feat: track podlet assets

README.md

@@ -152,7 +152,6 @@ The following values can be provided:
 -   `throwable` - {Boolean} - Defines whether an error should be thrown if a failure occurs during the process of fetching a podium component. Defaults to `false` - Optional.
 -   `excludeBy` - {Object} - Lets you define a set of rules where a `fetch` call will not be resolved if it matches. - Optional.
 -   `includeBy` - {Object} - Inverse of `excludeBy`. Setting both at the same time will throw. - Optional.
--   `earlyHints` - {boolean} - Can be used to disable early hints from being sent to the browser for this resource, see [HTTP Status 103 Early Hints](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/103).
 
 ##### `excludeBy` and `includeBy`
 

lib/http-outgoing.js

@@ -1,6 +1,6 @@
 import { PassThrough } from 'stream';
 import assert from 'assert';
-import { toPreloadAssetObjects, filterAssets } from './utils.js';
+import { filterAssets } from './utils.js';
 
 /**
  * @typedef {object} PodiumClientHttpOutgoingOptions
@@ -70,6 +70,7 @@ export default class PodletClientHttpOutgoing extends PassThrough {
     #uri;
     #js;
     #css;
+    #assetsReceived = false;
 
     /**
      * @constructor
@@ -332,6 +333,26 @@ export default class PodletClientHttpOutgoing extends PassThrough {
         return this.#isFallback;
     }
 
+    get assetsReceived() {
+        return this.#assetsReceived;
+    }
+
+    /**
+     * Set the assetsReceived flag.
+     * This is used to signal to the assets object that the client has received assets for a given podlet so it can track
+     * which podlets have sent their assets.
+     * @param {boolean} value
+     */
+    set assetsReceived(value) {
+        this.#assetsReceived = value;
+        if (this.#assetsReceived) {
+            this.#incoming?.assets?.addReceivedAsset(this.#name, {
+                js: this.js,
+                css: this.css,
+            });
+        }
+    }
+
     pushFallback() {
         // @ts-expect-error Internal property
         this.push(this.#manifest._fallback);
@@ -349,21 +370,8 @@ export default class PodletClientHttpOutgoing extends PassThrough {
                 : filterAssets('fallback', this.#manifest.css);
         this.push(null);
         this.#isFallback = true;
-        // assume the hints from the podlet have failed and fallback assets will be used
-        this.hintsReceived = true;
-    }
-
-    writeEarlyHints(cb = () => {}) {
-        if (this.#incoming.response.writeEarlyHints) {
-            const preloads = toPreloadAssetObjects([
-                ...(this.js || []),
-                ...(this.css || []),
-            ]);
-            const link = preloads.map((preload) => preload.toHeader());
-            if (link.length) {
-                this.#incoming.response.writeEarlyHints({ link }, cb);
-            }
-        }
+        // assume the assets from the podlet have failed and fallback assets will be used
+        this.assetsReceived = true;
     }
 
     get [Symbol.toStringTag]() {

lib/resolver.content.js

@@ -267,6 +267,9 @@ export default class PodletClientContentResolver {
                 }),
             );
 
+            // mark assets as received
+            outgoing.assetsReceived = true;
+
             // @ts-ignore
             pipeline([body, outgoing], (err) => {
                 if (err) {

lib/resolver.js

@@ -11,7 +11,6 @@ import Cache from './resolver.cache.js';
  * @typedef {object} PodletClientResolverOptions
  * @property {string} clientName
  * @property {import('abslog').AbstractLoggerOptions} [logger]
- * @property {boolean} [earlyHints]
  */
 
 export default class PodletClientResolver {

lib/resource.js

@@ -105,6 +105,8 @@ export default class PodiumClientResource {
             throw new TypeError(
                 'you must pass an instance of "HttpIncoming" as the first argument to the .fetch() method',
             );
+        // set expectation to receive a response from this podlet.
+        incoming.assets.addExpectedAsset(this.#options.name);
         const outgoing = new HttpOutgoing(this.#options, reqOptions, incoming);
 
