Re: [xmlblaster] questions on XmlBlaster XPATH subscriptions

[Marcel Ruff <mr at marcelruff.info>]

Peter.Weinstein at Altarum.org wrote:
> Hi,
>
> I'm having trouble finding a description of the semantics of XPATH
> subscriptions. I have several questions:
>
> 1) Can the XPATH key include a data value, as opposed to an attribute
> value? For example, if a published message includes:
>
>     <xmlBlaster>
>         <Header>
>             <Attribute>
>                 <label>evidenceAssembly1234</label>
>
> will I receive this messsage with an XPATH subscription with syntax
> something along the lines of:
>
>     /xmlBlaster/Header/Attriute/label[starts-with('evidenceAssembly')]

Yes, but you should start it with // as the hierarchy looks like

  http://www.xmlblaster.org/FAQ.html#XPATH

For better performance use absolute XPATH like

  /xmlBlaster/key/xmlBlaster/Header/Attriute/label[starts-with('evidenceAssembly')]

> 2) Can the XPATH key include multiple criteria, such that all must be true?

All must be true, it is nothing else than XPATH

> 3) Will the content of messages selected by an XPATH key include the entire
> messages as published (as opposed to subtrees identified by the XPATH key)?

A message consists of a 'key' a 'qos' and a 'content'
The 'content' is never touched by xmlBlaster and delivered as is.
The 'key' of the topic is not changed as well.
If you need a full text search (for example your 'content' shall
be used to filter) you need to use a MIME plugin:

http://www.xmlblaster.org/xmlBlaster/doc/requirements/mime.plugin.access.xpath.html

or for regex:

http://www.xmlblaster.org/xmlBlaster/doc/requirements/mime.plugin.access.regex.html

> 4) Does documentation or demo code exist that covers XPATH semantics well?

See above,
in

  xmlBlaster/testsuite/data/xml

there are some xml files i used to play with, for example:

  java DomQueryTest Agent.xml "xmlBlaster/key[ at oid='2' or  at oid='3']"

enjoy,

Marcel
> Thanks for your help!
> Peter
>
> --------------------------------------
> Peter Weinstein, Ph.D.
> Information Technology Scientist
> Altarum Institute
> 734-302-4701
> http://www.altarum.org
> http://www.umich.edu/~peterw/
> "Those who can, build." - Robert Moses
> --------------------------------------


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