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Today's Topics:
1. Re: Performance of Basex 7.0 XQuery execution (Leo W?rteler)
2. Re: Problems in using BaseX REST server -
IncompatibleClassChangeError javax.ws.rs.core.Response$Status
does not implement the requested interface (Pushkaraj Thorat)
3. Re: ajax and http server - cross-domain, jsonp or proxy?
(Godmar Back)
4. Re: ajax and http server - cross-domain, jsonp or proxy?
(Michael Seiferle)
----------------------------------------------------------------------
Message: 1
Date: Fri, 21 Oct 2011 14:12:50 +0200
From: Leo W?rteler <lw@basex.org>
To: Constantine Hondros <Constantine.Hondros@tomtom.com>
Cc: basex-talk <basex-talk@mailman.uni-konstanz.de>
Subject: Re: [basex-talk] Performance of Basex 7.0 XQuery execution
Message-ID: <4EA161C2.3060908@basex.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Dear Constantine,
Am 20.10.2011 09:44, schrieb Constantine Hondros:
> Of course, I am really interested in more useful queries such as:
>
> //tns:poi[not(tns:id = preceding-sibling::tns:poi/tns:id)]
this query basically compiles to two nested loops, the outer one
iterating over //tns:poi and the inner one over all preceding-siblings.
So it has an O(n^2) runtime.
> I guess what I am asking is ... while most XPath queries I run are quick to resolve, anything using preceding::, preceding-sibling:: or following::, following-sibling:: essentially runs too slowly to be workable - at least, on my sample dataset with about 100K sibling children of the root element.
Well, that's an extreme example, 100'000^2 is a huge number of nodes to
traverse. I performed some tests with
a) 10'000 sibling elements inside the root:
<root>
<item id="1"/>
<item id="2"/>
[...]
<item id="10000"/>
</root>
and the query //item[not(preceding-sibling::*)]
b) 10'000 nested elements:
<root>
<item id="1">
<item id="2">
[...]
<item id="10000"/>
[...]
</item>
</item>
</root>
and the query //item[not(ancestor::*)]
The timings I get are almost identical, replacing "preceding" with
"following" or "ancestor" with "descendant" doesn't change much.
> So is this any sort of known issue? Should I be looking at any sort of configuration options? Is there any way to profile the execution of the Xpath?
My guess is that the number of nodes on the *-sibling-axes is usually
much bigger than on the vertical axes, so an expensive algorithm gets
unusable earlier.
To return to your example query, you could drastically reduce its
runtime by only traversing the database once, comparing each node only
to the nodes with unique tns:ids found before. I'll use a left fold [1][2]:
fold-left(
function($seq, $x) {
if($seq/tns:id = $x/tns:id) then $seq
else ($seq, $x)
},
(),
//tns:poi
)
If you're OK with using not-yet-standard XQuery extensions, a map [3]
instead of a sequence can potentially be even faster:
let $map :=
fold-left(
function($map, $x) {
let $key := $x/tns:id
return if(map:contains($map, $key)) then $map
else map:new(($map, map:entry($key, $x)))
},
map:new(),
//tns:poi
)
for $key in map:keys($map)
return $map($key)
But this won't preserve the relative ordering of the results.
Hope that helped,
Cheers Leo
__________
[1] http://www.w3.org/TR/xpath-functions-30/#func-fold-left
[2] http://en.wikipedia.org/wiki/Fold_%28higher-order_function%29
[3] http://docs.basex.org/wiki/Map_Functions
------------------------------
Message: 2
Date: Sat, 22 Oct 2011 01:40:23 +0530
From: Pushkaraj Thorat <pushkaraj.thorat.devl@gmail.com>
To: Rositsa Shadura <rositsa.shadura@uni-konstanz.de>
Cc: basex-talk@mailman.uni-konstanz.de
Subject: Re: [basex-talk] Problems in using BaseX REST server -
IncompatibleClassChangeError javax.ws.rs.core.Response$Status does not
implement the requested interface
Message-ID:
<CAH5ngE_gf655mnLuTCAjStd2X1cmWKJQk8xYTErMyFv4QnMYeQ@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Thanks Rositsa!
It is bit late to reply, but indeed it is a good to know.
