diff --git a/services/lib/src/client-base-reactors/ClientBidiReactorBase.h b/services/lib/src/client-base-reactors/ClientBidiReactorBase.h
index 264653834..d69093b49 100644
--- a/services/lib/src/client-base-reactors/ClientBidiReactorBase.h
+++ b/services/lib/src/client-base-reactors/ClientBidiReactorBase.h
@@ -1,128 +1,143 @@
 #pragma once
 
 #include "BaseReactor.h"
 
 #include <grpcpp/grpcpp.h>
 
 namespace comm {
 namespace network {
 namespace reactor {
 
+// This is how this type of reactor works:
+// - repeat:
+//   - write a request to the server
+//   - read a response from the server
+// - terminate the connection
 template <class Request, class Response>
 class ClientBidiReactorBase : public grpc::ClientBidiReactor<Request, Response>,
                               public BaseReactor {
   std::shared_ptr<ReactorStatusHolder> statusHolder;
   std::shared_ptr<Response> response = nullptr;
   void nextWrite();
 
 protected:
   Request request;
 
 public:
   grpc::ClientContext context;
 
+  // this should be called explicitly right after the reactor is created
   void start();
 
+  // these methods come from the BaseReactor(go there for more information)
   void validate() override{};
   void doneCallback() override{};
   void terminateCallback() override{};
+  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // these methods come from gRPC
+  // https://github.com/grpc/grpc/blob/v1.39.x/include/grpcpp/impl/codegen/client_callback.h#L237
   void OnWriteDone(bool ok) override;
   void OnReadDone(bool ok) override;
   void terminate(const grpc::Status &status) override;
   void OnDone(const grpc::Status &status) override;
-  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // - argument request - request that's about to be prepared for the next cycle
+  // - argument previousResponse - response received during the previous cycle
+  // (may be nullptr)
+  // - returns status - if the connection is about to be
+  // continued, nullptr should be returned. Any other returned value will
+  // terminate the connection with a given status
   virtual std::unique_ptr<grpc::Status> prepareRequest(
       Request &request,
       std::shared_ptr<Response> previousResponse) = 0;
 };
 
 template <class Request, class Response>
 void ClientBidiReactorBase<Request, Response>::nextWrite() {
   this->request = Request();
   try {
     std::unique_ptr<grpc::Status> status =
         this->prepareRequest(this->request, this->response);
     if (status != nullptr) {
       this->terminate(*status);
       return;
     }
   } catch (std::runtime_error &e) {
     this->terminate(grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
     return;
   }
   this->StartWrite(&this->request);
 }
 
 template <class Request, class Response>
 void ClientBidiReactorBase<Request, Response>::start() {
   if (this->statusHolder->state != ReactorState::NONE) {
     return;
   }
   this->statusHolder->state = ReactorState::RUNNING;
   this->nextWrite();
   this->StartCall();
 }
 
 template <class Request, class Response>
 void ClientBidiReactorBase<Request, Response>::OnWriteDone(bool ok) {
   if (this->response == nullptr) {
     this->response = std::make_shared<Response>();
   }
   this->StartRead(&(*this->response));
 }
 
 template <class Request, class Response>
 void ClientBidiReactorBase<Request, Response>::OnReadDone(bool ok) {
   if (!ok) {
     // Ending a connection on the other side results in the `ok` flag being set
     // to false. It makes it impossible to detect a failure based just on the
     // flag. We should manually check if the data we received is valid
     this->terminate(grpc::Status::OK);
     return;
   }
   this->nextWrite();
 }
 
 template <class Request, class Response>
 void ClientBidiReactorBase<Request, Response>::terminate(
     const grpc::Status &status) {
   if (this->statusHolder->getStatus().ok()) {
     this->statusHolder->setStatus(status);
   }
   if (!this->statusHolder->getStatus().ok()) {
     std::cout << "error: " << this->statusHolder->getStatus().error_message()
               << std::endl;
   }
   if (this->statusHolder->state != ReactorState::RUNNING) {
     return;
   }
   this->terminateCallback();
   try {
     this->validate();
   } catch (std::runtime_error &e) {
     this->statusHolder->setStatus(
         grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
   }
   this->StartWritesDone();
   this->statusHolder->state = ReactorState::TERMINATED;
 }
 
