Basic prep

.github/workflows/ci.yml

@@ -17,11 +17,11 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [18.x]
+        node-version: [22.x]
         os: [ubuntu-latest]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     # extract branch name
     - if: github.event_name == 'pull_request'
       run: echo "BRANCH_NAME=${GITHUB_HEAD_REF}" >> $GITHUB_ENV
@@ -56,7 +56,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - uses: olegtarasov/[email protected]
         id: tagName

bin/solid

@@ -1,3 +1,3 @@
-#!/usr/bin/env node
+#!/usr/bin/env -S node --experimental-require-module
 const startCli = require('./lib/cli')
 startCli()

bin/solid.js

@@ -1,3 +1,3 @@
-#!/usr/bin/env node
+#!/usr/bin/env -S node --experimental-require-module
 const startCli = require('./lib/cli')
 startCli()

docker-image/src/Dockerfile

@@ -1,4 +1,4 @@
-FROM node:16-alpine
+FROM node:22-alpine
 
 # hadolint ignore=DL3018
 RUN apk add --no-cache openssl

lib/create-app.js

@@ -28,6 +28,11 @@ const ResourceMapper = require('./resource-mapper')
 const aclCheck = require('@solid/acl-check')
 const { version } = require('../package.json')
 
+const acceptEvents = require('express-accept-events').default
+const events = require('express-events-negotiate').default
+const eventID = require('express-prep/event-id').default
+const prep = require('express-prep').default
+
 const corsSettings = cors({
   methods: [
     'OPTIONS', 'HEAD', 'GET', 'PATCH', 'POST', 'PUT', 'DELETE'
@@ -61,6 +66,9 @@ function createApp (argv = {}) {
 
   const app = express()
 
+  // Add PREP support
+  app.use(acceptEvents, events, eventID, prep)
+
   initAppLocals(app, argv, ldp)
   initHeaders(app)
   initViews(app, configPath)

lib/handlers/delete.js

@@ -9,6 +9,8 @@ async function handler (req, res, next) {
   try {
     await ldp.delete(req)
     debug('DELETE -- Ok.')
+    // Add event-id for notifications
+    res.setHeader('Event-ID', res.setEventID())
     res.sendStatus(200)
     next()
   } catch (err) {

lib/handlers/get.js

@@ -17,6 +17,9 @@ const translate = require('../utils.js').translate
 const error = require('../http-error')
 
 const RDFs = require('../ldp').mimeTypesAsArray()
+const isRdf = require('../ldp').mimeTypeIsRdf
+
+const prepConfig = 'accept=("message/rfc822" "application/ld+json" "text/turtle")'
 
 async function handler (req, res, next) {
   const ldp = req.app.locals.ldp
@@ -103,22 +106,46 @@ async function handler (req, res, next) {
       debug('   sending data browser file: ' + dataBrowserPath)
       res.sendFile(dataBrowserPath)
       return
-    } else if (stream) {
+    } else if (stream) { // EXIT text/html
       res.setHeader('Content-Type', contentType)
       return stream.pipe(res)
     }
   }
 
   // If request accepts the content-type we found
+  // if (stream && negotiator.mediaType([contentType])) {
+  //   res.setHeader('Content-Type', contentType)
+  //   if (contentRange) {
+  //     const headers = { 'Content-Range': contentRange, 'Accept-Ranges': 'bytes', 'Content-Length': chunksize }
+  //     res.writeHead(206, headers)
+  //     return stream.pipe(res)
+  //   } else {
+  //     return stream.pipe(res)
+  //   }
+  // }
+
   if (stream && negotiator.mediaType([contentType])) {
-    res.setHeader('Content-Type', contentType)
+    let headers = {
+      'Content-Type': contentType
+    }
     if (contentRange) {
-      const headers = { 'Content-Range': contentRange, 'Accept-Ranges': 'bytes', 'Content-Length': chunksize }
-      res.writeHead(206, headers)
-      return stream.pipe(res)
-    } else {
-      return stream.pipe(res)
+      headers = {
+        ...headers,
+        'Content-Range': contentRange,
+        'Accept-Ranges': 'bytes',
+        'Content-Length': chunksize
+      }
+      res.statusCode = 206
     }
+
+    if (isRdf(contentType) && !res.sendEvents({
+      config: { prep: prepConfig },
+      body: stream,
+      isBodyStream: true,
+      headers
+    })) return
+    res.set(headers)
+    return stream.pipe(res)
   }
 
