Google Protocol Buffers v3.0.0-alpha-1 发布，新特性包括：
Removal of field presence logic for primitive value fields, removal
of required fields, and removal of default values. This makes proto3
significantly easier to implement with open struct representations,
as in languages like Android Java, Objective C, or Go. Removal of unknown fields. Removal of extensions, which are instead replaced by a new standard
type called Any. Fix semantics for unknown enum values. Addition of maps. Addition of a small set of standard types for representation of time,
dynamic data, etc. A well-defined encoding in JSON as an alternative to binary proto
encoding.
同时部分 proto3 支持 C++ 和 Java，目前上述的 6 和 7 暂时没有实现。详细介绍请看发行说明。
Protocol Buffers (ProtocolBuffer/ protobuf )是Google公司开发的一种数据描述语言，类似于XML能够将结构化数据序列化，可用于数据存储、通信协议等方面。现阶段支持C++、JAVA、Python等三种编程语言。 | 
