第72学习socketsever模块

socketsever里面有2大类：socketsever直接点击查看文档，有12个类

sever类：处理连接:"BaseServer", "TCPServer", "UDPServer","UnixStreamServer","UnixDatagramServer"

箭头是继承关系；

        | BaseServer |
        +------------+
              |
              v
        +-----------+        +------------------+
        | TCPServer |------->| UnixStreamServer |
        +-----------+        +------------------+
              |
              v
        +-----------+        +--------------------+
        | UDPServer |------->| UnixDatagramServer |
        +-----------+        +--------------------+

class ForkingUDPServer(ForkingMixIn, UDPServer)

class ForkingTCPServer(ForkingMixIn, TCPServer)

class ThreadingUDPServer(ThreadingMixIn, UDPServer)

class ThreadingTCPServer(ThreadingMixIn, TCPServer)

都是实现并发的，

Forking:代表进程

Threading：代表线程

备注：1、在liunx上直接相互替换可以使用，但是Windows上不行
     2、多进程的开销多余多线程。所有一般使用多线程，后面学习  

request类：处理通信:"BaseRequestHandler", "StreamRequestHandler","DatagramRequestHandler",

箭头是继承关系；

        +-----------+                +------------------+
        |BaseRequestHandler| ------->|StreamRequestHandler |

        +-----------+                 +------------------+
              |
              v
        +-----------+        
        | DatagramRequestHandler 
        +-----------+       

class DatagramRequestHandler(BaseRequestHandler)