[OpenLayers-Users] What is Open Layers

[Obe, Regina]

Robert,
> Whats the benefit of using OpenLayers ?

> When compared to what?

I'll try to take a stab at this question.  OpenLayers has drivers for commercial sources
like Google Maps and Virtual Earth which have their own javascript API.  In fact OpenLayers just provides
an abstraction layer on top of those APIs but uses them behind the scenes.

What does this mean - why wouldn't you just use the Virtual Earth,Google Maps, MultiMap, or WordWind apis if you wanted to use those sources? because each
is very different and if you want to overlay your own layers from GeoServer, MapServer, MapGuide, OpenStreetMap, or commercial layers from another OGC WMS provider  it becomes prohibitively difficult
to do so with those disparate raw apis.  Not to mention writing your own raw WMS client is not trivial.   This is where OpenLayers really shines because it allows these disparate GIS data feeds to interoperate.

So to me I think of OpenLayers as the ODBC,JDBC, DBI (except on client side of course) of the GIS world.

There is a bit of a downside to some of this (just as there is with using any abstraction layer).  For example OpenLayers doesn't support he 3D views of Google Maps and Virtual Earth or expose some of their other apis and there is probably a bit (no not much overhead to wrapping this layer over).  So to use it for the other 10-15% case - you may still need to learn and get into the guts of those apis.  For the 85-90% case it works well though.

Hope that helps,
Regina









-----------------------------------------
The substance of this message, including any attachments, may be
confidential, legally privileged and/or exempt from disclosure
pursuant to Massachusetts law. It is intended
solely for the addressee. If you received this in error, please
contact the sender and delete the material from any computer.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/openlayers-users/attachments/20081116/b049df8e/attachment.html