Glossary

The words these pages use, in alphabetical order.

Admit. The hook method that decides whether a peer may join an app’s coordination: accept, accept read-only, or reject.

App id. An app’s reverse-DNS name, such as com.slashbuilder.demo.notepad, set in its manifest.

App Context Kit. The Kit that is the root namespace for one running app: identity, directories, settings, modes, a roster entry, a session with a resource broker, and an opt-in way to find other copies of the app.

Candidate. A UI component proposed for the shared interface Kit, built from what several apps duplicate. See labs/interface_candidates. A candidate marked THIN has fewer than three real users.

Context. What an app receives from the App Context Kit when it starts: its directories, settings, notes for the person, session and peers. In Flutter, AppContextScope.of(context).

Core (role). In kits.lock, a Kit this book documents and whose own tests run in make test. The other roles are app-dep (needed by another Kit to build; fetched, not tested here) and reference (documented but not needed to build the apps).

Fetch. Downloading a Kit at its pinned commit into .kits/ with make setup or make fetch. No git is needed.

Hold. A reservation on a shared machine’s resources, taken from the Venue for the length of a job and released afterwards. A hold lasts for a lease; a crashed app keeps its hold until the lease runs out.

Hook. The five small methods an app supplies to say what coordination means for that app: channel, hello, admit, onPeer and onMessage. The App Context Kit finds and connects copies and routes messages; it never reads a payload.

Kit. A focused piece of SlashBuilder’s platform that owns one job. See the introduction.

Kit gap. Code an app wrote itself because a Kit lacked it. By rule it lives in the app’s lib/kit_gaps/ with a // KIT GAP: comment, and the line count of those folders measures what the Kits are missing.

Manifest. An app’s app.json: id, name, version, the Kit features it uses and its Venue settings.

Mock mode. A mode, switched on with APP_CONTEXT_MODE=mock, in which the outside world is replaced by in-memory fakes. Together with scratch mode (APP_CONTEXT_SCRATCH=<dir>, which puts every directory under one folder) it lets tests run without touching real files.

Peer. Another copy of the same app, on the same account, that the App Context Kit found and connected to.

Pin. The commit of a Kit that this repository uses, recorded in kits.lock. make lock shows how to move it.

Probe. A small program that exercises one thing and prints what happened. The apps’ tool/ folders hold probes that run an app’s own coordination code without a window. Probes of other Kits run in a private repository; the book carries only a summary.

Refusal. A typed answer from the Venue saying it will not grant a hold, for example because the app already holds its limit.

Roster. The set of presence files, one per running copy of an app, that lets apps (and the launcher demo) see who else is running on the machine.

Venue. The resource broker: a daemon that grants and tracks holds on a machine’s resources.