Implementation
The core of ArcIMS is a spatial server where most of the map related services are processed. On the server side, ArcIMS connector sits on top of web server and ArcIMS component and Application server works behind the scene. On the client side, the viewers can be thin client, custom clients or Esri desktop application like ArcMap, ArcExplorer, or ArcPad.
ArcIMS uses Esri's ArcXML to receive and respond to requests from the client. The data behind ArcIMS is usually stored in Shapefile format (an open specification) or an ArcSDE RDBMS database.
The Data Delivery Extension (DDE) is an extension to the ArcIMS product that delivers data to users in a data format and coordinate system of their own choosing, in order to have access to data in a format compatible with their local GIS applications.
ArcIMS has is no longer supported by ESRI and has been replaced by ArcGIS for Server and Arc GIS Online (AGO)
Read more about this topic: ArcIMS