 template <class Request, class Response>
 void ClientBidiReactorBase<Request, Response>::OnDone(
     const grpc::Status &status) {
   this->statusHolder->state = ReactorState::DONE;
   this->terminate(status);
   this->doneCallback();
 }
 
 template <class Request, class Response>
 std::shared_ptr<ReactorStatusHolder>
 ClientBidiReactorBase<Request, Response>::getStatusHolder() {
   return this->statusHolder;
 }
 
 } // namespace reactor
 } // namespace network
 } // namespace comm
diff --git a/services/lib/src/client-base-reactors/ClientReadReactorBase.h b/services/lib/src/client-base-reactors/ClientReadReactorBase.h
index a7529611e..ee3895b5c 100644
--- a/services/lib/src/client-base-reactors/ClientReadReactorBase.h
+++ b/services/lib/src/client-base-reactors/ClientReadReactorBase.h
@@ -1,107 +1,120 @@
 #pragma once
 
 #include "BaseReactor.h"
 
 #include <grpcpp/grpcpp.h>
 
 namespace comm {
 namespace network {
 namespace reactor {
 
+// This is how this type of reactor works:
+// - send a request to the server
+// - read N responses from the server
+// - terminate the connection
 template <class Request, class Response>
 class ClientReadReactorBase : public grpc::ClientReadReactor<Response>,
                               public BaseReactor {
   std::shared_ptr<ReactorStatusHolder> statusHolder;
   Response response;
 
 public:
   Request request;
   grpc::ClientContext context;
 
+  // this should be called explicitly right after the reactor is created
   void start();
 
+  // these methods come from the BaseReactor(go there for more information)
   void validate() override{};
   void doneCallback() override{};
   void terminateCallback() override{};
+  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // these methods come from gRPC
+  // https://github.com/grpc/grpc/blob/v1.39.x/include/grpcpp/impl/codegen/client_callback.h#L237
   void OnReadDone(bool ok) override;
   void terminate(const grpc::Status &status) override;
   void OnDone(const grpc::Status &status) override;
-  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // - argument response - response from the server that was read during the
+  // current cycle
+  // - returns status - if the connection is about to be
+  // continued, nullptr should be returned. Any other returned value will
+  // terminate the connection with a given status
   virtual std::unique_ptr<grpc::Status> readResponse(Response &response) = 0;
 };
 
 template <class Request, class Response>
 void ClientReadReactorBase<Request, Response>::start() {
   if (this->statusHolder->state != ReactorState::NONE) {
     return;
   }
   this->StartRead(&this->response);
   if (this->statusHolder->state != ReactorState::RUNNING) {
     this->StartCall();
     this->statusHolder->state = ReactorState::RUNNING;
   }
 }
 
 template <class Request, class Response>
 void ClientReadReactorBase<Request, Response>::OnReadDone(bool ok) {
   if (!ok) {
     // Ending a connection on the other side results in the `ok` flag being set
     // to false. It makes it impossible to detect a failure based just on the
     // flag. We should manually check if the data we received is valid
     this->terminate(grpc::Status::OK);
     return;
   }
   try {
     std::unique_ptr<grpc::Status> status = this->readResponse(this->response);
     if (status != nullptr) {
       this->terminate(*status);
       return;
     }
   } catch (std::runtime_error &e) {
     this->terminate(grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
   }
   this->StartRead(&this->response);
 }
 
