Re: [Exist-open] Concurrent tasks in XQuery....

[Adam R. <ad...@ex...>]

Yeah I think the best way would be to add an asynchronous function
call, and pass it an xquery function as a callback, you could keep
some state by passing parameters when you setup the callback,
something like -

httpclient:get-async($a as xs:anyURI, $b as xs:boolean, $c as
element()?, $d as function, $e as item()*, ...) as item()

Where -

$a is the URI to HTTP GET
$b is whether to persist cookies
$c is any HTTP Request Headers
$d is the callback function - from util:function()
$e are parameters to the callback function

In this way you can issue all the requests asynchronously one after
another and have a function called when each completes to do some post
processing. I would be quite happy to implement this if you need the
help, but somehow I think you will be fine. Underneath you might want
to use a static instance of the MultiThreadedConnectionManager from
the Apache Commons HTTPClient library for efficency and perhaps even
adjust all the functions in the httpclient module to use this.

http://hc.apache.org/httpclient-3.x/threading.html

Cheers Adam.


2008/6/19 Andrzej Jan Taramina <an...@ch...>:
>
> Figured I would tap the collective intelligence of the eXistentialists!
>
> I have a situation where I need to be able to issue multiple HTTP requests
> concurrently from an XQuery.  Doing them serially and blocking on each one would
> result in unacceptably long response times. BTW, each request would go to a
> different remote server.
>
> I don't believe there is any way currently to do this using eXist's XQuery
> implementation.
>
> Any ideas on how difficult it might be to extend eXist's XQuery implementation
> to support the concept of concurrent tasks, joins, timeouts and the like?
>
> Thanks!
>
> --
> Andrzej Taramina
> Chaeron Corporation: Enterprise System Solutions
> http://www.chaeron.com
>
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-- 
Adam Retter

eXist Developer
{ England }
ad...@ex...
irc://irc.freenode.net/existdb