Re: Business Objects and Async Message Based Systems

From: fritz (intrader_at_attglobal.net)
Date: 07/23/04 

Date: Fri, 23 Jul 2004 05:19:27 GMT

msnews.microsoft.com wrote:

> On of the nice aspects of a business object and localizing all the logic
> for validation / updates in a single object is that it lightens the load
> for the UI deveoper not to have to worry about such issues.
>
> So, for example, lets say that an Order that isn't an odd lot can't be
> submitted to the BE. Ideally I would want to bind the Size property to a
> sizeTextBox and an IsValid property to the submitButton. This way, if any
> rules are broken (and the size is not % 100) the send button won't enable.
>
> This provides real nice encapsulation. But on the flip side, setting the
> Size in the object will ALSO notify all the bound controls of the new
> size. That is undesirable. Becasue, for example, if there was an order
> blotter, I wouldn't want it to update also.
>
> The problem becomes more difficult when you think about the following
> situation ... an order with a size of 100,000. I open the order entry
> screen and change the size to 50,000. Then, while I am editing the object,
> the order size (lets say from a different trader) is changed to 200,000.
> If I had the order blotter open, I should see that change (and prob be
> notified in the order entry screen that the size chagned, but that is a
> different story.)
>
> So while I agree that the buiness object approach is a great way to go, I
> am having difficulty resolving issues like the one mentioned above.
>
> So ... was wondering if anyone else has worked on such problems ...
Seems to me that if 'something' has two separate rules, then that something
is realy two different entities.

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