Rework book server and client.

examples/book_server/book_db.h

@@ -0,0 +1,44 @@
+#ifndef BOOK_DB_H_
+#define BOOK_DB_H_
+
+#include <list>
+#include <string>
+
+#include "book.h"
+
+// Book database simulator.
+// There should be some database in a real product.
+
+class BookDB {
+public:
+  const std::list<Book>& books() const {
+    return books_;
+  }
+
+  const Book& Get(const std::string& id) const;
+
+  // Add a book, return the ID.
+  // NOTE: The ID of the input book will be ignored so should be empty.
+  std::string Add(const Book& book);
+
+  bool Set(const Book& book);
+
+  std::string GetPhoto(const std::string& id) const;
+
+  bool SetPhoto(const std::string& id, const std::string& photo);
+
+  bool Delete(const std::string& id);
+
+private:
+  std::list<Book>::const_iterator Find(const std::string& id) const;
+
+  std::list<Book>::iterator Find(const std::string& id);
+
+  // Allocate a new book ID.
+  std::string NewID() const;
+
+private:
+  std::list<Book> books_;
+};
+
+#endif  // BOOK_DB_H_