基本顺序是服务器(应用程序)启动，等待客户端发出请求。

The basic sequence is that a server (application) is started, which waits for the client to make a request.

youdao

然而，如果服务器没有任何信息，它将保持请求并等待客户端可用的更新信息。

However, if the server does not have any information, it holds the request and waits for an update to be available for the client.

youdao

SQS主要用于分布式系统间的通讯，把消息发送并存储到队列中，等待客户端使用。

SQS is used by distributed applications to communicate by sending messages to queues where they are stored awaiting to be consumed by clients.

youdao