diff --git a/.travis.yml b/.travis.yml
index fa51dc2d..fa074ba2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,10 +2,10 @@ sudo: required
 
 env:
   matrix:
-    - DOCKER_IMAGE=ubuntu:18.04 IGN_COLLECTION="blueprint" ROS_DISTRO="dashing"
-    - DOCKER_IMAGE=ubuntu:18.04 IGN_COLLECTION="blueprint" ROS_DISTRO="eloquent"
-    - DOCKER_IMAGE=ubuntu:18.04 IGN_COLLECTION="citadel" ROS_DISTRO="dashing"
-    - DOCKER_IMAGE=ubuntu:18.04 IGN_COLLECTION="citadel" ROS_DISTRO="eloquent"
+    - DOCKER_IMAGE=ubuntu:18.04 IGNITION_VERSION="blueprint" ROS_DISTRO="dashing"
+    - DOCKER_IMAGE=ubuntu:18.04 IGNITION_VERSION="blueprint" ROS_DISTRO="eloquent"
+    - DOCKER_IMAGE=ubuntu:18.04 IGNITION_VERSION="citadel" ROS_DISTRO="dashing"
+    - DOCKER_IMAGE=ubuntu:18.04 IGNITION_VERSION="citadel" ROS_DISTRO="eloquent"
 
 services:
   - docker
@@ -17,10 +17,10 @@ compiler:
 
 before_install:
   - echo $DOCKER_IMAGE
-  - echo $IGN_COLLECTION
+  - echo $IGNITION_VERSION
   - echo $ROS_DISTRO
   - docker pull $DOCKER_IMAGE
-  - docker run  -e IGN_COLLECTION -e ROS_DISTRO -d -v $(pwd):/code $DOCKER_IMAGE /bin/bash -c 'while true; do sleep 1; done'
+  - docker run  -e IGNITION_VERSION -e ROS_DISTRO -d -v $(pwd):/code $DOCKER_IMAGE /bin/bash -c 'while true; do sleep 1; done'
   - docker exec $(docker ps -aq) /bin/bash -c 'id'
 
 before_script:
diff --git a/.travis/build b/.travis/build
index 3f170af5..ecea5fc9 100755
--- a/.travis/build
+++ b/.travis/build
@@ -6,9 +6,9 @@ export COLCON_WS=~/ws
 export COLCON_WS_SRC=${COLCON_WS}/src
 export DEBIAN_FRONTEND=noninteractive
 
-if [ "$IGN_COLLECTION" == "blueprint" ]; then
+if [ "$IGNITION_VERSION" == "blueprint" ]; then
   IGN_DEPS="libignition-msgs4-dev libignition-transport7-dev libignition-gazebo2-dev"
-elif [ "$IGN_COLLECTION" == "citadel" ]; then
+elif [ "$IGNITION_VERSION" == "citadel" ]; then
   IGN_DEPS="libignition-msgs5-dev libignition-transport8-dev libignition-gazebo3-dev"
 else
   exit 1
diff --git a/ros_ign_bridge/CMakeLists.txt b/ros_ign_bridge/CMakeLists.txt
index f312164c..c71608cd 100644
--- a/ros_ign_bridge/CMakeLists.txt
+++ b/ros_ign_bridge/CMakeLists.txt
@@ -38,8 +38,8 @@ endif()
 include_directories(include)
 
 set(common_sources
-  src/convert_builtin_interfaces.cpp
-  src/builtin_interfaces_factories.cpp
+  src/convert.cpp
+  src/factories.cpp
 )
 
 set(bridge_executables
diff --git a/ros_ign_bridge/include/ros_ign_bridge/convert_builtin_interfaces.hpp b/ros_ign_bridge/include/ros_ign_bridge/convert.hpp
similarity index 97%
rename from ros_ign_bridge/include/ros_ign_bridge/convert_builtin_interfaces.hpp
rename to ros_ign_bridge/include/ros_ign_bridge/convert.hpp
index 67a0200c..64ff4458 100644
--- a/ros_ign_bridge/include/ros_ign_bridge/convert_builtin_interfaces.hpp
+++ b/ros_ign_bridge/include/ros_ign_bridge/convert.hpp
@@ -12,12 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#ifndef ROS_IGN_BRIDGE__CONVERT_BUILTIN_INTERFACES_HPP_
-#define ROS_IGN_BRIDGE__CONVERT_BUILTIN_INTERFACES_HPP_
+#ifndef ROS_IGN_BRIDGE__CONVERT_HPP_
+#define ROS_IGN_BRIDGE__CONVERT_HPP_
 
 #include <rclcpp/time.hpp>
 
-// include ROS 2 builtin messages
+// ROS 2 messages
 #include <geometry_msgs/msg/point.hpp>
 #include <geometry_msgs/msg/pose.hpp>
 #include <geometry_msgs/msg/pose_stamped.hpp>
@@ -41,7 +41,7 @@
 #include <std_msgs/msg/float32.hpp>
 #include <std_msgs/msg/string.hpp>
 
-// include Ignition builtin messages
+// Ignition messages
 #include <ignition/msgs.hh>
 