Regards
Pushkaraj
On Fri, Mar 4, 2011 at 3:01 AM, Rositsa Shadura <
rositsa.shadura@uni-konstanz.de> wrote:
> Hi all,
>
> I've just managed accidentally to reproduce the error. I noticed that the
> class javax.ws.rs.core.Response.**Status is defined in both
> jsr311-api-1.0.jar and jersey-core-1.4.jar but only the class in the
> jersey-core JAR implements the interface javax.ws.rs.core.Response.**StatusType.
> This is why it is important that the jersey-core JAR appears before the
> jsr311-api JAR in the classpath. When not the error occurs.
>
> Greetings,
> Rositsa
>
>
> On Thu, 20 Jan 2011 12:03:45 +0100, Michael Seiferle <
> michael.seiferle@uni-**konstanz.de <michael.seiferle@uni-konstanz.de>>
> wrote:
>
> Hi Pushkaraj,
>>
>> thanks in return for your response.
>> I will see if I can reproduce that in my VM; so far you are the first one
>> to report this issue, I'll let you know what I can find.
>>
>> Kind regards
>>
>> Michael
>>
>> Am 19.01.2011 um 20:19 schrieb Pushkaraj Thorat:
>>
>> Thanks for your response Michael,
>>>
>>> I am using java 1.6
>>>
>>> pushkaraj@toothless:~$ java -version
>>> java version "1.6.0_17"
>>> Java(TM) SE Runtime Environment (build 1.6.0_17-b04)
>>> Java HotSpot(TM) Server VM (build 14.3-b01, mixed mode)
>>> pushkaraj@toothless:~$
>>>
>>> Just to update, the rest server ran successfully on my windows machine.
>>> Not sure what problem faced on the linux(ubuntu) machine. I will debug once
>>> I get some time.
>>>
>>> Thanks, Pushkaraj
>>>
>>>
>>> On Tue, Jan 18, 2011 at 3:46 AM, Michael Seiferle <michael.seiferle@uni-
>>> **konstanz.de <michael.seiferle@uni-konstanz.de>> wrote:
>>> Dear Pushkaraj,
>>>
>>> I am deeply sorry for you having to mess around with that erroneous
>>> startup scripts.
>>> We fixed them in both the ZIP & DMG distribution, feel free to download
>>> them again.
>>>
>>> >> java.lang.**IncompatibleClassChangeError
>>> We have been trying to reproduce this error - but to no avail.
>>> Your error message might have to do something with your Java Version;
>>> please make sure you are running the latest version.
>>>
>>> Hope this helps! In case it does not, feel free to ask for more.
>>>
>>> Kind regards
>>>
>>> Michael
>>>
>>> Am 17.01.2011 um 22:00 schrieb Pushkaraj Thorat:
>>>
>>> > I am doing setup for REST enabled basex database with procedure
>>> mentioned in http://docs.basex.org/wiki/**JAX-RX_API<http://docs.basex.org/wiki/JAX-RX_API>URL.
>>> >
>>> > Configuring & starting server and running failed due to class not
>>> found, but later I've modified the ./basexrest script as: (Included all the
>>> jars in lib folder)
>>> >
>>> > ######START
>>> > #!/bin/bash
>>> > # Path to this script
>>> > PWD=`dirname $0`
>>> > # Paths to distributed files or source directories
>>> > BASEX=$PWD/BaseX.jar
>>> > BASEXAPI=$PWD/../lib/basex-**api.jar
>>> > # Classpath
>>> > LIB=$PWD/../lib
>>> > LIB_CP=""
>>> > for JAR_FILE in $LIB/*.jar
>>> > do
>>> > LIB_CP="$LIB/$JAR_FILE:$LIB_**CP"
>>> > done
>>> > CP=$BASEX:$BASEXAPI:$LIB_CP
>>> > # Options for virtual machine
>>> > VM=-Xmx1g
>>> > # Run REST server
>>> > java -cp "$CP" $VM org.basex.api.jaxrx.**JaxRxServer "$@"
>>> >
>>> > ######END
>>> >
>>> > after this, server started successfully, hit the URL -
>>> http://localhost:8984/basex/**jax-rx<http://localhost:8984/basex/jax-rx>I am getting following exception:
>>> >
>>> > java.lang.**IncompatibleClassChangeError: Class
>>> javax.ws.rs.core.Response$**Status does not implement the requested
>>> interface javax.ws.rs.core.Response$**StatusType
>>> > at com.sun.jersey.spi.container.**ContainerResponse.getStatus(**
>>> ContainerResponse.java:548)
>>> > at com.sun.jersey.spi.container.**ContainerResponse$**
>>> CommittingOutputStream.**commitWrite(ContainerResponse.**java:156)
>>> > at com.sun.jersey.spi.container.**ContainerResponse$**
>>> CommittingOutputStream.write(**ContainerResponse.java:133)
>>> > at org.basex.io.BufferedOutput.**flush(BufferedOutput.java:50)
>>> > at org.basex.io.PrintOutput.**flush(PrintOutput.java:126)
