[Geoserver-users] I need someone to dumb a few things down for me :)

GeoServer GeoServer User
1

Okay so I've got GeoServer setup and I can generate images of maps from the sample database. So I can do the basics of what the Users Guide discusses. I apologize if this is below the level of questions for this mailing list, but after reading through a number of books on GIS and on MapServer (couldn't find one on GeoServer) there are things that I still don't know how to do. I will happily document this stuff for inclusion into the Wiki :slight_smile:

1) Where do I get new data from? I want to grab data for Louisiana, but I'm not sure where I should get it from. Should I be buying this data from someone? All I really want are streets and such which seems to suggest that all I need is TIGER data, but I can't be sure.

2) Does GeoServer have a data format that it prefers/requires? If so, do I just import the data using the web interface and my data gets into that format?The website talks about supporting WFS-T and WMS, but those aren't import data formats as far as I have been able to find. Or more specifically, I can't find any 'free' public data in this format.

3) When I go to create my own output format, the tutorial doesn't really seem to help me. I want to create a zipped PNG file as output. Do I really have to put my class into the actual geoserver build as step 1 suggests? Can't formats be like plugins that simply implement the interface and sit in a directory that is scanned at startup and periodically thereafter?

4) Do I actually want/need to use a database with GeoServer? I had always considered it part of my architecture that I would use PostGIS, but I don't know if I need to.

5) If all I really want is a zipped PNG of a lat-lon out to a specified radius, am I really hitting the problem at the wrong level and should really be using the Geotools toolkit on which GeoServer is based?

2

Comments inline:

Brent Owens
(The Open Planning Project)

Gregory Pierce wrote:

Okay so I've got GeoServer setup and I can generate images of maps from the sample database. So I can do the basics of what the Users Guide discusses. I apologize if this is below the level of questions for this mailing list, but after reading through a number of books on GIS and on MapServer (couldn't find one on GeoServer) there are things that I still don't know how to do. I will happily document this stuff for inclusion into the Wiki :slight_smile:
  

This list is for any and all questions, so ask away =)

1) Where do I get new data from? I want to grab data for Louisiana, but I'm not sure where I should get it from. Should I be buying this data from someone? All I really want are streets and such which seems to suggest that all I need is TIGER data, but I can't be sure.
  

Data is the hard part. It is often free, in some countries, but hard to find. If you just want roads than tiger data should suffice.

2) Does GeoServer have a data format that it prefers/requires? If so, do I just import the data using the web interface and my data gets into that format?The website talks about supporting WFS-T and WMS, but those aren't import data formats as far as I have been able to find. Or more specifically, I can't find any 'free' public data in this format.
  

I think you are talking about what format the data is stored in, whether it be on disk on in a database. Geoserver prefers PostGIS, because it is the most heavily tested "data-store". WFS and WMS are ways of communicating data. WMS communicates in XML (requests) and ususally sends back responses in image formats (gif, png, jpg). WFS usually returns GML. So if you create feature types in geoserver that point to shapefiles or databases (whichever) then you can query and display that data remotely over the web with WFS/WMS.

3) When I go to create my own output format, the tutorial doesn't really seem to help me. I want to create a zipped PNG file as output. Do I really have to put my class into the actual geoserver build as step 1 suggests? Can't formats be like plugins that simply implement the interface and sit in a directory that is scanned at startup and periodically thereafter?

For Geoserver 1.3.x series, unfortunately you do have to put your output format into the build system. Don't be discouraged though, it is quite easy. For version 1.4 I think that is changing and it will be a lot easier to just drop in a new output format. But you will have to confirm with Justin (or other members of the list) on what the capabilities are exactly.

4) Do I actually want/need to use a database with GeoServer? I had always considered it part of my architecture that I would use PostGIS, but I don't know if I need to.

Databases are nice and fast, and you can do great/robust queries against them. They also handle concurrency issues across multiple geoserver instances. But, you do not need to use a database, shapefiles work just fine.

