A3.9 · Glossary & references · dive 3
The crosswalk
Each course idea mapped to the /elixir/phoenix chapter that
implements it — the nine F6 rungs as routes you can open.
The crosswalk is where the course's abstractions become routes: lifecycle, routing, ecto, contexts, heex, liveview, pubsub, deployment, live-dashboard — each 200, all under one master invariant. Pick an idea on the right to get its rung and route; the section below groups the rungs into the three shippable milestones.
Idea to rung to route · pick an idea
The crosswalk
A crosswalk row maps a course idea to the F6 rung that realises it, the
/elixir/phoenix chapter, and what that rung ships. The nine rungs are
verbatim from the F6 phoenix.roadmap.md — three milestones, one
shippable capability per rung, all of it over the unchanged Portal facade.
The master invariant spans all nine: the web layer calls only the
Portal facade and renders only the closed
%Portal.Error{} set.
The three milestones
The nine rungs climb in three milestones, each a shippable product step: ship the catalog, make it live, ship to users. Pick a milestone to light its rungs and read the end-state — the thing a real role can do once the milestone lands.
Rungs grouped into milestones · pick a milestone
A roadmap orders the work into shippable milestones — each a product step a real role can use, not a technical layer.
The crosswalk on the Portal
The crosswalk is the F6 phoenix.roadmap.md read as a lookup table. Take
"durable persistence": the roadmap line is F6.3, the milestone is "ship the catalog", the spec it
points at is the F6.3 triad, and the behaviour the line defines is none — the
line orders the work; the spec defines it. Open /elixir/phoenix/ecto and the
idea is built code: the Postgres adapter behind the F5 port, the changeset the parse boundary.
# One crosswalk row, from the F6 phoenix.roadmap.md: # idea: durable persistence # rung: F6.3 # milestone: ship the catalog # points at: the F6.3 spec triad (behaviour defined by the line = none) # route: /elixir/phoenix/ecto (the idea as built code) # Re-ordering the rungs never edits a spec — the line carries order, not behaviour.
A roadmap line orders the work and points at a spec; it defines no behaviour — re-ordering the rungs never edits a spec.
The F6 phoenix.roadmap.md is exactly that — nine lines, three
milestones, each pointing at a rung's spec and its
/elixir/phoenix chapter.
The crosswalk turns the course into routes — every idea to a rung, every rung to a chapter of built code, all of it under one master invariant.
References
The delivery sources behind the roadmap, and the sibling reference dives.
Sources
- Humble & Farley — Continuous Delivery — the roadmap, milestones, and releasable increments.
- Beck, K. — Extreme Programming Explained — small batches and the iteration cadence the rungs run to.
- Hunt & Thomas — The Pragmatic Programmer — the master invariant and thin-but-robust rungs.
Related in this course
- A3.9 · Glossary & references — the module hub.
- A3.9.1 · The glossary — the term index.
- A3.9.2 · The annotated sources — the previous dive.
- A3 · The roadmap layer — the chapter.
- F6 · The Portal on the web — the nine rungs as built code.