package library.domain;
message Author {
string id = 1;
string full_name = 2;
repeated library.domain.Book bibliography = 3;
}- Field
bibliography: Book
package library.domain;
message Book {
string isbn = 1;
string title = 2;
library.domain.Author author = 3;
library.domain.Publisher publisher = 4;
library.domain.Genre genre = 5;
}package library.domain;
message Publisher {
string id = 1;
string name = 2;
string address = 3;
}None
package library.domain;
enum Genre {
UNKNOWN = 0;
FICTION = 1;
NON_FICTION = 2;
SCI_FI = 3;
HISTORY = 4;
}