abstraction of mapogcsos.c common ogc bits

[Kralidis,Tom [Burlington]]

> -----Original Message-----
> From: Frank Warmerdam [mailto:warmerdam at pobox.com] 
> Sent: 18 October, 2006 12:52 PM
> To: Kralidis,Tom [Burlington]
> Cc: MAPSERVER-DEV at LISTS.UMN.EDU
> Subject: Re: [UMN_MAPSERVER-DEV] abstraction of mapogcsos.c 
> common ogc bits
> 
> Kralidis,Tom [Burlington] wrote:
> > What do people think about a generic mapowscommon.c / mapowscommon.h
> 
> Tom,
> 
> I think this seems reasonable as long as you don't feel this 
> would belong in mapows.c.
>

I would prefer to keep this separate from mapows.c for now.
mapowscommon.c would be a straight implementation of the OWS Common
spec, whereas mapows.c has bits which are not necessarily OWS
Common-sih, but important to MapServer.
 

> > This file would be a set of routines to cover the OWS Common 
> > Specification, and return XML objects which adhere to OWS Common.
> > 
> > The one immediate issue I would see is how these routines return 
> > objects.
> > 
> > With the exception of SOS, all of the other code for OGC XML is 
> > returned as some sort of msIO_printf.  SOS uses libxml2 to 
> make things happen.
> > 
> > Maybe Assefa/others can provide comments on using libxml2 
> compared to 
> > msIO_printf for XML.  If it were up to me, I'd go with doing things 
> > the
> > libxml2 way, as msIO_printf can be quite error prone for XML output 
> > and well formedness.  This would of course mean that any future 
> > development of OGC stuff in MapServer would be best to 
> align with the 
> > libxml2 way of doing things.
> 
> I'm not sure I understand the implications of this.  Would 
> this imply that WMS server support in the short term would 
> depend on libxml2 just for a shared exception function?  Or 
> is this really just about pushing other services to use 
> libxml2 in the future?
> 

The latter.  I wouldn't expect any existing code to have to be ported.

> I'm ok with migrating to libxml2 but it will add a new 
> dependency for the commonly used services and so I'd rather 
> not depend on it for WMS/WFS/WCS until such time as we make a 
> serious migration to it.  That is I don't want to add a 
> libxml2 dependency but only use it for a one or two little 
> things.  Does that make any sense?
>

Exactly.  I think it will add dependency only once serious migration is
taken by the MapServer OGC code.  Having said this, migration would be
easier once something like mapowscommon.c exists.
 
> Best regards,
> -- 
> ---------------------------------------+----------------------
> ----------
> ---------------------------------------+------
> I set the clouds in motion - turn up   | Frank Warmerdam, 
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | President OSGeo, 
> http://osgeo.org
> 
>