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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | Re: [gislist] RE: GISList: Cartography and Data Viewer |
| Date: |
08/28/2003 11:50:01 AM |
| From: |
Jeff Harrison |
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Dimitri,
Well, I never indicated that there was anything wrong with FTP. In fact, it's a great standard that enables interoperability. Also, you seem to refer only to the "GIS user" in your use cases. What about folks that only have a standard web browser and no GIS, even a low-cost one? Shouldn't they be able to access geospatial content as well and shouldn't content providers be able to publish their content to make it accessible to folks with a standard web browser that has no bells or whistles attached. Also, do you think that companies should develop map servers that enable them to service these types of customers?
Let's suppose for moment that all some user wants to do is put a background map into their application and they have internet connectivity. This could be for a variety of purposes, perhaps they are with a really important government agency and they need to create a background map for a briefing that they need to give in one hour and they have no GIS (call this person User W), or perhaps they are just a high school student trying to write a report for their earth science class (User X). Would it be useful if they could go to a web site and get that map and just integrate it quickly from something like http://wms.jpl.nasa.gov? Now let's assume that the government agency that published the Landsat-based maps that User W and X just accessed wanted to be really efficient and leverage other map content that has been publish across a common interface without having to post it themselves, so they go to http://nationalatlas.gov and pull in hundreds of layers of content without having
to publish it all themselves. Well sure, they should be able to do that too, and they do.
OK, now let's say I'm User Y, in the kitchen of a home that has still has no GIS (I know, they have a phone, a TV, a computer and still no GIS- not even a low cost one) and they want to find a site that makes maps available to inform the general public about hazards cause they are thinking about buying a cheap vacation home which looks suspiciously like it's in a floodplain (I don't know, just an example). Well, the maps are available on the Internet at www.hazardmaps.gov and can be viewed with a typical web browser. The user can view maps by hazard theme or create a custom view showing areas of hazard overlap. By the way, this site is pretty interesting to User Y cause they notice that these folks are accessing 22 "live map server" with 1555 map layers (pretty efficient). Well, why couldn't that govt agency provide the ability for more sophisticated users such as state or local government technicians to download files and upload their own hazard map data? This User ("Z") can
go to the same site and download files via FTP. Yep, it's right there and no problem and nothing wrong with that. Now one might see how a web-based front end to the FTP-based data discovery could be useful, so let's put it on an HTML page and make it easy for folks to use (like you suggest, maybe to get some VMAP content)...well you could go to http://ogcengine.nima.mil and see how User Z might look at some previews of coverage via a map server and then gets the FTP-available content (they can grab some VMAP 0, 1 whatever, and use it in a high-cost GIS).
These exercises in making information available were helped along by the efforts of folks working collaboratively to implement some simple specifications, FTP, WMS etc. and assume that there are multiple ways to get the job done.
Now lets say that another GIS user comes along (User "C" who can't find all that content that's out there in all the sites distributed across the web). Say they want to be able to search for available data sets to download (perhaps via FTP). Then wouldn't it be reasonable and useful for some folks to provide a metadata service that enables methods for publishing and discovering data that you want to distribute to users through all these ftp-enabled links? For example, publishers could make downloadable files accessible through the service via multiple methods, for example:
1. You have an XML-based metadata record that contains an on-line linkage to the downloadable file that is located on a site external to the service. The on-line linkage may be ftp or browser download, etc. The service could detect this reference and will redirect users that discover the data to the external site for download of the data.
2. You can enter basic metadata about the downloadable data. The metadata entry form provides you with a means to enter the URL to where the data is located. Again, users will be redirected to the external site for download of the data.
3. You can enter basic metadata about the downloadable data and upload your data files to the service for download by other users. The service
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