         if (this.#options.excludeBy) {
@@ -192,6 +194,8 @@ export default class PodiumClientResource {
             throw new TypeError(
                 'you must pass an instance of "HttpIncoming" as the first argument to the .stream() method',
             );
+        // set expectation to receive a response from this podlet.
+        incoming.assets.addExpectedAsset(this.#options.name);
         const outgoing = new HttpOutgoing(this.#options, reqOptions, incoming);
         this.#state.setInitializingState();
         this.#resolver.resolve(outgoing);

package.json

@@ -40,7 +40,7 @@
     "@hapi/boom": "10.0.1",
     "@metrics/client": "2.5.3",
     "@podium/schemas": "5.1.0",
-    "@podium/utils": "5.3.2",
+    "@podium/utils": "5.4.0",
     "abslog": "2.4.4",
     "http-cache-semantics": "^4.0.3",
     "lodash.clonedeep": "^4.5.0",

tests/integration.basic.test.js

@@ -710,3 +710,66 @@ tap.test(
         server.close();
     },
 );
+
+tap.test(
+    'integration - asset link header used to build a document head',
+    async (t) => {
+        t.plan(1);
+        const header = new PodletServer({
+            name: 'header',
+            assets: {
+                js: 'http://example.com/header/bar.js',
+                css: 'http://example.com/header/bar.css',
+            },
+        });
+        const footer = new PodletServer({
+            name: 'footer',
+            assets: {
+                js: 'http://example.com/footer/bar.js',
+                css: 'http://example.com/footer/bar.css',
+            },
+        });
+
+        const service = await Promise.all([header.listen(), footer.listen()]);
+
+        const client = new Client({ name: 'podiumClient' });
+
+        const headerClient = client.register(service[0].options);
+        const footerClient = client.register(service[1].options);
+
+        const incoming = new HttpIncoming({ headers });
+
+        const headerFetch = headerClient.fetch(incoming);
+        const footerFetch = footerClient.fetch(incoming);
+
+        incoming.assets.once('received', ({ js, css }) => {
+            const documentHead = `
+            <html>
+              <head>
+                ${css.map((style) => style.toHTML()).join('')}
+                ${js.map((script) => script.toHTML()).join('')}
+              </head>
+              <body>
+          `;
+
+            t.equal(
+                documentHead.trim().replace(/>\s*</g, '><'),
+                `<html>
+                  <head>
+                    <link href="http://example.com/header/bar.css" type="text/css" rel="stylesheet">
+                    <link href="http://example.com/footer/bar.css" type="text/css" rel="stylesheet">
+                    <script src="http://example.com/header/bar.js"></script>
+                    <script src="http://example.com/footer/bar.js"></script>
+                  </head>
+                  <body>`
+                    .trim()
+                    .replace(/>\s*</g, '><'),
+            );
+            t.end();
+        });
+
+        await Promise.all([headerFetch, footerFetch]);
+
+        await Promise.all([header.close(), footer.close()]);
+    },
+);