 template <class Request, class Response>
 void ClientReadReactorBase<Request, Response>::terminate(
     const grpc::Status &status) {
   if (this->statusHolder->getStatus().ok()) {
     this->statusHolder->setStatus(status);
   }
   if (!this->statusHolder->getStatus().ok()) {
     std::cout << "error: " << this->statusHolder->getStatus().error_message()
               << std::endl;
   }
   if (this->statusHolder->state != ReactorState::RUNNING) {
     return;
   }
   this->terminateCallback();
   try {
     this->validate();
   } catch (std::runtime_error &e) {
     this->statusHolder->setStatus(
         grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
   }
   this->statusHolder->state = ReactorState::TERMINATED;
 }
 
 template <class Request, class Response>
 void ClientReadReactorBase<Request, Response>::OnDone(
     const grpc::Status &status) {
   this->statusHolder->state = ReactorState::DONE;
   this->terminate(status);
   this->doneCallback();
 }
 
 template <class Request, class Response>
 std::shared_ptr<ReactorStatusHolder>
 ClientReadReactorBase<Request, Response>::getStatusHolder() {
   return this->statusHolder;
 }
 
 } // namespace reactor
 } // namespace network
 } // namespace comm
diff --git a/services/lib/src/client-base-reactors/ClientWriteReactorBase.h b/services/lib/src/client-base-reactors/ClientWriteReactorBase.h
index 03743c4fe..e135ad38d 100644
--- a/services/lib/src/client-base-reactors/ClientWriteReactorBase.h
+++ b/services/lib/src/client-base-reactors/ClientWriteReactorBase.h
@@ -1,114 +1,126 @@
 #pragma once
 
 #include "BaseReactor.h"
 
 #include <grpcpp/grpcpp.h>
 
 namespace comm {
 namespace network {
 namespace reactor {
 
+// This is how this type of reactor works:
+// - write N requests to the server
+// - terminate the connection
 template <class Request, class Response>
 class ClientWriteReactorBase : public grpc::ClientWriteReactor<Request>,
                                public BaseReactor {
   std::shared_ptr<ReactorStatusHolder> statusHolder;
   Request request;
 
   void nextWrite();
 
 public:
   Response response;
   grpc::ClientContext context;
 
+  // this should be called explicitly right after the reactor is created
   void start();
 
+  // these methods come from the BaseReactor(go there for more information)
   void validate() override{};
   void doneCallback() override{};
   void terminateCallback() override{};
+  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // these methods come from gRPC
+  // https://github.com/grpc/grpc/blob/v1.39.x/include/grpcpp/impl/codegen/client_callback.h#L237
   void OnWriteDone(bool ok) override;
   void terminate(const grpc::Status &status) override;
   void OnDone(const grpc::Status &status) override;
-  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // - argument request - request that should be edited and is going to be sent
+  // in the current cycle to the server
+  // - returns status - if the connection is about to be
+  // continued, nullptr should be returned. Any other returned value will
+  // terminate the connection with a given status
   virtual std::unique_ptr<grpc::Status> prepareRequest(Request &request) = 0;
 };
 
 template <class Request, class Response>
 void ClientWriteReactorBase<Request, Response>::nextWrite() {
   this->request = Request();
   try {
     std::unique_ptr<grpc::Status> status = this->prepareRequest(this->request);
     if (status != nullptr) {
       this->terminate(*status);
       return;
     }
   } catch (std::runtime_error &e) {
     this->terminate(grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
   }
   this->StartWrite(&this->request);
   if (!this->initialized) {
     this->StartCall();
     this->initialized = true;
   }
 }
 
 template <class Request, class Response>
 void ClientWriteReactorBase<Request, Response>::start() {
   if (this->start != ReactorState::NONE) {
     return;
   }
   this->statusHolder->state = ReactorState::RUNNING;
   this->nextWrite();
 }
 
 template <class Request, class Response>
 void ClientWriteReactorBase<Request, Response>::OnWriteDone(bool ok) {
   if (!ok) {
     this->terminate(grpc::Status(grpc::StatusCode::UNKNOWN, "write error"));
     return;
   }
   this->nextWrite();
 }
 
