Riak Protocol Buffers Messages

This repository contains the message definitions for the Protocol Buffers-based interface to Riak and various Erlang-specific utility modules for the message types.

This is distributed separately from the Riak server and clients, allowing it to serve as an independent representation of the supported messages. Additionally, the .proto descriptions are broken out by functional area:

• riak.proto contains "global" messages like the error message and the "server info" calls.
• riak_kv.proto contains messages related to Riak KV.

Other specifications may arise as more features are exposed via the PB interface.

Protocol

The Riak PBC protocol encodes requests and responses as Protocol Buffers messages. Each request message results in one or more response messages. As message type and length are not encoded by PB, they are sent on the wire as:

<length:32> <msg_code:8> <pbmsg>

• length is the length of msg_code (1 byte) plus the message length in bytes encoded in network order (big endian).

• msg_code indicates what is encoded as pbmsg

• pbmsg is the encoded protocol buffer message

On connect, the client can make requests and will receive responses. For each request message there is a corresponding response message, or the server will respond with an error message if something has gone wrong.

The client should be prepared to handle messages without any pbmsg (i.e. length == 1) for requests where the response is simply an acknowledgment.

In some cases, a client may receive multiple response messages for a single request. The response message will typically include a boolean done field that signifies the last message in a sequence.