>>> > at org.basex.data.XMLSerializer.**cls(XMLSerializer.java:206)
>>> > at org.basex.data.Serializer.**close(Serializer.java:219)
>>> > at org.basex.api.jaxrx.BXJaxRx$1.**code(BXJaxRx.java:96)
>>> > at org.basex.api.jaxrx.BXCode.**run(BXCode.java:53)
>>> > at org.basex.api.jaxrx.BXOutput.**write(BXOutput.java:53)
>>> > at com.sun.jersey.core.impl.**provider.entity.**
>>> StreamingOutputProvider.**writeTo(**StreamingOutputProvider.java:**71)
>>> > at com.sun.jersey.core.impl.**provider.entity.**
>>> StreamingOutputProvider.**writeTo(**StreamingOutputProvider.java:**57)
>>> > at com.sun.jersey.spi.container.**ContainerResponse.write(**
>>> ContainerResponse.java:299)
>>> >
>>>
>>>
>>> ______________________________**_________________
> BaseX-Talk mailing list
> BaseX-Talk@mailman.uni-**konstanz.de <BaseX-Talk@mailman.uni-konstanz.de>
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Message: 3
Date: Fri, 21 Oct 2011 17:23:14 -0400
From: Godmar Back <godmar@gmail.com>
To: colin mcenearney <colinmcenearney@yahoo.com>
Cc: "basex-talk@mailman.uni-konstanz.de"
<basex-talk@mailman.uni-konstanz.de>
Subject: Re: [basex-talk] ajax and http server - cross-domain, jsonp
or proxy?
Message-ID:
<CAB4+JYKE5EEBHSOM6Ui52dTNB55x3YuOEFk5sYeACuidtkW1cA@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Supporting JSON-P would be great; Michael mentioned that BaseX
supports it, but a search for JSON-P or 'callback' in the Wiki turns
up empty...
What's the callback argument used in JSON-P called? callback?
- Godmar
On Fri, Oct 21, 2011 at 12:51 AM, colin mcenearney
<colinmcenearney@yahoo.com> wrote:
> Hi Christian and Michael, and everyone.
> Thanks for your replies.
>
> I'm still having a little difficulty. Attempting to return results with
> method=jsonml I still get this error (using jquery's ajax methods):
>
> thrown error: [Exception... "Access to restricted URI denied" code: "1012"
>
> which I think is a result of sending an http-request across different ports.
>
> I think my question might be clearer with some background:? My idea for a
> simple app to learn the db is a blog, where each entry has its own xml file
> which contains, among other things, chunks of valid xhtml. I was envisioning
> a very simple interaction where javascript sends a get or post request and
> the db returns bits of xhtml.
>
> Can this be done without the use of additional server-side scripting? Maybe
> with direct calls to an xquery file like
> http://mysite.com/blog/blog.xq?categ=xmldb&level=beginner ?
>
> Colin
>
> ________________________________
> From: Christian Gr?n <christian.gruen@gmail.com>
> To: colin mcenearney <colinmcenearney@yahoo.com>
> Cc: "basex-talk@mailman.uni-konstanz.de"
> <basex-talk@mailman.uni-konstanz.de>
> Sent: Tuesday, October 18, 2011 11:54 AM
> Subject: Re: [basex-talk] ajax and http server - cross-domain, jsonp or
> proxy?
>
> Dear Colin,
>
> thanks for your e-mail.
>
>> I'm not really a developer so this might be an obvious question: using
>> basex's http server, what is the best strategy for ajax-style
>> communication
>> between browser and db?
>
> As Michael already pointed out, there is no "unique" strategy how to
> use BaseX with AJAX. One popular way is to use our new "json"
> serialization method, which allows you to directly return JSON from
> BaseX. A small example:
>
> 1. Start the HTTP server via "basexhttp -l" (the -l flag will
> communicate with the local database context; this way, no other socket
> connection will be used)
>
> 2. Via REST, retrieve a document or run a query and specify "jsonml"
> as output method:
> http://localhost:8984/rest/database/doc.xml?method=jsonml
>
> This way, the XML result will be directly serialized, using the JSONML
> syntax. If you have created your XML documents from JSON input files,
> you may as well use "json" as serialization format. Pleave check out
> our documentation as well:
>
> ? http://docs.basex.org/wiki/JSON_Functions
>
> Feel free to ask if this is not exactly what you are looking for.
