Attribute Assistant is not configured to work with ArcGIS for Server feature services, and therefore edits applied from the web are not "listened" by Attribute Assistant.
There is an ArcGIS Idea to implement the functionality in a web environment:
http://ideas.arcgis.com/ideaView?id=087E000000059fTIAQ
Also, others have configured the GeoEvent Processor to have similar functionality as the Attribute Assistant. There are methods for performing a variety of field calculations using the GeoEvent Processor, and therefore can be configured to do many of the Attribute Assistant methods.
As an alternative approach, you can implement a few features and workflow adjustments to use Attribute Assistant and Attribute Assistant-like methods against web edits.
- Host your web data through a "web" version.
- If you have a versioned SDE then creating a web version to host your feature services will keep all edits made online in that version. Then opening the data in ArcMap, you could Manually run the Create/Change rules on selected features. These selected features would be the new edits made to the data. Although it does not automatically use the Attribute Assistant when edits are made, this still uses the rules and methods of the Attribute Assistant. If you can put this into your workflow, it is one way of getting the value of Attribute Assistant into your web edits.
- Enable Editor Tracking
- Many people hate losing the ability to track who and when something was edited online. However, using Editor Tracking (not Attribute Assistant) to take this information, edits are tracked both in desktop and web environments. You can even leverage the security settings on ArcGIS for Server to force authentication from users to view/edit the data. This would then use their login as the editor.
- Nightly Python Scripts to update data
- Although this would take a bit of work, I have seen organizations implement update scripts using python to run a nightly basis and update data. For instance, if you have spatial methods in Attribute Assistant such as GENERATE ID BY INTERSECT, then you could implement a script to perform such functions on your data every night, to update the attributes. Experience with python scripting is obviously the caveat here, but this would require no schema change to your environment.
Ultimately, workarounds exist, but like many others, this functionality is desired in the web environment. With GeoEvent processor available however, I doubt there are any internal pushes from Esri to implement a web version of Attribute Assistant any time soon.
Good Luck!