Glossary

Terms in alphabetical order. Each links to the page that explains it.

App origin: the origin a native app’s document has for storage, since it has no URL: https://<app>.app.niso, or what the host sets with niso_dom_set_app_origin (Storage).

Baseline: the web’s own measure of which features work across browsers, from the web-features project. niso’s WPT suite runs every Baseline feature’s tests (Web platform support).

Binding: the code that gives a language the DOM: the JS binding (glue, niso_js.c, generated host functions) on each engine, JNI for the JVM, the C headers for C, Zig and Go.

Bracket (call bracket): what wraps every call into the core: catch panics, deliver what the call queued (tree moves, scripts, custom element reactions, microtasks, animation promises), end at a safe point, return a status (Architecture).

Composition: putting the C runtime header and the JS glue together at build time from sections that each belong to a crate (niso-compose, crates/niso-compose/sections.txt). “A build is the set of crates it links.”

Contract: a crate’s CONTRACT.md: what it owns, its API, its invariants, its threading and lifetime rules (Crates).

Driver: an interface a host can implement to replace a built-in part, such as the storage driver (Storage).

Engine: the JavaScript engine running a page: QuickJS-ng, V8 or JavaScriptCore through Node-API, or Porffor (Engines).

Glue: the JavaScript half of niso’s web APIs, shared by every engine (Glue).

Handle: a 64-bit generational id for a DOM object, never a pointer; 0 is null (The document).

Host: the native program around a document: it owns the window, runs the event loop each frame, draws the render stream and reports input. Apple (SwiftUI), Android (Compose), iced; niso-run and niso-node are headless hosts (Hosts).

IFC (inline formatting context): a run of inline content laid out as lines, such as a paragraph. Each is one native text view.

Layer: a crate’s level in the dependency order (L0 foundation, L1 web APIs and the document, L2 document extensions, L3 compositions), enforced by cargo xtask layers (Architecture).

Native control: an HTML element drawn as the platform’s own control while its appearance is auto (Native controls).

Native module: an API a page imports as niso:<name>, implemented in the app’s native code and declared in WebIDL (Native modules).

Platform style: the platform’s base sheet and --niso-* tokens a page asks for with the niso-platform-style meta (Platform style).

Render node: a box in the laid-out tree that the host keeps one native view for; its id is the DOM handle of the element or anonymous box generating it.

Render stream: the per-frame binary list of changes to the box tree that niso_render_frame returns and hosts apply (Rendering, format).

Safe point: the end of a call or task, with nothing borrowed, where objects freed during it get their freed callback.

Surface: an element with data-niso-surface, sent to a widget, Live Activity, notification or CarPlay instead of being drawn in the page (Surfaces).

Template: a surface’s box tree with text as strings, in the format template targets take (Surfaces).

Turn: one task with its microtask checkpoint, or one piece of input the host delivers; the unit the event loop runs.

Virtual time: the event loop skipping its clock ahead to the next due timer instead of waiting, so headless runs and tests take milliseconds.

Wake hook: the callback a document calls, from any thread, when something arrived (a worker’s message, the network, a native module) and the host should run it again.

WPT: web-platform-tests, the browsers’ shared conformance suite, which niso runs headless (Run WPT).