gwt-openlayers-users

[Gwt-openlayers-users] Fetching VectorFeatures via WFS and parsing GML

[Mikael C. <mik...@cl...>]

Hi all,


I'll be working on a project involving GWT-OL in the following weeks, and I
could use a little advice on how I am going to proceed.

To be quick, I'll be displaying regions on a map, and the color of each
region will be dynamically calculated on the fly based on GWT server-side
values. To complicate things up, some regions will be groups of regions,
also defined on the GWT server.
My first idea was to set up a GeoServer and fetch the features with WFS
GetFeature requests. From there I could display the features with whatever
style I wanted, and I could even make groups using
OpenLayers.Geometry.Collection<http://dev.openlayers.org/releases/OpenLayers-2.8/doc/apidocs/files/OpenLayers/Geometry/Collection-js.html#OpenLayers.Geometry.Collection.OpenLayers.Geometry.Collection>
.calculateBounds<http://dev.openlayers.org/releases/OpenLayers-2.8/doc/apidocs/files/OpenLayers/Geometry/Collection-js.html#OpenLayers.Geometry.Collection.calculateBounds>(or
so I hope I could).

But then I couldn't find a simple way to get features (and not layers) from
WFS, and I could'nt even manage to parse my GML with the corresponding GML3
class. I'm feeling a bit helpless...

The way I see it now, if I stay stuck, here's what I'll have to do :
Fetch the features with
com.google.gwt.http.client<http://google-web-toolkit.googlecode.com/svn/javadoc/1.6/com/google/gwt/http/client/package-frame.html>
Parse the GML with
com.google.gwt.xml.client<http://google-web-toolkit.googlecode.com/svn/javadoc/1.6/com/google/gwt/xml/client/package-frame.html>
And from that extract the posList, then generate the points, from that
instantiate the LinearRings and then I'll have my features. I feel like I
might be reinventing the wheel somewhere.

Just to give you the idea, my dream object would be like :
List<VectorFeature> features = *MyDreamObject*
.getFeaturesFromRemoteGML(WFS_URL);*
*
Has anyone ever tried something similar ?
Do you know anything that could help me ?
Any help would be MOST appreciated.

Thanks !


-- 
Mikael

Re: [Gwt-openlayers-users] Fetching VectorFeatures via WFS and parsing GML

[Mikael C. <mik...@cl...>]

Hi Josafat (and others),


Thanks for taking time to answer. And I'm happy I'm not the only one having
problems with this ! Anyway, I hope what follows will help you.

I have been pushing my research on GML parsing in OL, and I finally managed
to parse with GML.v3. It wasn't so hard, it's just that I'm not very good in
JS and I always need an example to make anything work.
That done, it was easy to implement that into GWT-OL's GML3. I'll have to do
a bit of refactoring and documenting before I can push anything to the
repository.

As for the other problem, the communication with the WFS server and the way
to query it, I'd still love to get any information you could provide me.


