diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index d1a13512d80b1cb8bca078f001987e958aa0e874..4074d6b0549e8ef54036c9a17f137bd042fb08d3 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -82,7 +82,7 @@ if(LINTING)
             "--warnings-as-errors=*"
             "--fix")
         set(_CMAKE_CXX_CLANG_TIDY_CHECKS
-          "--checks=*,-fuchsia-*,-llvmlibc-*,-cert-err58-cpp,-cppcoreguidelines-avoid-non-const-global-variables,-cppcoreguidelines-owning-memory,-modernize-use-trailing-return-type,-google-readability-avoid-underscore-in-googletest-name,-cppcoreguidelines-avoid-magic-numbers,-readability-magic-numbers,-cppcoreguidelines-avoid-goto,-hicpp-avoid-goto,-readability-function-cognitive-complexity")
+          "--checks=*,-fuchsia-*,-llvmlibc-*,-cert-err58-cpp,-cppcoreguidelines-avoid-non-const-global-variables,-cppcoreguidelines-owning-memory,-modernize-use-trailing-return-type,-google-readability-avoid-underscore-in-googletest-name,-cppcoreguidelines-avoid-magic-numbers,-readability-magic-numbers,-cppcoreguidelines-avoid-goto,-hicpp-avoid-goto,-readability-function-cognitive-complexity,-cppcoreguidelines-non-private-member-variables-in-classes,-misc-non-private-member-variables-in-classes")
     endif()
 else()
     message(STATUS "LINTING is OFF")
@@ -105,7 +105,8 @@ foreach (i RANGE "${len_test_cases}")
     target_link_libraries(${test_case_name} PRIVATE ${CONAN_LIBS_CAOSDB}
         ${CONAN_LIBS_GTEST} ${CONAN_LIBS_GRPC} ${CONAN_LIBS_ABSEIL}
         ${CONAN_LIBS_OPENSSL} ${CONAN_LIBS_C-ARES} ${CONAN_LIBS_BZIP2}
-        ${CONAN_LIBS_PROTOBUF} ${CONAN_LIBS_ZLIB} ${CONAN_LIBS_RE2})
+        ${CONAN_LIBS_PROTOBUF} ${CONAN_LIBS_ZLIB} ${CONAN_LIBS_RE2}
+        ${CONAN_LIBS_BOOST})
     target_include_directories(${test_case_name}
         PUBLIC ${CONAN_INCLUDE_DIRS} ${CMAKE_CURRENT_SOURCE_DIR})
     if(LINTING)
diff --git a/test/test_file_transmission.cpp b/test/test_file_transmission.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7c6a72d0b4d52ecd76d01d253e377473ce7954cf
--- /dev/null
+++ b/test/test_file_transmission.cpp
@@ -0,0 +1,158 @@
+/*
+ * This file is a part of the CaosDB Project.
+ *
+ * Copyright (C) 2021 Timm Fitschen <t.fitschen@indiscale.com>
+ * Copyright (C) 2021 IndiScale GmbH <info@indiscale.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+#include "caosdb/connection.h" // for Connection, ConnectionManager
+#include "caosdb/entity.h"
+#include "caosdb/entity/v1alpha1/main.pb.h"
+#include "caosdb/transaction.h"    // for Transaction, UniqueRe...
+#include "gtest/gtest-message.h"   // for Message
+#include "gtest/gtest-test-part.h" // for TestPartResult, SuiteApiResolver
+#include "gtest/gtest_pred_impl.h" // for Test, EXPECT_EQ, AssertionResult
+#include <memory>                  // for unique_ptr, allocator, __shar...
+#include <string>                  // for string
+namespace caosdb::transaction {
+using caosdb::entity::Entity;
+using caosdb::entity::v1alpha1::FileDownloadResponse;
+using caosdb::entity::v1alpha1::FileUploadResponse;
+using caosdb::entity::v1alpha1::RegisterFileDownloadResponse;
+using caosdb::entity::v1alpha1::RegisterFileUploadResponse;
+using caosdb::entity::v1alpha1::RegistrationStatus;
+using caosdb::entity::v1alpha1::TransmissionStatus;
+
+class test_file_transmission : public ::testing::Test {
+protected:
+  void SetUp() override {}
+
+  void TearDown() override {
+    // TODO(tf): delete all created entities
+  }
+};
+
+TEST_F(test_file_transmission, register_file_upload) {
+  const auto &connection =
+    caosdb::connection::ConnectionManager::GetDefaultConnection();
+
+  auto transaction(connection->CreateTransaction());
+  RegisterFileUploadResponse response;
+  EXPECT_EQ(response.status(),
+            RegistrationStatus::REGISTRATION_STATUS_UNSPECIFIED);
+
+  transaction->RegisterUploadFile(&response);
+
+  EXPECT_EQ(response.status(),
+            RegistrationStatus::REGISTRATION_STATUS_ACCEPTED);
+  EXPECT_FALSE(response.registration_id().empty());
+}
+
+TEST_F(test_file_transmission, file_upload) {
+  const auto &connection =
+    caosdb::connection::ConnectionManager::GetDefaultConnection();
+
+  auto transaction(connection->CreateTransaction());
+  RegisterFileUploadResponse registration_response;
+
+  transaction->RegisterUploadFile(&registration_response);
+  ASSERT_EQ(registration_response.status(),
+            RegistrationStatus::REGISTRATION_STATUS_ACCEPTED);
+  auto registration_id = registration_response.registration_id();
+
+  FileUploadResponse upload_response;
+  transaction->UploadFile(&upload_response, registration_id);
+
+  EXPECT_EQ(upload_response.status(),
+            TransmissionStatus::TRANSMISSION_STATUS_GO_ON);
+}
+
+TEST_F(test_file_transmission, file_insertion) {
+  const auto &connection =
+    caosdb::connection::ConnectionManager::GetDefaultConnection();
+
+  auto transaction(connection->CreateTransaction());
+  RegisterFileUploadResponse registration_response;
+
