Cap'n Proto Playground

Features

Made by former gRPC developer with better performance in mind
"Infinitely faster" than Protobuf (no serialization needed)
Data types: void, bool, int, float, string, bytes, list, structs, enums, interfaces, generics
Promise pipelining -- multiple RPC calls in one network round trip
No encryption or authentication

Python

pycapnp: GitHub, Docs

It's a wrapper around C++ library which uses its own event loop.

Pycapnp installation on Windows:

You're gonna need:
- Visual Studio 2017 with the following build tools:
  - Windows 10 SDK (10.0.17763.0)
  - Visual C++ Tools for CMake
- CMake (version >= 3.1)
Download and unzip https://capnproto.org/capnproto-c++-win32-0.7.0.zip
Go to capnproto-c++-0.7.0 directory
Run cmake -G "Visual Studio 15 2017" -A x64 .
Run Visual Studio as admin and openCap'n Proto.sln
Select Release build type
Build BUILD_ALL solution
Build INSTALL solution
Create a new Python virtual environment (further referred to as venv)
Clone or download Pycapnp

Modify extensions in setup.py (lines 138--143) to look like this:

extensions = [Extension("capnp.lib.capnp", ["capnp/lib/capnp.cpp"],
                        include_dirs=[".", "C:\Program Files (x86)\Cap'n Proto\include"],
                        library_dirs=["C:\Program Files (x86)\Cap'n Proto\lib"],
                        language='c++',
                        extra_compile_args=['--std=c++11'],
                        libraries=['capnpc', 'capnp-rpc', 'capnp', 'kj-async', 'kj', 'ws2_32', 'Advapi32'])]

Activate the virtual env and run python setup.py install --force-system-libcapnp
Good luck!

No code generation is needed, pycapnp does it on the fly.

To start non-encrypted server run:

python python/server.py 127.0.0.1 <PORT>

To start SSL server run:

python python/ssl_server.py 127.0.0.1 <PORT> ./keys/server.crt ./keys/server.key

To start non-encrypted client run:

python python/client.py 127.0.0.1 <PORT>

To start SSL client run:

python python/ssl_client.py 127.0.0.1 <PORT> ./keys/server.crt

Rust

capnproto-rust: GitHub, Docs

The library is future-based and tokio-compatible.

SSL support is provided by tokio-tls or tokio-openssl.

To build the project you need OpenSSL installed. For Windows use this distribution. Before running cargo build set OPENSSL_DIR variable to point to your OpenSSL installation directory.

To re-generate Rust definitions you need capnp binary (install instruction) and capnpc crate installed. Once you have these run:

capnp compile -orust:./rust/helloworld/src/ helloworld.capnp

To start non-encrypted server run:

./rust/helloworld/target/debug/server.exe 127.0.0.1:<PORT>

To start native SSL server run:

./rust/helloworld/target/debug/native_ssl_server.exe 127.0.0.1:<PORT> ./keys/server.p12

To start OpenSSL server run:

./rust/helloworld/target/debug/openssl_server.exe 127.0.0.1:<PORT> ./keys/server.crt ./keys/server.key