ArcGIS Explorer Online

= Overview =

ArcGIS Explorer Online is a free-to-use web based application that makes it easy for anyone to access services and file data:

http://explorer.arcgis.com

Network Traffic Architecture
ArcGIS Explorer Online is a Silverlight application, which means it is a hybrid of web application and client application. In terms of network traffic this means that though ArcGIS Explorer Online is a web application, all the connections to services it makes are made from the local system that is using the application (as opposed to the web server hosting the application.)

Traffic Capture - Adding Local Service to Map
Below is a play-by-play capture of the traffic generated when ArcGIS Explorer Online connects to a map service, either local or public (note that this is not all the traffic, just the important bits):

What about Proxies?
ArcGIS Explorer Online is proxy compliant, that is, we (Esri Support) have tested this internally and verified that ArcGIS Explorer Online functions properly with proxy servers including authenticating proxies (the most common and most problematic such as ISA).

Note: Since the ArcGIS Explorer Online behaves like a local application, it makes outbound connections, through a proxy server if applicable (usually the case) to any destination address.

But what if I'm sure the proxy is the cause?
While there have been reports that the presence of a proxy with ArcGIS Explorer Online has impacted clients within some organizations we suspect (after validating above) that these issues are specific to the proxy configuration of the organization.

Browser - Trust ArcGIS Server
Web Browser must add any ArcGIS Server Fully Qualified URL (http://yourserver.arcgis.com) to Trusted Sites that ArcGIS Explorer Online is accessing.

See:

Can't access my internal services on ArcGIS Explorer online http://kbuilder/preview.asp?dbid=39257

Cross Domain File Required
Cross Domain file (crossdomain.xml) must exist on the web root of the ArcGIS Server. Here is an example file that can be used for testing:  <!DOCTYPE cross-domain-policy SYSTEM "http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">    

Client Access Policy File Required
Client Access Policy file (clientaccesspolicy.xml) must exist on the web root of the ArcGIS Server. Here is an example file that can be used for testing:           

Proxy Configuration Requirement
Any proxies between ArcGIS Server and the local client must permit the local client to establish HTTP GET requests to the ArcGIS Server, either local or remote. The following URLs must be permitted to establish outbound connections from the local client to the ArcGIS Server:
 * http://explorer.arcgis.com
 * http://services.arcgisonline.com
 * http://yourserver.domain.com

Name Server Resolution
Some organizations have reported that adding a host file entry (%SYSTEMROOT%\system32\drivers\etc\hosts) as follows for the ArcGIS Server within their organization solves some issues: Windows Hosts File

192.168.1.1         yourserver
 * 1) ArcGIS Server IP    ArcGIS Server Hostname

192.168.1.1         yourserver.domain.com Note that if this does solve the problem, the root of the issue is likely a name server resolution issue specific to the organization (unless further investigation proves otherwise).