+  transaction->RegisterUploadFile(&registration_response);
+  ASSERT_EQ(registration_response.status(),
+            RegistrationStatus::REGISTRATION_STATUS_ACCEPTED);
+  auto registration_id = registration_response.registration_id();
+
+  FileUploadResponse upload_response;
+  transaction->UploadFile(&upload_response, registration_id);
+
+  Entity file_entity;
+  file_entity.SetRole("File");
+  file_entity.SetFileTransmissionId(registration_id, "test.txt");
+  file_entity.SetFilePath("test.txt");
+
+  transaction->InsertEntity(&file_entity);
+  transaction->Execute();
+
+  auto cleanup_transaction(connection->CreateTransaction());
+  cleanup_transaction->DeleteById(transaction->GetResultSet().At(0).GetId());
+  cleanup_transaction->Execute();
+}
+
+TEST_F(test_file_transmission, file_download) {
+  const auto &connection =
+    caosdb::connection::ConnectionManager::GetDefaultConnection();
+
+  auto upload_transaction(connection->CreateTransaction());
+  RegisterFileUploadResponse upload_registration_response;
+
+  upload_transaction->RegisterUploadFile(&upload_registration_response);
+  ASSERT_EQ(upload_registration_response.status(),
+            RegistrationStatus::REGISTRATION_STATUS_ACCEPTED);
+  auto registration_id = upload_registration_response.registration_id();
+
+  FileUploadResponse upload_response;
+  upload_transaction->UploadFile(&upload_response, registration_id);
+
+  Entity file_entity;
+  file_entity.SetRole("File");
+  file_entity.SetFileTransmissionId(registration_id, "test.txt");
+  file_entity.SetFilePath("test.txt");
+
+  upload_transaction->InsertEntity(&file_entity);
+  upload_transaction->Execute();
+
+  // Download by entity_id
+  auto download_transaction(connection->CreateTransaction());
+  RegisterFileDownloadResponse download_registration_response;
+  RegisterFileDownloadRequest download_registration_request;
+  download_registration_request.add_files()->set_entity_id(
+    upload_transaction->GetResultSet().At(0).GetId());
+  download_transaction->RegisterDownloadFile(download_registration_request,
+                                             &download_registration_response);
+  ASSERT_EQ(download_registration_response.status(),
+            RegistrationStatus::REGISTRATION_STATUS_ACCEPTED);
+
+  FileDownloadResponse download_response;
+  download_transaction->DownloadFile(&download_response,
+                                     download_registration_response);
+
+  EXPECT_EQ(download_response.chunk().data(), "this is some data");
+
+  // CLEANUP
+  auto cleanup_transaction(connection->CreateTransaction());
+  cleanup_transaction->DeleteById(
+    upload_transaction->GetResultSet().At(0).GetId());
+  cleanup_transaction->Execute();
+}
+
+} // namespace caosdb::transaction
diff --git a/test/test_transaction.cpp b/test/test_transaction.cpp
index b1879b369d8f0fcfa864155b7df56553358153ab..40ccc9dd353149600195e5ce47023a6e881f2dda 100644
--- a/test/test_transaction.cpp
+++ b/test/test_transaction.cpp
@@ -18,19 +18,25 @@
  * along with this program. If not, see <https://www.gnu.org/licenses/>.
  *
  */
-#include "caosdb/connection.h"         // for Connection, ConnectionManager
+#include "caosdb/connection.h" // for Connection, ConnectionManager
 #include "caosdb/data_type.h" // for AtomicDataType
-#include "caosdb/entity.h"             // for Entity, Messages, Message
+#include "caosdb/entity.h"     // for Entity, Messages, Message
+#include "caosdb/file_transmission/FileWriter.h" // for FileWriter
 #include "caosdb/message_code.h"       // for ENTITY_DOES_NOT_EXIST, Messag...
 #include "caosdb/status_code.h"        // for SUCCESS, StatusCode
-#include "caosdb/transaction.h"        // for Entity, Transaction, UniqueRe...
+#include "caosdb/transaction.h"        // for Entity, Transaction,...
 #include "caosdb/transaction_status.h" // for TransactionStatus, StatusCode
-#include "gtest/gtest-message.h"       // for Message
-#include "gtest/gtest-test-part.h"     // for TestPartResult, SuiteApiResolver
-#include "gtest/gtest_pred_impl.h"     // for Test, EXPECT_EQ, AssertionResult
-#include <memory>                      // for unique_ptr, allocator, __shar...
-#include <string>                      // for string
-#include <vector>                      // for vector
+#include <boost/filesystem/operations.hpp>  // for remove
+#include <boost/filesystem/path.hpp>        // for path
+#include <boost/filesystem/path_traits.hpp> // for filesystem
+#include <gtest/gtest-message.h>            // for Message
+#include <gtest/gtest-test-part.h> // for TestPartResult, SuiteApiResolver
+#include <gtest/gtest_pred_impl.h> // for Test, EXPECT_EQ, AssertionResult
+#include <memory>                  // for unique_ptr, allocator, __shar...
+#include <string>                  // for string
+#include <vector>                  // for vector
+
+namespace fs = boost::filesystem;
 namespace caosdb::transaction {
 using caosdb::entity::Importance;
 using caosdb::entity::Role;
@@ -42,15 +48,30 @@ using caosdb::entity::Property;
 
