workman/http-client的progress流式返回示例指的是php作为SSE客户端吗？

progress流式返回示例

<?php
require_once __DIR__ . '/vendor/autoload.php';

use Workerman\Connection\TcpConnection;
use Workerman\Http\Client;
use Workerman\Protocols\Http\Chunk;
use Workerman\Protocols\Http\Request;
use Workerman\Protocols\Http\Response;
use Workerman\Worker;

$worker = new Worker('http://0.0.0.0:1234');
$worker->onMessage = function (TcpConnection $connection, Request $request) {
    $http = new Client();
    $http->request('https://api.ai.com/v1/chat/completions', [
        'method' => 'POST',
        'data' => json_encode([
            'model' => 'gpt-3.5-turbo',
            'temperature' => 1,
            'stream' => true,
            'messages' => [['role' => 'user', 'content' => 'hello']],
        ]),
        'headers' => [
            'Content-Type' => 'application/json',
            'Authorization' => 'Bearer sk-xxx',
        ],
        'progress' => function($buffer) use ($connection) {
            $connection->send(new Chunk($buffer));
        },
        'success' => function($response) use ($connection) {
            $connection->send(new Chunk(''));
        },
    ]);
    $connection->send(new Response(200, [
        //"Content-Type" => "application/octet-stream",
        "Transfer-Encoding" => "chunked",
    ], ''));
};
Worker::runAll();

场景：php作为客户端请求SSE服务端
服务端按照官方workerman-sse实现的，SSE-WORKERMAN ，但是progress自定义的函数并未被调用,success定义的函数里一次获取到服务端的多条推送，对此不太理解，求解答