13.3.2 Ajax Request queueing
All Ajax requests must be put into a client side request queue before they are sent to the
server to ensure Ajax requests are processed in the order they are sent. The request that has been waiting in the queue the
longest is the next request to be sent. After a request is sent,the Ajax request callback function must remove the request
from the queue (also kNown as dequeuing). If the request completed successfully,it must be removed from the queue. If
there was an error,the client must be notified,but the request must still be removed from the queue so the next request
can be sent. The next request (the oldest request in the queue) must be sent. Refer to thejsf.ajax.request
JavaScript documentation for more specifics about the Ajax request queue.
这样做是为了确保服务器端的视图作用域bean的线程安全性.