[xsd-users] Keep a xsd library small

[Angelo Difino]

Boris Kolpackov wrote:
> Hi Angelo,
>
> Angelo Difino <angelo at cedeo.net> writes:
>
>   
>> first of all I'd like to say that xsd-codesynthesis rocks: after just few
>> days of it i was able to create the c++ classes of a quite 'complicated'
>> set of  schemas (that was already posted here few mouths ago').
>>     
>
> Thanks, I am glad you find it useful.
>
>
>   
>> Since this set of schema suffer of cyclic dependencies with inheritance,
>> I'm using the file-per-type option. I'm running the last release (3.2.0) 
>> of XSD on win32/vista...
>>
>> Everything works great, but the problem is the huge amount of files
>> and its size when I try to compile it (i'm using MSVisual c++ 2003).
>> The header and class file counts 872 and the built library is of 1GB
>> of size 
>>     
>
> You are probably building a static library. Unfortunately with 
> the file-per-type mode static libraries for non-trivial schemas
> are bound to be quite large. This is due to the large number of
> source files which, when compiled, all include instantiations of
> some common templates (this is especialy true when the --generate-
> polymorphic option is used). The static library is pretty much the
> archive of all the object files. When it is linked to an executable,
> the linker will remove all those duplicate template instantiations
> so the resulting binary will have the same size as if you used the
> file-per-schema mode.
>
> One solution to this problem is to use a shared library (DLL)
> instead of a static library since a shared library is mode like
> an executable in that all the duplicate template instantiations
> are removed. For example, I compiled your schemas on my GNU/Linux
> box and while the static library is 227MB, the shared library is
> 10MB.
>   

Hi Boris and all,
thank you very much for the hint! nowadays, with shared library, on 
win32 with msvc 9.0
i've reached 8 MB in debug and 4 in release... that's pretty ok ;)

> Here are some more tips for reducing the size/compilation time:
>
> 1. Specify root element with the --root-element option. In your
>    schema I eliminated about a hundred parsing/serialization
>    functions by adding '--root-element DIDL' to the command
>    line.
>   

'Unfortunally' i've to be able to use any of the root elemets (didl, 
rel-*, ...), so i've avoided to
specify the DIDL (but i've used it since it includes all the other 
sub-schemas)
type
> 2. Your schema is composed of several lower-level schema subsets.
>    If only one of the lower-level subsets involve the cyclic 
>    dependency, then you can compile only this subset in the
>    file-per-type mode and the rest in the default, file-per-
>    schema mode. Note that here the subset needs to be fairly
>    isolated in that all the schemas that it includes/imports
>    will be handled in the file-per-type mode. In your case,
>    there are two subsets that involve cyclic dependencies 
>    (rel-*.xsd and ipmpmsg.xsd/ipmpinfo.xsd) so the bulk of
>    the schema has to be compiled in the file-per-type mode.
>    However, there are still a few files that can be compiled
>    in the file-per-schema mode, namely, didl.xsd, didl-msx.xsd,
>    and mpeg4smp.xsd.
>
>    I compiled your schemas like so:
>
>    xsd cxx-tree --file-per-type ... rel-r.xsd ipmpinfo.xsd
>    xsd cxx-tree ... didl.xsd didl-msx.xsd mpeg4smp.xsd 
>
>    And the static library size went down to 175Mb.
>   
I see, but i prefer to manage all the schema on the same way
> 3. You can also try to split the offending schemas into two or
>    more files so that they don't involve cyclic dependencies
>    with inheritance (the resulting schema will be semantically
>    equivalent to the original). Then you can use the file-per-
>    schema mode.
>
> 4. When using the file-per-type mode it is recommended to use
>    precompiled headers to speed-up compilation. You would normally
>    include xml-schema.hxx into the precompiled header and then
>    include the precompiled header into each generated source
>    file using the --cxx-prologue option.
Ok, I've still to investigate on this issue!

Last question :) since the number of classes is quite big (about 800 ), 
I've decided
to organize this source code in several subfolders, labelled with the 
same name of the
schema they belong to.
I've wrote a batch file that simply move the files in the correct 
subfolder. Is there any
way to automatize it (something like "--output-dir dir", but for the 
different namespaces)?
I've included in attach an example of the batch file so you can look 
better what i
need... (if there is any way to do it!!! :) )

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