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Operational Review #11
SEDAC
- 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).
- At our data center, our operational experience with WMS includes serving a number of our data sets via a WMS server with plans to make additional data layers available via WMS over time. We have used several clients for viewing and testing: NASA’s WMS viewer, Carbon Tools, and ArcGIS. We are currently serving WMS data using Ionic’s RedSpider Enterprise product.
- 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?)
- We use WMS servers as a means to make our data easier to integrate with other types of geospatial data and information. We deploy WMS mainly as a means to provide visualization capabilities for our data for our users via whatever OGC-clients with which they are most familiar. The services work very well for visualization applications; we anticipate that WMS 1.3 will help in integrating time for animation and analysis in our applications.
- Why do you choose to use WMS over other protocols for your applications?
- We began to experiment with OGC standards a number of years ago. At our data center, we believe that these types of interoperability frameworks represent an important means to support our types of applied users and that these frameworks will become more prevalent over time. We do not rely solely on WMS, but also deploy WCS and WFS.
- Are the WMS systems easy to use? (e.g., Is it hard to learn how to use WMS systems?)
- The WMS specs are relatively easy to understand and implement. The difficulties we have encountered have arisen largely in the context of the software we have chosen to deploy to support these services.
- 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?)
- We do not have any complaints about the performance of our WMS server.
- 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?)
- Changes in the WMS specification can cause problems (e.g., we have not yet implemented WMS 1.3), though mostly in client development rather than service provision. Designing general-purpose layers for reuse in unknown clients/applications can be challenging – a layer that makes sense in the context of a SEDAC client and related data sets may be difficult to use in another client with different layers.
- How well do the WMS systems scale to large numbers of simultaneous users, or to large datasets?
- It would be difficult for us to answer this question for a number of reasons. First, typically we do not experience very large loads on our systems. Secondly, to answer this type of question you need to incorporate information about the system (hardware/software/network) that is serving the data, as well as other issues such as network latency over which we have very little control. To date, we have found that setting scale-dependant rendering rules has resolved all of our issues in dealing with large datasets.
- Can you provide information on user statistics of your WMS systems? How have the user statistics changed over time?
- Our first deployed WMS services had limited layers available in separate URLs with numeric naming conventions. After feedback from users, we have added more layers and grouped them by project or theme and used human-readable naming conventions to aid users. Additionally, we have added scale-dependant rendering rules to a few services to increase performance – rendering fewer features at smaller scales and the complete feature set only at large scales.
- Our WMS services have not been widely publicized to date, and as a result the total number of users is quite small (less than 2,000 map requests to date).
