When deploying the Lucity Web Map, the web server that hosts Lucity Web must be able to talk to the web server that hosts ArcGIS Server. If both of these applications are on the same server there is no further setup that needs to be done. However, it is common for these to be on two separate servers. When Lucity Web and Arc Server are hosted on two separate servers admins must setup either a ClientAccessPolicy.xml or a CrossDomainPolicy.xml. Silverlight will always first attempt to download and check for a ClientAccessPolicy file. If it cannot find the ClientAccessPolicy file, it will look for a CrossDomain.xml file.
Automatic Configuration
ArcGIS Server 10.1 and higher can handle this automatically using the ArcGIS Web Adaptor.
Manual Configuration
One or both of these files MUST be placed on the ArcGIS Server in the root folder that ArcGIS is installed to. For example:
ArcGIS Server is installed to C:\inetpub\wwwroot\ArcGIS\Manager - Place these files in C:\inetpub\wwwroot
ArcGIS Server is installed to C:\inetpub\gisroot\ArcGIS\Manager - Place these files in C:\inetpub\gisroot
The ClientAccessPolicy.xml and CrossDomainPolicy.xml open up a hole in the ArcGIS Server machine's security that allows Silverlight applications on other servers to communicate with ArcGIS Server. Which machines this hole allows depends on the policy used. Below are examples of these policies. Feel free to copy, paste, and modify these.