451-tools v1.0.3

451 Tools

Censorship resilient and distributed publishing. This repository contains a collection of scripts and tools to help you run your own censorship resilient web services. We mostly use Service Workers to achieve this.

Installation

npm install 451-tools

Table of contents

• Getting started
  • Usage
  • Configuration
• Bookmarking
  • Usage
  • API endpoints
  • Examples
• Fallback pages
  • Usage
  • Options
  • Examples
• Fallback assets
  • Usage
  • Options
• Content bundles
  • Usage
  • Options
• Fallback image
  • Usage
• Mirroring
  • Usage
  • Options
• UI components
  • Bookmark button
  • Traffic light

Getting started

To ensure smooth integration between our modules it is necessary to use the registerServiceWorkerController function. Make sure to include it in the options parameter when calling one of the modules, as illustrated below.

Inside your service worker:

import { registerBookmarkApi, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerBookmarkApi({ serviceWorkerController });

Individual modules can be configured by passing an object when calling the module function from your service worker. Next to that you can also configure all modules from one configuration file. You need to host that file on your server and pass the path of the file as a url parameter to your service worker registration path, as illustrated below.

From the client:

if ('serviceWorker' in navigator) {
  window.addEventListener('load', () => {
    const configurationVersion = 1;
    const serviceWorkerUrl = `/service-worker.js?configuration=${encodeURIComponent(`/static/service-worker-configuration.json?v=${configurationVersion}`)}`;
    navigator.serviceWorker
      .register(serviceWorkerUrl)
      .then((registration) => registration.update())
  });
}

Make sure to revision hash or version the configuration file, so that you can update it without having to update your service worker.

The configuration file should look like this, all modules are optional.

{
  "bookmark": {},
  "fallbackPages": {},
  "fallbackAssets": {}
}

For more information about the configuration options, see the documentation of the individual modules.

Timeout

The default timeout for network requests is 3 seconds. To adjust this timeout, pass it as an option while creating the Service Worker Controller:

const serviceWorkerController = registerServiceWorkerController({
  networkTimeoutSeconds: 10,
});

Bookmarking

We provide some API endpoints defined in the service worker to save pages for offline availability.

Inside your service worker:

import { registerBookmarkApi, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerBookmarkApi({ serviceWorkerController });

When your service worker is installed, you can now call the bookmark API, which is available at /451-tools/bookmark/.

GET /451-tools/bookmark/

Get all pages from the bookmark cache.

Response

An array of bookmarked pages.

Example

fetch('/451-tools/bookmark/', { method: 'GET' })
  .then(response => response.json())
  .then(pages => {
    console.log(pages);
  });

GET /451-tools/bookmark/{path}

Get a single page from the bookmark cache. Where the path is a url encoded path.

Response

200: A single bookmarked page.

404: The page was not found in the bookmark cache.

400: The path is not a valid url encoded path.

Example

fetch('/451-tools/bookmark/%2Fpath%2Fto%2Fthe%2Fpage%2F', { method: 'GET' })
  .then(response => response.json())
  .then(page => {
    console.log(page);
  });

POST /451-tools/bookmark/{path}

Add a page to the bookmark cache. Where the path is a url encoded path.

Request body

Example

fetch('/451-tools/bookmark/%2Fpath%2Fto%2Fthe%2Fpage%2F', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({ metadata: { title: 'Page title' } }),
});

DELETE /451-tools/bookmark/{path}

Delete a page from the bookmark cache. Where the path is a url encoded path.

Example

fetch('/451-tools/bookmark/%2Fpath%2Fto%2Fthe%2Fpage%2F', { method: 'DELETE' });

Fallback pages

We provide a fallback strategy for pages to use when the network is not available.

Inside your service worker:

import { registerFallbackPages, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerFallbackPages({ serviceWorkerController });

Calling registerFallbackPages is enough to get you started. It will render a default offline page whenever the network is not available. By default, it looks like this:

This page is somewhat customizable, it has support for basic theming and the default UI texts can be overwritten. However, in case this is not enough, we also support custom offline pages:

import { registerFallbackPages, registerFallbackHandlersPlugin } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerFallbackPages({
  serviceWorkerController,
  pages: [{
    url: '/my-offline-page/',
    revision: '1',
  }],
});

revision is not required, but it is highly recommended. Changing this value will cause a cache invalidation, which means we will re-cache the latest version.

⚠️ Please note that this module takes over the /451-tools/dashboard/ route regardless of the user's online status. The route is used to make the default offline page available for online users.

