ETAG is always the same about owin.compression HOT 12 CLOSED

The original idea is simply that if the server calculated value over the content ("body") is the same than client already has in ETAG, we don't need to compress and send the resource over the wire.

from owin.compression.

Hmm... Was the context.Response.Body empty at the time of calculation?

from owin.compression.

Hi,

after some tests, it turned out that the response buffer has the position pointing to the buffer end thus hashing always returns the same results.

So, this part matters

        let getMd5Hash (item:Stream) =
            item.Position <- 0L

With regards to context.Response.Body - it seems unrelated somehow and probably something to deal with many other middlewares I have.

There is one remark though, you make context.Respones.Body pointing to your buffer and don't restore it before exit. The middleware which executes on top that will try to access context.Response.Body after Next.Invoke might use the incorrect buffer. Not sure if that's a valid concern though.

from owin.compression.

I have not experienced this. So maybe the order of middleware-registration is significant.

from owin.compression.

All right,

but what's with regard to the stream position. Will you make the update to change the position into the beginning of the stream during the MD5 hash calculation?

from owin.compression.

Can you send a PR?

from owin.compression.

Is this only for streams?

from owin.compression.

Yeah, it's for streams. That's our use case. I'm not a F# developer, so I might be doing this the wrong way :)
You might want to check if it's allowed to perform seek operations on the stream. And to position the stream the same way you do in the code below.

from owin.compression.

Should we reset the position back to original,
e.g.

let getMd5Hash (item:Stream) =
    let hasPos = 
        if item.CanSeek && item.Position > 0L then
            let tmp = item.Position
            item.Position <- 0L
            Some tmp
        else None
    use md5 = System.Security.Cryptography.MD5.Create()
    let res = BitConverter.ToString(md5.ComputeHash(item)).Replace("-","")
    match hasPos with
    | Some x when item.CanSeek -> item.Position <- x
    | _ -> ()
    res

from owin.compression.

I didn't find any info about whether the middleware must persist the state of the Context.Response.Body stream. So I would assume this is not a requirement, however, it won't harm either :)

from owin.compression.

This is now added to NuGet version 1.1.18. Hopefully helps.

from owin.compression.

It works well. Thank you!

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