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From Rob Weir <robw...@apache.org>
Subject Re: [DL LOGIC] How to choose a mirror when more than 1 is available?
Date Sat, 07 Apr 2012 15:34:16 GMT
On Sat, Apr 7, 2012 at 10:13 AM, Marcus (OOo) <marcus.mail@wtnet.de> wrote:
> For our new release we will have a changed set of conditions:
>
> - new central mirror hosts for redirecting download requests
> - therefore also a new set of mirror server that host our builds
> - new set of supported platforms and languages
> - slighty changed file name schema
>
> To get this all under one hat, we have to improve the download logic that is
> currently done by JavaScript.
>
> To fulfill the first condition the download requests have to be split-up to
> more than 1 central mirror redirector.
>
> Here is a suggestion for choosing when (by random number) to redirect to
> which mirror:
>
> http://www.openoffice.org/download/test/index_new_dl.html
>
> Test results:
> - to make debugging easier I've included some screen output and comments
> - I've tested it locally with different combinations of active/inactive
>  hosts and it works well
> - the fallback method works well, too
> - I've tested different percent values as ratio, but not yet for the
>  2nd case
>
> What do you think?
>

The logic on the test pages works for me.

But two additional complexities:

1)  MirrorBrain let's us link directly to a download file.  We then
send the user to http://www.openoffice.org/download/contribute.html
while the file is downloading.  But SourceForge and Apache mirror
systems take the user to a different page (not controlled by us). So
in those cases the user does not see the contribute.html page.

Since the contribute.html page has very useful information for the
user, like links to the install instructions, information on support,
contributing to the project, etc., I think it is important that the
user sees this information in all paths.

What could we do? Pop-up (or pop-under) a new HTML page?  But that is
annoying to some users.

The Apache and SF approaches both direct a user off of the
OpenOffice.org website, which is risky.

2) What if we have more than three mirror systems?  It sounds like you
prefer to keep MirrorBrain.  That is fine with me. So maybe we have
Apache, SF and MirrorBrain?

Imagine an array of mirror networks, each with weights, in sorted
order from smallest to largest.  (or sort the array in code)

Apache:1
MirrorBrain:2
SourceForge:3

TotalWeight =  MirrorBrain + Apache + SourceForge == 6

x = rand()

if (x < Apache/TotalWeight)
    doApache()
else if (x < MirrorBrain/TotalWeight)
    doMirrorBrain()
else
    doSourceForge()

Something like that.

-Rob

> Marcus
>

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