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Operational Review #2
NASA Geospatial Interoperability Office
- Describe in a sentence or two your overall operational experience related to WMS. (e.g., scientific visualization; geospatial visualization, etc). What kinds of WMS servers and/or clients do you have experience with? (e.g., commercial products, open source, or independent implementations, please provide as much detail as possible).
- I've used WMS for many different kinds of visualization and image data delivery.
- Servers I've been involved in creating or configuring include open-source products such as the MIT OrthoServer and UMN Map Server; and JPL's WMS Global Mosaic.
- Clients I've been involved with include the UMN Mapserver's PHP client, a “plug-in” for ESRI's ArcView, and Compusult's WMSMerge (wITHIN NASA's ESG portal).
- I've also used clients such as NASA's WorldWind, UAH's Space-Time Toolkit, and the MAP05 viewer developed by NASA's Sci. Info. & Viz. Office (SIVO). And of course I've bound these clients to any number of servers – some commercial, some open source, some unique / homegrown.
- I've used WMS for many different kinds of visualization and image data delivery.
- What types of applications do you use WMS servers/clients for? Are they suitable for your applications? (e.g., Do they work well with the data types and data manipulations in your application?)
- I've often used WMS for on-demand access into large imagery collections; and for access to a variety of visualized “layers” overlaid in a common geospatial framework. As long as the desired output is a visual product expressible in 1 or 3 bands, WMS can do the job. (This is not a difficukt requirement for most visualization needs: by using predefined styles, clients can make the server reduce multi-spectral imagery to 3-band color composites in any number of ways.)
- Why do you choose to use WMS over other protocols for your applications?
- Like many other users and implementers I suppose, I choose WMS because of its widespread adoption, and its non-proprietary basis which ensures flexibility and future stability.
- Are the WMS systems easy to use? (e.g., Is it hard to learn how to use WMS systems?)
- Yes. (i.e., no :-)
- Does the performance of the WMS systems you have experienced meet your requirements? (e.g., Does it take a long time to access/view data in WMS systems?)
- The WMS protocol is simple enough that it can be streamlined as needed. I've seen this on JPL's WMS Global Mosaic, which (thanks primarily to clever server-side caching mechanisms) withstood an onslaught of requests from NASA's WorldWind client.
- What operational challenges do the WMS systems present? (e.g., Does it require advanced processing power, large amounts of memory, complex configuration, etc.? Are the systems easy to deploy and maintain?)
- WMS doesn't intrinsically require hefty resources. I've had fairly responsive WMS servers running on lowly Pentium-266 office machines.
- (Probably the main challenge is figuring out how to express a complex multi-dimensional dataset as WMS views using hierarchical layer descriptions and predefined styles.)
- How well do the WMS systems scale to large numbers of simultaneous users, or to large datasets?
- Because of WMS' low complexity requirements, servers that only do simple WMS things can easily scale up to large datasets or heavy use. Servers with extra bandwidth or CPU cycles can easily use those up by serving complex styling or creating complex views on the fly from available data. Large datasets are generally not a problem unless a server has no spatial indexing – but that's not a WMS issue.
- Can you provide information on user statistics of your WMS systems? How have the user statistics changed over time?
- I don't have useful statistics at hand, sorry.
