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Alex Yakunin

November 24, 2009

Visual tools: model designer & profiler

Finally I decided to surrender and start following "visual path". Visual tools are what people expect now -   frequently it does not matter how good your product / API is: no visual tools = there is nothing to speak about. Or, differently, if you're so cool, why you don't deliver visual designers, which are commonly expected? And you know, it's impossible to argue with this. It's simply clear we need them.

The next question is what people really expect from us. Currently I see the following weak areas:

Visual model designer

That's what business analysts and beginners expect first of all. We're going to build it over Visual Studio DSL Tools. I always though this is pretty hard problem, but after looking on DSL tools closer I discovered it must be much simpler than I though. Moreover, MEScontrol developers successfully use model designer built by MESware for integrators (it generates v3.9 models) - it is based on  DSL tools. So there is already a kind of prototype we can look at. Let's describe what our designer must do:
  • Design persistent models - add, edit and remove persistent classes (Entities, Structures and EntitySets) and properties there;
  • Support application of all DataObjects.Net attributes, such as [Association]; it must be possible to define mappings there as well.
  • Provide customizable T4 template-based code generation of entity code. Obviously, we'll generate partial classes you can extend with your own code.
  • Support modelling of IUpgradeHandlers, and, likely, even their automatic updates on changes in model.
  • It must be possible to reference externally defined persistent types there, including custom-typed EntitySets. This will allow to build separated models for each part of the application.
  • It should support reverse engineering - a feature allowing to (re)generate the model from existing database.
Query profiler

Possibly, this is even more important part. We're going to combine query debugging features of profiler we hav in v3.9 (if you don't know, it is very similar to LINQPad) and tracing features of NHProf to make a process of debugging DO4-based applications really simple and productive. We expect it providing the following features:
  • Possibility to attach a profiler to any remote DataObjects.Net Domain, if profiling is enabled in its configuration.
  • Event tracing. Nearly the same UI as in SQL Server Profiler, although I'd like to see better categorization, filtration and grouping features there.
  • Event analysis. Basically, we must be able to attach integrated & custom analyzers to the event streams we produce, and I hope Rx Framework will help us a lot here. Since results of analysis are event streams as well, their visualization must be similar to event tracing.
  • Custom code execution. Yes, I'd like this to be possible. DataObjects.Net profiling API must allow profiler to push C# \ VB.NET code to the server and execute it there capturing all the event.
  • Result visualization. Such custom code must be able to return results back to the profiler for visualization. I feel this is one of the most important and complex parts there: I'd like to see which properties of persistent objects are loaded and which are not, explore the relations there, support very large collections of entities, and, moreover, I'd like to be able to edit everything there.
  • Likely, later it will support other ORM tools. But our initial goal is to perfectly support just DO4.
So profiler must act not just as tracing & debugging tool, but nearly as SQL Server Management Studio: in fact, it allows you to do everything except changing the model.

Timeframe: we're going to start works on both parts from the beginning of December; visual designer is of #1 priority, so I hope we'll be able to show its alpha by the end of this year. Likely, this will delay some of planned v4.2 features, but not quite: I hope Alex Ilyin (LiveUI author, he will join DO4 team for few months) will help us a lot with this.

Any ideas and opinions are welcome.