WMS server time tests and issues

[Havard Tveite]

Yewondwossen Assefa wrote:
> Kralidis,Tom [Burlington] wrote:
>
>> Hi,
>>
>> I've been testing this out on latest CVS.  Observations:
>>
>> - OS: FC2
>> Linux devgeo.cciw.ca 2.6.5-1.358smp #1 SMP Sat May 8 09:25:36 EDT 2004
>> i686 i686 i386 GNU/Linux
>> - httpd: Apache 2.0.49
>>
>> I constructed a dummy .shp/.shx/.dbf with 4 columns 3 records with a
>> timefield.
>>
>> Here's a dump of what the shapefile is:
>>
>> stid | lat          | lon        | obsdate
>> ----------------------------------------------
>> tom  | 45.412766    | -71.920082 | 2004-10-12
>> bob  | 45.399400    | -75.704200 | 2003-09-30
>> joe  | 55.399400    | -95.704200 | 2002-03-17
>>
>>
>> ...and here's the time defines in LAYER/METADATA in mapfile:
>>
>>    "wms_timeextent" "2002-03-17/2004-10-12"
>>    "wms_timedefault" "2003-09-30"
>>    "wms_timeitem" "obsdate"
>>
>>
>> ...and here's my tests:
>>
>> Single value:
>>
>> http://devgeo.cciw.ca/cgi-bin/mapserv/ecows?version=1.1.1&service=WMS&re
>> quest=GetMap&layers=obs&format=image/gif&srs=EPSG:4326&transparent=TRUE&
>> exceptions=application%2Fvnd.ogc.se_inimage&bbox=-140.243500,28.606653,-
>> 51.243500,81.998653&width=500&height=300&time=2004-10-12-T00:00:00&style
>> s=default
>>
>> Result: no problem, as expected
>>
>> Multple value:
>>
>> http://devgeo.cciw.ca/cgi-bin/mapserv/ecows?version=1.1.1&service=WMS&re
>> quest=GetMap&layers=obs&format=image/gif&srs=EPSG:4326&transparent=TRUE&
>> exceptions=application%2Fvnd.ogc.se_inimage&bbox=-140.243500,28.606653,-
>> 51.243500,81.998653&width=500&height=300&time=2004-10-12-T00:00:00,2003-
>> 09-30-T00:00:00&styles=default
>>
>> Result: no problem, as expected
>>
>> Single range:
>>
>> http://devgeo.cciw.ca/cgi-bin/mapserv/ecows?version=1.1.1&service=WMS&re
>> quest=GetMap&layers=obs&format=image/gif&srs=EPSG:4326&transparent=TRUE&
>> exceptions=application%2Fvnd.ogc.se_inimage&bbox=-140.243500,28.606653,-
>> 51.243500,81.998653&width=500&height=300&time=2002-03-17-T00:00:00/2004-
>> 10-12-T00:00:00&styles=default
>>
>>
>> Result: when the start time or end time is out of range of the default.
>> For example, if you change the start year to 2001, only one point shows
>> up:
>>
>> http://devgeo.cciw.ca/cgi-bin/mapserv/ecows?version=1.1.1&service=WMS&re
>> quest=GetMap&layers=obs&format=image/gif&srs=EPSG:4326&transparent=TRUE&
>> exceptions=application%2Fvnd.ogc.se_inimage&bbox=-140.243500,28.606653,-
>> 51.243500,81.998653&width=500&height=300&time=2001-03-17-T00:00:00/2004-
>> 10-12-T00:00:00&styles=default
>>
>> ...so it looks like the default is returned when the range given is
>> outside the range defined in "wms_timeextent".
>>
>> Is this the expected behaviour?  As a WMS client, I would expect that
>> temporal queries would return everything inside two given dates, just
>> like a spatial query does.
>>
>> ..Tom
>>
>>
> I think that the specs indicates that if the given values are
> "incorrect" the server would return values for the default declared :
>
> Section C5.1 (Annexe C wms 1.1.1 ):
> " ...An OGC Web Service may declare a default for any dimension. A
> 'default' is optional but recommended. If a request does not include a
> value along this dimension, and a default has been declared, then the
> server shall send the default value..."

I read the specifications as follows:
If a request does not specify a value for a dimension, and there
is a default declared, the declared should be used.
The spec also says that if a default is not declared, such a
request *shall* result in an exception being thrown.

I thought that Tom *had* specified a value (range) for the
dimension, and hence this rule should not apply.
If the interval specified is out of the wms_timeextent range,
I would guess an exception should be returned, but I could not
find it documented in the WMS 1.1.1 spec.

If an interval *is* specified on the dimension, and the the
interval overlaps the range of "valid" times (wms_timeextent),
I would, as Tom, expect all the data within the overlapping
range to be returned.
(C.3 - the value of "multipleValues" is also relevant.)

--
Håvard Tveite
Department of Mathematical Sciences and Technology
Agricultural University of Norway
Drøbakveien 14, POBox 5003, N-1432 Ås, NORWAY
Phone: +47 64948857 Fax: +47 64948810 http://www.nlh.no/imt