JAXTHelper vs LibXSLTTransformer, which one is preferred?

[Peter Jentsch]

Am 04.09.12 13:16, schrieb Caolán McNamara:
> On Thu, 2012-08-30 at 10:10 +0900, mete0r wrote:
>> Hi,
>>
>> I'm developing an document import filter (which will be packaged as
>> an .oxt extension) and it needs to perform XSLT transformations during
>> the process of importing (I don't believe xsltfilter could cover these
>> process). So I'm finding a way to use XSLT transformation services
>> directly.
>>
>> In libreoffice 3.5.4, which I'm working with, there seem 2 UNO service,
>> i.e., com.sun.star.comp.JAXTHelper and
>> com.sun.star.comp.documentconversion.LibXSLTTransformer.
>>
>> Currently I'm using the later one (by specifiying its service name in
>> the ServiceManager.createInstanceWithContext()), but both are just
>> working fine for me. So here are my questions:
>>
>> 1. Which one is preferred to be used in regard to forward/backward
>> compatibility? It looks like LibXSLTTransformer is introduced later,
>> then will JAXTHelper be deprecated at some point in the future?
>>
>> 2. Or should I choose one of them conditionally according to the version
>> of the Libreoffice installation? If this is the case, from what version
>> should I use LibXSLTTransformer?
>>
>> 3. Or direct instantiation and use of them like these (not through
>> xsltfilter), is unsupported and discouraged way?
>>
>> Any guidance or comments would be greatly appreciated.
> This isn't an area I know much about, maybe Peter can give the best
> suggestions. But if the question ends up being "directly use the java
> backend vs directly use the libxslt-based backend" then I imagine the
> answer is to use the libxslt-based one.
>
> C.
>
>
Hi mete0r,

that's an interesting one: xslt filter uses LibXSLTTransformer as a
default that can be overriden with JAXTHelper, but we don't have a real
default for that.

JAXTHelper is, as you said, the older implemenetation, and is the one
still being used by Apache OpenOffice. It delegates transformation to a
bundled version of Saxon 9 (Java).

The main differences between the to services are as follows:

LibXSLTTransformer:

- fast initialization
- does not require Java
- supports XSLT 1.0 + most exslt extension (support for exslt within
LibO depending on a patch pending to be submitted by me)
- fast for most simple transformations
- extensions need to be written in C an incorporated into LibO source
(currently no dynamic loading of extension functions)

JAXTHelper:
- slow initialization
- requires Java
- supports XSLT 2.0
- contains some optimizations which make if a lot faster for some
complex transformations
- extensions need to be written in Java an can be bundled with LibO
extensions (supports dynamic loading of extension functions)

JAXTHelper is not going away in the near future, as it provides support
for XSLT 2.0, which is not going to appear in libxslt any time soon.

I'd suggest you choose on the criteria above, giving LibXSLTTransformer
a slight preference.

Cheers,

Peter