diff --git a/02_UsosMockup/UsosMockup.iml b/02_UsosMockup/UsosMockup.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/02_UsosMockup/UsosMockup.iml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/02_UsosMockup/src/Main.java b/02_UsosMockup/src/Main.java
new file mode 100644
index 0000000..3e59c38
--- /dev/null
+++ b/02_UsosMockup/src/Main.java
@@ -0,0 +1,5 @@
+public class Main {
+    public static void main(String[] args) {
+        System.out.println("Hello world!");
+    }
+}
\ No newline at end of file
diff --git a/02_UsosMockup/src/net/hypki/UsosMockup/db/Db.java b/02_UsosMockup/src/net/hypki/UsosMockup/db/Db.java
new file mode 100644
index 0000000..9aa3457
--- /dev/null
+++ b/02_UsosMockup/src/net/hypki/UsosMockup/db/Db.java
@@ -0,0 +1,8 @@
+package net.hypki.UsosMockup.db;
+
+import net.hypki.UsosMockup.modelobjects.DbObject;
+
+public interface Db {
+    void save(DbObject value);
+    DbObject get(String key);
+}
diff --git a/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/Classroom.java b/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/Classroom.java
new file mode 100644
index 0000000..41210ec
--- /dev/null
+++ b/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/Classroom.java
@@ -0,0 +1,32 @@
+package net.hypki.UsosMockup.modelobjects;
+
+public class Classroom extends DbObject {
+    private String location = null;
+
+    private int maxCapacity = 30;
+
+    public Classroom(String location) {
+        this.location = location;
+    }
+
+    public int getMaxCapacity() {
+        return maxCapacity;
+    }
+
+    public void setMaxCapacity(int maxCapacity) {
+        this.maxCapacity = maxCapacity;
+    }
+
+    @Override
+    String getKey() {
+        return getLocation();
+    }
+
+    public String getLocation() {
+        return location;
+    }
+
+    public void setLocation(String location) {
+        this.location = location;
+    }
+}
diff --git a/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/Course.java b/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/Course.java
new file mode 100644
index 0000000..a3d2e46
--- /dev/null
+++ b/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/Course.java
@@ -0,0 +1,57 @@
+package net.hypki.UsosMockup.modelobjects;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Course extends  DbObject {
+    private String name = null;
+
+    private int hours = 30;
+
+    private Classroom classroom;
+
+    private List<Student> students = null;
+
+    public Course(String name) {
+        this.name = name;
+    }
+
+    public int getHours() {
+        return hours;
+    }
+
+    public void setHours(int hours) {
+        this.hours = hours;
+    }
+
+    public Classroom getClassroom() {
+        return classroom;
+    }
+
+    public void setClassroom(Classroom classroom) {
+        this.classroom = classroom;
+    }
+
+    public List<Student> getStudents() {
+        if (students == null)
+            students = new ArrayList<>();
+        return students;
+    }
+
+    public void setStudents(List<Student> students) {
+        this.students = students;
+    }
+
+    @Override
+    String getKey() {
+        return getName();
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}
diff --git a/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/DbObject.java b/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/DbObject.java
new file mode 100644
index 0000000..ec840b9
--- /dev/null
+++ b/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/DbObject.java
@@ -0,0 +1,5 @@
+package net.hypki.UsosMockup.modelobjects;
+
+public abstract class DbObject {
+    abstract String getKey();
+}
diff --git a/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/Student.java b/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/Student.java
new file mode 100644
index 0000000..5c7b567
--- /dev/null
+++ b/02_UsosMockup/src/net/hypki/UsosMockup/modelobjects/Student.java
@@ -0,0 +1,35 @@
+package net.hypki.UsosMockup.modelobjects;
+
+public class Student extends DbObject {
+
+    private String name = null;
+    private String surname = null;
+
+    public Student(String name, String surname) {
+        this.name = name;
+        this.surname = surname;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        // TODO check if it is not empty
+
+        this.name = name;
+    }
+
+    public String getSurname() {
+        return surname;
+    }
+
+    public void setSurname(String surname) {
+        this.surname = surname;
+    }
+
+    @Override
+    String getKey() {
+        return getName() + " " + getSurname();
+    }
+}