Introduction

This is a repo created for an internal presentation to demonstrate some high level concepts of gRPC in Python.

This repo contains:

• An account protobuf
• A Python gRPC server implementation of account.proto
• A Python gRPC stub (client) implementation of account.proto

We implement two RPC methods to demonstrate:

• GetAccount - a unary connection (like a REST GET request/response)
• StreamIndustryIds - a client-side streaming connection (streams responses as an iterator from server)

There are three branches:

• main
  • original implementation
• 01-update-server-with-new-fields
  • add a new field to GetAccountResponse and update server to return the new field
  • client should continue to work
• 02-update-client-to-use-new-contract
  • update client to implement new contract

Presentation Slides

• Google Slides (Internal access only)
• Markdown version

Develop

Step 1: Create a virutalenv and install dependencies

Use your favourite tool to create virtual environment and install dependencies in requirements.txt.

Step 2: Generate python types and classes based on account.proto

In ./account_server/account_server and ./account_client/account_client, use the following command to generate three files:

• account_pb2.py
  • contains the generated message types and enums defined in the protobuf file
• account_pb2_grpc.py
  • contains the generated service servicer (server) and stub (stub) abstract classes to be implemented
• account_pb2.pyi
  • contains mypy types using the plugin mypy_protobuf

python -m grpc_tools.protoc \
  -I ../../protos \
  --plugin=protoc-en-mypy=/Users/alanlau/.pyenv/shims/protoc-gen-mypy \
  --mypy_out=. \
  --python_out=. \
  --grpc_python_out=. \
  ../../protos/account.proto

Rerun this step if you've made changes to the protobuf account.proto.

Step 3: Implement server and client code

The server code lives under ./account_server, and the stub (client) lives under ./account_client.

They can be updated independently of each other in the case of new field or features added in contract.

Step 4: Start server and client

python account_[server|client].py