 #include <ros_ign_bridge/convert_decl.hpp>
@@ -359,4 +359,4 @@ convert_ign_to_ros(
 
 }  // namespace ros_ign_bridge
 
-#endif  // ROS_IGN_BRIDGE__CONVERT_BUILTIN_INTERFACES_HPP_
+#endif  // ROS_IGN_BRIDGE__CONVERT_HPP_
diff --git a/ros_ign_bridge/include/ros_ign_bridge/bridge.hpp b/ros_ign_bridge/src/bridge.hpp
similarity index 95%
rename from ros_ign_bridge/include/ros_ign_bridge/bridge.hpp
rename to ros_ign_bridge/src/bridge.hpp
index 9727ac41..45f86a51 100644
--- a/ros_ign_bridge/include/ros_ign_bridge/bridge.hpp
+++ b/ros_ign_bridge/src/bridge.hpp
@@ -12,17 +12,17 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#ifndef ROS_IGN_BRIDGE__BRIDGE_HPP_
-#define ROS_IGN_BRIDGE__BRIDGE_HPP_
+#ifndef BRIDGE_HPP_
+#define BRIDGE_HPP_
 
 // include Ignition Transport
 #include <ignition/transport/Node.hh>
 
-#include <ros_ign_bridge/builtin_interfaces_factories.hpp>
-
 #include <memory>
 #include <string>
 
+#include "factories.hpp"
+
 namespace ros_ign_bridge
 {
 
@@ -110,4 +110,4 @@ create_bidirectional_bridge(
 
 }  // namespace ros_ign_bridge
 
-#endif  // ROS_IGN_BRIDGE__BRIDGE_HPP_
+#endif  // BRIDGE_HPP_
diff --git a/ros_ign_bridge/src/convert_builtin_interfaces.cpp b/ros_ign_bridge/src/convert.cpp
similarity index 99%
rename from ros_ign_bridge/src/convert_builtin_interfaces.cpp
rename to ros_ign_bridge/src/convert.cpp
index f23bae00..786bb245 100644
--- a/ros_ign_bridge/src/convert_builtin_interfaces.cpp
+++ b/ros_ign_bridge/src/convert.cpp
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <ros_ign_bridge/convert_builtin_interfaces.hpp>
+#include "ros_ign_bridge/convert.hpp"
 
 #include <limits>
 #include <string>
diff --git a/ros_ign_bridge/src/builtin_interfaces_factories.cpp b/ros_ign_bridge/src/factories.cpp
similarity index 98%
rename from ros_ign_bridge/src/builtin_interfaces_factories.cpp
rename to ros_ign_bridge/src/factories.cpp
index 6ecd0f87..0bf60282 100644
--- a/ros_ign_bridge/src/builtin_interfaces_factories.cpp
+++ b/ros_ign_bridge/src/factories.cpp
@@ -15,15 +15,14 @@
 #include <memory>
 #include <string>
 
-// include builtin interfaces
-#include "ros_ign_bridge/builtin_interfaces_factories.hpp"
-#include "ros_ign_bridge/convert_builtin_interfaces.hpp"
+#include "factories.hpp"
+#include "ros_ign_bridge/convert.hpp"
 
 namespace ros_ign_bridge
 {
 
 std::shared_ptr<FactoryInterface>
-get_factory_builtin_interfaces(
+get_factory_impl(
   const std::string & ros_type_name,
   const std::string & ign_type_name)
 {
@@ -289,7 +288,7 @@ get_factory(
   const std::string & ign_type_name)
 {
   std::shared_ptr<FactoryInterface> factory;
-  factory = get_factory_builtin_interfaces(ros_type_name, ign_type_name);
+  factory = get_factory_impl(ros_type_name, ign_type_name);
   if (factory) {
     return factory;
   }
diff --git a/ros_ign_bridge/include/ros_ign_bridge/builtin_interfaces_factories.hpp b/ros_ign_bridge/src/factories.hpp
similarity index 96%
rename from ros_ign_bridge/include/ros_ign_bridge/builtin_interfaces_factories.hpp
rename to ros_ign_bridge/src/factories.hpp
index 682f445e..dd26f143 100644
--- a/ros_ign_bridge/include/ros_ign_bridge/builtin_interfaces_factories.hpp
+++ b/ros_ign_bridge/src/factories.hpp
@@ -12,10 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#ifndef ROS_IGN_BRIDGE__BUILTIN_INTERFACES_FACTORIES_HPP_
-#define ROS_IGN_BRIDGE__BUILTIN_INTERFACES_FACTORIES_HPP_
+#ifndef FACTORIES_HPP_
+#define FACTORIES_HPP_
 
-// include ROS 2 messages
+// ROS 2 messages
 #include <geometry_msgs/msg/point.hpp>
 #include <geometry_msgs/msg/pose.hpp>
 #include <geometry_msgs/msg/pose_stamped.hpp>
@@ -39,22 +39,16 @@
 #include <std_msgs/msg/float32.hpp>
 #include <std_msgs/msg/string.hpp>
 
-// include Ignition Transport messages
+// Ignition messages
 #include <ignition/msgs.hh>
 
