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In preparation for the next public release of CSLA Light (CSLA .NET for Silverlight), I'm going to do a series of posts describing the basic process of creating a CSLA Light application. This first post will provide a high-level overview of the project structure and some concepts. First, it is important to realize that CSLA Light will support three primary physical architectures: a 3-tier (or SOA) model, a 3-tier mobile objects model and a 4-tier mobile objects model. At all times CSLA Light follows the same n-layer logical architecture of CSLA .NET, where the application has the following layers: Presentation/UI Business Data Access Data Storage The primary goal of CSLA Light and CSLA .NET is to support the creation of the Business layer in such a way that the interface points to the Presentation/UI layer and to the Data Access layer are clearly defined. To a small degree, CSLA Light will assist in the creation of the Presentation/UI layer by providing some custom Silverlight controls that solve common issues and reduce UI code. Like CSLA .NET, CSLA Light is not an ORM and does not really care how you talk to your database. It simply defines a set of CRUD operators - locations where you should invoke your Data Access layer to retrieve and update data. 3-Tier or SOA Model If you use CSLA Light in a 3-tier (or SOA) model, your physical tiers are: Silverlight Service Database You can treat these as tiers, or as separate applications where you use SOA concepts for communication between the applications. That's really up to you. In this case the focus of CSLA Light is entirely on the Silverlight tier . In that Silverlight tier, you'll have the following logical layers: Presentation/UI Business Data Access/Service Facade To do this, you configure the CSLA Light data portal to run in local mode and it calls the DataPortal_XYZ methods right there in the Silverlight client tier. You implement the DataPortal_XYZ methods to invoke remote services in the Service tier. CSLA Light doesn't care what those services look like or how they are implemented. They could be asmx, WCF, RSS, JSON, RESTful, SOAP-based - it just doesn't matter. If you can call it from Silverlight, you can use it. The CSLA Light data portal is designed to be asynchronous, because any calls to remote services in Silverlight will be an asynchronous operation. In other words, the data portal is designed to support you as you call these remote services asynchronously. The only requirement is that by the Read More...
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I've been engaged in a discussion around CSLA .NET on an MSDN architecture forum - you can see the thread here . I put quite a bit of time/effort into one of my replies, and I wanted to repost it here for broader distribution: I don’t think it is really fair to relate CSLA .NET to CSLA Classic. I totally rewrote the framework for .NET (at least 4 times actually – trying different approaches/concepts), and the only way in which CSLA .NET relates to CSLA Classic is through some of the high level architectural goals around the use of mobile objects and the minimization of UI code. The use of LSet in VB5/6, btw, was the closest approximation to the concept of a union struct from C or Pascal or a common block from FORTRAN possible in VB. LSet actually did a memcopy operation, and so wasn’t as good as a union struct, but was radically faster than any other serialization option available in VB at the time. So while it was far from ideal, it was the best option available back then. Obviously .NET provides superior options for serialization through the BinaryFormatter and NetDataContractSerializer, and CSLA .NET makes use of them. To be fair though, a union struct would still be radically faster Before I go any further, it is very important to understand the distinction between ‘layers’ and ‘tiers’. Clarity of wording is important when having this kind of discussion. I discuss the difference in Chapter 1 of my Expert 2005 Business Objects book, and in several blog posts – perhaps this one is best: http://www.lhotka.net/weblog/MiddletierHostingEnterpriseServicesIISDCOMWebServicesAndRemoting.aspx The key thing is that a layer is a logical separation of concerns , and a tier directly implies a process or network boundary. Layers are a design constraint, tiers are a deployment artifact. How you layer your code is up to you. Many people, including myself, often use assemblies to separate layers. But that is really just a crutch – a reminder to have discipline. Any clear separation is sufficient. But you are absolutely correct, in that a great many developers have trouble maintaining that discipline without the clear separation provided by having different code in different projects (assemblies). 1) CSLA doesn’t group all layers into a single assembly. Your business objects belong in one layer – often one assembly – and so all your business logic (validation, calculation, data manipulation, authorization, etc) are in that assembly. Also, because CSLA encourages the use of Read More...