 class test_transaction : public ::testing::Test {
 protected:
-  void SetUp() override {}
+  fs::path test_upload_file_1;
+  fs::path test_download_file_1;
+
+  void SetUp() override {
+    test_upload_file_1 = fs::path("test_upload_file_1_delete_me.dat");
+    test_download_file_1 = fs::path("test_download_file_1_delete_me.dat");
+
+    FileWriter writer(test_upload_file_1);
+    std::string buffer(1024, 'c');
+    for (int i = 0; i < 8; i++) {
+      writer.write(buffer);
+    }
+  }
 
   void TearDown() override {
+    fs::remove(test_upload_file_1);
+    fs::remove(test_download_file_1);
+
     const auto &connection =
       caosdb::connection::ConnectionManager::GetDefaultConnection();
     auto query_transaction(connection->CreateTransaction());
     query_transaction->Query("FIND ENTITY WITH id > 99");
     query_transaction->Execute();
-    if (query_transaction->GetResultSet().Size() > 0) {
+    if (query_transaction->GetResultSet().size() > 0) {
       auto delete_transaction(connection->CreateTransaction());
       for (const Entity &entity : query_transaction->GetResultSet()) {
         delete_transaction->DeleteById(entity.GetId());
@@ -60,6 +81,30 @@ protected:
   }
 };
 
+TEST_F(test_transaction, DISABLED_retrieve_manufacturer_by_id) {
+  const auto &connection =
+    caosdb::connection::ConnectionManager::GetDefaultConnection();
+
+  const auto *id = "107";
+  const auto *role = "RecordType";
+  const auto *name = "Manufacturer";
+  const auto *description = "A generic manufacturer of all kinds of products";
+  const auto *version = "0bea8f7b17f0130fa5701a6c3849b9f8bfa0651b";
+
+  auto transaction(connection->CreateTransaction());
+  transaction->RetrieveById(id);
+  transaction->Execute();
+
+  const auto &result_set = transaction->GetResultSet();
+
+  const auto &entity = result_set.at(0);
+  EXPECT_EQ(id, entity.GetId());
+  EXPECT_EQ(name, entity.GetName());
+  EXPECT_EQ(role, entity.GetRole());
+  EXPECT_EQ(description, entity.GetDescription());
+  EXPECT_EQ(version, entity.GetVersionId());
+}
+
 TEST_F(test_transaction, retrieve_non_existing) {
   const auto &connection =
     caosdb::connection::ConnectionManager::GetDefaultConnection();
@@ -74,14 +119,13 @@ TEST_F(test_transaction, retrieve_non_existing) {
   EXPECT_EQ(status.GetCode(), TransactionStatus::TRANSACTION_ERROR().GetCode());
   ASSERT_EQ(status.GetCode(), StatusCode::GENERIC_TRANSACTION_ERROR);
 
-  const auto &result_set =
-    dynamic_cast<const UniqueResult &>(transaction->GetResultSet());
+  const auto &result_set = transaction->GetResultSet();
 
