diff --git a/src/data/data.cc b/src/data/data.cc
new file mode 100644
index 000000000..290ef523b
--- /dev/null
+++ b/src/data/data.cc
@@ -0,0 +1,38 @@
+#include <xgboost/data.h>
+
+namespace xgboost {
+// implementation of inline functions
+void MetaInfo::Clear() {
+  num_row = num_col = 0;
+  labels.clear();
+  root_index.clear();
+  group_ptr.clear();
+  weights.clear();
+  base_margin.clear();
+}
+
+void MetaInfo::SaveBinary(dmlc::Stream *fo) const {
+  int version = kVersion;
+  fo->Write(&version, sizeof(version));
+  fo->Write(&num_row, sizeof(num_row));
+  fo->Write(&num_col, sizeof(num_col));
+  fo->Write(labels);
+  fo->Write(group_ptr);
+  fo->Write(weights);
+  fo->Write(root_index);
+  fo->Write(base_margin);
+}
+
+void MetaInfo::LoadBinary(dmlc::Stream *fi) {
+  int version;
+  CHECK(fi->Read(&version, sizeof(version)) == sizeof(version)) << "MetaInfo: invalid format";
+  CHECK_EQ(version, kVersion) << "MetaInfo: invalid format";
+  CHECK(fi->Read(&num_row, sizeof(num_row)) == sizeof(num_row)) << "MetaInfo: invalid format";
+  CHECK(fi->Read(&num_col, sizeof(num_col)) == sizeof(num_col)) << "MetaInfo: invalid format";
+  CHECK(fi->Read(&labels)) <<  "MetaInfo: invalid format";
+  CHECK(fi->Read(&group_ptr)) << "MetaInfo: invalid format";
+  CHECK(fi->Read(&weights)) << "MetaInfo: invalid format";
+  CHECK(fi->Read(&root_index)) << "MetaInfo: invalid format";
+  CHECK(fi->Read(&base_margin)) << "MetaInfo: invalid format";
+}
+}  // namespace xgboost