I have an ArcSDE geodatabase which contains multiple relationship classes.
If I add this layer to ArcMap, the relationship is automatically applied (eg, the Identify dialog allows me to drill-down to the related features).
However, if I publish this map document to ArcGIS Server, the REST endpoints for the layer don't show the relationship classes.
Similarly, if I create a new ArcMap document and create a Relate within ArcMap (using > Joins and Relates in the TOC) this also fails to appear in ArcGIS Server's REST directory.
This sample REST directory does show the related data. How has this been set up?