-  const auto &entity = result_set.GetEntity();
+  const auto &entity = result_set.at(0);
   EXPECT_EQ(id, entity.GetId());
   EXPECT_TRUE(entity.HasErrors());
-  ASSERT_EQ(entity.GetErrors().Size(), 1);
-  EXPECT_EQ(entity.GetErrors().At(0).GetCode(),
+  ASSERT_EQ(entity.GetErrors().size(), 1);
+  EXPECT_EQ(entity.GetErrors().at(0).GetCode(),
             MessageCode::ENTITY_DOES_NOT_EXIST);
 }
 
@@ -102,16 +146,15 @@ TEST_F(test_transaction, insert_without_delete) {
   ASSERT_TRUE(insert_status.IsTerminated());
   ASSERT_FALSE(insert_status.IsError());
 
-  const auto &insert_result_set =
-    dynamic_cast<const UniqueResult &>(insert_transaction->GetResultSet());
+  const auto &insert_result_set = insert_transaction->GetResultSet();
 
-  const auto &new_entity = insert_result_set.GetEntity();
+  const auto &new_entity = insert_result_set.at(0);
   EXPECT_FALSE(new_entity.GetId().empty());
   EXPECT_FALSE(new_entity.HasErrors());
   // Should have a warning since it has no properties
   EXPECT_TRUE(new_entity.HasWarnings());
-  EXPECT_EQ(new_entity.GetWarnings().Size(), 1);
-  EXPECT_EQ(new_entity.GetWarnings().At(0).GetCode(),
+  EXPECT_EQ(new_entity.GetWarnings().size(), 1);
+  EXPECT_EQ(new_entity.GetWarnings().at(0).GetCode(),
             MessageCode::ENTITY_HAS_NO_PROPERTIES);
 }
 
@@ -132,16 +175,15 @@ TEST_F(test_transaction, insert_delete) {
   ASSERT_TRUE(insert_status.IsTerminated());
   ASSERT_FALSE(insert_status.IsError());
 
-  const auto &insert_result_set =
-    dynamic_cast<const UniqueResult &>(insert_transaction->GetResultSet());
+  const auto &insert_result_set = insert_transaction->GetResultSet();
 
-  const auto &new_entity = insert_result_set.GetEntity();
+  const auto &new_entity = insert_result_set.at(0);
   EXPECT_FALSE(new_entity.GetId().empty());
   EXPECT_FALSE(new_entity.HasErrors());
   // Should have a warning since it has no properties
   EXPECT_TRUE(new_entity.HasWarnings());
-  EXPECT_EQ(new_entity.GetWarnings().Size(), 1);
-  EXPECT_EQ(new_entity.GetWarnings().At(0).GetCode(),
+  EXPECT_EQ(new_entity.GetWarnings().size(), 1);
+  EXPECT_EQ(new_entity.GetWarnings().at(0).GetCode(),
             MessageCode::ENTITY_HAS_NO_PROPERTIES);
 
   auto delete_transaction(connection->CreateTransaction());
@@ -154,10 +196,9 @@ TEST_F(test_transaction, insert_delete) {
   ASSERT_TRUE(delete_status.IsTerminated());
   ASSERT_FALSE(delete_status.IsError());
 
-  const auto &delete_result_set =
-    dynamic_cast<const UniqueResult &>(delete_transaction->GetResultSet());
+  const auto &delete_result_set = delete_transaction->GetResultSet();
 
-  const auto &deleted_entity = delete_result_set.GetEntity();
+  const auto &deleted_entity = delete_result_set.at(0);
   EXPECT_EQ(deleted_entity.GetId(), new_entity.GetId());
   EXPECT_FALSE(deleted_entity.HasErrors());
 }
@@ -179,10 +220,9 @@ TEST_F(test_transaction, insert_delete_with_parent) {
   ASSERT_TRUE(insert_status.IsTerminated());
   ASSERT_FALSE(insert_status.IsError());
 
-  const auto &insert_result_set =
-    dynamic_cast<const UniqueResult &>(insert_transaction->GetResultSet());
+  const auto &insert_result_set = insert_transaction->GetResultSet();
 
-  const auto &inserted_rt = insert_result_set.GetEntity();
+  const auto &inserted_rt = insert_result_set.at(0);
 
   Entity rec;
   rec.SetRole(Role::RECORD);
@@ -202,10 +242,9 @@ TEST_F(test_transaction, insert_delete_with_parent) {
   ASSERT_TRUE(rec_insert_status.IsTerminated());
   ASSERT_FALSE(rec_insert_status.IsError());
 
-  const auto &rec_result_set =
-    dynamic_cast<const UniqueResult &>(rec_transaction->GetResultSet());
+  const auto &rec_result_set = rec_transaction->GetResultSet();
 
