···637637TODO
638638639639640640-641641----
642642-643643-Let's create the client during the server init:
644644-645645-```typescript
646646-/** index.ts **/
647647-import { NodeOAuthClient } from '@atproto/oauth-client-node'
648648-649649-// static async create() {
650650-// ...
651651-652652-const publicUrl = env.PUBLIC_URL
653653-const url = publicUrl || `http://127.0.0.1:${env.PORT}`
654654-const oauthClient = new NodeOAuthClient({
655655- clientMetadata: {
656656- client_name: 'AT Protocol Express App',
657657- client_id: publicUrl
658658- ? `${url}/client-metadata.json`
659659- : `http://localhost?redirect_uri=${encodeURIComponent(`${url}/oauth/callback`)}`,
660660- client_uri: url,
661661- redirect_uris: [`${url}/oauth/callback`],
662662- scope: 'profile offline_access',
663663- grant_types: ['authorization_code', 'refresh_token'],
664664- response_types: ['code'],
665665- application_type: 'web',
666666- token_endpoint_auth_method: 'none',
667667- dpop_bound_access_tokens: true,
668668- },
669669- stateStore: new StateStore(db),
670670- sessionStore: new SessionStore(db),
671671-})
672672-673673-// ...
674674-// }
675675-```
676676-677677-There's quite a bit of configuration which is [explained in the OAuth guide](#todo). We host that config at `/client-metadata.json` as part of the OAuth flow.
678678-679679-```typescript
680680-/** src/routes.ts **/
681681-682682-// OAuth metadata
683683-router.get(
684684- '/client-metadata.json',
685685- handler((_req, res) => {
686686- return res.json(oauthClient.clientMetadata)
687687- })
688688-)
689689-```
690690-691691----
692692-693693-694694-695695-We're going to need to track two kinds of information:
696696-697697-- **OAuth State**. This is information about login flows that are in-progress.
698698-- **OAuth Sessions**. This is the active session data.
699699-700700-The `oauth-client-node` library handles most of this for us, but we need to create some tables in our SQLite to store it. Let's update `/src/db.ts` for this.
701701-702702-```typescript
703703-// ...
704704-// Types
705705-706706-export type DatabaseSchema = {
707707- auth_session: AuthSession
708708- auth_state: AuthState
709709-}
710710-711711-export type AuthSession = {
712712- key: string
713713- session: string // JSON
714714-}
715715-716716-export type AuthState = {
717717- key: string
718718- state: string // JSON
719719-}
720720-721721-// Migrations
722722-723723-migrations['001'] = {
724724- async up(db: Kysely<unknown>) {
725725- await db.schema
726726- .createTable('auth_session')
727727- .addColumn('key', 'varchar', (col) => col.primaryKey())
728728- .addColumn('session', 'varchar', (col) => col.notNull())
729729- .execute()
730730- await db.schema
731731- .createTable('auth_state')
732732- .addColumn('key', 'varchar', (col) => col.primaryKey())
733733- .addColumn('state', 'varchar', (col) => col.notNull())
734734- .execute()
735735- },
736736- async down(db: Kysely<unknown>) {
737737- await db.schema.dropTable('auth_state').execute()
738738- await db.schema.dropTable('auth_session').execute()
739739- },
740740-}
741741-742742-// ...
743743-```
744744-745745-746746-----
747747-748748-749749-Data in the Atmosphere is stored on users' personal servers. It's almost like each user has their own website. Our goal is to aggregate data from the users into our SQLite.
750750-751751-Think of our app like a Google. If Google's job was to say which emoji each website had under `/status.txt`, then it would show something like:
752752-753753-- `nytimes.com` is feeling 📰 according to `https://nytimes.com/status.txt`
754754-- `bsky.app` is feeling 🦋 according to `https://bsky.app/status.txt`
755755-- `reddit.com` is feeling 🤓 according to `https://reddit.com/status.txt`
756756-757757-The Atmosphere works the same way, except we're going to check `at://nytimes.com/com.example.status/self`. Literally, that's it! Each user has a domain, and each record gets published under an atproto URL.
758758-759759-```
760760-AT Protocol
761761- ▼
762762-at://nytimes.com/com.example.status/self
763763- ▲ ▲ ▲
764764- The user The data type The record name
765765-```
766766-767767-When somebody logs into our app, they'll give read & write access to their personal `at://`. We'll use that to write the `/com.example.status/self` record. Then we'll crawl the Atmosphere for all the other `/com.example.status/self` records, and aggregate them into our SQLite database for fast reads.
768768-769769-Believe it or not, that's how most apps on the Atmosphere are built, including [Bluesky](#todo).