diff --git a/domain/pom.xml b/domain/pom.xml
new file mode 100644
index 0000000..f55aaad
--- /dev/null
+++ b/domain/pom.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>ms-library</artifactId>
+        <groupId>org.example</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>domain</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <optional>true</optional>
+        </dependency>
+    </dependencies>
+
+</project>
\ No newline at end of file
diff --git a/domain/src/main/java/org/exemple/data/BookDto.java b/domain/src/main/java/org/exemple/data/BookDto.java
new file mode 100644
index 0000000..629b23d
--- /dev/null
+++ b/domain/src/main/java/org/exemple/data/BookDto.java
@@ -0,0 +1,21 @@
+package org.exemple.data;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@AllArgsConstructor
+@NoArgsConstructor
+@Builder
+public class BookDto {
+
+    private Long id;
+
+    private String title;
+
+    private String description;
+
+    private Double price;
+}
\ No newline at end of file
diff --git a/domain/src/main/java/org/exemple/ports/api/BookServicePort.java b/domain/src/main/java/org/exemple/ports/api/BookServicePort.java
new file mode 100644
index 0000000..d9ae9e3
--- /dev/null
+++ b/domain/src/main/java/org/exemple/ports/api/BookServicePort.java
@@ -0,0 +1,18 @@
+package org.exemple.ports.api;
+
+import org.exemple.data.BookDto;
+
+import java.util.List;
+
+public interface BookServicePort {
+
+    BookDto addBook(BookDto bookDto);
+
+    void deleteBookById(Long id);
+
+    BookDto updateBook(BookDto bookDto);
+
+    List<BookDto> getBooks();
+
+    BookDto getBookById(Long bookId);
+}
diff --git a/domain/src/main/java/org/exemple/ports/spi/BookPersistencePort.java b/domain/src/main/java/org/exemple/ports/spi/BookPersistencePort.java
new file mode 100644
index 0000000..c7fb63d
--- /dev/null
+++ b/domain/src/main/java/org/exemple/ports/spi/BookPersistencePort.java
@@ -0,0 +1,19 @@
+package org.exemple.ports.spi;
+
+import org.exemple.data.BookDto;
+
+import java.util.List;
+
+public interface BookPersistencePort {
+
+    BookDto addBook(BookDto bookDto);
+
+    void deleteBookById(Long id);
+
+    BookDto updateBook(BookDto bookDto);
+
+    List<BookDto> getBooks();
+
+    BookDto getBookById(Long bookId);
+
+}
diff --git a/domain/src/main/java/org/exemple/service/BookServiceImpl.java b/domain/src/main/java/org/exemple/service/BookServiceImpl.java
new file mode 100644
index 0000000..1ff0106
--- /dev/null
+++ b/domain/src/main/java/org/exemple/service/BookServiceImpl.java
@@ -0,0 +1,41 @@
+package org.exemple.service;
+
+import org.exemple.data.BookDto;
+import org.exemple.ports.api.BookServicePort;
+import org.exemple.ports.spi.BookPersistencePort;
+
+import java.util.List;
+
+public class BookServiceImpl implements BookServicePort {
+
+    private BookPersistencePort bookPersistencePort;
+
+    public BookServiceImpl(BookPersistencePort bookPersistencePort) {
+        this.bookPersistencePort = bookPersistencePort;
+    }
+
+    @Override
+    public BookDto addBook(BookDto bookDto) {
+        return bookPersistencePort.addBook(bookDto);
+    }
+
+    @Override
+    public void deleteBookById(Long id) {
+        bookPersistencePort.deleteBookById(id);
+    }
+
+    @Override
+    public BookDto updateBook(BookDto bookDto) {
+        return bookPersistencePort.updateBook(bookDto);
+    }
+
+    @Override
+    public List<BookDto> getBooks() {
+        return bookPersistencePort.getBooks();
+    }
+
+    @Override
+    public BookDto getBookById(Long bookId) {
+        return bookPersistencePort.getBookById(bookId);
+    }
+}