diff --git a/include/mqttpublisherbase.h b/include/mqttpublisherbase.h
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/include/mqttpublisherbase.h
diff --git a/include/mqttsubscriberbase.h b/include/mqttsubscriberbase.h
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/include/mqttsubscriberbase.h
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 543ce86..34432bc 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -31,9 +31,12 @@ include(compiler)
 
 include_directories(
     ${CMAKE_CURRENT_SOURCE_DIR}/../logutils
+    ${CMAKE_CURRENT_SOURCE_DIR}/../include
 )
 
 set(SRC_LIST
+    ${CMAKE_CURRENT_SOURCE_DIR}/mqttpublisherbase.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/mqttsubscriberbase.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/clientpaho.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/commondefs.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/connectionstatus.cpp
diff --git a/src/compat-chrono.h b/src/compat-chrono.h
index cec6df8..c383852 100644
--- a/src/compat-chrono.h
+++ b/src/compat-chrono.h
@@ -48,7 +48,11 @@ To ceil(const std::chrono::duration<Rep, Period>& d)
 {
     To t = std::chrono::duration_cast<To>(d);
     if (t < d)
+    {
         return t + To{ 1 };
+    }
+
+    // or else...
     return t;
 }
 
diff --git a/src/mqttpublisherbase.cpp b/src/mqttpublisherbase.cpp
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/src/mqttpublisherbase.cpp
diff --git a/src/mqttsubscriberbase.cpp b/src/mqttsubscriberbase.cpp
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/src/mqttsubscriberbase.cpp