http://ayende.comAyende @ RahienCopyright (C) Ayende Rahien 2004 - 2021 (c) 202660Ok, I see what you're saying. I had considered this but thought it would end up in too many round trips to the database, and concluded that there just must be another way! I always considered reporting as the one place where it was ok to break rules in order to improve performance, and this has led to the reporting system I'm working on to end up having some calculations defined in both TSQL and .NET... http://ayende.com/2503/developing-for-scalable-applications#comment5http://ayende.com/2503/developing-for-scalable-applications#comment5Thu, 07 Jun 2007 14:09:41 GMTMike G, I won't do the report from the OLTP DB, I would move the data to a separate DB and report from there, the ETL process from the DBs would handle the sale tax calc using the domain http://ayende.com/2503/developing-for-scalable-applications#comment4http://ayende.com/2503/developing-for-scalable-applications#comment4Wed, 06 Jun 2007 19:32:52 GMTAyende, I'm not sure I understand. If you put the salestax calculation in the domain (domain objects I assume), how would a report (from an SP) use this calculation? http://ayende.com/2503/developing-for-scalable-applications#comment3http://ayende.com/2503/developing-for-scalable-applications#comment3Wed, 06 Jun 2007 19:30:27 GMTMike G, I would put it in the domain, because that is the most flexible place as far as I am concerned. If I needed it for something else, like reporting, I would handle that in the ETL process, using my domain. http://ayende.com/2503/developing-for-scalable-applications#comment2http://ayende.com/2503/developing-for-scalable-applications#comment2Wed, 06 Jun 2007 18:16:26 GMTI have a question about using OR/M and StoredProcs/Views in general in the context of a DDD application. Say you have some calculated value like salestax. It can be calculated in the domain objects, or in the application services, or in the db itself. As a general design principle, you would only want this calculation to be defined in one place, right? So how could you ever write a storedproc or view which returns with something like salestax? Should the calculation be done in a db function that gets used by the other layers? http://ayende.com/2503/developing-for-scalable-applications#comment1http://ayende.com/2503/developing-for-scalable-applications#comment1Wed, 06 Jun 2007 17:43:32 GMT