Regards,

Mikael



2010/3/3 Josafat Guerrero <jos...@gm...>

> Hi everyone,
>
> I have also been working on a OL-GWT project  with almost the same
> requirements as yours.
> First, I would like to state something about this problem
>
> - gwt-openlayers api is mostly a wrapper for  OL (as far as  I know)
> - Thera are some classes without implementation, as GML for the read method
> - Certainly, is really complicated to do some work, because some of the
> documentation for GWT-OL api is not done or unfinished
>
>
> From my experience, It is necessary  to create some utility classes to
> acomplish the work you are trying to do.
> Indeed, I am also trying to solve the same problem at this precise moment,
> and I agree with you, most of the ideas behind OL are more 'layer' oriented
> than feature oriented.
>
> Choosing GML as a representation its possible because it it already
> serializable, so you can trasfer without great complications, but there is a
> lack for GML parser on the client side(with GWT).
>
> Maybe we have to look directly at the OL documentation to accomplish this
> problem and write the proper interface.
>
> Best Regards
>
>
> El mar 3, 2010, a las 12:25 p.m., Mikael Couzic escribió:
>
> Hi all,
>
>
> I'll be working on a project involving GWT-OL in the following weeks, and I
> could use a little advice on how I am going to proceed.
>
> To be quick, I'll be displaying regions on a map, and the color of each
> region will be dynamically calculated on the fly based on GWT server-side
> values. To complicate things up, some regions will be groups of regions,
> also defined on the GWT server.
> My first idea was to set up a GeoServer and fetch the features with WFS
> GetFeature requests. From there I could display the features with whatever
> style I wanted, and I could even make groups using
> OpenLayers.Geometry.Collection<http://dev.openlayers.org/releases/OpenLayers-2.8/doc/apidocs/files/OpenLayers/Geometry/Collection-js.html#OpenLayers.Geometry.Collection.OpenLayers.Geometry.Collection>
> .calculateBounds<http://dev.openlayers.org/releases/OpenLayers-2.8/doc/apidocs/files/OpenLayers/Geometry/Collection-js.html#OpenLayers.Geometry.Collection.calculateBounds>(or so I hope I could).
>
> But then I couldn't find a simple way to get features (and not layers) from
> WFS, and I could'nt even manage to parse my GML with the corresponding GML3
> class. I'm feeling a bit helpless...
>
> The way I see it now, if I stay stuck, here's what I'll have to do :
> Fetch the features with com.google.gwt.http.client<http://google-web-toolkit.googlecode.com/svn/javadoc/1.6/com/google/gwt/http/client/package-frame.html>
> Parse the GML with com.google.gwt.xml.client<http://google-web-toolkit.googlecode.com/svn/javadoc/1.6/com/google/gwt/xml/client/package-frame.html>
> And from that extract the posList, then generate the points, from that
> instantiate the LinearRings and then I'll have my features. I feel like I
> might be reinventing the wheel somewhere.
>
> Just to give you the idea, my dream object would be like :
> List<VectorFeature> features = *MyDreamObject*
> .getFeaturesFromRemoteGML(WFS_URL);*
> *
> Has anyone ever tried something similar ?
> Do you know anything that could help me ?
> Any help would be MOST appreciated.
>
> Thanks !
>
>
> --
> Mikael
>
> ------------------------------------------------------------------------------
> Download Intel&#174; Parallel Studio Eval
> Try the new software tools for yourself. Speed compiling, find bugs
> proactively, and fine-tune applications for parallel performance.
> See why Intel Parallel Studio got high marks during beta.
>
> http://p.sf.net/sfu/intel-sw-dev_______________________________________________
> Gwt-openlayers-users mailing list
> Gwt...@li...
> https://lists.sourceforge.net/lists/listinfo/gwt-openlayers-users
>
>
>
> ************************************************
> L. en C.C. Josafat Isaí Guerrero Iñiguez
> UNidad de Informatica Geoespacial
> Instituto de Geografía
> Universidad Nacional Autónoma de México
>
> jo...@ci...
> jos...@gm...
>
> ************************************************
>
>
>
>

Re: [Gwt-openlayers-users] Fetching VectorFeatures via WFS and parsing GML

[Edwin C. <com...@gm...>]

Hi Mikael,

Just I quick reply:

Have you looked at the latest BasicWFS example code in the showcase?
There is some stuff that needs to be added to WFS protocol, but it
should work similar to the examples on dev.openlayers.

The only thing is that the GwtOpenLayersProxy is not working properly,
perhaps because I put in resourceUrl where it should be targetUrl.

The proxy class should be refactored in my opinion so that the url
param is not different for GET and POST.

The docs are not in good shape everywhere, so that's a bit of a pity indeed.

If anyone feels free to work on the GwtOpenLayersProxy and get the
BasicWFS sample running that would be great. I won't have time to work
on it as I just became father of a beautiful daugther.

Greetings,
Edwin



On 3 March 2010 19:25, Mikael Couzic <mik...@cl...> wrote:
> Hi all,
>
>
> I'll be working on a project involving GWT-OL in the following weeks, and I
> could use a little advice on how I am going to proceed.
>
> To be quick, I'll be displaying regions on a map, and the color of each
> region will be dynamically calculated on the fly based on GWT server-side
> values. To complicate things up, some regions will be groups of regions,
> also defined on the GWT server.
> My first idea was to set up a GeoServer and fetch the features with WFS
> GetFeature requests. From there I could display the features with whatever
> style I wanted, and I could even make groups using
> OpenLayers.Geometry.Collection.calculateBounds (or so I hope I could).
>
> But then I couldn't find a simple way to get features (and not layers) from
> WFS, and I could'nt even manage to parse my GML with the corresponding GML3
> class. I'm feeling a bit helpless...
>
> The way I see it now, if I stay stuck, here's what I'll have to do :
> Fetch the features with com.google.gwt.http.client
> Parse the GML with com.google.gwt.xml.client
> And from that extract the posList, then generate the points, from that
> instantiate the LinearRings and then I'll have my features. I feel like I
> might be reinventing the wheel somewhere.
>
> Just to give you the idea, my dream object would be like :
> List<VectorFeature> features =
> MyDreamObject.getFeaturesFromRemoteGML(WFS_URL);
>
> Has anyone ever tried something similar ?
> Do you know anything that could help me ?
> Any help would be MOST appreciated.
>
> Thanks !
>
>
> --
> Mikael
>
> ------------------------------------------------------------------------------
> Download Intel&#174; Parallel Studio Eval
> Try the new software tools for yourself. Speed compiling, find bugs
> proactively, and fine-tune applications for parallel performance.
> See why Intel Parallel Studio got high marks during beta.
> http://p.sf.net/sfu/intel-sw-dev
> _______________________________________________
> Gwt-openlayers-users mailing list
> Gwt...@li...
> https://lists.sourceforge.net/lists/listinfo/gwt-openlayers-users
>
>