-  const auto &inserted_rec = rec_result_set.GetEntity();
+  const auto &inserted_rec = rec_result_set.at(0);
 
   EXPECT_FALSE(inserted_rec.GetId().empty());
 
@@ -219,14 +258,13 @@ TEST_F(test_transaction, insert_delete_with_parent) {
   ASSERT_TRUE(rec_retrieve_status.IsTerminated());
   ASSERT_FALSE(rec_retrieve_status.IsError());
 
-  const auto &retrieve_result_set =
-    dynamic_cast<const UniqueResult &>(retrieve_transaction->GetResultSet());
-  const auto &retrieved_rec = retrieve_result_set.GetEntity();
+  const auto &retrieve_result_set = retrieve_transaction->GetResultSet();
+  const auto &retrieved_rec = retrieve_result_set.at(0);
 
   EXPECT_EQ(retrieved_rec.GetName(), rec.GetName());
-  EXPECT_EQ(retrieved_rec.GetParents().Size(), 1);
-  EXPECT_EQ(retrieved_rec.GetParents().At(0).GetId(), inserted_rt.GetId());
-  EXPECT_EQ(retrieved_rec.GetParents().At(0).GetName(), rt.GetName());
+  EXPECT_EQ(retrieved_rec.GetParents().size(), 1);
+  EXPECT_EQ(retrieved_rec.GetParents().at(0).GetId(), inserted_rt.GetId());
+  EXPECT_EQ(retrieved_rec.GetParents().at(0).GetName(), rt.GetName());
 
   auto rec_deletion(connection->CreateTransaction());
 
@@ -268,10 +306,9 @@ TEST_F(test_transaction, insert_delete_with_property) {
   ASSERT_TRUE(prop_insert_status.IsTerminated());
   ASSERT_FALSE(prop_insert_status.IsError());
 
-  const auto &prop_result_set =
-    dynamic_cast<const UniqueResult &>(prop_insertion->GetResultSet());
+  const auto &prop_result_set = prop_insertion->GetResultSet();
 
-  const auto &inserted_prop = prop_result_set.GetEntity();
+  const auto &inserted_prop = prop_result_set.at(0);
   EXPECT_FALSE(inserted_prop.GetId().empty());
 
   // create and insert record type with the above property
@@ -294,10 +331,9 @@ TEST_F(test_transaction, insert_delete_with_property) {
   ASSERT_TRUE(rt_insert_status.IsTerminated());
   ASSERT_FALSE(rt_insert_status.IsError());
 
-  const auto &rt_result_set =
-    dynamic_cast<const UniqueResult &>(rt_insertion->GetResultSet());
+  const auto &rt_result_set = rt_insertion->GetResultSet();
 
-  const auto &inserted_rt = rt_result_set.GetEntity();
+  const auto &inserted_rt = rt_result_set.at(0);
   EXPECT_FALSE(inserted_rt.GetId().empty());
 
   // retrieve inserted rt for testing
@@ -309,15 +345,14 @@ TEST_F(test_transaction, insert_delete_with_property) {
   ASSERT_TRUE(rt_retrieve_status.IsTerminated());
   ASSERT_FALSE(rt_retrieve_status.IsError());
 
-  const auto &rt_retrieve_results =
-    dynamic_cast<const UniqueResult &>(rt_retrieval->GetResultSet());
+  const auto &rt_retrieve_results = rt_retrieval->GetResultSet();
 
-  const auto &retrieved_rt = rt_retrieve_results.GetEntity();
+  const auto &retrieved_rt = rt_retrieve_results.at(0);
   EXPECT_EQ(inserted_rt.GetId(), retrieved_rt.GetId());
   EXPECT_EQ(rt.GetName(), retrieved_rt.GetName());
-  EXPECT_EQ(retrieved_rt.GetProperties().Size(), 1);
+  EXPECT_EQ(retrieved_rt.GetProperties().size(), 1);
 
-  const auto &retrieved_prop_rt = retrieved_rt.GetProperties().At(0);
+  const auto &retrieved_prop_rt = retrieved_rt.GetProperties().at(0);
   EXPECT_EQ(retrieved_prop_rt.GetName(), prop_ent.GetName());
   EXPECT_EQ(retrieved_prop_rt.GetId(), inserted_prop.GetId());
   EXPECT_EQ(retrieved_prop_rt.GetDataType(), prop_ent.GetDataType());
@@ -349,10 +384,9 @@ TEST_F(test_transaction, insert_delete_with_property) {
   ASSERT_TRUE(rec_insert_status.IsTerminated());
   ASSERT_FALSE(rec_insert_status.IsError());
 