 template <class Request, class Response>
 void ClientWriteReactorBase<Request, Response>::terminate(
     const grpc::Status &status) {
   if (this->statusHolder->getStatus().ok()) {
     this->statusHolder->setStatus(status);
   }
   if (!this->statusHolder->getStatus().ok()) {
     std::cout << "error: " << this->statusHolder->getStatus().error_message()
               << std::endl;
   }
   if (this->statusHolder->state != ReactorState::RUNNING) {
     return;
   }
   this->terminateCallback();
   try {
     this->validate();
   } catch (std::runtime_error &e) {
     this->statusHolder->setStatus(
         grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
   }
   this->statusHolder->state = ReactorState::TERMINATED;
   this->StartWritesDone();
 }
 
 template <class Request, class Response>
 void ClientWriteReactorBase<Request, Response>::OnDone(
     const grpc::Status &status) {
   this->statusHolder->state = ReactorState::DONE;
   this->terminate(status);
   this->doneCallback();
 }
 
 template <class Request, class Response>
 std::shared_ptr<ReactorStatusHolder>
 ClientWriteReactorBase<Request, Response>::getStatusHolder() {
   return this->statusHolder;
 }
 
 } // namespace reactor
 } // namespace network
 } // namespace comm
diff --git a/services/lib/src/server-base-reactors/ServerBidiReactorBase.h b/services/lib/src/server-base-reactors/ServerBidiReactorBase.h
index d1ed86ab7..85444d479 100644
--- a/services/lib/src/server-base-reactors/ServerBidiReactorBase.h
+++ b/services/lib/src/server-base-reactors/ServerBidiReactorBase.h
@@ -1,157 +1,172 @@
 #pragma once
 
 #include "BaseReactor.h"
 
 #include <grpcpp/grpcpp.h>
 
 #include <atomic>
 #include <iostream>
 #include <memory>
 #include <string>
 
 namespace comm {
 namespace network {
 namespace reactor {
 
 struct ServerBidiReactorStatus {
   grpc::Status status;
   bool sendLastResponse;
   ServerBidiReactorStatus(
       grpc::Status status = grpc::Status::OK,
       bool sendLastResponse = false)
       : status(status), sendLastResponse(sendLastResponse) {
   }
 };
 
+// This is how this type of reactor works:
+// - repeat:
+//   - read a request from the client
+//   - write a response to the client
+// - terminate the connection
 template <class Request, class Response>
 class ServerBidiReactorBase : public grpc::ServerBidiReactor<Request, Response>,
                               public BaseReactor {
   std::shared_ptr<ReactorStatusHolder> statusHolder;
   Request request;
   Response response;
 
 protected:
   ServerBidiReactorStatus status;
   bool readingAborted = false;
 
 public:
   ServerBidiReactorBase();
 
+  // these methods come from the BaseReactor(go there for more information)
   void terminate(const grpc::Status &status) override;
   void validate() override{};
   void doneCallback() override{};
   void terminateCallback() override{};
+  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // these methods come from gRPC
+  // https://github.com/grpc/grpc/blob/v1.39.x/include/grpcpp/impl/codegen/client_callback.h#L237
   void OnDone() override;
   void OnReadDone(bool ok) override;
   void OnWriteDone(bool ok) override;
-  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
   void terminate(ServerBidiReactorStatus status);
   ServerBidiReactorStatus getStatus() const;
   void setStatus(const ServerBidiReactorStatus &status);
 
+  // - argument request - request that was sent by the client and received by
+  // the server in the current cycle
+  // - argument response - response that will be sent to the client in the
+  // current cycle
+  // - returns status - if the connection is about to be
+  // continued, nullptr should be returned. Any other returned value will
+  // terminate the connection with a given status
   virtual std::unique_ptr<ServerBidiReactorStatus>
   handleRequest(Request request, Response *response) = 0;
 };
 
 template <class Request, class Response>
 ServerBidiReactorBase<Request, Response>::ServerBidiReactorBase() {
   this->statusHolder->state = ReactorState::RUNNING;
   this->StartRead(&this->request);
 }
 
 template <class Request, class Response>
 void ServerBidiReactorBase<Request, Response>::terminate(
     const grpc::Status &status) {
   this->terminate(ServerBidiReactorStatus(status));
 }
 