   // If it is not in our RDFs we can't even translate,
@@ -130,6 +157,14 @@ async function handler (req, res, next) {
     // Translate from the contentType found to the possibleRDFType desired
     const data = await translate(stream, baseUri, contentType, possibleRDFType)
     debug(req.originalUrl + ' translating ' + contentType + ' -> ' + possibleRDFType)
+    const headers = {
+      'Content-Type': possibleRDFType
+    }
+    if (isRdf(contentType) && !res.sendEvents({
+      config: { prep: prepConfig },
+      body: data,
+      headers
+    })) return
     res.setHeader('Content-Type', possibleRDFType)
     res.send(data)
     return next()

lib/handlers/notify.js

@@ -0,0 +1,101 @@
+module.exports = handler
+
+const libPath = require('path/posix')
+
+const headerTemplate = require('express-prep/templates').header
+const solidRDFTemplate = require('../rdf-notification-template')
+
+const ALLOWED_RDF_MIME_TYPES = [
+  'application/ld+json',
+  'application/activity+json',
+  'text/turtle'
+]
+
+function getActivity (method) {
+  if (method === 'DELETE') {
+    return 'Delete'
+  }
+  return 'Update'
+}
+
+function getParentActivity (method, status) {
+  if (method === 'DELETE') {
+    return 'Remove'
+  }
+  if (status === 201) {
+    return 'Add'
+  }
+  return 'Update'
+}
+
+function handler (req, res, next) {
+  const { trigger, defaultNotification } = res.events.prep
+
+  const { method } = req
+  const { statusCode } = res
+  const eventID = res.getHeader('event-id')
+
+  const parent = `${libPath.dirname(req.path)}/`
+  const parentID = res.setEventID(parent)
+  const fullUrl = new URL(req.path, `${req.protocol}://${req.hostname}/`)
+  const parentUrl = new URL(parent, fullUrl)
+
+  // Date is a hack since node does not seem to provide access to send date.
+  // Date needs to be shared with parent notification
+  const eventDate = res._header.match(/^Date: (.*?)$/m)?.[1] ||
+    new Date().toUTCString()
+
+  // If the resource itself newly created,
+  // it could not have been subscribed for notifications already
+  if (!((method === 'PUT' || method === 'PATCH') && statusCode === 201)) {
+    trigger({
+      generateNotification (
+        negotiatedFields
+      ) {
+        const mediaType = negotiatedFields['content-type']
+
+        if (ALLOWED_RDF_MIME_TYPES.includes(mediaType?.[0])) {
+          return `${headerTemplate(negotiatedFields)}\r\n${solidRDFTemplate({
+            activity: getActivity(method),
+            eventID,
+            object: String(fullUrl),
+            date: eventDate,
+            // We use eTag as a proxy for state for now
+            state: res.getHeader('ETag'),
+            mediaType
+          })}`
+        } else {
+          return defaultNotification({
+            ...(res.method === 'POST') && { location: res.getHeader('Content-Location') }
+          })
+        }
+      }
+    })
+  }
+
+  // Write a notification to parent container
+  // POST in Solid creates a child resource
+  if (method !== 'POST') {
+    trigger({
+      path: parent,
+      generateNotification (
+        negotiatedFields
+      ) {
+        const mediaType = negotiatedFields['content-type']
+        if (ALLOWED_RDF_MIME_TYPES.includes(mediaType?.[0])) {
+          return `${headerTemplate(negotiatedFields)}\r\n${solidRDFTemplate({
+            activity: getParentActivity(method, statusCode),
+            eventID: parentID,
+            date: eventDate,
+            object: String(parentUrl),
+            target: statusCode === 201 ? String(fullUrl) : undefined,
+            eTag: undefined,
+            mediaType
+          })}`
+        }
+      }
+    })
+  }
+
+  next()
+}

lib/handlers/patch.js

@@ -91,6 +91,8 @@ async function patchHandler (req, res, next) {
       return writeGraph(graph, resource, ldp.resourceMapper.resolveFilePath(req.hostname), ldp.serverUri)
     })
 
