diff --git a/core-buffer/include/FastH5Writer.hpp b/core-buffer/include/FastH5Writer.hpp
index 6db76f2..67249ba 100644
--- a/core-buffer/include/FastH5Writer.hpp
+++ b/core-buffer/include/FastH5Writer.hpp
@@ -3,6 +3,8 @@
 
 #include <cstdint>
 #include <vector>
+#include <string>
+#include <H5Cpp.h>
 
 template <class B>
 class FastH5Writer {
@@ -13,8 +15,10 @@ class FastH5Writer {
     const uint16_t y_frame_size_;
     const uint16_t x_frame_size_;
 
-    std::string current_output_file_;
+    std::string current_output_filename_;
+    H5::H5File current_output_file_;
     H5::DataSet current_image_dataset_;
+    uint64_t current_pulse_id_;
 
     void create_image_dataset();
 
diff --git a/core-buffer/src/FastH5Writer.cpp b/core-buffer/src/FastH5Writer.cpp
index 0ffe01a..4045ca2 100644
--- a/core-buffer/src/FastH5Writer.cpp
+++ b/core-buffer/src/FastH5Writer.cpp
@@ -1,5 +1,5 @@
 #include "FastH5Writer.hpp"
-#include <H5Cpp.h>
+
 
 template<>
 FastH5Writer<uint16_t>::FastH5Writer(
@@ -8,16 +8,15 @@ FastH5Writer<uint16_t>::FastH5Writer(
         const uint16_t x_frame_size) :
             n_frames_per_file_(n_frames_per_file),
             y_frame_size_(y_frame_size),
-            x_frame_size_(y_frame_size)
+            x_frame_size_(y_frame_size),
+            current_output_filename_(""),
+            current_output_file_(),
+            current_image_dataset_(),
+            current_pulse_id_(0)
 {
 //    // Each element in uint16_t has 2 bytes.
 //    size_t n_bytes = 2 * y_frame_size * x_frame_size;
-    auto file = H5::H5File(target_filename.c_str(), H5F_ACC_TRUNC);
-
-
-
-
-    create_dataset("image", frame_size, n_frames_per_file, "uint16");
+//    auto file = H5::H5File(target_filename.c_str(), H5F_ACC_TRUNC);
 }
 
 template <class B>
@@ -40,4 +39,16 @@ void FastH5Writer<B>::create_image_dataset()
 
     current_image_dataset_ = current_output_file_.createDataSet(
             "image", dataset_data_type, dataspace, dataset_properties);
+}
+
+template <class B>
+void FastH5Writer<B>::set_pulse_id(const uint64_t pulse_id)
+{
+    current_pulse_id_ = pulse_id;
+}
+
+template <class B>
+void FastH5Writer<B>::write_data(const char *buffer)
+{
+    
 }
\ No newline at end of file