Re: [Gwt-openlayers-users] Fetching VectorFeatures via WFS and parsing GML

[Mikael C. <mik...@cl...>]

Hi everyone,


First of all, congratulations Edwin for your daughter !

Now back to our problem :
To make it quick and simple, I added a read() method in WFSProtocol. It
allows me to get an array of VectorFeatures, having a complete control on
how I add them to my Vector layer.
I'll push it soon.

For the moment, I haven't used the proxy, I bypassed the problem by
deploying my app in the same GlassFish that my GeoServer.

Final step :
Creating new geometries with collections of geometries (still battling with
the JS).


Mikael



2010/3/4 Edwin Commandeur <com...@gm...>

> Hi Mikael,
>
> Just I quick reply:
>
> Have you looked at the latest BasicWFS example code in the showcase?
> There is some stuff that needs to be added to WFS protocol, but it
> should work similar to the examples on dev.openlayers.
>
> The only thing is that the GwtOpenLayersProxy is not working properly,
> perhaps because I put in resourceUrl where it should be targetUrl.
>
> The proxy class should be refactored in my opinion so that the url
> param is not different for GET and POST.
>
> The docs are not in good shape everywhere, so that's a bit of a pity
> indeed.
>
> If anyone feels free to work on the GwtOpenLayersProxy and get the
> BasicWFS sample running that would be great. I won't have time to work
> on it as I just became father of a beautiful daugther.
>
> Greetings,
> Edwin
>
>
>
> On 3 March 2010 19:25, Mikael Couzic <mik...@cl...>
> wrote:
> > Hi all,
> >
> >
> > I'll be working on a project involving GWT-OL in the following weeks, and
> I
> > could use a little advice on how I am going to proceed.
> >
> > To be quick, I'll be displaying regions on a map, and the color of each
> > region will be dynamically calculated on the fly based on GWT server-side
> > values. To complicate things up, some regions will be groups of regions,
> > also defined on the GWT server.
> > My first idea was to set up a GeoServer and fetch the features with WFS
> > GetFeature requests. From there I could display the features with
> whatever
> > style I wanted, and I could even make groups using
> > OpenLayers.Geometry.Collection.calculateBounds (or so I hope I could).
> >
> > But then I couldn't find a simple way to get features (and not layers)
> from
> > WFS, and I could'nt even manage to parse my GML with the corresponding
> GML3
> > class. I'm feeling a bit helpless...
> >
> > The way I see it now, if I stay stuck, here's what I'll have to do :
> > Fetch the features with com.google.gwt.http.client
> > Parse the GML with com.google.gwt.xml.client
> > And from that extract the posList, then generate the points, from that
> > instantiate the LinearRings and then I'll have my features. I feel like I
> > might be reinventing the wheel somewhere.
> >
> > Just to give you the idea, my dream object would be like :
> > List<VectorFeature> features =
> > MyDreamObject.getFeaturesFromRemoteGML(WFS_URL);
> >
> > Has anyone ever tried something similar ?
> > Do you know anything that could help me ?
> > Any help would be MOST appreciated.
> >
> > Thanks !
> >
> >
> > --
> > Mikael
> >
> >
> ------------------------------------------------------------------------------
> > Download Intel&#174; Parallel Studio Eval
> > Try the new software tools for yourself. Speed compiling, find bugs
> > proactively, and fine-tune applications for parallel performance.
> > See why Intel Parallel Studio got high marks during beta.
> > http://p.sf.net/sfu/intel-sw-dev
> > _______________________________________________
> > Gwt-openlayers-users mailing list
> > Gwt...@li...
> > https://lists.sourceforge.net/lists/listinfo/gwt-openlayers-users
> >
> >
>



-- 
Mikael Couzic
Pôle Business Intelligence
Groupe Cliris