Google Protocol Buffer 有各种版本的代码包，Python C/C++、JAVA、C、OBJ-C、.NET等，嵌入式设备中使用的protobuf版本，我们选择的是nanoprobuf。
1）Google Protocol Buffer 的使用和原理
https://www.ibm.com/developerworks/cn/linux/l-cn-gpb/index.html
2）Nanopb - protocol buffers with small code size
To use the nanopb library, you need to do two things:
- Compile your .proto files for nanopb, using protoc.
- Include pb_encode.c, pb_decode.c and pb_common.c in your project.
The easiest way to get started is to study the project in "examples/simple". It contains a Makefile, which should work directly under most Linux systems. However, for any other kind of build system, see the manual steps in README.txt in that folder.
simple.c
message SimpleMessage {
required int32 lucky_number = ;
}
#include <stdio.h>
#include <pb_encode.h>
#include <pb_decode.h>
#include "simple.pb.h" int main()
{
/* This is the buffer where we will store our message. */
uint8_t buffer[];
size_t message_length;
bool status; /* Encode our message */
{
/* Allocate space on the stack to store the message data.
*
* Nanopb generates simple struct definitions for all the messages.
* - check out the contents of simple.pb.h!
* It is a good idea to always initialize your structures
* so that you do not have garbage data from RAM in there.
*/
SimpleMessage message = SimpleMessage_init_zero; /* Create a stream that will write to our buffer. */
pb_ostream_t stream = pb_ostream_from_buffer(buffer, sizeof(buffer)); /* Fill in the lucky number */
message.lucky_number = ; /* Now we are ready to encode the message! */
status = pb_encode(&stream, SimpleMessage_fields, &message);
message_length = stream.bytes_written; /* Then just check for any errors.. */
if (!status)
{
printf("Encoding failed: %s\n", PB_GET_ERROR(&stream));
return ;
}
} /* Now we could transmit the message over network, store it in a file or
* wrap it to a pigeon's leg.
*/ /* But because we are lazy, we will just decode it immediately. */ {
/* Allocate space for the decoded message. */
SimpleMessage message = SimpleMessage_init_zero; /* Create a stream that reads from the buffer. */
pb_istream_t stream = pb_istream_from_buffer(buffer, message_length); /* Now we are ready to decode the message. */
status = pb_decode(&stream, SimpleMessage_fields, &message); /* Check for errors... */
if (!status)
{
printf("Decoding failed: %s\n", PB_GET_ERROR(&stream));
return ;
} /* Print the data contained in the message. */
printf("Your lucky number was %d!\n", message.lucky_number);
} return ;
}