<?php
/**
 * Class Resp Used to simulate WS response
 */
class Resp {
    private $r = array(1 => 'A', 2 => 'B');

    public function re() {
        return $this->r[rand(1,2)];
    }
}

/**
 * Class Some Used to show PHP GOTO functionality
 */
class Some {

    /**
     * @var string Holds request answer
     */
    private $result = '';

    /**
     * @param null $service
     * @return string
     */
    public function request($service = null) {
        $_req = new Resp();
        if ($service == 'WS') {
            // hypothetical call to the REST webservice
            // cURL...
            $this->result = $_req->re();

            if ($this->result === 'A') {
                return "WS";
            } else {
                goto Go1;
            }
        } else {
            Go1:
            // execute direct DB call to get result
            $this->result = "DB";

            return $this->result;
        }
    }
}

$r1 = new Some();
echo $r1->request('WS') . "\n";
echo $r1->request('WS') . "\n";
echo $r1->request('WS') . "\n";
echo $r1->request('WS') . "\n";
echo $r1->request('WS') . "\n";
echo $r1->request('WS') . "\n";
echo $r1->request() . "\n";
echo $r1->request() . "\n";
echo $r1->request() . "\n";
?>

Random answers:
WS
DB
DB
DB
WS
WS
DB
DB
DB