 template <class Request, class Response>
 void ServerBidiReactorBase<Request, Response>::OnDone() {
   this->statusHolder->state = ReactorState::DONE;
   this->doneCallback();
   // This looks weird but apparently it is okay to do this. More information:
   // https://phabricator.ashoat.com/D3246#87890
   delete this;
 }
 
 template <class Request, class Response>
 void ServerBidiReactorBase<Request, Response>::terminate(
     ServerBidiReactorStatus status) {
   this->setStatus(status);
   try {
     this->terminateCallback();
     this->validate();
   } catch (std::runtime_error &e) {
     this->setStatus(ServerBidiReactorStatus(
         grpc::Status(grpc::StatusCode::INTERNAL, e.what())));
   }
   if (this->statusHolder->state != ReactorState::RUNNING) {
     return;
   }
   if (this->getStatus().sendLastResponse) {
     this->StartWriteAndFinish(
         &this->response, grpc::WriteOptions(), this->getStatus().status);
   } else {
     this->Finish(this->getStatus().status);
   }
   this->statusHolder->state = ReactorState::TERMINATED;
 }
 
 template <class Request, class Response>
 ServerBidiReactorStatus
 ServerBidiReactorBase<Request, Response>::getStatus() const {
   return this->status;
 }
 
 template <class Request, class Response>
 void ServerBidiReactorBase<Request, Response>::setStatus(
     const ServerBidiReactorStatus &status) {
   this->status = status;
 }
 
 template <class Request, class Response>
 void ServerBidiReactorBase<Request, Response>::OnReadDone(bool ok) {
   if (!ok) {
     this->readingAborted = true;
     // Ending a connection on the other side results in the `ok` flag being set
     // to false. It makes it impossible to detect a failure based just on the
     // flag. We should manually check if the data we received is valid
     this->terminate(ServerBidiReactorStatus(grpc::Status::OK));
     return;
   }
   try {
     this->response = Response();
     std::unique_ptr<ServerBidiReactorStatus> status =
         this->handleRequest(this->request, &this->response);
     if (status != nullptr) {
       this->terminate(*status);
       return;
     }
     this->StartWrite(&this->response);
   } catch (std::runtime_error &e) {
     this->terminate(ServerBidiReactorStatus(
         grpc::Status(grpc::StatusCode::INTERNAL, e.what())));
   }
 }
 
 template <class Request, class Response>
 void ServerBidiReactorBase<Request, Response>::OnWriteDone(bool ok) {
   if (!ok) {
     this->terminate(ServerBidiReactorStatus(
         grpc::Status(grpc::StatusCode::ABORTED, "write failed")));
     return;
   }
   this->StartRead(&this->request);
 }
 
 template <class Request, class Response>
 std::shared_ptr<ReactorStatusHolder>
 ServerBidiReactorBase<Request, Response>::getStatusHolder() {
   return this->statusHolder;
 }
 
 } // namespace reactor
 } // namespace network
 } // namespace comm
diff --git a/services/lib/src/server-base-reactors/ServerReadReactorBase.h b/services/lib/src/server-base-reactors/ServerReadReactorBase.h
index da3abbdba..2bcf2e567 100644
--- a/services/lib/src/server-base-reactors/ServerReadReactorBase.h
+++ b/services/lib/src/server-base-reactors/ServerReadReactorBase.h
@@ -1,109 +1,120 @@
 #pragma once
 
 #include "BaseReactor.h"
 
 #include <grpcpp/grpcpp.h>
 
 #include <atomic>
 #include <iostream>
 #include <memory>
 #include <string>
 
 namespace comm {
 namespace network {
 namespace reactor {
 
+// This is how this type of reactor works:
+// - read N requests from the client
+// - write a final response to the client (may be empty)
+// - terminate the connection
 template <class Request, class Response>
 class ServerReadReactorBase : public grpc::ServerReadReactor<Request>,
                               public BaseReactor {
   std::shared_ptr<ReactorStatusHolder> statusHolder;
   Request request;
 
 protected:
   Response *response;
 
 public:
   ServerReadReactorBase(Response *response);
 
