Thanks for this. I think a wiki page comparing these various XML type
formats with links to various examples eould be extremely usefull - for
me at least!<br><br>I've had a go at creating this - probably entirely
incorrect but perhaps you could correct / add to this? I've marked
things with ??? where I am unsure about something or examples seem to
be broken or where a simple change would improve the usefulness of the
example considerably.
<br><br><a href="http://trac.openlayers.org/wiki/XML" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">http://trac.openlayers.org/wiki/XML</a><br><br>I
don't want to blunder in and mess up your wiki, but I think maybee a
main 'features' or 'overview' page would be good linking from the
documentation page - <a href="http://trac.openlayers.org/wiki/Documentation" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">http://trac.openlayers.org/wiki/Documentation</a> which could then link to things such as this XML page
<span class="e" id="q_1151deef20fa2ffe_1"><br><br><br><div><span class="gmail_quote">On 19/09/2007, <b class="gmail_sendername">
Christopher Schmidt</b> <<a href="mailto:crschmidt@metacarta.com" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">crschmidt@metacarta.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
On Wed, Sep 19, 2007 at 10:43:33AM +0100, mike wrote:<br>> Hi,<br>><br>> Is there any documentation of the merits / purpose and intended future<br>> developments of the various XML layers such as GeoRSS, GML, KML etc?
<br><br>Well, the versions in 2.4 were very minimal: Primarily designed to get<br>people started. Specifically, KML had no polygon support, and was<br>readonly, GeoRSS was write only, etc. The resutl of this, however, was
<br>that in 2.5 we got both of those fixed: GeoRSS is now a full Atom/RSS<br>GeoRSS Simple parser, KML supports all KML 2.1 Geometries, etc.<br><br>I have no idea if our GML parser is *valid*, but it has always been the<br>
most complete, I believe because its development was funded as part of<br>Cameron Shorter's OWS Testbed work. (I could be wrong on this.)<br><br>> They seem to be very similar and almost interchangable, and I'm
<br>> finding this a bit confusing.<br><br>Some day in the distant future, when OpenLayers does everything you need<br>and new features are just a memory, all Vector Formats will have a<br>complete mapping of their formats into OpenLayers constructs as best as
<br>the client is able. (This does mean that there are many things that they<br>will be missing -- For example, we will not be representing the altitude<br>of KML features in OpenLayers, so far as I can predict.)<br><br>
At the moment, they are as complete as people have wanted to make them,
<br>and no more. In some casees (GML, via OGC, and soon I believe KML via<br>the OWS-5 work), specific Formats have gotten a boost due to outside<br>funding of development, thus they may be more complete. In other cases<br>
(GeoJSON) the spec is relatively complete and simple in and of itself,<br>and the authors of the spec happen to be OpenLayers contributors.<br><br>> For example, I'm using GeoRSS to draw markers, and KML to draw lines.
<br>> However, this excellent GeoRSS Serialise example seems to be an edit /<br>> draw component for lines and polys:<br>> <a href="http://dev.openlayers.org/sandbox/ahocevar/sldRenderer/examples/georss-serialize.html" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
http://dev.openlayers.org/sandbox/ahocevar/sldRenderer/examples/georss-serialize.html</a><br><br>There's actually probably no reason that you *have* to use GeoRSS to<br>draw markers anymore: it could be done with just a little bit of styling
<br>work on a vector layer. It's not trivial yet, because there is no<br>pressing business case telling me why I should do it, and presumably no<br>one else has had one either.<br><br>> Equally, KML boasts support for styles, although this is not
<br>> implemented yet, and if we are accepting the Google definition, then<br>> KML should support both markers and lines / polys.<br><br>I'm assuming when you say "KML boasts support", you don't mean within
<br>OpenLayers, but in general. If we accept that, we should also support<br>Photo Overlays and 3D. We can't do that :) However, mapping the full<br>set of KML data that *can* be represented into OpenLayers is the<br>
eventual goal: just not neccesarily a high priority.<br><br>> Is there a twiki page for this or a good resource I could refer to?<br>> I'm considering developing this further and I'd like to make sure I'm
<br>> doing the right thing before I start... Also if anyone if actively<br>> developing in this area I'd be very interested to discuss and see if I<br>> can help.<br><br>Not really. Docs are the weakest point on the project, but if you have
<br>specific questions I'm glad to answer them, and you can turn them into a<br>wikipage. Also, I'm often on IRC, <a href="http://irc.freenode.net/" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">
irc.freenode.net</a>, #openlayers, as are<br>40+ other extremely intelligent contributors to the project, many of
<br>whom would be glad to help.<br><br>> My other point is about combined layers - I'd like to create a layer in the<br>> layerswitcher which shows markers and lines / polys (i.e. SVG I assume). Is<br>> it possible to make a combined layer or wrap two layers into one in some
<br>> way?<br><br>Several. But it's likely that you just want to use a Vector layer with<br>an externalGraphic: see the vector-features.html page for styling<br>examples. (The only time this wouldn't be true is if you were required
<br>to support Safari 2.)<br><br>Regards,<br>--<br>Christopher Schmidt<br>MetaCarta</blockquote></div></span><br>