asio-grpc VS Protobuf

Since I can never remember what arguments to pass to protobuf_generate to create Protobuf and gRPC source files, I wrote an article about it. It provides a copy-paste-able code snippet along with an explanation of all arguments that protobuf_generate accepts, how to format it nicely using cmake-format and how to make things easier with asio-grpc.

Asio-grpc makes exactly that possible by providing an Asio execution_context compatible interface to the CompletionQueue. It supports all types of RPCs (including generic ones), completion tokens, cancellation, as well as libunifex sender/receiver (if you want to try out what might become std::execution). The latest release (v1.7.0) also introduced a GrpcStream class for writing Rust/Golang select-style code.

It hasn't been without issue, however. Problems that may lie in official google-maintained libraries are of course present and required design changes, and I was even prompted to write my own bitset library that outperforms the C++ standard's by a factor of 60. Madness. Right?

Or check out the asio-grpc repository directly if you are looking to write asynchronous gRPC services with the features of Boost.Asio like C++20 coroutines, std::futures, stackless coroutines, callbacks and Boost.Coroutines.

It's because they changed the versioning format: https://github.com/protocolbuffers/protobuf/releases?page=5

But I suppose old version still receive bugfixes.

For at least 4 years protobuf has had decent support for self-describing messages (very similar to avro) as well as reflection

https://github.com/protocolbuffers/protobuf/blob/main/src/go...

Xgooglers trying to make do on the cheap will just create a Union of all their messages and include the message def in a self-describing message pattern. Super-sensitive network I/O can elide the message def (empty buffer) and any for RecordIO clone well file compression takes care of the definition.

Definitely useful to be able to dig out old defs but protobuf maintainers have surprisingly added useful features so you don’t have to.

Bonus points tho for extracting the protobuf defs that e.g. Apple bakes into their binaries.

gRPC Gateway is a protoc plugin that reads gRPC service definitions and generates a reverse proxy server that translates a RESTful JSON API into gRPC.

To use more recent versions of protoc in future applications, you can download them from the Protobuf repository.

Use the Protobuf CLI protoc and the plugin protoc-gen-tonic.

> didn’t find any standard for separating protobuf messages

The fact that protobufs are not self-delimiting is an endless source of frustration, but I know of 2 standards:

- SerializeDelimited* is part of the protobuf library: https://github.com/protocolbuffers/protobuf/blob/main/src/go...

- Riegeli is "a file format for storing a sequence of string records, typically serialized protocol buffers. It supports dense compression, fast decoding, seeking, detection and optional skipping of data corruption, filtering of proto message fields for even faster decoding, and parallel encoding": https://github.com/google/riegeli

It looks like it is in fact universal. Just glancing at the code here, it looks like the tool searches any arbitrary file for bytes that look like encoded protobuf descriptors, specifically looking for bytes that are plausibly the beginning of a FileDescriptorProto message defined here:

https://github.com/protocolbuffers/protobuf/blob/main/src/go...

This takes advantage of the fact that such descriptors are commonly compiled into programs that use protobuf. The descriptors are usually embedded as constant byte arrays. That said, not all protobuf implementations embed the descriptors and those that do often have an option to inhibit such embedding (at the expense of losing some dynamic introspection features).

Not much. You can check the source code in https://github.com/protocolbuffers/protobuf. For example, for serializing a boolean in C#: https://github.com/protocolbuffers/protobuf/blob/main/csharp/src/Google.Protobuf/WritingPrimitives.cs#L165. Strings and objects are a bit more complicated, but it is all about turning the data into its byte representation.