underlying XML support and implementation

Frank Warmerdam warmerdam at POBOX.COM
Tue Apr 3 21:49:52 EDT 2007


Kralidis,Tom [Burlington] wrote:
> Actually, GetFeature / GetObservation would be the target use case to do
> XSLT prior to output.  Plus, it would depend on the volume of the
> response.  Definitely more discussion and caution required here.

Tom,

As I think has been mentioned before, I'm fine with doing XSLT on
GetFeature results in memory when that is desired.  I am just concerned
about turning the GetFeature code into libxml2 based such that the
response document is always built in memory.

> I understand.  Can something like this be done in small
> chunks/iterations vs. an overhaul?  For example, if I were to
> strategize, I would move forward in the following manner:
> 
> - WCS (Capabilities, DescribeCoverage)
> - WFS (all operations)
> - WMS (GetCapabilities, GetFeatureInfo, DescribeLayer, GetStyles)

Some operations can easily be done in isolation, while other likely
come in groups.  I could *imagine* trying to rework all the capabilities
code to use libxml2 in one big pass if we were also trying to do OWS
support properly and perhaps adding WMS 1.3.  Most of the other
operations are fairly isolated.

> As well, could this be for "future development", i.e. for WFS 1.1.0
> support (if/when implemented), the developer would ensure that libxml2
> is used and the code is updated.

Well, I don't think we could have one version of WFS done with libxml2
and another with printfs unless the versions were so different we didn't
want to share anything.

> If one of MapServer's key "selling" points is / will be the significant
> support of OGC specifications (most of which inherently deal with XML),
> I believe this approach will prove worthwhile in the long run.

A transition to libxml2 has some benefits, but I don't see that it is any
way a requirement for implementing OGC specifications so I'm not sure that
the above point is compelling.

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



More information about the mapserver-dev mailing list