[WiX-devs] Avoiding re-downloading of payloads

[Heath S. <he...@ou...>]

I'm looking into fixing http://wixtoolset.org/issues/3060/ (rather, I'm fixing it anyway and was wondering if it already was so may as well pick this up) and have determined a couple different ways but wanted to get architecture guidance (or feedback in general).
Mainly, is a layout directory considered a local cache? I'm assuming not, since "cache" also carries some guarantees like that the file is protected (at least in per-machine cases). I ask, because one way is to check if we're doing a layout and, if so, track the layout path as the cache. This will avoid adding cache actions.
Similarly, I could add a member to track a layout specifically and avoid adding cache actions, but that blurs the line between cache and layout directory.
If we want to disassociate the cache and layout (as they appear to be now), the most straight forward way is to consider the layout directory (if doing a layout, or maybe just query the variable anytime since maybe the BA wants that to be considered regardless of bundle action) in CacheVerifyLocalContainerOrPayload(). We still plan cache actions, but not until before downloading it do we consider whether it's already downloaded. I'm leaning toward this one given that a layout isn't really a cache, but if we want to consider layout as a type of cache than the ideas above make more sense.
Thoughts?


Heath Stewart
Software Engineer
Visual Studio, Microsoft
http://blogs.msdn.com/heaths