Updated documentation of the Spring configuration.

src/main/java/cz/cvut/kbss/ear/setup/config/AppConfig.java

@@ -25,9 +25,10 @@ import org.springframework.context.annotation.Import;
  * It is good to separate configuration of different components of the application, because they can then be configured
  * independently for example in tests.
  */
+// This annotation is required when services without separate interfaces are used. It causes cglib-based proxies of
+// the services to be used - see http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/context/annotation/EnableAspectJAutoProxy.html#proxyTargetClass--
 @EnableAspectJAutoProxy(proxyTargetClass = true)
-@Configuration
-@EnableMBeanExport
-@Import({WebAppConfig.class, PersistenceConfig.class, ServiceConfig.class})
+@Configuration  // This class is a Spring configuration
+@Import({WebAppConfig.class, PersistenceConfig.class, ServiceConfig.class}) // Import additional configuration classes
 public class AppConfig {
 }

src/main/java/cz/cvut/kbss/ear/setup/service/TeacherService.java

@@ -14,6 +14,10 @@ public class TeacherService {
     @Autowired
     private TeacherDao teacherDao;
 
+    // Declarative transaction demarcation. readOnly set to true is good for retrieval operations, because it
+    // may involve less locking on the lower layers
+    // If the services are split into interfaces and implementations, the @Transactional annotation usually goes
+    // to the interface, so that ic can apply to all possible implementations of the service
     @Transactional(readOnly = true)
     public List<Teacher> findAll() {
         return teacherDao.findAll();
@@ -24,6 +28,7 @@ public class TeacherService {
         return teacherDao.findByName(firstName, lastName) != null;
     }
 
+    // No readOnly here, because we modify the data in this operation
     @Transactional
     public void persist(Teacher teacher) {
         teacherDao.persist(teacher);

src/test/java/cz/cvut/kbss/ear/setup/dao/BaseDaoTestRunner.java

@@ -35,6 +35,7 @@ won't be available for autowiring in tests inheriting from this class.
 // Reset the Spring context after each tests, recreating all the beans
 @DirtiesContext(classMode = DirtiesContext.ClassMode.AFTER_EACH_TEST_METHOD)
 //extend the transactions to whole tests in order to rollback the changes after each test
+// Se also http://docs.spring.io/spring/docs/current/spring-framework-reference/html/integration-testing.html#testcontext-tx
 @Transactional(transactionManager = "txManager")
 public abstract class BaseDaoTestRunner {
 }