How authorization is managed and handled in magento2

Question

I found below code on custom API file :

public function orderDetails($params)
{
    $customerID = $this->userContext->getUserId();
    if(empty($customerID)){
        return[[
            'error_code' => 1001,
            "message"=>"Validation Failed",
            'error_desc'   => 'Unable to locate customer'
        ]];
    }
    .........
    .......
}

Few Points :

• $this->userContext is object of class Magento\Authorization\Model\UserContextInterface

My Questions are :

• How magento handles authentication in API's.
• What data we need to send and where so that Magento\Authorization\Model\UserContextInterface can set customer id
• What data i need to send so that i can get the User Id from UserContextInterface class, like code above

I am not getting how and from where the data are set and retrieve related to user on API's.

Answer 1

Magento 2 have below 2 API

1. SOAP
2. REST

Three types of authentication:

1. Third-party applications authenticate with OAuth 1.0a.
2. Mobile applications authenticate using tokens.
3. Administrators and customers are authenticated with login credentials.

Most common authentication is Token based authentication. To access API you need integration token. As part of authentication you need to use integration token

How to access API you can follow below link

https://devdocs.magento.com/guides/v2.3/get-started/bk-get-started-api.html

For authentication check below link

https://devdocs.magento.com/guides/v2.3/get-started/authentication/gs-authentication.html