Protocol Buffers (a.k.a. protobuf) is Google's language-neutral, platform-neutral, extensible mechanism for serializing structured data. TizenRT features a port for protobuf version 3.5.1, with support for C++ language. You can find details of protobuf at https://github.com/google/protobuf.

Before you proceed with the rest of the documentation below, please note the following points:

Note

1. In case you have just recently installed gRPC, and wish to install Protobuf to work along with gRPC, please ignore this document, and refer to the installation instructions under Installing Protobuf with gRPC instead.

2. In case you have installed Protobuf using the instructions in this document, and wish to additionally install gRPC, then please make sure you install the correct version of protobuf to use along with gRPC. It is not really necessary to un-install this version of protobuf, but you will need to maintain different protobuf versions at different paths, and establish the precedence in the $PATH variable. Therefore, to avoid complicating the build, it is recommended to un-install any previous version of protobuf and install the version that you need.

The following sections detail the steps required to build protobuf on TizenRT, and to build and run TizenRT applications that use protobuf.

Build protobuf

protobuf takes in specifications for services and messages in a special proto file (with file extension .proto), and translates these specifications to actual C++ code that can be used by applications. For the translation to happen, protobuf needs a protocol complier called protoc to compile the specification .proto file. Below are mentioned two approaches for installing protoc in your build environment (host OS):

Installing protoc from source

protoc can be installed from source by using the link below:

• https://github.com/google/protobuf

Installing protoc release from GitHub

The appropriate protoc release can be fetched and installed using the steps below:

• http://google.github.io/proto-lens/installing-protoc.html

Having installed protoc in the build environment, the following steps are detailed for configuring TizenRT's menuconfig for building protobuf

Build protobuf on TizenRT

Protocol Buffers in menuconfig should be selected under [External Libraries > protocol buffer]. Currently, protobuf configuration is supported only for applications that use gRPC(see artik053/grpc under build/configs directory). In the future, protobuf configurations will be extended to cover applications that do not strictly require gRPC.

The following sections describes how to quickly verify the working of protobuf on TizenRT, and how to build a new application that uses protobuf.

Quick Start

TizenRT provides a sample program for protobuf, named addressbook_main that serializes and deserializes user data. addressbook_main program could be selected under below menuconfig

[Application Configuration > Examples > Protocol Buffers example]

Having selected the application as shown above, build it as follows:

$ make

Add new application for protocol buffer

In general, steps for adding new application to TizenRT is explained in this link: https://github.com/Samsung/TizenRT/blob/master/apps/HowtoAddNewApp.md. More specifically, applications using protobuf require the additional build options:

1. Application should point the header file path for protobuf, as shown:

CXXFLAGS  += -I$(TOPDIR)/../external/protobuf/src/

2. TizenRT doesn't support RTTI now so a no rtti option should be set accordingly, as shown.

CXXFLAGS  += -DGOOGLE_PROTOBUF_NO_RTTI -D__TizenRT__

Interested developers can refer to example/protbuf/Makefile for additional details.