ZendService\Api

This is a micro HTTP framework to consume generic API calls in PHP. This framework can be used to create PHP libraries that consume specific HTTP API using simple configuration array (or files). This project uses the Zend\Http\Client component of Zend Framework 2.

Release note

This code is in alpha version, please don't use it in a production environment.

Installation

You can install this component using composer with following commands:

curl -s https://getcomposer.org/installer | php
php composer.phar install

Usage

The ZendService\Api component can be used to facilitate the consume of generic API using HTTP. The micro HTTP framework is able to configure the header, method, body, and query string of a HTTP request according to specific API parameters. This mapping is provided using a special PHP configuration array.

You can specify the API parameters using the setApi method. This method accepts two parameters: the name of the API and a closure (callback) that returns the configuration with a PHP array.

Let see an example, image you need to consume an authentication API call with a POST HTTP request using a JSON data format with the following parameters: username and password. The HTTP request can be represented as follow:

PUT /v1/auth HTTP/1.1
Host: localhost
Connection: close
Content-Type: application/json
Content-Length: 57

{ 'auth' : { 'username' : 'admin', 'password' : 'test' }}

You need to configure the API call using the setApi method in this way (we use the auth name for this API):

use ZendService\Api\Api;

$api = new Api();
$api->setApi('auth', function ($params) {
    return array(
        'uri' => 'http://localhost/v1/auth',
        'header' => array(
            'Content-Type' => 'application/json'
        ),
        'method' => 'POST',
        'body' => json_encode(array(
            'auth' => array(
                'username' => $params[0],
                'password' => $params[1]
            )
        )),
        'response' => array(
            'valid_codes' => array('200')
        )
    );
});

After that you can execute the API call using the function auth (this function is managed by the magic __call function of PHP):

$result = $api->auth('username', 'password');
if ($api->isSuccess()) {
    var_dump($result);
} else {
    printf("Error (%d): %s\n", $api->getStatusCode(), $api->getErrorMsg());
}

The mapping with the auth arguments and the API specification is managed using the array $params. You have to use the numerical index of the $params to match the order of the arguments in the function. Using the configuration array you can specify all the HTTP data for the API request (headers, body, uri, etc). You can also specify the HTTP status code for the successful requests using the valid_codes parameter in the response section.

Using a configuration file

You can also use a configuration file for the API calls instead of using the setApi method. You need to create a PHP file with the same name of the API call. This file contains the API configuration array. For instance, for the previous example you have to create a auth.php file containing the following array:

return array(
    'uri' => 'http://localhost/v1/auth',
    'header' => array(
        'Content-Type' => 'application/json'
    ),
    'method' => 'POST',
    'body' => json_encode(array(
        'auth' => array(
            'username' => $params[0],
            'password' => $params[1]
        )
    )),
    'response' => array(
        'valid_codes' => array('200')
    )
);

You need to set the directory containing this configuration file using the setApiPath as follow:

use ZendService\Api\Api;

$api = new Api();
$api->setApiPath('path/to/api/config');
$result = $api->auth('username', 'password');
if ($api->isSuccess()) {
    var_dump($result);
} else {
    printf("Error (%d): %s\n", $api->getStatusCode(), $api->getErrorMsg());
}

Set the base URL for the API calls

If you need to call different API from the same base URL you can use the setUri function. This function set the base URL and you can use relative URI for the specific API calls, for instance imagine you need to consume an OpenStack service with the URL http://identity.api.openstack.org, we can set this address as base URL and use relative address for each API call.

use ZendService\Api\Api;

$api = new Api();
$api->setUri('http://identity.api.openstack.org');
$api->setApi('authentication', function ($params) {
    return array(
        'uri' => '/v2.0/tokens',
        'header' => array(
            'Content-Type' => 'application/json'
        ),
        'method' => 'POST',
        'body' => json_encode(array(
            'auth' => array(
                'passwordCredentials' => array(
                    'username' => $params[0],
                    'password' => $params[1]
                )
            )
        )),
        'response' => array(
            'valid_codes' => array('200', '203')
        )
    );
});
$result = $api->authentication('username', 'password');
if ($api->isSuccess()) {
    printf("Authenticate!\n");
} else {
    printf("Error (%d): %s\n", $api->getStatusCode(), $api->getErrorMsg());
}

Note the use of the relative address in the uri parameter of the API configuration.

Query string in the API calls

If you need to pass a query string for an API HTTP call you can use the setQueryParams method of the Api class. For instance, imagine you need to pass the HTTP query string ?auth=strong in the previous example, you can use the following code:

use ZendService\Api\Api;

$api = new Api();
$api->setQueryParams(array( 'auth' => 'strong' ));
$result = $api->authenticate('username', 'password');
if ($api->isSuccess()) {
    printf("OK!\n");
} else {
    printf("Error (%d): %s\n", $api->getStatusCode(), $api->getErrorMsg());
}

You can reset the query string calling the setQueryParams() function without a parameter.

Set the default HTTP headers

You can specify a default HTTP headers to be used for all the HTTP calls. For instance, if you need to call a vendor API passing an authentication token using a special header field you can use this feature to set a default headers to be used for all the next API calls.

To set a default headers you can use the setHeaders function, below is reported an example:

use ZendService\Api\Api;

$api = new Api();
$api->setApiPath('path/to/api/config');
$api->setHeaders(array( 'X-Auth-Token' => 'token' ));
$result = $api->test('foo');
if ($api->isSuccess()) {
    var_dump($result);
} else {
    printf("Error (%d): %s\n", $api->getStatusCode(), $api->getErrorMsg());
}

The test API will execute a HTTP request using the headers specified in the test.php configuration file plus the X-Auth-Token header. Basically, the headers specified in the configuration file are merged with the default one specified using the setHeaders function. You can overwrite the default headers using the same header key in the configuration file.