On 04/07/2012 09:45 PM, Dennis E. Hamilton wrote:
I agree that it is far more appealing to do this server side rather
than have the client user agent have to fire up only to do a
redirect.
It also leaves open the prospect of handling the failure modes more
effectively.
Of course, that change can be done at any time, perhaps when there is
no peak load on the horizon?
- Dennis
I'll take a look at this when I get a moment this weekend. I understand
Dennis's concern about the scarey aspects of changing mirror sites in
the JS we currently use especially given the number of committers we
have now with access to the entire web tree.
I'm assuming if we did use server-side mirror selection logic, we would
just specify the Apache mirror for ooo ---
http://apache.tradebit.com/pub/incubator/ooo/ -- and let server side
logic figure it out from there.
-----Original Message----- From: Dave Fisher
[mailto:[email protected]] Sent: Saturday, April 07, 2012 20:02
To: [email protected] Subject: Re: [DL LOGIC] How to
choose a mirror when more than 1 is available?
Hi Joe,
While everyone else might be ignoring the distinction between the
Apache closer cgi/ezt and the current OOo javascript methods, I
haven't missed the difference. One is server and the other client.
You've mentioned where the various example pieces are, but to make it
really easy would you mind providing the two or three key urls into
the svn repos? I'm interested, but not in a hurry.
Thanks, Dave
On Apr 7, 2012, at 1:09 PM, Joe Schaefer wrote:
If you're really paranoid about the ASF mirrors you can use ezt to
embed the [preferred] mirror inside some javascript within the page
and run a test HEAD request on the url to ensure it exists.
I don't see the point of the MirrorBrain stuff
at this point tho- will just make things more messy than they
already are dealing with SF + ASF mirrors.
----- Original Message -----
From: Rob Weir<[email protected]> To:
[email protected] Cc: Sent: Saturday, April 7, 2012
4:03 PM Subject: Re: [DL LOGIC] How to choose a mirror when more
than 1 is available?
On Sat, Apr 7, 2012 at 3:35 PM, Marcus
(OOo)<[email protected]> wrote:
Am 04/07/2012 07:38 PM, schrieb Marcus (OOo):
Am 04/07/2012 05:34 PM, schrieb Rob Weir:
On Sat, Apr 7, 2012 at 10:13 AM, Marcus
(OOo)<[email protected]>
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.
This should work also for SourceForge. The root path is
always the
same.
We just need to add a subdir and file name.
I don't know how to do it for Apache.
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.
ACK
What could we do? Pop-up (or pop-under) a new HTML page?
But that
is
annoying to some users.
Right
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?
Yes, would be great. Another available system as possible
backup is not bad.
For any change of the number of available systems we have to
adapt the JS logic.
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.
Redirecting due to weighted values looks good. But also this
is working with a fixed set of mirror hosts. A forth had to
be build in and therefore the logic has to be adapted.
Thanks for your feedback. I'll adapt the script later in the
evening.
I've adapted it now. But I'm not sure if it's working correct
with some
disabled mirrors.
I'm not sure my logic was right in the above code. For example,
if two mirrors have the same weight it would always pick the
first one in the array.
But take a look at the approach in this article:
http://www.javascriptkit.com/javatutors/weighrandom2.shtml
I think that is much clearer and easier to use.
Essentially, it says if you want weighted random selection with
weights like:
Apache:1 MirrorBrain:2 SourceForge:3
Then create an array with each item repeated according to its
weight, so:
Apache MirrorBrain MirrorBrain SourceForge SourceForge
SourceForge
Then just pick a random number 0...length-1 and return the value
at that index.
As for unavailable mirrors, or even unavailable servers within a
mirror network, is there really anything we can do? Other than
tell the user to refresh and try again?
-Rob
Marcus
--
------------------------------------------------------------------------
MzK
"Women and cats will do as they please,
and men and dogs should relax and get used to the idea."
-- Robert Heinlein
