... Yes, thanks, that was very helpfull. ... The only thing I am ignorant of is the publish-subscribe technique you mention - can you refer to some reference...
... Well, I just found your blog: http://www.udidahan.com/2008/08/11/command-query-separation-and-soa/ Thanks for a well written introduction. /Jørn...
Hi i'm very interested to know more about CQS but still having difficulty to understand the advantage of it. I just wondering if there any good example on how...
Vernon, ... Sometimes. ... Not when it exposes conditions to users who don't know how to handle them. ... scenario? This is what tasks are about. In a...
... I guess the "changes the relevant parts" element is the *key* feature here? Assume a record with for instance two fields "Title" and "Age". One task would...
Jørn, You've got it right. The only thing is that while it may decrease the need for versioning, there are contexts where we may still need it. In those...
The versioning is on the entity but if you are building from commands and you have a version number you can solve conflicts quite easily in cases like the one...
... From a business perspective, there is no conflict when different parts of the entity are modified by different users. Even with a simple entity-based...
... Ok, we generally use read committed, which on Oracle is a pretty safe isolation level. It's rare to get an Oracle shop to use repeatable read. But I admit...
Hi, 1) versioning on commands is not enough to conclude with a consistent result unless you have only one mutable command updating the object for all use...
Hi, If only DTO are transferred to client, we might end up with one entity corresponding several kinds of DTO. For example, one customer with id 1 can have...
Hi, So how can you know you should throw a "application exception"? It would be generic, if we think it is a merge conflict. If we do not think the version ...
All, nbplopes wrote: <snip> There are too many factual errors, misuse of words and ignoring of things that have been meticulously pointed out by Udi on how...
... And also the other way round: one value object with information from several entities. A list view, for example, could be done with a value that itself has...
... You seem to have missed that this thread is about applying Command and Query Separation. Changes is about applying Commands, not State changes. When a...
Hi, Two things. One on state transfer, One on lock. 1. State transfer Get DTO from server to client essentially is transferring the new state of some entities...
Hi Rickard, I understand the the name UOW is not new. It is new to me since I started reading about patterns. Nevertheless I've been applying such techniques...
On another note, I haven't read all the posts, so if some things that I've mentioned have been written by someone else (Udi or anyone else) I appologise for...
... Doesn't this mean that you either have the entire database on the client, or at least the ones you are interested in (i.e. if you ever touch an entity it...
Rickard, On another note, CQS as of yet is still a principle not a pattern. A principle that I've neen using (but not knew the name, learned when I came to...
Hi Rickard I like the idea of Composite Oriented Programming. Is anything published (web or elsewhere)? Have you considered supporting process algebraic...
Nuno I think you are the only person that believes we are talking about the CQS principle from Bertrand Meyer. CQS is the same concept but applied as an...
It's too bad but when I see the sender of a message is 'nblopes', I delete it regardless of the subject line. All y'all are a lot more patient than I. ... -- ...
+1 I would kindly ask to everybody to stop this, and keep the respect level to at least humane-minimum level to concentrate on DDD problems (we already have...
Hi Pete I don't want to be pedantic, but ... (I am going to be!) The semantics of a contract (as in classical DbC) are that, if a pre-condition is violated,...
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