Can MapViewer view 3rd party spatial/GIS data?
No, but it can use map images from a Webmap Server. MapViewer 10.1.2 supports a new theme type called WMS-Theme, which can be used to import a map layer generated by any 3rd party’s OGC WMS 1.1 compliant server. Here is a sample XML map request for MapViewer that includes a WMS theme. Note you can also add WMS themes through the Java API. Note the parameters specified in the WMS theme are for illustration only.