Is ErMapper's IWS helpful with MapServer?

[Frank Warmerdam]

On 9/23/05, Carlo Calvino <carlo.calvino at email.it> wrote:
> Hello everybody,
> anyone knows if ErMapper's Image Web Server is of any help with MapServer?
> Has UMN Image Web Server alone the same capabilities of ErMapper?
> Some people use these two applications together: I wonder why.

Carlo,

I'm no expert on IWS, but I'll try to give my impressions.

First UMN MapServer does not have the same capabilities as IWS.
IWS maintains up open connection from the client to the server to
continuous update an image view as the user roams around and zooms.
This give a significantly more interactive experience than can ever be
achieved with MapServer in a traditional http request environment.   You
can think of ka-Map/Google maps as an attempt to provide something
vaguely similar, but IWS (potentially) can make this seamless.

I would add that IWS delivers content with ECW compression which
is significantly better than JPEG for instance.  MapServer could deliver
individual images in ECW format, but it really depends on having a
client that supports ECW.  IWS achieves that by requiring a custom client
app or plugin.

On the other hand, MapServer certainly can quite practically and
efficiently serve from massive image databases.

My understanding is that IWS just serves image data from a big pre-rendered
image file on disk.  For that reason, it is not suitable for complex,
and dynamic
rendering which is well addressed by MapServer.

I'm not too sure how they could be effectively used together.  It would be
nice if the IWS client could also pull a layer from WMS (perhaps it does?)
Then mapserver could serve dynamic content overlayed on imagery
from IWS.

So, from my point of view MapServer is a generic mapserver for dynamic
and static content to a generic web browser.

IWS is a custom imagery delivery solution requiring a custom client side
plugin, but can provide a degree of interactivity and performance that
would otherwise be essentially impossible to achieve.

Best regards,
--
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