Hi Rich,
I've added this feature request to our list. Jon Blower might have some
thoughts on this as well.
One thing that I wonder about is client support. In particular, does
Godiva2 support this? Again, a question for Jon.
Ethan
On 12/22/2010 6:00 AM, Rich Signell wrote:
> For getCapabilities requests, it would be great if the TDS would
> express the available times using the WMS multiple time interval
> syntax if it is more efficient than listing each time value
> separately.
>
> This can result in huge (100 or more) savings in the WMS
> getCapabilities size when dealing with model output, which is usually
> equally spaced, but perhaps with a few gaps. Instead of listing
> every available time step in ISO format, as is done currently
>
> In WMS 1.1.1, Annex C.3 states that multiple intervals are allowed in
> the "Extent" element.
> In WMS 1.3.0, Annex C.2 states that multiple intervals are allowed in
> the "Dimension" element.
>
> Both list the sample format: "min1/max1/res1,min2/max2/res2,..."
> (thanks to Kyle Wilcox for digging out this info)
>
> For example, we have a dataset
>
> http://testbedapps.sura.org/thredds/clean.html?dataset=estuarine_hypoxia/ch3d/agg
>
> that contains hourly output over 21 years (183984 time records) for 11
> different variables. There are only 4 gaps longer than 1 hour.
>
> If you access the WMS getCapabilities document for this dataset, be
> prepared to wait for a while, because it's 51Mb!!
>
> The problem is that each time value is listed in ISO ASCII:
> <Dimension name="time" units="ISO8601" multipleValues="true"
> current="true" default="2006-01-01T00:00:00.000Z">
> 1985-01-01T01:00:00.000Z,1985-01-01T02:00:00.000Z,1985-01-01T03:00:00.000Z,1985-01-01T04:00:00.000Z,1985-01-01T05:00:00.000Z,1985-01-01T06:00:00.000Z,1985-01-01T07:00:00.000Z,1985-01-01T08:00:00.000Z,1985-01-01T09:00:00.000Z,1985-01-01T10:00:00.000Z,
> ...
>
> which goes on for 5MB of ASCII values and then this whole mess is
> repeated for each variable "layer".
>
> Instead, the entire time record could be simply expressed using 5
> intervals of the form:
>
> "1985-01-01T01:00:00.000Z/1988-12-31T00:00:00.000Z/PT3600S",
> "1989-01-01T01:00:00.000Z/1992-12-31T00:00:00.000Z/PT3600S",
> "1993-01-01T01:00:00.000Z/2000-12-31T00:00:00.000Z/PT3600S",
> "2001-01-01T01:00:00.000Z/2004-12-31T00:00:00.000Z/PT3600S",
> "2005-01-01T01:00:00.000Z/2006-01-01T00:00:00.000Z/PT3600S",
>
>
> Existing way (every time step written out): 51MB
> New way (specifying intervals): 100Kb (500 times
> smaller!!!!!)
>
> This would greatly reduce the file sizes on Motherlode, our IOOS
> testbed server, and every other TDS (or WMS, actually) with aggregated
> model output.
