Blogs

My last musings on a observed misuse of ubiquitous language (UL) led to deeper comments than I had ever realized when writing the story down. To many a non native speaker ubiquitous is at first hearing a strange word, as far as I know it is not widely used outside the world of IT. The sounding reminds of (un-)ambiguous, a term often found in the same context. There is a relation between these two words and IMHO that was the heart of the comments and led me to take another dive into the idea of UL. The term Ubiquitous Language was brought to the world of software by Eric Evans in his classic book Domain Driven Design (DDD). Where it is defined as a language based on a model and spoken by both domain experts and developers. It should be “more robust than the lowest common denominator” (p.25). Domain experts “should object to terms or structures that are .. inadequate to domain understanding” and developers “should watch for ambiguity ..” (p.27) So a good UL is a powerful common unambiguous language spoken by all experts , whatever their background, to communicate on a software system. Note the stress on the word expert. Now some people involved are not an expert. Take the old lady in my previous story...

I just read a post from fellow devlicio.us'er Billy McCafferty and was considering what influences my own solutions to these concerns (ie, repositories, data transfer, etc) now. There has been an abrupt shift/growth in my thinking this year in how I perceive my domain and how I interact with or scale it. CQRS, perceived by some as a shiny new toy, and the discussions it provokes has definitely contributed to the maturity of the project I have been on by increasing its quality and adaptability. Why? My experience has been the simple shift to being concerned about what all these things are doing (behavioral mindset) instead of what they look like (stateful mindset). I now see that the decision to expose domain state at all should be one of the first decisions to make and its implications on the various infrastructural concerns should be well-understood. This seems to drive divers decisions both within the domain and how it is consumed or utilized without. The first casualty of this shift was the getters and setters (whether exposed as properties or GetX()/SetX() methods). Hiding as much state as possible radically increases the freedom in the domain, especially when going down the event-sourcing route. As you know, the moment you...

Obviously, S#arp Architecture is the bee's knees when it comes to developing ASP.NET MVC applications. ;) But as a project evolves and gets larger, "out of the box" S#arp Architecture 1.0 guidance runs into a few pain points. Particularly, there's poor use of the application services layer, the separation between controllers and application services is not very clear, entity listing pages become performance bottlenecks as the domain model gets sizable, there is no command/query separation (CQS) "out of the box", and unit tests require re-occurring maintenance to deal with changes in the number of constructor parameters to controllers and application services. While the amicable and adroit Alec Whittington (who is taking over the lead role from me on S#arp Architecture) is hard at work upgrading S#arp Architecture to accommodate recent dependency upgrades and accommodating ASP.NET MVC 2, I wanted to take a stab at resolving some of the issues that I've run into, on S#arp projects over the past year. I've developed and included a sample project, built on S#arp Architecture 1.0 Q3 2009, for the following key reasons: To resolve some "pain points" that develop as S#arp projects grow to large...

If you’re using MSpec ( Machine.Specifications ), you’ve no doubt run into the verbosity of it. Here’s a typical specification in MSpec [ Subject ( "Registering as new a usergroup" )] public class when_requesting_registration_page { Establish context = () => { }; Because of = () => { }; It should_display_blank_registration_form = () => { }; } The code is usually divided into three areas, the Establish that defines the context, Because which is defined as the action to take, and finally one or more benefits that are defined as It sections. Having this layout makes it easier to understand specifications and both the console runner as well as ReSharper’s MSpec runner remove underscores and provide a nice formatting. Live Templates However when it comes to typing all this in, well all those brackets and symbols become tiring. For that I normally use ReSharper Live Templates. If you’re not familiar with these, think of them as code snippets that allow interaction. Each template is uniquely identified by a shortcut, which is a series of characters. To invoke it, you simply type the characters and hit TAB. It then inserts some code. Up to this point it’s like a normal snippet. The twist...

To all of my loyal subscribers welcome back. I’ve transferred my original feed to this blog. From now on I will be talking cloud computing though and will no longer focus on Domain Driven Design, there is enough content on that topic nowadays anyway. But if you’re interested in cloud, and particulary windows azure, stay tuned… [...] Read More...

The next DC ALT.NET meeting is taking place on 2/24/2010 from 7-9PM.  Stay tuned to the mailing list for more information as it becomes available.  In this meeting, once again we have George Dinwiddie, to give a talk on talk in the language of the business and what tools along the way can help us.  Below is a description of the event.  We hope to see you there! This year we have a lot of great sessions in store including Mono, Domain Driven Design, Git and other DVCS for the .NET developer, more JavaScript topics and a lot more.  If you’re in the Washington, DC area, sign up for the list and hopefully you can join us. A ''Lingua Franca'' to Ensure You Get the Right System The business tells the IT department what it wants. The developers build it. The testers expect it to do something different. And neither of these turn out to be what the business had in mind. Has this ever happened to you? IT departments have always struggled with getting clear and unambiguous requirements. Automated acceptance tests that check the system with examples make a big impact on coordinating the work of developers and testers. Unfortunately, they’re often incomprehensible code to the business people asking for the...

Back to the fun stuff. Series link here . As a reminder of what I’m talking about, here’s the picture from Mark : What I’m going to be talking about is section #1 from Mark’s picture, and in particular, I’m going to going over a number of concepts including: The Reporting Store Eventual Consistency You don’t need your Domain Once you have one, why not more? “Reporting” doesn’t just mean Reporting One of the first things that I found difficult when learning about CQRS was the use of the term “Reporting.” Because I come from a SQL background, when I hear the term “Reporting” in IT contexts, I think about reports, e.g. last month’s sales report. Because of how the term is normally used, I’m not sure if there is a different word that should be used here. However, especially with all of the stuff I just wrote about traditional reporting, there are a couple of concepts that are starting to make more sense to me, since it turns out that some of the concepts of CQRS are simply things that we’ve been doing already, but refined. The first thing to keep in mind is this: The Reporting Store (as separated from the Event Store, which is up in section #3 of the picture) is a logical concept, and as such does not have to be physically separated. Having...