Table of Contents

• Exercises — Month 5 · Week 1 (gRPC, Architecture & Microservices)
• Prompts
  • 1. varint — protobuf base-128 varints
  • 2. frames — gRPC length-prefixed framing
  • 3. statuscode — gRPC canonical status model
• Results

Exercises — Month 5 · Week 1 (gRPC, Architecture & Microservices)

Standard-library-only exercises that rebuild the machinery beneath gRPC: the protobuf wire format, length-prefixed streaming frames, and the canonical status-code error model. Run all tests:

go test ./exercises/month-05/week-1/...

Prompts

1. varint — protobuf base-128 varints

Implement AppendUvarint/ReadUvarint (the encoding behind every protobuf field tag and VARINT value) plus ZigZagEncode/ZigZagDecode for signed sint fields. Handle truncated and overlong (>10-byte) input with errors.

• Each output byte carries 7 payload bits, low group first; bit 0x80 = "more".
• ZigZag maps -1 -> 1, 1 -> 2, so small negatives stay small.
• Cross-check byte counts against encoding/binary.PutUvarint.

2. frames — gRPC length-prefixed framing

Implement WriteFrame/ReadFrame/ReadAll for the 5-byte gRPC frame: [1 flag byte][4 big-endian length bytes][payload].

• Use io.ReadFull; a clean end-of-stream is io.EOF, a cut mid-frame is io.ErrUnexpectedEOF.
• Bound the payload allocation with a maxSize to reject hostile length prefixes.
• Zero-length payloads must round-trip.

3. statuscode — gRPC canonical status model

Implement the Code type (0–16) with String(), a Status{Code, Message} error whose Err() returns nil for OK, FromError (plain errors -> Unknown, wrapped statuses recovered via errors.As), and HTTPStatus (the grpc-gateway code→HTTP table).

Results

Exercise	Focus	Status
varint	protobuf varint + zigzag encoding	✅ green
frames	length-prefixed streaming frames	✅ green
statuscode	gRPC status codes + HTTP mapping	✅ green