Mapserver <=> ArcIMS comparison

[Michael Anderson]

    I have been using both ArcIMS and MapServer for a few months. Before I 
give my opinion on a comparison, I would like to point out that the scope of 
what ArcIMS and MapServer attempt to do is different. ArcIMS has several 
components designed to do things that MapServer alone doesn’t address. This 
includes html and applet based viewers for the client as well as several 
components on the server. The components on the server include the 
application server, manager components, and the spatial servers. The spatial 
server is what renders the images, handles spatial queries, extracts 
features, etc. The manager components allow you to build “Map Services” (map 
files), create web sites using the map services, and publish the sites.  The 
application server allows you to distribute pieces of your application over 
multiple machines and pool several machines to handle increased loads.  It 
also allows you to use COM and Cold Fusion in your application as the 
“connector” between the web server and application server. ArcIMS has two 
additional components that start and stop processes and delete images on a 
schedule.
	MapServer alone is only analogous to the spatial server, but the other 
features can be added using other tools. Other than being able to use fewer 
data formats, MapServer is a better spatial server than ArcIMS’s. By using 
an existing web application server you can get the additional functionality 
with a minimal amount of work. I am using Zope, which is Python based, as my 
application server. It is also Open Source. It is a much better application 
server than the ArcIMS component. In addition to allowing you to distribute 
your application, and pool machines, it also handles user authentication, 
and gives Unix like permissions to files, URLs, and operations. It also 
handles publishing the sites easily. I haven’t gotten around to using it to 
make the map files or the web site though. I use ArcView to make the map 
files and have someone else make the web site. Zope does allow me to share 
single html and JavaScript files across multiple web sites, which makes 
maintenance a lot easier. It is also possible to use Zope as a connector to 
ArcIMS so a single application could use both MapServer and ArcIMS (as well 
as other GIS engines). I am also aware of a Java based application server 
called Enhydra that is also Open Source. I have installed it, but haven’t 
had much time to use it, so I can’t really say what it can do. There are 
also commercial application servers available like IBM’s WebSphere. You 
could probably do a lot with Cold Fusion as well.

That said, here is my 2 cents on the advantages and disadvantages of ArcIMS:

Advantages of ArcIMS
- distribute applications over multiple machines
- Native integration with the Geography Network. MapServer can be made to 
work within the geography network.
- Includes software to handle routine tasks like making the map services 
(map files), designing web sites, etc.
- Supports more data formats – especially raster
- Better support for storing spatial data in RDBMS through SDE
- You don’t have to try to sell a relatively unknown product (MapServer) and 
philosophy (Open Source)

Disadvantages of ArcIMS
- speed (even running mapserv as regular cgi it is much faster)
- resource hog
- limited OS (no Linux)
- less stable. My ArcIMS experience is on NT so that may be more a 
reflection of the OS than ArcIMS.
- poorer support
- source code unavailable
- cost

Mike

Michael Anderson
Spatial Information Technologies, Inc.

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