-  const auto &rec_result_set =
-    dynamic_cast<const UniqueResult &>(rec_insertion->GetResultSet());
+  const auto &rec_result_set = rec_insertion->GetResultSet();
 
-  const auto &inserted_rec = rec_result_set.GetEntity();
+  const auto &inserted_rec = rec_result_set.at(0);
   EXPECT_FALSE(inserted_rec.GetId().empty());
 
   // Retrieve the record and verify paretn and property
@@ -364,20 +398,19 @@ TEST_F(test_transaction, insert_delete_with_property) {
   ASSERT_TRUE(rec_retrieve_status.IsTerminated());
   ASSERT_FALSE(rec_retrieve_status.IsError());
 
-  const auto &rec_retrieve_results =
-    dynamic_cast<const UniqueResult &>(rec_retrieval->GetResultSet());
+  const auto &rec_retrieve_results = rec_retrieval->GetResultSet();
 
-  const auto &retrieved_rec = rec_retrieve_results.GetEntity();
+  const auto &retrieved_rec = rec_retrieve_results.at(0);
   EXPECT_EQ(rec.GetName(), retrieved_rec.GetName());
   EXPECT_EQ(inserted_rec.GetId(), retrieved_rec.GetId());
-  EXPECT_EQ(retrieved_rec.GetParents().Size(), 1);
-  EXPECT_EQ(retrieved_rec.GetProperties().Size(), 1);
+  EXPECT_EQ(retrieved_rec.GetParents().size(), 1);
+  EXPECT_EQ(retrieved_rec.GetProperties().size(), 1);
 
-  const auto &retrieved_parent_rec = retrieved_rec.GetParents().At(0);
+  const auto &retrieved_parent_rec = retrieved_rec.GetParents().at(0);
   EXPECT_EQ(retrieved_parent_rec.GetName(), rt.GetName());
   EXPECT_EQ(retrieved_parent_rec.GetId(), inserted_rt.GetId());
 
-  const auto &retrieved_prop_rec = retrieved_rec.GetProperties().At(0);
+  const auto &retrieved_prop_rec = retrieved_rec.GetProperties().at(0);
   EXPECT_EQ(retrieved_prop_rec.GetName(), prop_ent.GetName());
   EXPECT_EQ(retrieved_prop_rec.GetId(), inserted_prop.GetId());
   EXPECT_EQ(retrieved_prop_rec.GetDataType(), prop_ent.GetDataType());
@@ -397,18 +430,18 @@ TEST_F(test_transaction, test_multi_retrieve) {
   auto status = transaction->WaitForIt();
 
   ASSERT_TRUE(status.IsTerminated());
-  ASSERT_FALSE(status.IsError());
+  ASSERT_TRUE(status.IsError());
 
   const auto &result_set = transaction->GetResultSet();
 
-  EXPECT_EQ(result_set.Size(), 3);
-  EXPECT_EQ(result_set.At(1).GetId(), "21");
-  EXPECT_EQ(result_set.At(1).GetName(), "unit");
-  EXPECT_FALSE(result_set.At(1).HasErrors());
+  EXPECT_EQ(result_set.size(), 3);
+  EXPECT_EQ(result_set.at(1).GetId(), "21");
+  EXPECT_EQ(result_set.at(1).GetName(), "unit");
+  EXPECT_FALSE(result_set.at(1).HasErrors());
 
-  EXPECT_EQ(result_set.At(2).GetId(), "22");
-  EXPECT_TRUE(result_set.At(2).HasErrors());
-  EXPECT_EQ(result_set.At(2).GetErrors().At(0).GetCode(),
+  EXPECT_EQ(result_set.at(2).GetId(), "22");
+  EXPECT_TRUE(result_set.at(2).HasErrors());
+  EXPECT_EQ(result_set.at(2).GetErrors().at(0).GetCode(),
             MessageCode::ENTITY_DOES_NOT_EXIST);
 }
 
@@ -430,10 +463,9 @@ TEST_F(test_transaction, insert_update_delete) {
   ASSERT_TRUE(insert_status.IsTerminated());
   ASSERT_FALSE(insert_status.IsError());
 
-  const auto &insert_result_set =
-    dynamic_cast<const UniqueResult &>(insert_transaction->GetResultSet());
+  const auto &insert_result_set = insert_transaction->GetResultSet();
 
-  const auto &new_entity = insert_result_set.GetEntity();
+  const auto &new_entity = insert_result_set.at(0);
   EXPECT_FALSE(new_entity.GetId().empty());
   EXPECT_FALSE(new_entity.HasErrors());
 