+  // these methods come from the BaseReactor(go there for more information)
   void validate() override{};
   void doneCallback() override{};
   void terminateCallback() override{};
+  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // these methods come from gRPC
+  // https://github.com/grpc/grpc/blob/v1.39.x/include/grpcpp/impl/codegen/client_callback.h#L237
   void OnReadDone(bool ok) override;
   void terminate(const grpc::Status &status) override;
   void OnDone() override;
-  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // - argument request - data read from the client in the current cycle
+  // - returns status - if the connection is about to be
+  // continued, nullptr should be returned. Any other returned value will
+  // terminate the connection with a given status
   virtual std::unique_ptr<grpc::Status> readRequest(Request request) = 0;
 };
 
 template <class Request, class Response>
 ServerReadReactorBase<Request, Response>::ServerReadReactorBase(
     Response *response)
     : response(response) {
   this->statusHolder->state = ReactorState::RUNNING;
   this->StartRead(&this->request);
 }
 
 template <class Request, class Response>
 void ServerReadReactorBase<Request, Response>::OnReadDone(bool ok) {
   if (!ok) {
     // Ending a connection on the other side results in the `ok` flag being set
     // to false. It makes it impossible to detect a failure based just on the
     // flag. We should manually check if the data we received is valid
     this->terminate(grpc::Status::OK);
     return;
   }
   try {
     std::unique_ptr<grpc::Status> status = this->readRequest(this->request);
     if (status != nullptr) {
       this->terminate(*status);
       return;
     }
   } catch (std::runtime_error &e) {
     this->terminate(grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
     return;
   }
   this->StartRead(&this->request);
 }
 
 template <class Request, class Response>
 void ServerReadReactorBase<Request, Response>::terminate(
     const grpc::Status &status) {
   this->statusHolder->setStatus(status);
   try {
     this->terminateCallback();
     this->validate();
   } catch (std::runtime_error &e) {
     this->statusHolder->setStatus(
         grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
   }
   if (!this->statusHolder->getStatus().ok()) {
     std::cout << "error: " << this->statusHolder->getStatus().error_message()
               << std::endl;
   }
   if (this->statusHolder->state != ReactorState::RUNNING) {
     return;
   }
   this->Finish(this->statusHolder->getStatus());
   this->statusHolder->state = ReactorState::TERMINATED;
 }
 
 template <class Request, class Response>
 void ServerReadReactorBase<Request, Response>::OnDone() {
   this->statusHolder->state = ReactorState::DONE;
   this->doneCallback();
   // This looks weird but apparently it is okay to do this. More information:
   // https://phabricator.ashoat.com/D3246#87890
   delete this;
 }
 
 template <class Request, class Response>
 std::shared_ptr<ReactorStatusHolder>
 ServerReadReactorBase<Request, Response>::getStatusHolder() {
   return this->statusHolder;
 }
 
 } // namespace reactor
 } // namespace network
 } // namespace comm
diff --git a/services/lib/src/server-base-reactors/ServerWriteReactorBase.h b/services/lib/src/server-base-reactors/ServerWriteReactorBase.h
index a9db947ce..bdff4379e 100644
--- a/services/lib/src/server-base-reactors/ServerWriteReactorBase.h
+++ b/services/lib/src/server-base-reactors/ServerWriteReactorBase.h
@@ -1,131 +1,144 @@
 #pragma once
 
 #include "BaseReactor.h"
 
 #include <grpcpp/grpcpp.h>
 
 #include <atomic>
 #include <iostream>
 #include <memory>
 #include <string>
 
 namespace comm {
 namespace network {
 namespace reactor {
 
+// This is how this type of reactor works:
+// - read a request from the client
+// - write N responses to the client
+// - terminate the connection
 template <class Request, class Response>
 class ServerWriteReactorBase : public grpc::ServerWriteReactor<Response>,
                                public BaseReactor {
   std::shared_ptr<ReactorStatusHolder> statusHolder;
   Response response;
   bool initialized = false;
 
   void nextWrite();
 
 protected:
   // this is a const ref since it's not meant to be modified
   const Request &request;
 
 public:
   ServerWriteReactorBase(const Request *request);
 
