Getting started

Installation¶

Building from source¶

protobluff is built using Autotools and can be linked as a static or shared library. It has no runtime dependencies and is fully self-contained, except for the code generator which depends on the original Protocol Buffers runtime and is necessary to generate bindings from .proto schema files. If the original library is not available, the generator is not built. The following commands build and install the protobluff library and code generator:

./autogen.sh &&
./configure &&
make &&
make test &&
make install

protobluff should compile and run on all UNIX systems (including Linux and Mac OS) as it adheres to the C99 and C++98 standards, has no dependencies (except for the code generator) and makes no system calls.

After installing protobluff, the code generator can be used to generate bindings from .proto schema files to get started. See this section for more information.

Additional options¶

By default, protobluff is compiled aggressively optimized with -O3 and some further optimizations which make it nearly impossible to debug. If debugging is necessary, optimizations should be disabled. Stripped compilation will remove all symbols that are not defined in the public header files, allowing further optimizations. Enabling the coverage report is necessary to determine unit test coverage, and thus only needed during development.

./configure
  --disable-optimized # No optimizations (default: enabled)
  --enable-stripped   # Strip internal symbols (default: disabled)
  --enable-coverage   # Coverage report (default: disabled)

Using the code generator¶

The code generator is tightly integrated with the protoc compiler toolchain included in the default Protocol Buffers distribution. Use the protoc command to invoke the protobluff code generator through the --protobluff_out flag, to generate and write the respective .pb.h and .pb.c files to a specific location:

protoc --protobluff_out=. *.proto

The .pb.h header files contain the bindings, the .pb.c source files contain the descriptor definitions and defaults which are referenced by the bindings. Therefore, the source files must be compiled together with your project.

Using the generated bindings¶

Here's a usage example taken from the original description of the Google Protocol Buffers library and adapted to protobluff:

/* Create an empty journal to assemble a new person message */
pb_journal_t journal = pb_journal_create_empty();

/* Create a person message */
pb_message_t person = person_create(&journal);

/* Define the values we want to set */
pb_string_t name   = pb_string_init_from_chars("John Doe"),
            email  = pb_string_init_from_chars("jdoe@example.com"),
            home   = pb_string_init_from_chars("+1-541-754-3010"),
            mobile = pb_string_init_from_chars("+1-541-293-8228");
int32_t     id     = 1234;

/* Set values on person message and check return codes */
pb_error_t error = PB_ERROR_NONE;
do {
  if ((error = person_put_name(&person, &name)) ||
      (error = person_put_id(&person, &id)) ||
      (error = person_put_email(&person, &email)))
    break;

  /* Set home number */
  pb_message_t phone1 = person_create_phone(&person);
  if (!(error = person_phonenumber_put_number(&phone1, &home)) &&
      !(error = person_phonenumber_put_type_home(&phone1))) {

    /* Set mobile number */
    pb_message_t phone2 = person_create_phone(&person);
    if (!(error = person_phonenumber_put_number(&phone2, &mobile)) &&
        !(error = person_phonenumber_put_type_mobile(&phone2))) {

      /* Dump the journal */
      pb_journal_dump(&journal);

      /* The encoded message can be accessed as follows */
      // const uint8_t *data = pb_journal_data(&journal);
      // const size_t   size = pb_journal_size(&journal);
    }
    person_phonenumber_destroy(&phone2);
  }
  person_phonenumber_destroy(&phone1);
} while (0);

/* Print error, if any */
if (error)
  fprintf(stderr, "ERROR: %s\n", pb_error_string(error));

/* Cleanup and invalidate */
person_destroy(&person);

/* Free all allocated memory and return */
pb_journal_destroy(&journal);

First the name, email and id of the person are written and then the two phone numbers. However, the order of operations is not important. protobluff will ensure that the fields are written in the right place, so we could also write the name, then create the mobile phone number, add the email and id, change the phone number again and add the home phone number last. The result will be the same. See the examples folder for more usage examples.

Linking¶

Manually¶

For the generated bindings to function, your project must be linked against the protobluff runtime. The recommended way is to dynamically link the shared library. Therefore, the following compiler and linker flags must be obtained and added to your build toolchain:

pkg-config --cflags protobluff # Add output to compiler flags
pkg-config --libs   protobluff # Add output to linker flags

See this section for more information on the available runtimes.

Autotools¶

If you're using Autotools, the PKG_CHECK_MODULES macro will take care of the heavy lifting. Adding the following line to your configure.ac file will place the compiler flags into the variable protobluff_CFLAGS and the linker flags into the variable protobluff_LDFLAGS:

PKG_CHECK_MODULES([protobluff], [protobluff])