feat: Restrict channels to 2 weeks by default

config/http/notifications/webhooks/routes.json

@@ -44,7 +44,7 @@
       "@id": "urn:solid-server:default:NotificationTypeHandler",
       "@type": "WaterfallHandler",
       "handlers": [
-        { "@id": "urn:solid-server:default:WebHookSubscriber" },
+        { "@id": "urn:solid-server:default:WebHookRouter" },
         { "@id": "urn:solid-server:default:WebHookUnsubscriber" },
         { "@id": "urn:solid-server:default:WebHookWebId" }
       ]

config/http/notifications/webhooks/subscription.json

@@ -3,12 +3,13 @@
   "@graph": [
     {
       "comment": "Handles the subscriptions targeting a WebHookSubscription2021.",
-      "@id": "urn:solid-server:default:WebHookSubscriber",
+      "@id": "urn:solid-server:default:WebHookRouter",
       "@type": "OperationRouterHandler",
       "baseUrl": { "@id": "urn:solid-server:default:variable:baseUrl" },
       "allowedMethods": [ "HEAD", "GET", "POST" ],
       "allowedPathNames": [ "/WebHookSubscription2021/$" ],
       "handler": {
+        "@id": "urn:solid-server:default:WebHookSubscriber",
         "@type": "NotificationSubscriber",
         "channelType": { "@id": "urn:solid-server:default:WebHookSubscription2021" },
         "converter": { "@id": "urn:solid-server:default:RepresentationConverter" },

config/http/notifications/websockets/subscription.json

@@ -3,12 +3,13 @@
   "@graph": [
     {
       "comment": "Handles the subscriptions targeting a WebSocketChannel2023.",
-      "@id": "urn:solid-server:default:WebSocket2023Subscriber",
+      "@id": "urn:solid-server:default:WebSocket2023Router",
       "@type": "OperationRouterHandler",
       "baseUrl": { "@id": "urn:solid-server:default:variable:baseUrl" },
       "allowedMethods": [ "HEAD", "GET", "POST" ],
       "allowedPathNames": [ "/WebSocketChannel2023/$" ],
       "handler": {
+        "@id": "urn:solid-server:default:WebSocket2023Subscriber",
         "@type": "NotificationSubscriber",
         "channelType": { "@id": "urn:solid-server:default:WebSocketChannel2023Type" },
         "converter": { "@id": "urn:solid-server:default:RepresentationConverter" },
@@ -35,7 +36,7 @@
       "@id": "urn:solid-server:default:NotificationTypeHandler",
       "@type": "WaterfallHandler",
       "handlers": [
-        { "@id": "urn:solid-server:default:WebSocket2023Subscriber" }
+        { "@id": "urn:solid-server:default:WebSocket2023Router" }
       ]
     },
 

documentation/markdown/usage/notifications.md

@@ -200,3 +200,27 @@ The available fields are:
   A new notification will only be sent out after this much time has passed since the previous notification.
 * **`accept`**: A description of the `content-type(s)` in which the client would want to receive the notifications.
   Expects the same values as an `Accept` HTTP header.
+
+## Important note for server owners
+
+There is not much restriction on who can create a new notification channel,
+only `Read` permissions on the target resource are required.
+It is therefore possible for the server to accumulate created channels.
+As these channels still get used every time their corresponding resource changes,
+this could degrade server performance.
+
+For this reason, the server is by default configured to always remove notification channels after 2 weeks.
+You can modify this behaviour by adding the following block to your configuration:
+
+```json
+{
+  "@id": "urn:solid-server:default:WebSocket2023Subscriber",
+  "@type": "NotificationSubscriber",
+  "maxDuration": 20160
+}
+```
+
+`maxDuration` defines after how many minutes every channel will be removed.
+Setting this value to 0 will allow channels to exist forever.
+Similarly, for changing the maximum duration of webhook channels you can use the identifier
+`urn:solid-server:default:WebHookSubscriber`.

src/server/notifications/ListeningActivityHandler.ts

@@ -60,13 +60,12 @@ export class ListeningActivityHandler extends StaticHandler {
       // No need to wait on this to resolve before going to the next channel.
       // Prevent failed notification from blocking other notifications.
       this.handler.handleSafe({ channel, activity, topic, metadata })
-        .then((): Promise<void> => {
+        .then(async(): Promise<void> => {
           // Update the `lastEmit` value if the channel has a rate limit
           if (channel.rate) {
             channel.lastEmit = Date.now();
             return this.storage.update(channel);
           }
-          return Promise.resolve();
         })
         .catch((error): void => {
           this.logger.error(`Error trying to handle notification for ${id}: ${createErrorMessage(error)}`);

src/server/notifications/NotificationSubscriber.ts

@@ -46,6 +46,7 @@ export interface NotificationSubscriberArgs {
    * Overrides the expiration feature of channels, by making sure they always expire after the `maxDuration` value.
    * If the expiration of the channel is shorter than `maxDuration`, the original value will be kept.
    * Value is set in minutes. 0 is infinite.
+   * Defaults to 20160 minutes, which is 2 weeks.
    */
   maxDuration?: number;
 }
@@ -76,7 +77,7 @@ export class NotificationSubscriber extends OperationHttpHandler {
     this.permissionReader = args.permissionReader;
     this.authorizer = args.authorizer;
     this.storage = args.storage;
-    this.maxDuration = (args.maxDuration ?? 0) * 60 * 1000;
+    this.maxDuration = (args.maxDuration ?? 20160) * 60 * 1000;
   }
 
   public async handle({ operation, request }: OperationHttpHandlerInput): Promise<ResponseDescription> {