refactor(app): share application components and request services

src/services/application.js

@@ -0,0 +1,40 @@
+import { createSourceSlot } from '../app/sourceSlot.js';
+import { createApplicationRequestServices } from './requests.js';
+
+// Compatibility owners are page-scoped, like the viewer and its layer registry.
+const defaults = createApplicationRequestServices();
+const slots = Object.fromEntries(
+  Object.entries({
+    boundaries: ['query'],
+    terrain: ['getHeights'],
+    regional: ['getBrief'],
+    weather: ['getConditions'],
+    summary: ['summarize'],
+  }).map(([name, methods]) => [
+    name,
+    createSourceSlot(defaults[name], methods, `${name} service`),
+  ]),
+);
+export const applicationServices = Object.freeze(
+  Object.fromEntries(
+    Object.entries(slots).map(([name, slot]) => [name, slot.source]),
+  ),
+);
+
+/** Supply selected services before constructing the application; release after its consumers. */
+export function configureApplicationServices(services) {
+  const releases = [];
+  try {
+    for (const [name, service] of Object.entries(services)) {
+      if (!slots[name])
+        throw new TypeError(`Unknown application service: ${name}`);
+      releases.push(slots[name].configure(service));
+    }
+  } catch (error) {
+    for (const release of releases.reverse()) release();
+    throw error;
+  }
+  return () => {
+    for (const release of releases.reverse()) release();
+  };
+}