tests/resource.test.js

@@ -822,3 +822,178 @@ tap.test(
         t.end();
     },
 );
+
+tap.test(
+    'Resource().fetch - assets received event emitted once all link header assets received - single resource component',
+    async (t) => {
+        t.plan(1);
+        const server = new PodletServer({
+            version: '1.0.0',
+            assets: {
+                js: '/foo/bar.js',
+                css: '/foo/bar.css',
+            },
+        });
+        const service = await server.listen();
+
+        const client = new Client({ name: 'podiumClient' });
+        const component = client.register(service.options);
+
+        const incoming = new HttpIncoming({ headers: {} });
+
+        incoming.assets.on('received', () => {
+            t.ok(true);
+            t.end();
+        });
+
+        await component.fetch(incoming);
+
+        await server.close();
+    },
+);
+
+tap.test(
+    'Resource().fetch - assets received event emitted once all assets received - resource is failing',
+    async (t) => {
+        t.plan(3);
+        const server = new PodletServer({
+            version: '1.0.0',
+            assets: {
+                js: '/foo/bar.js',
+                css: '/foo/bar.css',
+            },
+            content: '/does/not/exist',
+        });
+        const service = await server.listen();
+
+        const client = new Client({ name: 'podiumClient' });
+        const component = client.register(service.options);
+
+        const incoming = new HttpIncoming({ headers: {} });
+
+        incoming.assets.on('received', (assets) => {
+            t.ok(true);
+            t.equal(assets.js.length, 1);
+            t.equal(assets.css.length, 1);
+            t.end();
+        });
+
+        await component.fetch(incoming);
+
+        await server.close();
+    },
+);
+
+tap.test(
+    'Resource().fetch - assets received event emitted once all assets received - multiple resource components',
+    async (t) => {
+        t.plan(3);
+        const server1 = new PodletServer({
+            name: 'one',
+            version: '1.0.0',
+            assets: {
+                js: '/foo/bar.js',
+                css: '/foo/bar.css',
+            },
+        });
+        const service1 = await server1.listen();
+        const server2 = new PodletServer({
+            name: 'two',
+            version: '1.0.0',
+            assets: {
+                js: '/foo/bar.js',
+                css: '/foo/bar.css',
+            },
+        });
+        const service2 = await server2.listen();
+        const server3 = new PodletServer({
+            name: 'three',
+            version: '1.0.0',
+            assets: {
+                js: '/foo/bar.js',
+                css: '/foo/bar.css',
+            },
+        });
+        const service3 = await server3.listen();
+
+        const client = new Client({ name: 'podiumClient' });
+        const component1 = client.register(service1.options);
+        const component2 = client.register(service2.options);
+        const component3 = client.register(service3.options);
+
+        const incoming = new HttpIncoming({ headers: {} });
+
+        incoming.assets.on('received', (assets) => {
+            t.equal(assets.js.length, 3);
+            t.equal(assets.css.length, 3);
+            t.ok(true);
+            t.end();
+        });
+
+        await Promise.all([
+            component1.fetch(incoming),
+            component2.fetch(incoming),
+            component3.fetch(incoming),
+        ]);
+
+        await server1.close();
+        await server2.close();
+        await server3.close();
+    },
+);
+
+tap.test(
+    'Resource().fetch - waitForAssets method - multiple resource components',
+    async (t) => {
+        t.plan(3);
+        const server1 = new PodletServer({
+            name: 'one',
+            version: '1.0.0',
+            assets: {
+                js: '/foo/bar.js',
+                css: '/foo/bar.css',
+            },
+        });
+        const service1 = await server1.listen();
+        const server2 = new PodletServer({
+            name: 'two',
+            version: '1.0.0',
+            assets: {
+                js: '/foo/bar.js',
+                css: '/foo/bar.css',
+            },
+        });
+        const service2 = await server2.listen();
+        const server3 = new PodletServer({
+            name: 'three',
+            version: '1.0.0',
+            assets: {
+                js: '/foo/bar.js',
+                css: '/foo/bar.css',
+            },
+        });
+        const service3 = await server3.listen();
+
+        const client = new Client({ name: 'podiumClient' });
+        const component1 = client.register(service1.options);
+        const component2 = client.register(service2.options);
+        const component3 = client.register(service3.options);
+
+        const incoming = new HttpIncoming({ headers: {} });
+
+        const c1 = component1.fetch(incoming);
+        const c2 = component2.fetch(incoming);
+        const c3 = component3.fetch(incoming);
+
+        const assets = await incoming.waitForAssets();
+        t.equal(assets.js.length, 3);
+        t.equal(assets.css.length, 3);
+        t.ok(true);
+
+        await Promise.all([c1, c2, c3]);
+
+        await server1.close();
+        await server2.close();
+        await server3.close();
+    },
+);