Rockford Lhotka

 Wednesday, November 12, 2008

Expert C# 2008 Business Objects book coverYou can now purchase the "alpha" of Expert C# 2008 Business Objects online as an ebook directly from the Apress web site. This gets you early access to the content, and access to the final ebook content when it is complete.

While their website indicates you can provide feedback during the writing process, the reality with this book is that I'm only three chapters from being completely done with the final review, so it is terribly close to being final already :)

Wednesday, November 12, 2008 8:12:05 AM (Central Standard Time, UTC-06:00)  #    Disclaimer
 Wednesday, November 5, 2008

Magenic is sponsoring a webcast about CSLA .NET for Silverlight on November 13. The presenter is my colleague, Sergey Barskiy. Sergey is one of the lead developers on the CSLA .NET 3.6 project, and this should be a very educational webcast.

Wednesday, November 5, 2008 1:31:21 PM (Central Standard Time, UTC-06:00)  #    Disclaimer
 Saturday, November 1, 2008

image I'm giving four talks at VS Live in Dallas, plus participating in a community panel Tuesday evening. You can see my list of talks here, which includes a talk specifically focused on CSLA .NET (due to popular demand from attendees at previous VS Live shows).

I have a special promo code you can use when registering to get $300 off registration. Just use code SPLHO when registering online.

Saturday, November 1, 2008 10:54:48 AM (Central Standard Time, UTC-06:00)  #    Disclaimer
 Friday, October 31, 2008

PDC 2008 was a lot of fun - a big show, with lots of announcements, lots of sessions and some thought-provoking content. I thought I'd through out a few observations. Not really conclusions, as those take time and reflection, so just some observations.

Windows Azure, the operating system for the cloud, is intriguing. For a first run at this, the technology seems surprisingly complete and contains a pretty reasonable set of features. I can easily see how web sites, XML services and both data-centric and compute-centric processing could be built for this platform. For that matter, it looks like it would be perhaps a week's work to get my web site ported over to run completely in Azure.

The real question is whether that would even make sense, and that comes down to the value proposition. One big component of value is price. Like anyone else, I pay a certain amount to run my web site. Electricity, bandwidth, support time, hardware costs, software costs, etc. I've never really sorted out an exact cost, but it isn't real high on a per-month basis. And I could host on any number of .NET-friendly hosting services that have been around for years, and some of them are pretty inexpensive. So the question becomes whether Azure will be priced in such a way that it is attractive to me. If so, I'm excited about Azure!! If not, then I really don't care about Azure.

I suspect most attendees went through a similar thought process. If Microsoft prices Azure for "the enterprise" then 90% of the developers in the world simply don't care about Azure. But if Microsoft prices Azure for small to mid-size businesses, and for the very small players (like me) then 90% of the developers in the world should (I think) really be looking at this technology

Windows 7 looks good to me. After the Tuesday keynote I was ready to install it now. As time goes by the urgency has faded a bit - Vista has stabilized nicely over the past 6-8 months and I really like it now. Windows 7 has some nice-sounding new features though. Probably the single biggest one is reduced system resource requirements. If Microsoft can deliver on that part of the promise I'll be totally thrilled. Though I really do want multi-monitor RDP and the ability to manage, mount (and even boot from) vhd files directly from the host OS.

In talking to friends of mine that work at Microsoft, my level of confidence in W7 is quite high. A couple of them have been running it for some time now, and while it is clearly pre-beta, they have found it to be a very satisfying experience. When I get back from all my travels I do think I'll have to buy a spare HD for my laptop and give it a try myself.

The Oslo modeling tools are also interesting, though they are more future-looking. Realistically this idea of model-driven development will require a major shift in how our industry thinks about and approaches custom software development. Such a massive shift will take many years to occur, regardless of whether the technology is there to enable it. It is admirable that Microsoft is taking such a gamble - building a set of tools and technologies for something that might become acceptable to developers in the murky future. Their gamble will pay off if we collectively decide that the world of 3GL development really is at an end and that we need to move to higher levels of abstraction. Of course we could decide to stick with what has (and hasn't) worked for 30+ years, in which case modeling tools will go the way of CASE.

But even if some of the really forward-looking modeling ideas never become palatable, many of the things Microsoft is doing to support modeling are immediately useful. Enhancements to Windows Workflow are a prime example, as is the M language. I've hard a hard time getting excited about WF, because it has felt like a graphical way to do FORTRAN. But some of the enhancements to WF directly address my primary concerns, and I can see myself getting much more interested in WF in the relatively near future. And the ability of the M language to define other languages (create DSLs), where I can create my own output generator to create whatever I need - now that is really, really cool!