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I spent some time over the past few days using my prototype Silverlight serializer to build a prototype Silverlight data portal. It is still fairly far from complete, but at least I've proved out the basic concept and uncovered some interesting side-effects of living in Silverlight. The good news is that the basic concept of the data portal works. Defining objects that physically move between the Silverlight client and a .NET web server is practical, and works in a manner similar to the pure .NET data portal. The bad news is that it can't work exactly like the pure .NET data portal, and the technique does require some manual effort when creating the business assemblies (yes, plural). The approach I'm taking involves having two business assemblies (VS projects) that share many of the same code files. Suppose you want to have a Person object move between the client and server. You need Person in a Silverlight class library and in a .NET class library . This means two projects are required, even if they have the same code file. Visual Studio makes this reasonable, because you can create the file in one project (say the Silverlight class library) and then Add Existing Item and use the Link feature to get that same file included into a .NET class library project. I also make the class be a partial class, so I can add extra code to the .NET class library implementation. The result is: BusinessLibrary.Client (Silverlight class library) -> Person.cs BusinessLibrary.Server (.NET class library) -> Person.cs (linked from BusinessLibrary.Client) -> Person.Server.cs One key thing is that both projects build a file called BusinessLibrary.dll . Also, because Person.cs is a shared file, it obviously has the same namespace. This is all very important, because the serializer requires that the fully qualified type name ("namespace.type,assembly") be the same on client and server. In my case it is "BusinessLibrary.Person,BusinessLibrary". The Person.Server.cs file contains the server-only parts of the Person class - it is just the rest of the partial class. The only catch here is that it can not define any fields because that would obviously confuse the serializer since those fields wouldn't exist on the client. Well, actually it could define fields as long as they were marked as NonSerialized. Of course you could also have a partial Person.Client.cs in the Silverlight class library - though I haven't found a need for that just yet. One thing I'm debating is whether the Read More...
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Someone on the CSLA .NET discussion forum recently asked what new .NET 3.5 features I used in CSLA .NET 3.5. The poster noted that there are a lot of new features in .NET 3.5, which is true. They also included some .NET 3.0 features as "new", though really those features have now been around for 15 months or so and were addressed in CSLA .NET 3.0. CSLA .NET 3.0 already added support for WCF, WPF and WF, so those technologies had very little impact on CSLA .NET 3.5. My philosophy is to use new technologies only if they provide value to me and my work. In the case of CSLA .NET this is extended slightly, such that I try to make sure CSLA .NET also supports new technologies that might be of value to people who use CSLA .NET. While .NET 3.5 has a number of new technologies at various levels (UI, data, languages), many of them required no changes to CSLA to support. I like to think this is because I'm always trying to look into the future as I work on CSLA, anticipating at least some of what is coming so I can make the transition smoother. For example, this is why CSLA .NET 2.0 introduced a provider model for the data portal - because I knew WCF was coming in a couple years and I wanted to be ready. Since CSLA .NET already supported data binding to WPF, Windows Forms and Web Forms, there was no real work to do at the UI level for .NET 3.5. I actually removed Csla.Wpf.Validator because WPF now directly supplies that behavior, but I really didn't add anything for UI support because it is already there. Looking forward beyond 3.5, it is possible I'll need to add support for ASP.NET MVC because that technology eschews data binding in favor of other techniques to create the view - but it is too early to know for sure what I'll do in that regard. Since CSLA .NET has always abstracted the business object concept from the data access technique you choose, it automatically supported LINQ to SQL (and will automatically support ADO.NET EF too). No changes required to do that were required, though I did add Csla.Data.ContextManager to simplify the use of L2S data context objects (as a companion to the new Csla.Data.ConnectionManager for raw ADO.NET connections). And I enhanced Csla.Data.DataMapper to have some more powerful mapping options that may be useful in some L2S or EF scenarios. LINQ to Objects did require some work. Technically this too was optional, but I felt it was critical, and so there is now "LINQ to CSLA" functionality provided in 3.5 (thanks to my colleague Read More...
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