5) If all I really want is a zipped PNG of a lat-lon out to a specified radius, am I really hitting the problem at the wrong level and should really be using the Geotools toolkit on which GeoServer is based?
  

A zipped PNG format would be very easy to make with geoserver, and you would be getting all the other code for free if you use geotools/geoserver: rendering of the image, reprojection, queries, exports to numerous output formats, reading from multiple storage formats...
Geoserver is a web server, so if you don't need it to function as such, then another more light-weight tool is probably ideal.

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Gregory Pierce wrote:

Okay so I've got GeoServer setup and I can generate images of maps from the sample database. So I can do the basics of what the Users Guide discusses. I apologize if this is below the level of questions for this mailing list, but after reading through a number of books on GIS and on MapServer (couldn't find one on GeoServer) there are things that I still don't know how to do. I will happily document this stuff for inclusion into the Wiki :slight_smile:

Great! The best place in the wiki would probably be the FAQ, since you've obviously read through stuff and found these holes. And no need to apologize, the mailing list is for questions that aren't in the docs, which is obviously the case here. (these are really all great faq questions)

1) Where do I get new data from? I want to grab data for Louisiana, but I'm not sure where I should get it from. Should I be buying this data from someone? All I really want are streets and such which seems to suggest that all I need is TIGER data, but I can't be sure.

Yeah, TIGER data should be fine for your needs. It would be nice to start a page though linking to good, free data. You can get 2000 line data in shapefiles here: http://www.esri.com/data/download/census2000_tigerline/index.html We've got extensive tutorials on how to load it up at: http://docs.codehaus.org/display/GEOSDOC/Loading+TIGER+data (though weirdly I can't seem to find the link to the actual original download there, anyone know it?) Note you can also just make use of http://sigma.openplans.org - we've already got the WMS/WFS of most all of tiger set up for you. You can remix and reuse what you'd like. Another interface to it is here: http://geo.openplans.org/cholmes/ol-cache.html

2) Does GeoServer have a data format that it prefers/requires? If so, do I just import the data using the web interface and my data gets into that format?The website talks about supporting WFS-T and WMS, but those aren't import data formats as far as I have been able to find. Or more specifically, I can't find any 'free' public data in this format.

The data formats that GeoServer reads in are available at: http://docs.codehaus.org/display/GEOSDOC/DataStores So you'll need your data in one of those formats. The recommended way is probably to get it in to PostGIS, ogr2ogr is a great tool for doing that.

3) When I go to create my own output format, the tutorial doesn't really seem to help me. I want to create a zipped PNG file as output. Do I really have to put my class into the actual geoserver build as step 1 suggests? Can't formats be like plugins that simply implement the interface and sit in a directory that is scanned at startup and periodically thereafter?

Yup. I guess the tutorial isn't clear, but if you create those three files, stick them in a jar, and put them on your classpath or in WEB-INF/lib, the GeoServer will scan them at start-up. Note that for zipped PNG you should do it as a WMS output format, not WFS as the tutorial is for. But the way it works is very similar.

4) Do I actually want/need to use a database with GeoServer? I had always considered it part of my architecture that I would use PostGIS, but I don't know if I need to.

Probably. You could just use shapefiles if you want, but we generally recommend a real spatial db. If you're allowing any user editing it's essential. And it's recommended for larger datasets.

5) If all I really want is a zipped PNG of a lat-lon out to a specified radius, am I really hitting the problem at the wrong level and should really be using the Geotools toolkit on which GeoServer is based?

No, GeoServer is probably what you want. Do check out the 1.4.x branch, which is more geared towards plug-ins. And indeed the output format should be updated a bit since it uses spring instead of the factoryspi thing. http://docs.codehaus.org/display/GEOSDEV/Home is the information you want. You could hit it purely at GeoTools, but GeoServer gives you some nice helpful pieces, that are useful for your problem.

best regards,

Chris

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