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Ignatius Mikheev
Ignatius Mikheev

Precache Updated UPD

When a user later revisits your web app and you have a new service worker with different precached assets, workbox-precaching will look at the new list and determine which assets are completely new and which of the existing assets need updating, based on their revisioning. Any new assets, or updating revisions, will be added to the cache during the new service worker's install event.

Precache Updated

The response strategy used in this route is cache-first: the precached response will be used, unless that cached response is not present (due to some unexpected error), in which case a network response will be used instead.

The order in which you call precacheAndRoute() or addRoute() is important. You would normally want to call it early on in your service worker file, before registering any additional routes with registerRoute(). If you did call registerRoute() first, and that route matched an incoming request, whatever strategy you defined in that additional route will be used to respond, instead of the cache-first strategy used by workbox-precaching.

Previous versions of workbox-precaching allowed the precache manifest to contain string URLs in addition objects with a url and revision property. In version 5 this is deprecated. Now you must always pass an object and in order to prevent Workbox from revisioning the URL in the cache, you must explicitly set the revision property to null. Passing a string will continue to work (with a warning) in version 5, but in version 6 this will no longer be supported.

It's strongly recommended that you use one of Workbox's build tools to generate this precache manifest. Never hardcode revision info into a "hand written" manifest, as precached URLs will not be kept up to date unless the revision info reflects the URL's contents!

By default, search parameters that start with utm_ or exactly match fbclid are removed, meaning that a request for /about.html?utm_campaign=abcd will be fulfilled with a precached entry for /about.html.

Requests ending in a / will, by default, be matched against entries with an index.html appended to the end. This means an incoming request for / can automatically be handled with the precached entry /index.html.

If a request fails to match the precache, we'll add .html to the end to support "clean" URLs (a.k.a. "pretty" URLs). This means a request like /about will be handled by the precached entry for /about.html.

There are times when you might need to read a precached asset directly, outside the context of the routing that workbox-precaching can automatically perform. For instance, you might want to precache partial HTML templates that then need to be retrieved and used when constructing a full response.

In general, you can use the Cache Storage API to obtain the precached Response objects, but there is one wrinkle: the URL cache key that needs to be used when calling cache.match() might contain a versioning parameter that workbox-precaching automatically creates and maintains.

If you are using your own PrecacheController instance, instead of using the default instance via precacheAndRoute, you should call the matchPrecache() or getCacheKeyForURL() methods directly on that instance.

Most releases of Workbox maintain the same format for storing precached data, and precaches created by older versions of Workbox can normally be used as-is by newer releases. Rarely, though, there is a breaking change in precaching storage that requires existing users to re-download everything, and which renders previously precached data obsolete. (Such a change happened in between the Workbox v3 and v4 releases.)

An additional, optional property called integrity can be added to any entry in the precache manifest. If provided, it will be used as the integrity value when constructing the Request used to populate the cache. If there's a mismatch, the precaching process will fail.

Determining which precache manifest entries should have integrity properties, and figuring out the appropriate values to use, is outside the scope of Workbox's build tools. Instead, developers who want to opt-in to this functionality should modify the precache manifest that Workbox generates to add in the appropriate info themselves. The manifestTransform option in Workbox's build tools configuration can help:

One feature of service workers is the ability to save files to the cache when the service worker is installing. This is referred to as "precaching". Precaching makes it possible to serve cached files to the browser without going to the network. Use precaching for critical assets that your site needs even when offline: main page, styles, fallback image and essential scripts.Why should you use Workbox? #Using Workbox for precaching is optional. You can write your own code to precache critical assets when the service worker is installing. The primary benefit of using Workbox is its out-of-the-box version control. You'll run into a lot less trouble updating precached assets using Workbox than if you had to manage the versioning and updating of these files on your own.Precache manifests #Precaching is driven by a list of URLs and associated versioning information for each URL. Taken together, this information is known as a precache manifest. The manifest is the "source of truth" for the state of everything meant to be in the precache for a given version of a web app. A precache manifest, in the format used by Workbox, looks something like:

Iam trying to implement networkfirst strategy using sw-precache.Now iam able to cache the data and able to serve from offline. If i change the data (i.e: changed the header from 'hello' to 'Welcome') in page not get reflecting it always taking the data from the cache its getting update only if i unregistered the service worker or clear the site data then only i can get my data

The steps will also create a sub folder with the name of the computer failing the Readiness Check and another sub folder indicating which step that failed. In this case ReadinessFailed. I rename the smsts.log to -precache to indicate what task sequence that was run (the readiness check is also being run in the actual in-place upgrade task sequence).

This group runs if the previous action also ran, which translates to every single step in the previous group, making sure that everything is precached. If the packageID already exists in the CM cache, the content is kept in the cache and not re-downloaded.

I believe this is contrary to what you recommend. If I set the precache task sequences to download all content locally before running the task sequence will it download / cache ALL driver packages for ALL hardware models specified in the task sequence before running . I cater for 25 different models of HP, Dell and Lenovo machines and only want to locally cache the required WIM files for each specific model.

As stated above, Workbox is a rethink on their old service worker libraries and tools. Personally I used sw-precache before but I found the generated service worker code it created difficult to read. Workbox fixes this (in my opinion) as its modular and much easier to reason with. Find a list of all the packages in Workbox here.

If you inspect your generated service-worker.js file you'll notice it's quite small in size (in comparison to sw-precache). It will contain the file revisions and an import to workbox-sw where the actual work will happen.

If you set the 2 TS variables at the start of your PreCache TS, it will remain on the client cache. SMSTSPersistContent & Set SMSTSPerserveContent. Then when you upgrade TS runs, as long as the content hasn't changed from the time you precached to the time you run the upgrade, it will use the upgrade content you already downloaded.

We try to schedule a machine pretty quick after it is cached. However, if it does fall during the the period where we updated the WIM, because the deployment is set to required, it will start to cache again in the background once it receives the updated policy. Thank you for the question, I'll try to update the post soon to cover that.

Correct, it only downloads the driver pack it needs because it's not actually referenced in the TS. This also means that it will not download before it runs, because it would only download referenced items, hense we run a precache / compatscan TS, so it can download the drivers based on the variables in the middle of the TS running.

Do you have several additional items besides the Upgrade Media that you're trying to Cache? You'd have to do it dynamically similar to how we do driver downloads. Drivers don't download until during the precache TS run time.

Awesome work Gary "and Friends"! Question - is there a way I could set up just one PreCache TS to deploy many Version of Windows 10 (i.e. Professional, Enterprise, x64, x86) without having the machine precache ALL versions of Windows 10? That would take up a TON of drive space on the machines. Currently, I have to have 4 separate deployments to get this done.

Since we are going to add PWA to your application, we need to configure the service worker so that your application can work offline. To do this, we need to configure the service worker's precache manifest, which will include all the resources of your application (basically we need to instruct the service worker what resources to store in cache storage so that it can be used for network requests interception and when the application is offline).

Once the application registers the service worker, the browser will try to install it downloading all the resources in the service worker's precache manifest. Once all the resources downloaded and stored in the cache storage by the browser, it will try to activate the service worker to take the control of the application.


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