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Fraser Goffin wrote:
> 4. Large lists are still a problem right ?. It is not unusual in the
> financial services sector for many lists to be > 200 entries, a
> reasonable number to be > 1000 and a few that are >10,000. Using
> schematon XSLT would be a bit impractical wouldn't it ?
ISO Schematron and Schematron 1.6 have a <let> expression* which allows
you to, for example, have an XPath to gather the codes once into a
variable, then test against that variable. So you don't need to
download the external document and traverse the tree each time.
However, you would have to iterate through the list each time, which is
still time consuming. There are various optimization trick possible for
extreme cases: for example, of the top of my head (Xpaths may be shonky
here)
<sh:rule context="thing[@code]">
<sch:let name="codes"
value="document('http://www.eg.com/codes')/*/codes"/>
<sch:assert test=" $codes/codes/. = @code" >
the code should be found on the list
</sch:code>
</sch:rule>
Use 26 rules
<sh:rule context="thing[starts-with(@code, 'A')]">
<sch:let name="codes"
value="document('http://www.eg.com/codes')/*/codes[starts-with(@code,'A')]"/>
<sch:assert test=" $codes/codes/. = @code" >
the code should be found on the list
</sch:code>
</sch:rule>
<sh:rule context="thing[starts-with(@code, 'B')]">
<sch:let name="codes"
value="document('http://www.eg.com/codes')/*/codes[starts-with(@code,'B')]"/>
<sch:assert test=" $codes/codes/. = @code" >
the code should be found on the list
</sch:code>
</sch:rule>
...
Brute force, but sometimes effective. (Note that there is no reason why
an assertion
should not require several rules or assert statements to support it. The
assertion text
is not a comment on the XPath, but a postive statement of something
which the XPath
partially or fully checks. )
Or another workaround can be to use URLs: have a little servlet that
accepts a code
as an argument then returns <true/> or <false/> as the result. Then your
assertion
test constructs a URL with the code insterted into a URL query. Again,
not always
the best way to do things, but certainly a method that is not so
available to XSD
etc.
<sch:assert
test="document(concat('http://www.eg.com/servlet/codes?code=',
@code))/true">
the code should be found on the list
</sch:assert>
Cheers
Rick Jelliffe
* It follows XSLT's let exactly. Trivial to add to an existing
implementation in one line in the straightforward way.
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