@@ -444,7 +476,7 @@ TEST_F(test_transaction, insert_update_delete) {
 
   // UPDATE
   auto update_transaction(connection->CreateTransaction());
-  auto update_entity(retrieve_transaction->GetResultSet().At(0));
+  auto update_entity(retrieve_transaction->GetResultSet().at(0));
   update_entity.SetName("RT1-Update");
 
   update_transaction->UpdateEntity(&update_entity);
@@ -454,8 +486,8 @@ TEST_F(test_transaction, insert_update_delete) {
   ASSERT_TRUE(update_status.IsTerminated());
   ASSERT_FALSE(update_status.IsError());
 
-  EXPECT_EQ(update_transaction->GetResultSet().Size(), 1);
-  const auto &updated_entity = update_transaction->GetResultSet().At(0);
+  EXPECT_EQ(update_transaction->GetResultSet().size(), 1);
+  const auto &updated_entity = update_transaction->GetResultSet().at(0);
 
   EXPECT_EQ(updated_entity.GetId(), new_entity.GetId());
   EXPECT_FALSE(updated_entity.HasErrors());
@@ -471,10 +503,9 @@ TEST_F(test_transaction, insert_update_delete) {
   ASSERT_TRUE(delete_status.IsTerminated());
   ASSERT_FALSE(delete_status.IsError());
 
-  const auto &delete_result_set =
-    dynamic_cast<const UniqueResult &>(delete_transaction->GetResultSet());
+  const auto &delete_result_set = delete_transaction->GetResultSet();
 
-  const auto &deleted_entity = delete_result_set.GetEntity();
+  const auto &deleted_entity = delete_result_set.at(0);
   EXPECT_EQ(deleted_entity.GetId(), new_entity.GetId());
   EXPECT_FALSE(deleted_entity.HasErrors());
 }
@@ -496,18 +527,17 @@ TEST_F(test_transaction, test_query) {
   ASSERT_TRUE(insert_status.IsTerminated());
   ASSERT_FALSE(insert_status.IsError());
 
-  const auto &insert_result_set =
-    dynamic_cast<const UniqueResult &>(insert_transaction->GetResultSet());
+  const auto &insert_result_set = insert_transaction->GetResultSet();
 
-  const auto &new_entity = insert_result_set.GetEntity();
+  const auto &new_entity = insert_result_set.at(0);
   EXPECT_FALSE(new_entity.GetId().empty());
   EXPECT_FALSE(new_entity.HasErrors());
 
   auto query_transaction(connection->CreateTransaction());
   query_transaction->Query("FIND ENTITY WITH id = " + new_entity.GetId());
   query_transaction->Execute();
-  EXPECT_EQ(query_transaction->GetResultSet().Size(), 1);
-  EXPECT_EQ(query_transaction->GetResultSet().At(0).GetId(),
+  EXPECT_EQ(query_transaction->GetResultSet().size(), 1);
+  EXPECT_EQ(query_transaction->GetResultSet().at(0).GetId(),
             new_entity.GetId());
   // No count query, so no count result should be present
   EXPECT_TRUE((query_transaction->GetCountResult() < 0));
@@ -516,7 +546,7 @@ TEST_F(test_transaction, test_query) {
   count_query_trans->Query("COUNT ENTITY WITH id = " + new_entity.GetId());
   count_query_trans->Execute();
   // No result set in a count query
-  EXPECT_EQ(count_query_trans->GetResultSet().Size(), 0);
+  EXPECT_EQ(count_query_trans->GetResultSet().size(), 0);
   EXPECT_EQ(count_query_trans->GetCountResult(), 1);
 }
 
@@ -538,10 +568,9 @@ TEST_F(test_transaction, test_query_with_retrieve) {
   ASSERT_TRUE(insert_rt1_status.IsTerminated());
   ASSERT_FALSE(insert_rt1_status.IsError());
 
-  const auto &insert_rt1_results =
-    dynamic_cast<const UniqueResult &>(insert_rt1_transaction->GetResultSet());
+  const auto &insert_rt1_results = insert_rt1_transaction->GetResultSet();
 
-  const auto &inserted_rt1 = insert_rt1_results.GetEntity();
+  const auto &inserted_rt1 = insert_rt1_results.at(0);
   EXPECT_FALSE(inserted_rt1.GetId().empty());
   EXPECT_FALSE(inserted_rt1.HasErrors());
 
@@ -559,10 +588,9 @@ TEST_F(test_transaction, test_query_with_retrieve) {
   ASSERT_TRUE(insert_rt2_status.IsTerminated());
   ASSERT_FALSE(insert_rt2_status.IsError());
 
-  const auto &insert_rt2_results =
-    dynamic_cast<const UniqueResult &>(insert_rt2_transaction->GetResultSet());
+  const auto &insert_rt2_results = insert_rt2_transaction->GetResultSet();
 
-  const auto &inserted_rt2 = insert_rt2_results.GetEntity();
+  const auto &inserted_rt2 = insert_rt2_results.at(0);
   EXPECT_FALSE(inserted_rt2.GetId().empty());
   EXPECT_FALSE(inserted_rt2.HasErrors());
 
