bchwallet with protobuf over HTTP

This is a proof of concept implementation of bchwallet to connect to bchwallet from PHP using protocol buffers over HTTP.

Why?

We want to bring BitcoinCash (BCH) to WordPress. About 35% of the web is run on WordPres (December 2019).

Current Problem

This must run on all default PHP installations on common shared hosting platforms.

There are 2 C extensions for PHP to run gRPC (grpc.so and protobuf.so) and one of them (grpc.so) is mandatory to run gRPC (the protobuf.so is optional for better performance).

See: gRPC with PHP quickstart

Neither of these 2 C extensions is bundled with default PHP installations (and will not be anytime soon as done with cURL, Mysql driver, ...).

Furthermore, as of now (June 2020) it seems unlikely there will ever be a native gRPC client implemented in PHP.

Solution

Use Protocol Buffers over HTTP multipart POST (without gRPC as transport layer). We get the advantages of sending binary data over the wire without having to wait for gRPC support on common shared hosting platforms.

As the request + response messages in bchwallet are protocol buffers we can easily integrate it with the new server rpcserver/server.go (no need to maintain a completely different HTTP JSON API).

See server_proto.go for the proof-of-concept.

Alternative solutions

Keep the bchwallet (and bchd) legacy HTTP JSON API updated - including upcoming SLP support - and we can use JSON to integrate bchwallet into WordPress.

Running this proof of concept

Requirements

Go >= 1.13
PHP >= 7.3

Sending protobuf messages

1. start bchd daemon
2. start this bchwallet daemon
3. cd php && composer install
4. run php/index.php in the shell or browser

This sends a protobuf test message (PingRequest) as defined in the bchwallet api.proto file using HTTP multipart POST with the binary protocol buffer data in the request body.

Compiling .proto files

We created a Docker image to generate PHP code of the official bchwallet api.proto file. This will only generate protocol buffer PHP code of all message blocks, skipping all gRPC service blocks and streams.

cd php/docker
docker build --tag grpc_php:1.0 .
cd ..
docker run --rm   -v $(pwd)/proto-php:/out   -v $(pwd)/../rpc:/protos   grpc_php:1.0

License

bchwallet is licensed under the liberal ISC License.

Contact

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