Re: [thredds] Simple fix => much smaller TDS WMS GetCapabilities size (for model output)

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.


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
> 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.

  • 2010 messages navigation, sorted by:
    1. Thread
    2. Subject
    3. Author
    4. Date
    5. ↑ Table Of Contents
  • Search the thredds archives: