Feedback from ICommand

Question

I have an ICommand implementation which is stand-alone. It modifies information on an entity. The same entity is bound to a View, as a property of the View's ViewModel.

What I want to achieve is, the entity (and hence the ViewModel, hence - the View) to update with the new information, after the command is executed. The way I understand it, ICommand-s are one-way street. They modify the underlying data, but are not supposed to give a direct result.

So I have achieved this by sending a Message from within the Command at the end of its execution, by using the MVVMLight framework. The View Model which exposes the entity also subscribes to the same message and updates itself, when the message is received (updated info is passed as property of the message).

The added benefit is that other View Models can also subscribe and react to the same event. What 'smells' about it, though, is that the backbone of this implementation is events. From what I've read, the whole concept of events doesn't fit well within the MVVM pattern. Or cross-VM communication is OK to be done this way?

Example:

Domain Model

• User
  • First Name
  • Last Name
  • Full Name { get { return First Name + Last Name } }

View Model

• User View Model - wraps around the User Domain Model, but doesn't store an instance of it
  • string First Name
  • string Last Name
  • string Full Name (Note: Doesn't know anything about how it's calculated)
  • ICommand Change First Name
  • Method: MapFromDomainModel(UserDomainModel). Invoked when the View Model receives UserDomainChanged message.

Command

• Change First Name : ICommand
  • Changes the First Name in the User Domain Model
  • Sends a UserDomainChanged(UserDomainModel) message

See, in this example the View Model doesn't know how Full Name is calculated and doesn't/shouldn't know that when First Name is changed, the Full Name should be changed too. That's why the Command is working directly on the Domain Model and triggers the Message.

Also, I may have other Views on in the Window, which have View Models bound to the same User Domain Model. By subscribing to the same message they can update themselves independently.

Is this a good approach? Is there a better one?