> Christian
>
>
>
> _______________________________________________
> BaseX-Talk mailing list
> BaseX-Talk@mailman.uni-konstanz.de
> https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk
>
>
------------------------------
Message: 4
Date: Sat, 22 Oct 2011 00:07:50 +0200
From: Michael Seiferle <michael.seiferle@uni-konstanz.de>
To: Godmar Back <godmar@gmail.com>
Cc: "basex-talk@mailman.uni-konstanz.de"
<basex-talk@mailman.uni-konstanz.de>
Subject: Re: [basex-talk] ajax and http server - cross-domain, jsonp
or proxy?
Message-ID: <961D4106-66F3-4054-8621-2286E0F5E8C4@uni-konstanz.de>
Content-Type: text/plain; charset=utf-8
Dear Godmar,
Sorry if my recent reply was misleading there is no explicit support for jsonp at the moment but to build it yourself (pad the result with the help of xquery).
I guess it could be added in case s/o wants to do it :-)
Michael
On 21.10.2011, at 23:23, Godmar Back <godmar@gmail.com> wrote:
> Supporting JSON-P would be great; Michael mentioned that BaseX
> supports it, but a search for JSON-P or 'callback' in the Wiki turns
> up empty...
>
> What's the callback argument used in JSON-P called? callback?
>
> - Godmar
>
> On Fri, Oct 21, 2011 at 12:51 AM, colin mcenearney
> <colinmcenearney@yahoo.com> wrote:
>> Hi Christian and Michael, and everyone.
>> Thanks for your replies.
>>
>> I'm still having a little difficulty. Attempting to return results with
>> method=jsonml I still get this error (using jquery's ajax methods):
>>
>> thrown error: [Exception... "Access to restricted URI denied" code: "1012"
>>
>> which I think is a result of sending an http-request across different ports.
>>
>> I think my question might be clearer with some background: My idea for a
>> simple app to learn the db is a blog, where each entry has its own xml file
>> which contains, among other things, chunks of valid xhtml. I was envisioning
>> a very simple interaction where javascript sends a get or post request and
>> the db returns bits of xhtml.
>>
>> Can this be done without the use of additional server-side scripting? Maybe
>> with direct calls to an xquery file like
>> http://mysite.com/blog/blog.xq?categ=xmldb&level=beginner ?
>>
>> Colin
>>
>> ________________________________
>> From: Christian Gr?n <christian.gruen@gmail.com>
>> To: colin mcenearney <colinmcenearney@yahoo.com>
>> Cc: "basex-talk@mailman.uni-konstanz.de"
>> <basex-talk@mailman.uni-konstanz.de>
>> Sent: Tuesday, October 18, 2011 11:54 AM
>> Subject: Re: [basex-talk] ajax and http server - cross-domain, jsonp or
>> proxy?
>>
>> Dear Colin,
>>
>> thanks for your e-mail.
>>
>>> I'm not really a developer so this might be an obvious question: using
>>> basex's http server, what is the best strategy for ajax-style
>>> communication
>>> between browser and db?
>>
>> As Michael already pointed out, there is no "unique" strategy how to
>> use BaseX with AJAX. One popular way is to use our new "json"
>> serialization method, which allows you to directly return JSON from
>> BaseX. A small example:
>>
>> 1. Start the HTTP server via "basexhttp -l" (the -l flag will
>> communicate with the local database context; this way, no other socket
>> connection will be used)
>>
>> 2. Via REST, retrieve a document or run a query and specify "jsonml"
>> as output method:
>> http://localhost:8984/rest/database/doc.xml?method=jsonml
>>
>> This way, the XML result will be directly serialized, using the JSONML
>> syntax. If you have created your XML documents from JSON input files,
>> you may as well use "json" as serialization format. Pleave check out
>> our documentation as well:
>>
>> http://docs.basex.org/wiki/JSON_Functions
>>
>> Feel free to ask if this is not exactly what you are looking for.
>> Christian
>>
>>
>>
>> _______________________________________________
>> BaseX-Talk mailing list
>> BaseX-Talk@mailman.uni-konstanz.de
>> https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk
>>
>>
> _______________________________________________
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