Define a domain exception.

[tangxuehua]

Define a domain exception.

[tangxuehua]

After some consideration, we decide do not define a domain exception class. We allow user to throw any exception in the domain. And enode framework check if it catch the ENodeException, then the command will be retry authomatically. ENode framework will enusre that the ENodeException will only be throwed by enode framework, and commonly this exception in the command handler is throwed when user call context.Get method. If this method throw ENodeException, that means there are some io exceptions occurrs when accessing the redis memory cache or event store. So in this case, the command should be retried always until success.

[tangxuehua]

For the above design, developer should understand the developing rule that if the command handler throws ENodeException, than the command handler will be retried automatically; otherwise the command will not be retried and the error will back to user (like controller).

Developer can throw any exception in the command handler except ENodeException.