text: … something on Domain Driven Development – Ingeniously Simple – Medium
  Another, more illustrative example perhaps, would be one Bounded Context for vegetables, and one for herbs and spices. Notice here, the term "Pepper" can appear in both Ubiquitous Languages but with two different meanings — black pepper, and capsicums. Vaughn uses the example of the word Policy which can have many different meanings across an Insurance business.
  But I think this is also an area DDD and I mostly agree on, the problem is objects that are open access on the data they are supposed to be encapsulating — every field has a setter and can be modified by anything else. This is the real danger, and on the project I just mentioned there was no constraint; and this gives you spaghetti code; or the Big Ball of Mud (BBoM) Vaughn talks about.
  Related to this, but a step further was CQRS — Command Query Responsibility Separation since you ask. Effectively this is having a clear distinction between pure queries with no side effects (I'll return to that in a moment) which are therefore read-only, and Commands which change the state of the system in some way (of course an audit function will muddy the water). I remember discussing this and regarding it as reasonably good practice, doing it when I could. It also reminded me of using a PUT in http (a command), getting nothing but a 202 status back, and then confirming it had worked with a GET (a query).
  The no-side effect mantra is a good rule, and I have long adhered to this, remembering when I worked with my now-colleague Jeff Foster before, and you often hear developers saying to each other "Don't do that — Jeff doesn't like side-effects".
  On top of which I've always tried to return something from a method so that you are able to detect that something happened — otherwise it's just blind faith. This is what I really struggled with at a startup last year; everything was a void and there was no way to test or assert on it; therefore it wasn't really tested. We were building Castles on Clouds.