SharePoint Online service worker functionality

Rolands Strakis 121

Hello,

I'd like to understand what SharePoint Online service worker does, and is it possible to register your own service workers?

Why I'm asking this - I've registered service worker with scope https://tenant.sharepoint.com/sites/, so that I can intercept events from any site collection in my tenant. But I've noticed that SharePoint Online also has service worker registered in root scope - odspserviceworkerproxy.aspx.

If I register my service worker with more specific scope, then only my service worker will receive all the requests, say, from site https://tenant.sharepoint.com/sites/xxx.

So, what does SharePoint Online service worker do, so I can understand, what will be the impact of adding my service worker?

Accepted answer

Rolands Strakis 121 Reputation points

2021-07-07T11:33:43.783+00:00

So, after talking to Microsoft support, it seems that this service worker is used for SharePoint Online partial offline availability. I've checked and yes, when that service worker is disabled, then I don't have page cached to access offline. But when it's enabled, I do get some page offline.
It is not perfect now, but could be updated over the time, as they are constantly updating it. Last update was 10 days ago (you can see by the logs generated by odspserviceworkerproxy.aspx.
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Allen Xu_MSFT 13,776 Reputation points

2021-07-08T01:23:55.04+00:00

@Rolands Strakis ，

Thanks for sharing the detailed information here. You can accept your answer via "Accept Answer" button. It will be helpful to others who encounter similar problems to yours in this forum. Much appreciated for your contribution!
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1 additional answer

Allen Xu_MSFT 13,776 Reputation points

2021-06-29T06:06:11.62+00:00

Hi @Rolands Strakis ,

As per my knowledge, we can register service workers to SharePoint Online sites so that the service workers can intercept all requests from the current website and make judgments (you need to code the corresponding judgment program), and if you need to initiate a request to the server, it will be transferred to the server. If the cache can be used directly, it will directly return to the cache and no longer transfer it to the server.

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Rolands Strakis 121 Reputation points

2021-06-29T06:23:23.243+00:00

Yep, that's service worker functionality.
But I'm worried about SharePoint Online service worker.

As you can see here, this is the default SharePoint Online service worker, which has scope of root site. If I register my service worker with more specific scope, say https://xxx.sharepoint.com/sites/yyy, then all events will be caught by my service worker for yyy site. And I'm worried that this might break something that SharePoint Online service worker was doing.
That's why I'd like to understand, what it is doing, exactly?

Allen Xu_MSFT 13,776 Reputation points

2021-06-30T06:50:39.33+00:00

@Rolands Strakis ,

I can't find any official documentation to explain this. I think it is a standard helper from Microsoft included in all modern sites. It is automatically installed, registered, started on the browser and render client side cache every time a modern page is displayed. I don't think your customized service worker wolud conflict with it.

Rolands Strakis 121 Reputation points

2021-06-30T08:34:40.927+00:00

Well, I didn't think so too, but I've checked how service worker scope works. If service worker has closer scope, then it will receive all events that are sent to that URL.
I've checked with 2 of my service workers. One was at https://xxx.sharepoint.com/sites/yyy and the other was https://xxx.sharepoint.com/sites/yyy/SitePages. When I was on page https://xxx.sharepoint.com/sites/yyy/SitePages/zzz.aspx then I appeared as client for https://xxx.sharepoint.com/sites/yyy/SitePages service worker.

Rolands Strakis 121 Reputation points

2021-07-01T10:55:17.117+00:00

@Allen Xu_MSFT Sorry, had some issues writing previous comment. Please, see this comment for full details.

Well, I didn't think so too, but I've checked how service worker scope works. If service worker has closer scope, then it will receive all events that are sent to that URL.
I've checked with 2 of my service workers. One was at https://xxx.sharepoint.com/sites/yyy and the other was https://xxx.sharepoint.com/sites/yyy/SitePages. When I was on page https://xxx.sharepoint.com/sites/yyy/SitePages/zzz.aspx then I appeared as client for https://xxx.sharepoint.com/sites/yyy/SitePages service worker.

SharePoint Online service worker (odspserviceworkerproxy.aspx) won't receive any events, because it doesn't have the page as client. My service worker(service-worker.js) will receive all those events, because the page is its client.
I'm not 100% sure if my service worker doesn't handle fetch event will SharePoint Online service worker handle it instead, but I really doubt. So, I believe that my service worker isn't giving SharePoint Online service worker any room to breath.

Allen Xu_MSFT 13,776 Reputation points

2021-07-06T07:43:56.637+00:00

@Rolands Strakis ,

Thanks for your detailed reply. But I have little knowledge about SharePoint service worker and I couldn't find any documentation explaining this. I would suggest creating a service request in Micorosft 365 admin center so that you will get more professional suggestions.

Rolands Strakis 121 Reputation points

2021-07-06T10:47:10.937+00:00

Alright, will post information here afterwards.
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