... pgs. ... hear ... I use Design By Contract routinely in all my serious projects. We develop web applications using C# and ASP.Net. As far as technology, I...
... good enough. Fair enough. But I don't think of Design By Contract and Test Driven Design as mutually exclusive techniques. I prefer to use both. I find...
First off, DDD great book and a great source of information. 2ndly, an issue that is bothering me lately regarding exposing your Domain Model to a client (i.e....
... [...] ... Good topic. Part of the issue is whether your web container is remotely located from your EJB container, or co-located. If remotely located, and...
Hi Randy, Thanks for the response. Yeah, I do also favour using a Service Layer, even in non-distributed applications. Essentially: Web Client -> Business...
Has anyone experimented with using Pico or Spring with POJO services? The business delegate layer bugs me a bit. Might make sense to "hide clients from the...
Randy, Just to be clear, if using SSB EJB's as your service objects, any persistence operations (lazy loads) that occur outside the service layer (EJB) would...
There is another option. I don't know if there is a pattern name for it but in .NET they call it DataSet and now in Java they call it DataGraph (see the JSR...
Hey Hawaii-Five-Oh, You must have been reading my mind. Here's the message I just sent off to Evans last night. ... I'm working on a WebSphere app that has...
Steve, First let me just say, this is a great topic - not just because I need to explore these issue, but because it's not really talked about in the book (or...
... I've never used "Business Delegate", but I have used different Strategies in the persistence layer to achieve the same goal (i.e. allowing UI development...
... Yes. I haven't found that to be an issue in practice. ... For me the primary redeeming advantage is distributed transaction coordination. I don't use the...
Primary reason - I like using a Local SLSB for transaction demarcation, security and to have that course-grained business service layer...and I want to...
Randy, Thanks for your helpful reply. Regarding distributed transactions: We just start and stop a JTA transaction in our servlet filter, so we get XA...
... Scott, Well, I'm not sure exactly how to partition the SSB beans. I guess it does roughly correspond to repositories, in that they could be partitioned...
... I see. Sorry for the idiot post, then. As for how to partition a domain model into services, I don't think of it that way. I need to re-read DDD, but in...
Actually, I think there is a deep question here. Is a domain object most properly an abstraction of some thing in the problem domain, or is it OK to group...
<academic-theory> Good question. I have to admit, I'm not a big fan of a fixed service layer and have trouble grasping it. It seems to me that most things...
... I agree: events are thrown off by the execution of domain logic. But, where in the architecture are the events listened for? What objects "handle" those...
I don't know if this article will help or not but here you go (warning MS centric) http://msdn.microsoft.com/architecture/patterns/default.aspx?pull=/library/e...
... I suggest reading Rikard Oberg (alien intelligence as someone said?) blog (http://www.jroller.com/page/rickard). There are several good ideas and in the...
... The request/response mechanism is, by its nature, procedural. The Service Layer is a bridge between the procedural outside world and the Domain Model. A...
Randy, Thanks for the reply. At least in the app I'm working on right now, most of the events are triggered by some change in state of a persistent domain...
I think we may be misunderstanding each other. Sometimes I don't communicate well! By 'service layer', I mean something in addition to whatever you use to...
... Right. The Service layer's job is to translate a procedural request/response mechanism into the appropriate invocations of Domain objects. It, however you...
Hi Steve, ... My pleasure; it's been a good exchange. ... So don't let someone write another service that activates the lease. (Patient: "Doctor, it hurts...
Randy, Thanks again for the reply. Your advise on partitioning and refactoring towards a domain model should help us a lot. I don't want to belabor the...
... I don't think domain objects have to be just little fine-grained objects. Using composition, we can aggregate little domain objects into larger ones. I...
