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RE: [Resource Timing] Handling duplicate requests

From: Jatinder Mann <jmann@microsoft.com>
Date: Wed, 30 Jan 2013 01:30:51 +0000
To: "public-web-perf@w3.org" <public-web-perf@w3.org>
Message-ID: <c0bcd1e0fb9944e3b4ff17f62f37af25@BLUPR03MB065.namprd03.prod.outlook.com>
After reading the spec more carefully, I don't think we will need to make a change to clarify case #1, where two requestors in the same documents are asking for the same resource, or case #2, where two requestors in different documents are asking for the same resource.

The definition of each attribute already covers case #2. E.g., for domainLookupStart attribute, the spec states if "the resource is retrieved from relevant application caches or local resources, this attribute must return the same value as fetchStart". In this case, the domainLookupStart in the second document would return the same value as fetchStart, the time immediately before the browser starts to fetch this resource, not 0 as was mentioned before. It's unlikely this resource wouldn't be fetched and would already be in an in-memory cache (and if it is in an in-memory cache, it shouldn't be in the timeline).

In case number 1, where two requestors are in the same document, it's likely that the first request will be fetched from the network layer and the second from the browser's in-memory cache. In that case, only the first resource would be included in the timeline, for it is the only resource to be fetched from the networking layer. If the second request was fetched from the networking layer as well, it would need to be included in the timeline.

I would consider this open item closed.

Thanks,
Jatinder
Received on Wednesday, 30 January 2013 01:31:37 UTC

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