Topic Name: 主题名称：
The label attached to an Application Message which is matched against the Subscriptions
known to the Server. The Server sends a copy of the Application Message to each Client
that has a matching Subscription.
附加到应用程序消息上的标签，该标签与服务器已知的订阅相匹配。服务器向每个具有匹
配订阅的客户端发送应用程序消息的副本。
Topic Filter: 主题筛选：
An expression contained in a Subscription, to indicate an interest in one or more
topics. A Topic Filter can include wildcard characters.
订阅中包含的表达式，用于表示对一个或多个主题的兴趣。主题筛选器可以包含通配符。
Session: 会话：
A stateful interaction between a Client and a Server.
客户端和服务器之间的有状态交互。
Some Sessions last only as long as the Network Connection, others can span multiple
consecutive Network Connections between a Client and a Server.
一些会话仅持续网络连接的时间，其他会话可以跨越客户端和服务器之间的多个连续网络
连接。
MQTT Control Packet: MQTT控制包：
A packet of information that is sent across the Network Connection. The MQTT
specification defines fourteen different types of Control Packet, one of which (the
PUBLISH packet) is used to convey Application Messages.
通过网络连接发送的信息包。MQTT规范定义了14种不同类型的控制包，其中之一(发布
包)用于传递应用程序消息。
1.3 Normative references 1.3 规范性参考文献
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
http://www.ietf.org/rfc/rfc2119.txt
[RFC3629]
Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, November 2003
http://www.ietf.org/rfc/rfc3629.txt
[RFC5246]
Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August
2008.
http://www.ietf.org/rfc/rfc5246.txt
[RFC6455]
Fette, I. and A. Melnikov, "The WebSocket Protocol", RFC 6455, December 2011.