+    // Add event-id for notifications
+    res.setHeader('Event-ID', res.setEventID())
     // Send the status and result to the client
     res.status(resourceExists ? 200 : 201)
     res.send(result)

lib/handlers/post.js

@@ -72,6 +72,8 @@ async function handler (req, res, next) {
     // Handled by backpressure of streams!
     busboy.on('finish', function () {
       debug('Done storing files')
+      // Add event-id for notifications
+      res.setHeader('Event-ID', res.setEventID())
       res.sendStatus(200)
       next()
     })
@@ -91,6 +93,8 @@ async function handler (req, res, next) {
         debug('File stored in ' + resourcePath)
         header.addLinks(res, links)
         res.set('Location', resourcePath)
+        // Add event-id for notifications
+        res.setHeader('Event-ID', res.setEventID())
         res.sendStatus(201)
         next()
       },

lib/handlers/put.js

@@ -77,6 +77,8 @@ async function putStream (req, res, next, stream = req) {
     // Fails with Append on existing resource
     if (!req.originalUrl.endsWith('.acl')) await checkPermission(req, resourceExists)
     await ldp.put(req, stream, getContentType(req.headers))
+    // Add event-id for notifications
+    res.setHeader('Event-ID', res.setEventID())
     res.sendStatus(resourceExists ? 204 : 201)
     return next()
   } catch (err) {

lib/ldp-middleware.js

@@ -10,6 +10,7 @@ const del = require('./handlers/delete')
 const patch = require('./handlers/patch')
 const index = require('./handlers/index')
 const copy = require('./handlers/copy')
+const notify = require('./handlers/notify')
 
 function LdpMiddleware (corsSettings) {
   const router = express.Router('/')
@@ -23,10 +24,10 @@ function LdpMiddleware (corsSettings) {
 
   router.copy('/*', allow('Write'), copy)
   router.get('/*', index, allow('Read'), header.addPermissions, get)
-  router.post('/*', allow('Append'), post)
-  router.patch('/*', allow('Append'), patch)
-  router.put('/*', allow('Append'), put)
-  router.delete('/*', allow('Write'), del)
+  router.post('/*', allow('Append'), post, notify)
+  router.patch('/*', allow('Append'), patch, notify)
+  router.put('/*', allow('Append'), put, notify)
+  router.delete('/*', allow('Write'), del, notify)
 
   return router
 }

lib/rdf-notification-template.js

@@ -0,0 +1,66 @@
+const CONTEXT_ACTIVITYSTREAMS = 'https://www.w3.org/ns/activitystreams'
+const CONTEXT_NOTIFICATION = 'https://www.w3.org/ns/solid/notification/v1'
+const CONTEXT_XML_SCHEMA = 'http://www.w3.org/2001/XMLSchema'
+
+function generateJSONNotification ({
+  activity: type,
+  eventId: id,
+  date: published,
+  object,
+  target,
+  state = undefined
+}) {
+  return {
+    published,
+    type,
+    id,
+    object,
+    ...(type === 'Add') && { target },
+    ...(type === 'Remove') && { origin: target },
+    ...(state) && { state }
+  }
+}
+
+function generateTurtleNotification ({
+  activity,
+  eventId,
+  date,
+  object,
+  target,
+  state = undefined
+}) {
+  const stateLine = `\n    notify:state "${state}" ;`
+
+  return `@prefix as: <${CONTEXT_ACTIVITYSTREAMS}#> .
+@prefix notify: <${CONTEXT_NOTIFICATION}#> .
+@prefix xsd: <${CONTEXT_XML_SCHEMA}#> .
+
+<${eventId}> a as:${activity} ;${state && stateLine}
+    as:object ${object} ;
+    as:published "${date}"^^xsd:dateTime .`.replaceAll('\n', '\r\n')
+}
+
+function serializeToJSONLD (notification, isActivityStreams = false) {
+  notification['@context'] = [CONTEXT_NOTIFICATION]
+  if (!isActivityStreams) {
+    notification['@context'].unshift(CONTEXT_ACTIVITYSTREAMS)
+  }
+  return JSON.stringify(notification, null, 2)
+}
+
+function rdfTemplate (props) {
+  const { mediaType } = props
+  if (mediaType[0] === 'application/activity+json' || (mediaType[0] === 'application/ld+json' && mediaType[1].get('profile')?.toLowerCase() === 'https://www.w3.org/ns/activitystreams')) {
+    return serializeToJSONLD(generateJSONNotification(props), true)
+  }
+
+  if (mediaType[0] === 'application/ld+json') {
+    return serializeToJSONLD(generateJSONNotification(props))
+  }
+
+  if (mediaType[0] === 'text/turtle') {
+    return generateTurtleNotification(props)
+  }
+}
+
+module.exports = rdfTemplate