[Geoserver-devel] WMS, format, mime types and 1.1/1.3 differences

Hi,
I am looking into http://jira.codehaus.org/browse/GEOS-4615 out
of a report that some WMS 1.1 client cannot handle GS geotiff
output because the content type does not correspond 1-1 to the
value declared in the request and found this in the spec:

------------------------------------------

The return value of a valid Service request shall correspond to the
type requested in the
FORMAT parameter. In an HTTP environment, the Content-type header of
the response
shall be exactly the MIME type given in the request.

------------------------------------------

Now... the spec is overall a bit retarded on this. One can have output
formats that do not have an official mime type or have variants around,
they should have allowed to associate a descriptive name with a standard
mime type in the capabilities document, something like
<Format mime="image/tiff">geotiff</Format>
but I guess we're way too late for that.

Anyways, I see that the WMS 1.3 capabilities output lists only mime types
instead. Nice, but doing so it shaves off a few formats as well, there is
no more a distinction between geotiff and tiff, nor there is a distinction
between png and png8, tiff and tiff8, geotiff and geotiff8.
This is not just cutting away handy aliases, it's cutting away functionality.

I guess the only way to handle this is starting to be creative about mime types?
image/png; mode=8bit
image/tiff; mode=8bit
image/geotiff
image/geotiff; mode=8bit

and then roll out in the capabilites new output formats with that mime as the
output?

Opinions?

Cheers
Andrea

--
-------------------------------------------------------
Ing. Andrea Aime
GeoSolutions S.A.S.
Tech lead

Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy

phone: +39 0584 962313
fax: +39 0584 962313

http://www.geo-solutions.it
http://geo-solutions.blogspot.com/
http://www.youtube.com/user/GeoSolutionsIT
http://www.linkedin.com/in/andreaaime
http://twitter.com/geowolf

-------------------------------------------------------

Yeah I found this strange as well… when I ran up against it before I thought we could potentially use a cite hack for this but I like the solution you present better. +1.

On Fri, Jun 10, 2011 at 7:09 AM, Andrea Aime <andrea.aime@anonymised.com> wrote:

Hi,
I am looking into http://jira.codehaus.org/browse/GEOS-4615 out
of a report that some WMS 1.1 client cannot handle GS geotiff
output because the content type does not correspond 1-1 to the
value declared in the request and found this in the spec:


The return value of a valid Service request shall correspond to the
type requested in the
FORMAT parameter. In an HTTP environment, the Content-type header of
the response
shall be exactly the MIME type given in the request.


Now… the spec is overall a bit retarded on this. One can have output
formats that do not have an official mime type or have variants around,
they should have allowed to associate a descriptive name with a standard
mime type in the capabilities document, something like
geotiff
but I guess we’re way too late for that.

Anyways, I see that the WMS 1.3 capabilities output lists only mime types
instead. Nice, but doing so it shaves off a few formats as well, there is
no more a distinction between geotiff and tiff, nor there is a distinction
between png and png8, tiff and tiff8, geotiff and geotiff8.
This is not just cutting away handy aliases, it’s cutting away functionality.

I guess the only way to handle this is starting to be creative about mime types?
image/png; mode=8bit
image/tiff; mode=8bit
image/geotiff
image/geotiff; mode=8bit

and then roll out in the capabilites new output formats with that mime as the
output?

Opinions?

Cheers
Andrea

Ing. Andrea Aime
GeoSolutions S.A.S.
Tech lead

Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy

phone: +39 0584 962313
fax: +39 0584 962313

http://www.geo-solutions.it
http://geo-solutions.blogspot.com/
http://www.youtube.com/user/GeoSolutionsIT
http://www.linkedin.com/in/andreaaime
http://twitter.com/geowolf



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