This package is the single source of truth for the shapes of a tile manifest (MASL), its resources, and the responses produced when resolving a resource, and for the security policy of tile origins. It ships the schema data and that policy; everything else is types, which erase at compile time.

Install #

npm install @dasl/tile-lexicon

Runtime exports #

import { masl, maslHTTPHeaders } from '@dasl/tile-lexicon';

masl.id;                    // 'ing.dasl.masl'
masl.defs.masl.required;    // ['name', 'resources']
maslHTTPHeaders['content-type']; // { type: 'string' }

masl — the ing.dasl.masl lexicon document (the masl object definition and the tid-keyed main record that instantiates it into an AT record).
maslHTTPHeaders — the set of HTTP headers a MASL resource may carry, expressed as lexicon property definitions.

Policy #

The security policy for tile origins lives here, once, so that @dasl/tile-server, @dasl/tile-loader and every deployment agree, and it is edited in one place:

import { tileCSP, runtimeCSP, deadCSP, runtimeHeaders, deadHeaders, tileResponseHeaders } from '@dasl/tile-lexicon';

tileCSP: for tile documents (what the worker serves). Scripting is unrestricted; connect-src, frame-src and form-action keep every byte on the tile's own origin; webrtc 'block'; the tile sandbox.
runtimeCSP / runtimeHeaders: for the loader runtime under /.well-known/web-tiles/, tighter still (connect-src 'none').
deadCSP / deadHeaders: for anything else a tile origin answers: loads nothing, runs nothing, opaque origin.
tileResponseHeaders(headers): a resource's own headers with the policy added. A CSP the tile declares is kept and enforced alongside; speculation rules and remote Link targets are dropped. The mothership runs every response through it.

Types #

Type-only imports (import type { … }) give you the vocabulary the other packages speak:

import type {
  Masl, StoredMasl, WriterMasl, InMemoryMasl, AnyMasl,
  ResourceEntry, StoredResourceEntry, WriterResourceEntry, InMemoryResourceEntry,
  CidLink, BlobRef, MaslHeaders,
  MaslResponse, MaslResponseOk, MaslResponseError,
  MaslIcon, MaslScreenshot, MaslSizing,
} from '@dasl/tile-lexicon';

Masl<E> is generic over the shape of its resource entries, because the same manifest is described differently depending on context:

Alias	Resource `src` is…	Used by
`StoredMasl`	a `CidLink` / `BlobRef` read from a CAR or AT record	`@dasl/tile-car-reader`, AT/CAR loaders
`WriterMasl`	a `CidLink` / `BlobRef` filled in on write (optional while building)	`@dasl/tile-writer`, `atile`
`InMemoryMasl`	raw bytes (`ArrayBuffer` / `Uint8Array` / `string`)	memory & webXDC loaders
`AnyMasl`	any of the above	`@dasl/tile-loader`

Part of DASL tiles #

@dasl/tiles — meta-package re-exporting the whole toolkit
@dasl/tile-loader — load tiles in the browser
@dasl/tile-server — the browser tile-loading server
@dasl/tile-writer — write tiles into .tile files
@dasl/tile-car-reader — read tiles from a CAR file
@dasl/atile — the tile-publishing CLI

License #

Apache-2.0