Service graph evolution tutorial

This tutorial turns system growth into something inspectable. You will run graph scenarios, compare contract changes, and see how compatible services join the graph without upstream rewrites.

By Enrico Piovesan Updated June 22, 2026

Tutorial route

Use the in-page route block to move through the graph progression without relying on footer links for the main sequence.

Open source folder All UMA examples Previous: Metadata Orchestration Next: Trust Boundaries

What you will learn

how service graphs emerge from contracts and event compatibility
how Git-style diffs expose architecture changes
how broken compatibility fails visibly and recovers predictably

Prerequisites

Rust 1.76 or newer
Node.js 20 or newer
a checkout of the repository

Full tutorial

Enter the example
```
cd chapter-08-service-graph
```
List the graph labs
```
./scripts/list_labs.sh
```

Validate the first scenario contracts

./scripts/validate_graph_contracts.sh lab1-upload-only

Run the upload-only graph

./scripts/run_graph_demo.sh lab1-upload-only

Inspect the contract change to image tagging

./scripts/contract_diff.sh lab1-upload-only lab2-image-tagger

Run the indexer graph

./scripts/run_graph_demo.sh lab3-indexer

Compare a compatibility break

./scripts/graph_diff.sh lab3-indexer lab4-broken-compat

Run the full smoke path
```
./scripts/smoke_graph_labs.sh
```

What to inspect

After each command, look for these proof points. They are the signals that connect the code example back to the UMA architecture claim.

capability lines
consumes and emits lines
Edges
Waiting Consumers

Acceptance check

The chapter-level validation path is:

./scripts/smoke_graph_labs.sh

Return to the repository root for the final acceptance gate:

cd ..
./scripts/smoke_reader_paths.sh

Where to go next

Chapter 9 adds explicit trust and runtime enforcement.

Open source folder All UMA examples Read Chapter 9: Services to Systems → Previous: Metadata Orchestration Next: Trust Boundaries