The non-data descriptor is likely to be used to return a callable object.
非数据描述符最常用于返回一个可调用对象。
2
For non-CMP applications, the resource authentication is identified by the res-auth deployment descriptor.
对于非cmp应用程序，资源认证由res - auth部署描述符来标识。
3
When dealing with multiple file descriptors, an application typically sets each file descriptor as non-blocking (as shown in Listing 1) and issues a read on one file descriptor at a time.