protobuf

protobuf

gRPC传输用这个挺好的，跨语言调用

• 足够简单
• 序列化后体积小
• 解析速度比XML块
• 多语言支持
• 兼容性好

proto3

这里就先不提proto2了

文件后缀名是.proto

Message & intersection

syntax = "proto3";//compile is proto3

message SearchRequest {
  string query = 1;
  int32 page_number = 2;
  int32 result_per_page = 3;
}

Type

double, float, int32, int64, uint32, uint64, sint32, sint64,(s* is more effcient in negative number)
fixed32, fixed64, sfixed32, sfixed64, bool, string, bytes.

repeated //by index
Timestamp
Duration
Struct
ListValue

默认值：

string ""
bytes ""
bool false
numeric 0
enums 0
message fields are language-dependent.

enum

message SearchRequest {
  string query = 1;
  int32 page_number = 2;
  int32 result_per_page = 3;
  enum Corpus {
    UNIVERSAL = 0;
    WEB = 1;
    IMAGES = 2;
    LOCAL = 3;
    NEWS = 4;
    PRODUCTS = 5;
    VIDEO = 6;
  }
  Corpus corpus = 4;
}
////////////////////////////////////////////////////////////
message MyMessage1 {
  enum EnumAllowingAlias {
    option allow_alias = true;//same variable in different enums, need this options. 
    UNKNOWN = 0;
    STARTED = 1;
    RUNNING = 1;
  }
}
message MyMessage2 {
  enum EnumNotAllowingAlias {
    UNKNOWN = 0;
    STARTED = 1;
    // RUNNING = 1;  // Uncommenting this line will cause a compile error inside Google and a warning message outside.
  }
}

using other message

message SearchResponse {
  repeated Result results = 1;
}

message Result {
  string url = 1;
  string title = 2;
  repeated string snippets = 3;
}

Importing Definitions

JAVA is not suitable

Nested Types

as deeply as U like

//1**************************
//straight Nested another message
message SearchResponse {
  repeated Result results = 1;
}

message Result {
  string url = 1;
  string title = 2;
  repeated string snippets = 3;
}

//2**************************
//nest partial message
message SomeOtherMessage {
  SearchResponse.Result result = 1;
}

any

one of

have many fields but use at most one field once.

a oneof cannot be repeated.

message SampleMessage {
  oneof test_oneof {
    string name = 4;
    SubMessage sub_message = 9;
  }
}

SampleMessage message;
message.set_name("name");
CHECK(message.has_name());
message.mutable_sub_message();   // Will clear name field.
CHECK(!message.has_name());

Maps

map<string, Project> projects = 3;

Define Services

service SearchService {
  rpc Search(SearchRequest) returns (SearchResponse);
}

Generating Classes

protoc --proto_path=IMPORT_PATH --cpp_out=DST_DIR --java_out=DST_DIR --python_out=DST_DIR --go_out=DST_DIR --ruby_out=DST_DIR --objc_out=DST_DIR --csharp_out=DST_DIR path/to/file.proto
# *_out point the DST_DIR of the output
# proto_path points the import_PATH?
# path/to/file.proto is the file be compiling.