μpb (often written 'upb') is a small protobuf implementation written in C.
upb is the core runtime for protobuf languages extensions in Ruby, PHP, and (soon) Python.
While upb offers a C API, the C API & ABI are not stable. For this reason, upb is not generally offered as a C library for direct consumption, and there are no releases.
upb has comparable speed to protobuf C++, but is an order of magnitude smaller in code size.
Like the main protobuf implementation in C++, it supports:
- a generated API (in C)
- reflection
- binary & JSON wire formats
- text format serialization
- all standard features of protobufs (oneofs, maps, unknown fields, extensions, etc.)
- full conformance with the protobuf conformance tests
upb also supports some features that C++ does not:
- optional reflection: generated messages are agnostic to whether reflection will be linked in or not.
- no global state: no pre-main registration or other global state.
- fast reflection-based parsing: messages loaded at runtime parse just as fast as compiled-in messages.
However there are a few features it does not support:
- text format parsing
- deep descriptor verification: upb's descriptor validation is not as exhaustive
as
protoc.
For Ruby, use RubyGems:
$ gem install google-protobuf
For PHP, use PECL:
$ sudo pecl install protobuf
Please see CONTRIBUTING.md.