Choosing ArcIMS Connectors and Viewers
Continued...
Making the Choice
The audience and the functionality required are
the two most important aspects to consider when choosing a connector
and viewer.
- Is the site an Internet or an Intranet site?
- What browsers will clients use?
- What is the user community's level of GIS knowledge?
- What functionality is going to be used?
- How much customization is needed?
If the site is going to be an Intranet site, one
of the Java Viewers might be the right choice. Asking users to install
plug-ins or pushing the plug-ins onto their desktop is much easier
within an organization. The Java Viewers support additional capabilities,
such as MapNotes and EditNotes, that the HTML Viewer does not. Once
the applets are loaded by the client, data and maps are served very
quickly but customizing either Java Viewer is limited compared to
other viewers.
If the site will be an Internet site, the HTML
Viewer, ActiveX Connector, ColdFusion Connector, or AppServerLink
should all be considered. The major reason to use the HTML Viewer
is that its functionality is robust without modification. ArcIMS
Designer outputs a full suite of precoded functions. Documentation
for the HTML Viewer describes its functions, variables, and methods,
and the HTML Viewer is supported on all platforms for both client
and server. The developer needs only to know HTML and JavaScript
to create a site using the HTML Viewer. The HTML Viewer's major
drawback is that it is thicker than other connector clients and
response time can be slow, especially when accessing large datasets.
All the custom connectors create thinner clients
because the code resides on the server and is not downloaded to
the client. Choose a connector based on two major factors-environment
and resources. If a Windows Server with Microsoft IIS is implemented,
the ActiveX Connector is an easy choice. If this is not the case,
any of the connectors is a viable choice. For those with a UNIX
server, the ColdFusion or AppServerLink Connectors are viable options,
but not the ActiveX Connector.
Another important consideration in choosing a connector
is the availability of specific skill sets. If VB skills are available,
then the ActiveX Connector can be used. Likewise, if staff have
ColdFusion skills, then the ColdFusion Connector may be the best
choice. HTML and JavaScript are the easiest skill sets to learn
and are necessary for all connector options, so if skills in other
areas are lacking, the HTML and Java Viewers provide the best options.
Java skills, harder to come by and not as easy to learn, should
be present if the AppServerLink option is considered. Although all
connectors come with documentation, the Servlet Connector documentation
is the most complete.
Table
1: ArcIMS Connector/Viewer Cross-Reference [PDF-65 KB]
Table 1 cross-references all the factors discussed
and can be used as a quick guide to help in the decision making
process when choosing a connector. Ultimately, any of the connectors
and viewers can be used to perform just about any task. The information
provided here should help ArcIMS developers make the most appropriate
viewer/connector combination.
For more information, contact
Scott Steigerwald, Consultant
Idea Integration
E-mail: scott.steigerwald@idea.com
About the Author
Scott Steigerwald has a master's degree in geography from the State
University of New York at Buffalo. He is currently a GIS developer
with Idea Integration in Denver, Colorado.
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