This was actually a simple problem in th end, I assumed that the [Required] annotation would check that the association was present and not null. It seems that all it actually does is check that in this case that FrequencyId is not null. And there was the problem in that I was using a long and not a nullable long (long?). Once I made the change to make them nullable the validation started working as expected even with the bindings which made no sense to me. If anyone could explain them that would be great! Phil

Prism is open source. So you can probably look at the source code itself to get a better idea. You can use the IModuleCatalog interface if you want to implement something on your own. Too much of heaven can bring you underground Heaven can always turn around Too much of heaven, our life is all hell bound Heaven, the kill that makes no sound

Still trying to solve this, anyone got any ideas at all?

If I understand you are essentially calling a WCF service from within a WCF service method correct. In which case, then yes all the end points need to be defined. The code doesn't know that it is executing from within a service, an exe, or a webpage, it just knows it needs to connect to a service and needs to know how. I know the language. I've read a book. - _Madmatt

Ok, I'll give that a go, thanks for the help Ian, many Kudos!

I now find I have quite a few "attribute" tables in my schemas. Customer now wants 2nd mobile - add a phone attribute linked to the customer table. I have one app that is ALL attributes, it tends to get nasty when trying to retrieve data, monstrous number of joins. Which goes to prove you can go too far down that path.

The only reaslistic alternative is to use dynamic SQL (sql strings) but that is plain ugly. Also chaining multiple conditionals can nail a query to the wall. What I often do is use the "required" conditions to get a subset into a temp table and then start deleting records from the temp table or use the conditional filtering on the temp table Never underestimate the power of human stupidity RAH

Ok, I figured out that if I change the reference.cs file for each of my web references then everything works. The namespaces match and now I can access what I want. However, as i'm sure you'll all know as soon as I update the webreference it reverts back to the other names space of ComsLayer.. So what i need to do is be able to set a default value of this namespace to XGSDev.XeroxOrderTracking.OrderTrackingService.ComsLayer. I found out that in the properties of the Reference.map you can enter a custom tool namespace. Enter your namespace here and everything will work!! Phil