1. For simple validation (just value) we can still use JSF validation. 2. For complex validation I use drools (jBoss Rules). It nicely integrated with Seam Page Flow (see seam samples). You can express your validation in rule set. IMHO it looks like quite elegantly. You can define as complex rules as you want. And validation logic is separated. And most important, it works steadily. I have not experienced any problems yet. Denis. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3970396#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...