+  // this should be called explicitly right after the reactor is created
   void start();
 
+  // these methods come from the BaseReactor(go there for more information)
   void validate() override{};
   void doneCallback() override{};
   void terminateCallback() override{};
+  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // these methods come from gRPC
+  // https://github.com/grpc/grpc/blob/v1.39.x/include/grpcpp/impl/codegen/client_callback.h#L237
   virtual void initialize(){};
   void OnWriteDone(bool ok) override;
   void terminate(const grpc::Status &status);
   void OnDone() override;
-  std::shared_ptr<ReactorStatusHolder> getStatusHolder() override;
 
+  // - argument response - should be filled with data that will be sent to the
+  // client in the current cycle
+  // - returns status - if the connection is about to be
+  // continued, nullptr should be returned. Any other returned value will
+  // terminate the connection with a given status
   virtual std::unique_ptr<grpc::Status> writeResponse(Response *response) = 0;
 };
 
 template <class Request, class Response>
 void ServerWriteReactorBase<Request, Response>::terminate(
     const grpc::Status &status) {
   this->statusHolder->setStatus(status);
   try {
     this->terminateCallback();
     this->validate();
   } catch (std::runtime_error &e) {
     this->statusHolder->setStatus(
         grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
   }
   if (!this->statusHolder->getStatus().ok()) {
     std::cout << "error: " << this->statusHolder->getStatus().error_message()
               << std::endl;
   }
   if (this->statusHolder->state != ReactorState::RUNNING) {
     return;
   }
   this->Finish(this->statusHolder->getStatus());
   this->statusHolder->state = ReactorState::TERMINATED;
 }
 
 template <class Request, class Response>
 ServerWriteReactorBase<Request, Response>::ServerWriteReactorBase(
     const Request *request)
     : request(*request) {
   // we cannot call this->start() here because it's going to call it on
   // the base class, not derived leading to the runtime error of calling
   // a pure virtual function
   // start has to be exposed as a public function and called explicitly
   // to initialize writing
 }
 
 template <class Request, class Response>
 void ServerWriteReactorBase<Request, Response>::nextWrite() {
   try {
     if (!this->initialized) {
       this->initialize();
       this->initialized = true;
     }
     this->response = Response();
     std::unique_ptr<grpc::Status> status = this->writeResponse(&this->response);
     if (status != nullptr) {
       this->terminate(*status);
       return;
     }
     this->StartWrite(&this->response);
   } catch (std::runtime_error &e) {
     std::cout << "error: " << e.what() << std::endl;
     this->terminate(grpc::Status(grpc::StatusCode::INTERNAL, e.what()));
   }
 }
 
 template <class Request, class Response>
 void ServerWriteReactorBase<Request, Response>::start() {
   this->statusHolder->state = ReactorState::RUNNING;
   this->nextWrite();
 }
 
 template <class Request, class Response>
 void ServerWriteReactorBase<Request, Response>::OnDone() {
   this->doneCallback();
   // This looks weird but apparently it is okay to do this. More information:
   // https://phabricator.ashoat.com/D3246#87890
   delete this;
 }
 
 template <class Request, class Response>
 std::shared_ptr<ReactorStatusHolder>
 ServerWriteReactorBase<Request, Response>::getStatusHolder() {
   return this->statusHolder;
 }
 
 template <class Request, class Response>
 void ServerWriteReactorBase<Request, Response>::OnWriteDone(bool ok) {
   if (!ok) {
     this->terminate(grpc::Status(grpc::StatusCode::INTERNAL, "writing error"));
     return;
   }
   this->nextWrite();
 }
 
 } // namespace reactor
 } // namespace network
 } // namespace comm