diff --git a/.gitignore b/.gitignore
index 589d3fb13..64f833e2d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,19 +1,19 @@
-target
-.metadata
-.settings
-.classpath
-.project
-*.class
-# Package Files #
-*.jar
-*.war
-*.ear
-.idea
-*.iml
-*.swp
+target
+.metadata
+.settings
+.classpath
+.project
+*.class
+# Package Files #
+*.jar
+*.war
+*.ear
+.idea
+*.iml
+*.swp
 datanucleus.log
 /bin/
 /bin/
 /bin/
-
-data-mapper/src/main/resources/log4j.xml
\ No newline at end of file
+*.log
+data-mapper/src/main/resources/log4j.xml
diff --git a/double-checked-locking/src/main/resources/logback.xml b/double-checked-locking/src/main/resources/logback.xml
new file mode 100644
index 000000000..c4c3058de
--- /dev/null
+++ b/double-checked-locking/src/main/resources/logback.xml
@@ -0,0 +1,52 @@
+<!--
+
+    The MIT License
+    Copyright (c) 2014 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<configuration>
+    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
+        <file>double-checked-locking.log</file>
+        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+            <fileNamePattern>double-checked-locking-%d.log</fileNamePattern>
+            <maxHistory>5</maxHistory>
+        </rollingPolicy>
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <logger name="com.iluwatar" additivity="false">
+        <level value="DEBUG"/>
+        <appender-ref ref="FILE"/>
+    </logger>
+
+    <root level="WARN">
+        <appender-ref ref="STDOUT"/>
+    </root>
+
+</configuration>
diff --git a/layers/src/main/resources/logback.xml b/layers/src/main/resources/logback.xml
new file mode 100644
index 000000000..e122ac350
--- /dev/null
+++ b/layers/src/main/resources/logback.xml
@@ -0,0 +1,57 @@
+<!--
+
+    The MIT License
+    Copyright (c) 2014 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<configuration>
+    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
+        <file>layers.log</file>
+        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+            <fileNamePattern>layers-%d.log</fileNamePattern>
+            <maxHistory>5</maxHistory>
+        </rollingPolicy>
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <logger name="com.iluwatar" additivity="false">
+        <level value="DEBUG"/>
+        <appender-ref ref="FILE"/>
+    </logger>
+
+    <logger name="org.hibernate" additivity="false">
+        <level value="ERROR"/>
+        <appender-ref ref="STDOUT"/>
+    </logger>
+
+    <root level="WARN">
+        <appender-ref ref="STDOUT"/>
+    </root>
+
+</configuration>
diff --git a/publish-subscribe/src/main/resources/logback.xml b/publish-subscribe/src/main/resources/logback.xml
new file mode 100644
index 000000000..95bed0150
--- /dev/null
+++ b/publish-subscribe/src/main/resources/logback.xml
@@ -0,0 +1,52 @@
+<!--
+
+    The MIT License
+    Copyright (c) 2014 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<configuration>
+    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
+        <file>publish-subscribe.log</file>
+        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+            <fileNamePattern>publish-subscribe-%d.log</fileNamePattern>
+            <maxHistory>5</maxHistory>
+        </rollingPolicy>
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <logger name="com.iluwatar" additivity="false">
+        <level value="DEBUG"/>
+        <appender-ref ref="FILE"/>
+    </logger>
+
+    <root level="WARN">
+        <appender-ref ref="STDOUT"/>
+    </root>
+
+</configuration>
diff --git a/repository/src/main/resources/logback.xml b/repository/src/main/resources/logback.xml
new file mode 100644
index 000000000..1b8cc5678
--- /dev/null
+++ b/repository/src/main/resources/logback.xml
@@ -0,0 +1,52 @@
+<!--
+
+    The MIT License
+    Copyright (c) 2014 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<configuration>
+    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
+        <file>repository.log</file>
+        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+            <fileNamePattern>repository-%d.log</fileNamePattern>
+            <maxHistory>5</maxHistory>
+        </rollingPolicy>
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <logger name="com.iluwatar" additivity="false">
+        <level value="DEBUG"/>
+        <appender-ref ref="FILE"/>
+    </logger>
+
+    <root level="WARN">
+        <appender-ref ref="STDOUT"/>
+    </root>
+
+</configuration>
diff --git a/service-layer/src/main/java/com/iluwatar/servicelayer/hibernate/HibernateUtil.java b/service-layer/src/main/java/com/iluwatar/servicelayer/hibernate/HibernateUtil.java
index eead0e197..9fc3047b5 100644
--- a/service-layer/src/main/java/com/iluwatar/servicelayer/hibernate/HibernateUtil.java
+++ b/service-layer/src/main/java/com/iluwatar/servicelayer/hibernate/HibernateUtil.java
@@ -60,7 +60,7 @@ public final class HibernateUtil {
                 .setProperty("hibernate.dialect", "org.hibernate.dialect.H2Dialect")
                 .setProperty("hibernate.connection.url", "jdbc:h2:mem:test;DB_CLOSE_DELAY=-1")
                 .setProperty("hibernate.current_session_context_class", "thread")
-                .setProperty("hibernate.show_sql", "true")
+                .setProperty("hibernate.show_sql", "false")
                 .setProperty("hibernate.hbm2ddl.auto", "create-drop").buildSessionFactory();
       } catch (Throwable ex) {
         LOGGER.error("Initial SessionFactory creation failed.", ex);
diff --git a/service-layer/src/main/resources/logback.xml b/service-layer/src/main/resources/logback.xml
new file mode 100644
index 000000000..e02933e70
--- /dev/null
+++ b/service-layer/src/main/resources/logback.xml
@@ -0,0 +1,57 @@
+<!--
+
+    The MIT License
+    Copyright (c) 2014 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<configuration>
+    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
+        <file>service-layer.log</file>
+        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
+            <fileNamePattern>service-layer-%d.log</fileNamePattern>
+            <maxHistory>5</maxHistory>
+        </rollingPolicy>
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%-5p [%d{ISO8601,UTC}] %c: %m%n</pattern>
+        </encoder>
+    </appender>
+
+    <logger name="com.iluwatar" additivity="false">
+        <level value="DEBUG"/>
+        <appender-ref ref="FILE"/>
+    </logger>
+
+    <logger name="org.hibernate" additivity="false">
+        <level value="ERROR"/>
+        <appender-ref ref="STDOUT"/>
+    </logger>
+
+    <root level="WARN">
+        <appender-ref ref="STDOUT"/>
+    </root>
+
+</configuration>