-#include <ros_ign_bridge/factory.hpp>
-
 #include <memory>
 #include <string>
 
+#include "factory.hpp"
+
 namespace ros_ign_bridge
 {
-
-std::shared_ptr<FactoryInterface>
-get_factory_builtin_interfaces(
-  const std::string & ros_type_name,
-  const std::string & ign_type_name);
-
 std::shared_ptr<FactoryInterface>
 get_factory(
   const std::string & ros_type_name,
@@ -522,4 +516,4 @@ Factory<
 
 }  // namespace ros_ign_bridge
 
-#endif  // ROS_IGN_BRIDGE__BUILTIN_INTERFACES_FACTORIES_HPP_
+#endif  // FACTORIES_HPP_
diff --git a/ros_ign_bridge/include/ros_ign_bridge/factory.hpp b/ros_ign_bridge/src/factory.hpp
similarity index 96%
rename from ros_ign_bridge/include/ros_ign_bridge/factory.hpp
rename to ros_ign_bridge/src/factory.hpp
index 4f565c80..78eecb43 100644
--- a/ros_ign_bridge/include/ros_ign_bridge/factory.hpp
+++ b/ros_ign_bridge/src/factory.hpp
@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#ifndef ROS_IGN_BRIDGE__FACTORY_HPP_
-#define ROS_IGN_BRIDGE__FACTORY_HPP_
+#ifndef FACTORY_HPP_
+#define FACTORY_HPP_
 
 #include <ignition/transport/Node.hh>
 
@@ -24,7 +24,7 @@
 #include <memory>
 #include <string>
 
-#include "ros_ign_bridge/factory_interface.hpp"
+#include "factory_interface.hpp"
 
 namespace ros_ign_bridge
 {
@@ -149,4 +149,4 @@ class Factory : public FactoryInterface
 
 }  // namespace ros_ign_bridge
 
-#endif  // ROS_IGN_BRIDGE__FACTORY_HPP_
+#endif  // FACTORY_HPP_
diff --git a/ros_ign_bridge/include/ros_ign_bridge/factory_interface.hpp b/ros_ign_bridge/src/factory_interface.hpp
similarity index 91%
rename from ros_ign_bridge/include/ros_ign_bridge/factory_interface.hpp
rename to ros_ign_bridge/src/factory_interface.hpp
index 3ae95140..b3b1c555 100644
--- a/ros_ign_bridge/include/ros_ign_bridge/factory_interface.hpp
+++ b/ros_ign_bridge/src/factory_interface.hpp
@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#ifndef  ROS_IGN_BRIDGE__FACTORY_INTERFACE_HPP_
-#define  ROS_IGN_BRIDGE__FACTORY_INTERFACE_HPP_
+#ifndef  FACTORY_INTERFACE_HPP_
+#define  FACTORY_INTERFACE_HPP_
 
 // include ROS 2
 #include <rclcpp/rclcpp.hpp>
@@ -63,4 +63,4 @@ class FactoryInterface
 
 }  // namespace ros_ign_bridge
 
-#endif  // ROS_IGN_BRIDGE__FACTORY_INTERFACE_HPP_
+#endif  // FACTORY_INTERFACE_HPP_
diff --git a/ros_ign_bridge/src/parameter_bridge.cpp b/ros_ign_bridge/src/parameter_bridge.cpp
index 8b9b2abf..fc28a1e5 100644
--- a/ros_ign_bridge/src/parameter_bridge.cpp
+++ b/ros_ign_bridge/src/parameter_bridge.cpp
@@ -18,14 +18,14 @@
 // include Ignition Transport
 #include <ignition/transport/Node.hh>
 
-#include <ros_ign_bridge/bridge.hpp>
-
 #include <iostream>
 #include <list>
 #include <memory>
 #include <string>
 #include <vector>
 
+#include "bridge.hpp"
+
 // Direction of bridge.
 enum Direction
 {
diff --git a/ros_ign_bridge/src/static_bridge.cpp b/ros_ign_bridge/src/static_bridge.cpp
index 80b5ba2f..e16d078a 100644
--- a/ros_ign_bridge/src/static_bridge.cpp
+++ b/ros_ign_bridge/src/static_bridge.cpp
@@ -17,11 +17,11 @@
 // include Ignition Transport
 #include <ignition/transport/Node.hh>
 
-#include <ros_ign_bridge/bridge.hpp>
-
 #include <memory>
 #include <string>
 
+#include "bridge.hpp"
+
 //////////////////////////////////////////////////
 int main(int argc, char * argv[])
 {
diff --git a/ros_ign_image/src/image_bridge.cpp b/ros_ign_image/src/image_bridge.cpp
index c0ef9fac..8e2c82f8 100644
--- a/ros_ign_image/src/image_bridge.cpp
+++ b/ros_ign_image/src/image_bridge.cpp
@@ -16,7 +16,7 @@
 
 #include <rclcpp/rclcpp.hpp>
 #include <image_transport/image_transport.h>
-#include <ros_ign_bridge/convert_builtin_interfaces.hpp>
+#include <ros_ign_bridge/convert.hpp>
 
 #include <iostream>
 #include <memory>