[discovery] first draft of DiscoveryClient

packages/discovery/package.json

@@ -32,10 +32,14 @@
   },
   "devDependencies": {
     "@solid-notifications/types": "^0.0.0",
-    "@solid/community-server": "^5.1.0",
+    "@solid/community-server": "^6.0.1",
     "@types/jest": "^29.5.0",
     "jest": "^29.5.0",
     "solid-test-utils": "^0.0.0",
     "ts-jest": "^29.1.0"
+  },
+  "dependencies": {
+    "@janeirodigital/interop-utils": "^1.0.0-rc.20",
+    "n3": "^1.16.4"
   }
 }

packages/discovery/src/client.ts

@@ -0,0 +1,66 @@
+import { DataFactory } from 'n3'
+import { parseTurtle, getDescriptionResource, getOneMatchingQuad, getAllMatchingQuads, NOTIFY, getStorageDescription } from '@janeirodigital/interop-utils'
+import type { DatasetCore } from '@rdfjs/types'
+import { ChannelType, SubscriptionService } from '@solid-notifications/types'
+
+export class DiscoveryClient {
+
+  private parser: {
+    contentType: 'text/turtle' | 'application/ld+json',
+    parse: typeof parseTurtle
+  }
+  constructor(private authnFetch: typeof fetch) {
+    // TODO pass Turtle or JSON-LD parser and set accordignly
+    this.parser = {
+      contentType: 'text/turtle',
+      parse: parseTurtle
+    }
+  }
+
+  async findService(resourceUri: string, channelType: ChannelType): Promise<SubscriptionService | null> {
+
+    const storageDescription = await this.fetchStorageDescription(resourceUri)
+    console.log([...storageDescription])
+
+    // TODO handle multiple matching services
+    const serviceNode = getOneMatchingQuad(storageDescription, null, NOTIFY.channelType, DataFactory.namedNode(channelType))?.subject
+    if (!serviceNode) return null
+    const features = getAllMatchingQuads(storageDescription, serviceNode, NOTIFY.feature).map(quad => quad.object.value)
+    return {
+      id: serviceNode.value,
+      channelType,
+      feature: features
+    }
+  }
+
+
+  // TODO use some rdf-fetch util
+  async fetchResource(resourceUri): Promise<DatasetCore> {
+    const response = await this.authnFetch(resourceUri, {
+      headers: {
+        'Accept': this.parser.contentType
+      }
+    })
+    return this.parser.parse(await response.text(), response.url)
+  }
+
+  async discoverStorageDescription(resourceUri: string): Promise<string> {
+    const response = await this.authnFetch(resourceUri, { method: 'head' })
+    return getStorageDescription(response.headers.get('Link'))
+  }
+
+  async fetchStorageDescription(resourceUri): Promise<DatasetCore> {
+    const storageDescriptionUri = await this.discoverStorageDescription(resourceUri)
+    return this.fetchResource(storageDescriptionUri)
+  }
+
+  async discoverDescriptionResource(resourceUri: string): Promise<string> {
+    const response = await this.authnFetch(resourceUri, { method: 'head' })
+    return getDescriptionResource(response.headers.get('Link'))
+  }
+
+  async fetchDescriptionResource(resourceUri): Promise<DatasetCore> {
+    const resourceDescriptionUri = await this.discoverDescriptionResource(resourceUri)
+    return this.fetchResource(resourceDescriptionUri)
+  }
+}

packages/discovery/src/index.ts

@@ -1 +1 @@
-export * from "./getDescribedByUri";
+export * from "./client";

packages/discovery/test/client.test.ts

@@ -0,0 +1,60 @@
+import SolidTestUtils from "solid-test-utils";
+import { DiscoveryClient } from "../src/client";
+import { DC, NOTIFY } from "@janeirodigital/interop-utils";
+
+describe("discovery", () => {
+  const stu = new SolidTestUtils();
+  beforeAll(async () => stu.beforeAll());
+  afterAll(async () => stu.afterAll());
+
+  const cardUri = "http://localhost:3001/example/profile/card"
+
+  test("discoverStorageDescription", async () => {
+    const client = new DiscoveryClient(stu.authFetch)
+    const storageDescriptionUri = await client.discoverStorageDescription(cardUri)
+    expect(storageDescriptionUri).toBe('http://localhost:3001/example/.well-known/solid');
+  });
+
+  test("fetchStorageDescription", async () => {
+    const client = new DiscoveryClient(stu.authFetch)
+    const dataset = await client.fetchStorageDescription(cardUri)
+    expect(dataset.match(null, NOTIFY.subscription, NOTIFY.WebhookChannel2023)).toBeTruthy()
+  });
+
+  test("discoverDescriptionResource", async () => {
+    const client = new DiscoveryClient(stu.authFetch)
+    const resourceDescriptionUri = await client.discoverDescriptionResource(cardUri)
+    expect(resourceDescriptionUri).toBe('http://localhost:3001/example/profile/card.meta');
+  });
+
+  test("fetchDescriptionResource", async () => {
+    const client = new DiscoveryClient(stu.authFetch)
+    const dataset = await client.fetchDescriptionResource(cardUri)
+    expect(dataset.match(null, DC.modified)).toBeTruthy()
+  });
+
+  test("find Webhook service", async () => {
+    const client = new DiscoveryClient(stu.authFetch)
+    const service = await client.findService(cardUri, NOTIFY.WebhookChannel2023.value)
+    expect(service).toEqual(expect.objectContaining({
+      id: 'http://localhost:3001/.notifications/WebhookChannel2023/',
+      channelType: NOTIFY.WebhookChannel2023.value
+    }))
+  });
+
+  test("find Web Socket service", async () => {
+    const client = new DiscoveryClient(stu.authFetch)
+    const service = await client.findService(cardUri, NOTIFY.WebSocketChannel2023.value)
+    expect(service).toEqual(expect.objectContaining({
+      id: 'http://localhost:3001/.notifications/WebSocketChannel2023/',
+      channelType: NOTIFY.WebSocketChannel2023.value
+    }))
+  });
+
+  test("find non existing service", async () => {
+    const client = new DiscoveryClient(stu.authFetch)
+    //@ts-ignore
+    const service = await client.findService(cardUri, 'https://fake.example/SomeChannel')
+    expect(service).toBeNull()
+  });
+});

packages/solid-test-utils/package.json

@@ -28,7 +28,7 @@
   },
   "devDependencies": {
     "@inrupt/solid-client-authn-core": "^1.14.0",
-    "@solid/community-server": "^5.1.0",
+    "@solid/community-server": "^6.0.1",
     "node-fetch": "^3.3.1"
   }
 }

packages/types/src/NotificationChannel.ts

@@ -1,6 +1,11 @@
+export enum ChannelType {
+  WebhookChannel2023 = 'http://www.w3.org/ns/solid/notifications#WebhookChannel2023',
+  WebSocketChannel2023 = 'http://www.w3.org/ns/solid/notifications#WebSocketChannel2023',
+}
+
 export interface NotificationChannel {
   id: string;
-  type: string;
+  type: ChannelType; // TODO channel types should be extendible
   topic: string | string[];
   receiveFrom: string;
   sendTo?: string;