\Api;
/**
* Interface CatalogRuleRepositoryInterface
* @api
* @since 100.1.0
*/
interface CatalogRuleRepositoryInterface
{
/**
* @param \Magento\CatalogRule\Api\Data\RuleInterface $rule
* @return \Magento\CatalogRule\Api\Data\RuleInterface
* @throws \Magento\Framework\Exception\CouldNotSaveException
* @since 100.1.0
*/
public function save(\Magento\CatalogRule\Api\Data\RuleInterface $rule);
/**
* @param int $ruleId
* @return \Magento\CatalogRule\Api\Data\RuleInterface
* @throws \Magento\Framework\Exception\NoSuchEntityException
* @since 100.1.0
*/
public function get($ruleId);
/**
* @param \Magento\CatalogRule\Api\Data\RuleInterface $rule
* @return bool
* @throws \Magento\Framework\Exception\CouldNotDeleteException
* @since 100.1.0
*/
public function delete(\Magento\CatalogRule\Api\Data\RuleInterface $rule);
/**
* @param int $ruleId
* @return bool
* @throws \Magento\Framework\Exception\CouldNotDeleteException
* @since 100.1.0
*/
public function deleteById($ruleId);
}
An interface implementation is declared in the di.xml as <preference />
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<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
...
<preference for="Magento\CatalogRule\Api\CatalogRuleRepositoryInterface" type="Magento\CatalogRule\Model\CatalogRuleRepository"/>
...
</config>
The Magento\CatalogRule\Model\CatalogRuleRepository implements the default methods of theCatalogRuleRepositoryInterface: save, get, delete, deleteById.
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namespace Magento\CatalogRule\Model;
use Magento\CatalogRule\Api\Data;
use Magento\Framework\Exception\CouldNotDeleteException;
use Magento\Framework\Exception\CouldNotSaveException;
use Magento\Framework\Exception\NoSuchEntityException;
use Magento\Framework\Exception\ValidatorException;
class CatalogRuleRepository implements \Magento\CatalogRule\Api\CatalogRuleRepositoryInterface
{
...
/**
* {@inheritdoc}
*/
public function save(Data\RuleInterface $rule)
{
...
}
/**
* {@inheritdoc}
*/
public function get($ruleId)
{
...
}
/**
* {@inheritdoc}
*/
public function delete(Data\RuleInterface $rule)
{
...
}
/**
* {@inheritdoc}
*/
public function deleteById($ruleId)
{
...
}
}
API types
The following items are considered types of APIs:
- Directory structure
- Configuration files structure
- Events
- Client API
- Provider API (SPI)
Directory structure and configuration file structure are types of APIs because extension developers use them. Developers write configurations, and place their static files in specified folders; so if the configuration file structure or directory structure changes in subsequent releases, modules and extensions may break.