Project 16: Basic RPC Calculator

A calculator service using Sun RPC with rpcgen-generated stubs.

Quick Reference

Attribute Value
Primary Language C
Alternative Languages N/A
Difficulty Level 3 (Advanced)
Time Estimate See main guide
Knowledge Area Distributed Systems, RPC
Tooling See main guide
Prerequisites See main guide

What You Will Build

A calculator service using Sun RPC with rpcgen-generated stubs.

Why It Matters

This project builds core skills that appear repeatedly in real-world systems and tooling.

Core Challenges

  • rpcgen syntax → Writing .x interface files
  • XDR types → Serializing complex structures
  • portmapper → Registering and looking up services

Key Concepts

  • Map the project to core concepts before you code.

Real-World Outcome

# Define the interface (calc.x)
$ cat calc.x
program CALC_PROG {
    version CALC_VERS {
        int ADD(operands) = 1;
        int SUBTRACT(operands) = 2;
        int MULTIPLY(operands) = 3;
    } = 1;
} = 0x31230000;

# Generate stubs
$ rpcgen calc.x
# Creates: calc.h, calc_clnt.c, calc_svc.c, calc_xdr.c

# Start server
$ ./calc_server &
Registered with portmapper: program 0x31230000, version 1

# Run client
$ ./calc_client localhost add 5 3
Result: 8

$ ./calc_client localhost multiply 7 6
Result: 42

# Query portmapper
$ rpcinfo -p localhost | grep 31230000
    100000    4   tcp    111  portmapper
0x31230000    1   tcp  45678  calc

Implementation Guide

  1. Reproduce the simplest happy-path scenario.
  2. Build the smallest working version of the core feature.
  3. Add input validation and error handling.
  4. Add instrumentation/logging to confirm behavior.
  5. Refactor into clean modules with tests.

Milestones

  • Milestone 1: Minimal working program that runs end-to-end.
  • Milestone 2: Correct outputs for typical inputs.
  • Milestone 3: Robust handling of edge cases.
  • Milestone 4: Clean structure and documented usage.

Validation Checklist

  • Output matches the real-world outcome example
  • Handles invalid inputs safely
  • Provides clear errors and exit codes
  • Repeatable results across runs

References

  • Main guide: UNIX_IPC_STEVENS_VOL2_MASTERY.md
  • Primary references are listed in the main guide