Pass an object with the following properties to the registerFallbackPages function:

customProperties

A list of all the over writable custom properties and their default values.

templateStrings

A list of all the over writable UI text strings and their default values.

Default offline page with customization

import { registerFallbackPages, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerFallbackPages({
  serviceWorkerController,
  customProperties: {
    'primary-color': 'blue',
  },
  templateStrings: {
    pageTitle: 'My Offline Page',
  },
});

Custom offline page

import { registerFallbackPages, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerFallbackPages({
  serviceWorkerController,
  pages: [{
    url: '/my-offline-page/',
    revision: '1',
  }],
});

Multiple offline pages

For most cases, a single fallback is enough. However, we support an optional refererRegex property. This can, for example, be used to render a different fallback page for users who came from a search engine:

import { registerFallbackPages, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerFallbackPages({
  serviceWorkerController,
  pages: [{
    url: '/my-offline-page/',
    revision: '1',
  },
    {
      url: "/google-search-offline-page/",
      revision: "1",
      refererRegex: "https://(www.)?(google).com/",
    },
  ],
});

Fallback assets

We provide a fallback strategy for assets to use when the network is not available.

Inside your service worker:

import { registerFallbackAssets, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerFallbackAssets({
  serviceWorkerController,
  assets: [
    {
      url: '/main.css',
      revision: '1',
    },
    {
      url: '/main.js',
      revision: '1',
    },
  ],
});

revision is not required, but it is highly recommended. Changing this value will cause a cache invalidation, which means we will re-cache the latest version.

Pass an object with the following properties to the registerFallbackAssets function:

Content bundles

You can define a list of pages as content bundles to be cached by the service worker. These are pages that you want to be available offline.

Inside your service worker:

import { registerContentBundles, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerContentBundles({
  serviceWorkerController,
  pages: [
    {
      url: '/content-bundle-1/',
      revision: '1',
    },
    {
      url: '/content-bundle-2/',
      revision: '1',
    },
  ],
});

Fallback image

We provide a fallback strategy for images, it returns a fallback SVG for uncached images.

Inside your service worker:

import { registerFallbackImage, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerFallbackImage({ serviceWorkerController });

Mirroring

In order to keep a website more available you can configure alternative mirrors where the website is hosted. The service worker will always try to get resources from the primary domain. But once the primary domain fails and mirrors are configured content will be fetched from one of the configured mirrors. We will timeout and cancel a request after 3 seconds.

We mark a mirror and its status, which means that for subsequent requests a mirror that was marked as up will be used for the next 10 minutes. We feel that this leads to a faster user experience because we will not encounter the timeout for every request that is done.

If all mirrors fail the offline fallback pages strategy as defined in fallback pages will be used. If the offline fallbakc page is not configured the request will simply fail.

Inside your service worker:

import { registerMirroring, registerServiceWorkerController } from '451-tools';

const serviceWorkerController = registerServiceWorkerController();
registerMirroring({ serviceWorkerController });

⚠️ Please note that the order of registering modules is important. Especially with mirroring. Since it will match all document requests and same origin requests it is important to register it last.

Once the service worker is installed, you can call the mirror status API endpoint, which is available at /451-tools/mirror-status/. It will return the status of where the content is coming from. The response looks like this:

{
  "status": "up" // or "unknown", "down", "low" 
}

Pass an object with the following properties to the registerMirroring function:

UI components

In addition to our modules, we offer a set of UI components that come in the form of web components. While these components may offer added functionality, their primary function is to provide an alternative approach to implementing our modules without requiring any JavaScript coding.

Bookmark button

The button displays the bookmark status of the related page - whether it is currently bookmarked or not. In addition, it enables users to bookmark or unbookmark the page with just a click. Please note that this button requires the bookmarking module to function properly.

Usage

Inside your HTML:

<bookmark-button
  path="/my-page"
  bookmark-text="Bookmark"
  remove-bookmark-text="Remove Bookmark"
>
</bookmark-button>

Attributes

Pass the following attributes to the bookmark-button component:

Styling

Use the following selector:

bookmark-button::part(button) {
  background-color: rebeccapurple;
  color: white;
}

Traffic light

The component displays the user's network status - it can either be online or offline.

Usage

Inside your HTML:

<traffic-light
  href="/offline/"
  online-text="You are online."
  offline-text="You are offline."
>
</traffic-light>

Attributes

Pass the following attributes to the traffic-light component:

Styling

Use the following selectors:

traffic-light::part(button) {
  /* General button selector. */
}

traffic-light::part(online) {
  /* Online button selector. */
}

traffic-light::part(offline) {
  /* Offline button selector. */
}