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External XQuery

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Jonty

External XQuery

I am using XQuery like this:

<p:processor name="oxf:xmldb-query">
<p:input name="datasource" href="datasource.xml"/>
<p:input name="query">
<xdb:query collection="/db/cms" create-collection="true">
xquery version "1.0";
<news>
{
for $article in /news/article
return $article
}
</news>
</xdb:query>
</p:input>
<p:output name="data" ref="data"/>
</p:processor>

Can I move the xquery to an external file so I can do something like this:

<p:processor name="oxf:xmldb-query">
<p:input name="datasource" href="datasource.xml"/>
<p:input name="query" href="news.xq"/>
<p:output name="data" ref="data"/>
</p:processor>

Also, why do we need the collection attribute? Can you not use the collection() function in the XQuery? What is create-collection attribute for and are there other attributes?

Are there other ways to implement XQuery (with eXist and passing data to xsl)?

Thanks

Jon

Erik Bruchez

Re: External XQuery

Administrator

Jonty wrote:

> I am using XQuery like this:
>
> <p:processor name="oxf:xmldb-query">
> <p:input name="datasource" href="datasource.xml"/>
> <p:input name="query">
> <xdb:query collection="/db/cms" create-collection="true">
> xquery version "1.0";
> <news>
> {
> for $article in /news/article
> return $article
> }
> </news>
> </xdb:query>
> </p:input>
> <p:output name="data" ref="data"/>
> </p:processor>
>
> Can I move the xquery to an external file so I can do something like this:
>
> <p:processor name="oxf:xmldb-query">
> <p:input name="datasource" href="datasource.xml"/>
> <p:input name="query" href="news.xq"/>
> <p:output name="data" ref="data"/>
> </p:processor>

You can, but I don't think oxf:xmldb-query supports a plain query in the
file. It only supports the query embedded within xdb:query.

> Also, why do we need the collection attribute? Can you not use the
> collection() function in the XQuery? What is create-collection attribute for
> and are there other attributes?

I think that the collection is required by the XML:DB API. You can
probably use the root collection, /db, if you don't care about passing
another collection. Yes, you can use the collection() function.

The create-collection attribute creates the collection if it's missing
when set to "true". If set to "false" and the collection doesn't exist,
then you will get an error.

> Are there other ways to implement XQuery (with eXist and passing data to
> xsl)?

You can submit a query using the REST API, by using the
oxf:xforms-submission processor. Note that with the REST API as well,
you POST queries in particular collections.

-Erik

--
Orbeon Forms - Web Forms for the Enterprise Done the Right Way
http://www.orbeon.com/

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Jonty

Re: External XQuery

Thanks for clearing that up and taking the time to answer all these queries. It's extremely helpful.

Is there any difference in terms of performance with these two approaches?

Erik Bruchez wrote

Jonty wrote:
> I am using XQuery like this:
>
> <p:processor name="oxf:xmldb-query">
> <p:input name="datasource" href="datasource.xml"/>
> <p:input name="query">
> <xdb:query collection="/db/cms" create-collection="true">
> xquery version "1.0";
> <news>
> {
> for $article in /news/article
> return $article
> }
> </news>
> </xdb:query>
> </p:input>
> <p:output name="data" ref="data"/>
> </p:processor>
>
> Can I move the xquery to an external file so I can do something like this:
>
> <p:processor name="oxf:xmldb-query">
> <p:input name="datasource" href="datasource.xml"/>
> <p:input name="query" href="news.xq"/>
> <p:output name="data" ref="data"/>
> </p:processor>

You can, but I don't think oxf:xmldb-query supports a plain query in the
file. It only supports the query embedded within xdb:query.

> Also, why do we need the collection attribute? Can you not use the
> collection() function in the XQuery? What is create-collection attribute for
> and are there other attributes?

I think that the collection is required by the XML:DB API. You can
probably use the root collection, /db, if you don't care about passing
another collection. Yes, you can use the collection() function.

The create-collection attribute creates the collection if it's missing
when set to "true". If set to "false" and the collection doesn't exist,
then you will get an error.

> Are there other ways to implement XQuery (with eXist and passing data to
> xsl)?

You can submit a query using the REST API, by using the
oxf:xforms-submission processor. Note that with the REST API as well,
you POST queries in particular collections.

-Erik

--
Orbeon Forms - Web Forms for the Enterprise Done the Right Way
http://www.orbeon.com/

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Alessandro Vernet

Re: External XQuery

Administrator

Jonty,

On 6/20/07, Jonty <[hidden email]> wrote:
> Thanks for clearing that up and taking the time to answer all these queries.
> It's extremely helpful.
>
> Is there any difference in terms of performance with these two approaches?

The xmldb-query uses the XML:DB API, which won't go through HTTP. With
xforms:submission there will be some overhead as request and response
will go through HTTP. If you are using xforms:submission and
performance becomes an issue, you can check if this is the bottleneck,
and if it is the case switch to xmldb-query. Overall, using
xforms:submission has a number of benefits, maybe the most important
one being simplicity, so this would be my preferred choice.

Alex
--
Orbeon Forms - Web 2.0 Forms, open-source, for the Enterprise
http://www.orbeon.com/

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Erik Bruchez

Re: External XQuery

Administrator

Alex,

> On 6/20/07, Jonty <[hidden email]> wrote:
>> Thanks for clearing that up and taking the time to answer all these
>> queries.
>> It's extremely helpful.
>>
>> Is there any difference in terms of performance with these two
>> approaches?
>
> The xmldb-query uses the XML:DB API, which won't go through HTTP. With
> xforms:submission there will be some overhead as request and response
> will go through HTTP. If you are using xforms:submission and
> performance becomes an issue, you can check if this is the bottleneck,
> and if it is the case switch to xmldb-query. Overall, using
> xforms:submission has a number of benefits, maybe the most important
> one being simplicity, so this would be my preferred choice.

You are not right that XML:DB doesn't go through HTTP: it will, unless
you access an embedded eXist database.

So I don't think it is a question of overhead (although to be sure we
should do some profiling), but rather of architecture, mainly whether
you want to have some middleware writting in XPL or whether you want to
access eXist directly from XForms.

-Erik

--
Orbeon Forms - Web Forms for the Enterprise Done the Right Way
http://www.orbeon.com/

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