title: MVVM-Light: Where to put WCF call in ViewModel
body: <p>I'm building a WP7 app that gets all its data through WCF services. I want to implement MVVM-Light in it but in tutorials I've done, I see that in the ViewModelLocator it wants to create a static instance of all my ViewModels when the app starts.
  My problem is that in my constructors for my VM's is where I make my WCF calls with the results of course coming back in the callback. It is in the callback where I assign the results to my observable collection that my Views see. This works fine when not using MVVM-Light but if I implement it I can't have these WCF calls at startup as they pass parameters not known/available until the user uses the app (selecting items, etc.)
  I tried moving my calls to the WCF to the getter of my observable collection but it keeps calling the WCF in an endless loop.
  In all the samples of MVVM-light that I've seen I haven't seen anyone calling WCF services.
  Any suggestions as to where to put my WCF calls in the model?</p>