@@ -580,10 +608,9 @@ TEST_F(test_transaction, test_query_with_retrieve) {
   ASSERT_TRUE(insert_rt3_status.IsTerminated());
   ASSERT_FALSE(insert_rt3_status.IsError());
 
-  const auto &insert_rt3_results =
-    dynamic_cast<const UniqueResult &>(insert_rt3_transaction->GetResultSet());
+  const auto &insert_rt3_results = insert_rt3_transaction->GetResultSet();
 
-  const auto &inserted_rt3 = insert_rt3_results.GetEntity();
+  const auto &inserted_rt3 = insert_rt3_results.at(0);
   EXPECT_FALSE(inserted_rt3.GetId().empty());
   EXPECT_FALSE(inserted_rt3.HasErrors());
 
@@ -598,7 +625,7 @@ TEST_F(test_transaction, test_query_with_retrieve) {
   ASSERT_FALSE(find_status.IsError());
 
   const auto &find_results = find_transaction->GetResultSet();
-  EXPECT_EQ(find_results.Size(), 3);
+  EXPECT_EQ(find_results.size(), 3);
 
   // only retrieve rt1 and rt2 by id
   const std::vector<std::string> ids = {inserted_rt1.GetId(),
@@ -616,7 +643,7 @@ TEST_F(test_transaction, test_query_with_retrieve) {
   ASSERT_FALSE(find_and_retrieve_status.IsError());
 
   const auto &result_set_a = find_and_retrieve->GetResultSet();
-  EXPECT_EQ(result_set_a.Size(), 3);
+  EXPECT_EQ(result_set_a.size(), 3);
 
   // retrieve rt1 and rt2 by ID and count all TestRTs
   auto count_and_retrieve(connection->CreateTransaction());
@@ -631,8 +658,68 @@ TEST_F(test_transaction, test_query_with_retrieve) {
 
   const auto &result_set_b = count_and_retrieve->GetResultSet();
   // TODO(fspreck) Re-enable once we implemented this
-  // EXPECT_EQ(result_set_b.Size(), 2);
+  // EXPECT_EQ(result_set_b.size(), 2);
   EXPECT_EQ(count_and_retrieve->GetCountResult(), 3);
 }
 
+TEST_F(test_transaction, test_file_upload) {
+  const auto &connection =
+    caosdb::connection::ConnectionManager::GetDefaultConnection();
+
+  Entity file;
+  file.SetRole("File");
+  file.SetFilePath("test.txt");
+  file.SetLocalPath(test_upload_file_1);
+
+  auto insert_transaction(connection->CreateTransaction());
+  insert_transaction->InsertEntity(&file);
+  insert_transaction->ExecuteAsynchronously();
+
+  auto insert_status = insert_transaction->WaitForIt();
+
+  ASSERT_TRUE(insert_status.IsTerminated());
+  EXPECT_EQ(insert_status.GetCode(), StatusCode::SUCCESS);
+
+  const auto &insert_results = insert_transaction->GetResultSet();
+
+  const auto &inserted_file = insert_results.at(0);
+  EXPECT_FALSE(inserted_file.GetId().empty());
+  EXPECT_FALSE(inserted_file.HasErrors());
+}
+
+TEST_F(test_transaction, test_file_download) {
+  const auto &connection =
+    caosdb::connection::ConnectionManager::GetDefaultConnection();
+
+  Entity file;
+  file.SetRole("File");
+  file.SetFilePath("test.txt");
+  file.SetLocalPath(test_upload_file_1);
+
+  auto insert_transaction(connection->CreateTransaction());
+  insert_transaction->InsertEntity(&file);
+  insert_transaction->Execute();
+
+  const auto &insert_results = insert_transaction->GetResultSet();
+
+  const auto &inserted_file = insert_results.at(0);
+  ASSERT_FALSE(inserted_file.GetId().empty());
+  ASSERT_FALSE(inserted_file.HasErrors());
+
+  auto download_transaction(connection->CreateTransaction());
+  download_transaction->RetrieveAndDownloadFilesById(
+    inserted_file.GetId(), test_download_file_1.string());
+  download_transaction->ExecuteAsynchronously();
+  download_transaction->WaitForIt();
+
+  const auto &download_results = download_transaction->GetResultSet();
+  ASSERT_EQ(download_results.size(), 1);
+
+  const auto &downloaded_file = download_results.at(0);
+  ASSERT_FALSE(downloaded_file.GetId().empty());
+  ASSERT_FALSE(downloaded_file.HasErrors());
+  EXPECT_EQ(downloaded_file.GetLocalPath().string(),
+            test_download_file_1.string());
+}
+
 } // namespace caosdb::transaction