diff --git a/ext_interface.cpp b/ext_interface.cpp
new file mode 100644
index 0000000..d289e20
--- /dev/null
+++ b/ext_interface.cpp
@@ -0,0 +1,87 @@
+#include <string>
+#include <sdbusplus/server.hpp>
+#include <phosphor-logging/log.hpp>
+#include <ext_interface.hpp>
+
+// Mapper
+constexpr auto MAPPER_BUSNAME = "xyz.openbmc_project.ObjectMapper";
+constexpr auto MAPPER_PATH = "/xyz/openbmc_project/object_mapper";
+constexpr auto MAPPER_INTERFACE = "xyz.openbmc_project.ObjectMapper";
+
+// Reboot count
+constexpr auto REBOOTCOUNTER_PATH("/org/openbmc/sensors/host/BootCount");
+constexpr auto REBOOTCOUNTER_INTERFACE("org.openbmc.SensorValue");
+
+using namespace phosphor::logging;
+
+/**
+ * @brief Get DBUS service for input interface via mapper call
+ *
+ * This is an internal function to be used only by functions within this
+ * file.
+ *
+ * @param[in] bus -  DBUS Bus Object
+ * @param[in] intf - DBUS Interface
+ * @param[in] path - DBUS Object Path
+ *
+ * @return distinct dbus name for input interface/path
+ **/
+std::string getService(sdbusplus::bus::bus& bus,
+                       const std::string& intf,
+                       const std::string& path)
+{
+
+    auto mapper = bus.new_method_call(MAPPER_BUSNAME,
+                                      MAPPER_PATH,
+                                      MAPPER_INTERFACE,
+                                      "GetObject");
+
+    mapper.append(path);
+    mapper.append(std::vector<std::string>({intf}));
+
+    auto mapperResponseMsg = bus.call(mapper);
+
+    if (mapperResponseMsg.is_method_error())
+    {
+        // TODO openbmc/openbmc#851 - Once available, throw returned error
+        throw std::runtime_error("ERROR in mapper call");
+    }
+
+    std::map<std::string, std::vector<std::string>> mapperResponse;
+    mapperResponseMsg.read(mapperResponse);
+
+    if (mapperResponse.empty())
+    {
+        // TODO openbmc/openbmc#1712 - Handle empty mapper resp. consistently
+        throw std::runtime_error("ERROR in reading the mapper response");
+    }
+
+    return mapperResponse.begin()->first;
+}
+
+
+int getBootCount()
+{
+    auto bus = sdbusplus::bus::new_default();
+
+    auto rebootSvc = getService(bus,
+                                REBOOTCOUNTER_INTERFACE,
+                                REBOOTCOUNTER_PATH);
+
+    sdbusplus::message::variant<int> rebootCount = 0;
+    auto method = bus.new_method_call(rebootSvc.c_str(),
+                                      REBOOTCOUNTER_PATH,
+                                      REBOOTCOUNTER_INTERFACE,
+                                      "getValue");
+
+    auto reply = bus.call(method);
+    if (reply.is_method_error())
+    {
+        log<level::ERR>("Error in BOOTCOUNT getValue");
+        // TODO openbmc/openbmc#851 - Once available, throw returned error
+        throw std::runtime_error("ERROR in reading BOOTCOUNT");
+    }
+    reply.read(rebootCount);
+
+    return (sdbusplus::message::variant_ns::get<int>(rebootCount));
+}