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Hi Ben, The analogy with JPEG2000 and JPIP is a good one (although I'm not an expert either). My experience of applications that use JPIP streaming (e.g. accessing high-res satellite data from an Antarctic research ship with very low bandwidth) is that these applications depend upon the advanced features of the protocol to function correctly (e.g. to manage bandwidth). A WCS approach might effectively remove some of these features: a client doesn't know exactly how much data to expect in response to a request so it can't manage bandwidth. In other words, I see WCS as providing a common baseline, not as a protocol that attempts to support all of these features. Does anyone know how the JPEG2000/JPIP community feel about WCS?
But my impression is that others think that we should abandon the CF-netCDF encoding spec. and ONLY be proposing CF-OPeNDAP. Is that the heart of the suggestion that's on the table in terms of the OPeNDAP part of the discussion?
My personal opinion is that if I want to use the internet to access FES data losslessly, and my application understands the NetCDF data model and the CF conventions, I should use OPeNDAP as it gives me (very nearly) all the information I need and tools are readily available.* I see no need for WCS to satisfy this use case. If, on the other hand, I have a GIS application that has a map-based data model and understands GeoTIFFs, I might well want to access FES data through a WCS - but it's no good returning me a NetCDF file because I won't be able to understand it. Instead it would be much more useful to have a WCS that reads CF-NetCDF data and produces GeoTIFFs. A mapping of CF-NetCDF to WCS concepts is still necessary to understand how this mapping actually takes place - what information is preserved, what is lost and so forth. Best wishes, Jon * The issue of asynchronous access to large-volume data still needs to be solved however... The WCSplus team are experimenting with asynchronous access and OPeNDAP doesn't support this. However, I think there's an OPeNDAP working group addressing this. This one is still up in the air. On Wed, Sep 24, 2008 at 2:37 PM, Ben Domenico <Ben@xxxxxxxxxxxxxxxx> wrote:
Hi all, Many important topics have come up in these discussions. In this note, I'm going to try to confine my remarks to the OPeNDAP question. Within the WCS, the JPEG2000 community has proposed both a JPEG2000 extension standard and one for JPIP. I am not an expert on JPEG or JPIP but my understanding is that JPEG2000 is similar to our CF-netCDF extension in that it is an encoding specification whereas JPIP is actually an access protocol and as such it is similar to OPeNDAP. I had been thinking of that dual approach as a model for what we might eventually do for netCDF and OPeNDAP in the WCS world. But my impression is that others think that we should abandon the CF-netCDF encoding spec. and ONLY be proposing CF-OPeNDAP. Is that the heart of the suggestion that's on the table in terms of the OPeNDAP part of the discussion? -- Ben On Wed, Sep 24, 2008 at 4:57 AM, Jon Blower <j.d.blower@xxxxxxxxxxxxx> wrote:
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