Once I get done with my book and all my fall travel, you can bet I'll be exploring the use of M to create a specialized language to simplify the creation of CSLA .NET business classes :)

There were numerous talks about .NET 4.0 and the future of C# and VB.

Probably the single biggest thing on the language front is that Microsoft has finally decided to sync VB and C# so they have feature parity. Enough of this back-and-forth with different features, the languages will now just move forward together. A few years ago I would have argued against this, because competition breeds innovation. But today I don't think it matters, because the innovation is coming from F#, Ruby, Python and various other languages and initiatives. Both VB and C# have such massive pre-existing code-bases (all the code we've written) that they can't move rapidly or explore radical ideas - while some of these other languages are more free to do just that.

The framework itself has all sorts of changes and improvements. I spent less time looking at this than at Azure and Oslo though, so I honestly just don't have a lot to say on it right now. I look at .NET 4.0 and Visual Studio 2010 as being more tactical - things I'll spend a lot of time on over the next few months anyway - so I didn't see so much need to spend my time on it during PDC.

Finally, there were announcements around Silverlight and WPF. If anyone doubts that XAML is the future of the UI on Windows and (to some degree) the web, now is the time to wake up and smell the coffee. I'm obviously convinced Silverlight is going to rapidly become the default technology for building business apps, with WPF and Ajax as fallback positions, and everything at the PDC simply reinforced this viewpoint.

The new Silverlight and WPF toolkits provide better parity between the two XAML dialects, and show how aggressively Microsoft is working to achieve true parity.

But more important is the Silverlight intersection with Azure and Live Mesh. The fact that I can build smart client apps that totally host in Azure or the Mesh is compelling, and puts Silverlight a notch above WPF in terms of being the desired start-point for app development. Yes, I really like WPF, but even if it can host in Azure it probably won't host in Mesh, and in neither case will it be as clean or seamless.

So while I fully appreciate that WPF is good for that small percentage of business apps that need access to DirectX or rich client-side resources, I still think most business apps will work just fine with access to the monitor/keyboard/mouse/memory/CPU provided by Silverlight.

A couple people asked why I think Silverlight is better than Ajax. To me this is drop-dead simple. I can write a class in C# or VB that runs on the client in Silverlight. I can write real smart client applications that run in the browser. And I can run that exact same code on the server too. So I can give the user a very interactive experience, and then re-run that same code on the server because I don't trust the client.

To do that in Ajax you'd either have to write your code twice (in C# and in Javascript), or you'd have to do tons of server calls to simulate the interactivity provided by Silverlight - and that obviously won't scale nearly the same as the more correct Silverlight solution.

To me it is a no-brainer - Ajax loses when it comes to building interactive business apps like order entry screens, customer maintenance screens, etc.

That's not to say Ajax has no home. The web and browser world is really good at displaying data, and Ajax makes data display more interesting that simple HTML. I strongly suspect that most "Silverlight" apps will make heavy use of HTML/Ajax for data display, but I just can't see why anyone would willingly choose to create data entry forms or other interactive parts of their app outside of Silverlight.

And that wraps up my on-the-flight-home summary of thoughts about PDC.

Next week I'm speaking at the Patterns and Practices Summit in Redmond, and then I'll be at Tech Ed EMEA in Barcelona. I'm doing a number of sessions at both events, but what's cool is that at each event I'm doing a talk specifically about CSLA .NET for Silverlight. And in December I'll be at VS Live in Dallas, where I'll also give a talk directly on using CSLA .NET.

Friday, October 31, 2008 7:10:16 PM (Central Standard Time, UTC-06:00)  #    Disclaimer
 Thursday, October 23, 2008

This blog post indicates no, based on a number of good arguments.

It is really true that Silverlight 2.0, out of the box, has a lot of holes or gaps that must be filled in or worked around.

Of course my shameless plug is for CSLA .NET for Silverlight, which fills in most of those gaps. We did encounter the issues listed, and many others. Ultimately CSLA .NET for Silverlight is the result of around 9-10 man-months of effort. That's 9-10 man-months of time finding, researching and solving issues around business application development in Silverlight 2.0.

So while I agree that just picking up Silverlight and running with it will require some serious effort (as compared to WPF, Windows Forms or Web Forms), I don't think that's the whole story. The reality is that frameworks and tools will come into existence (or already have in the case of CSLA .NET) that bring Silverlight's productivity at least up to the level of WPF.

Then the argument becomes that WPF (and Silverlight) lack solid tooling for building the UI. When compared to the designers available for Windows Forms and Web Forms that's absolutely true. However, if you look under the covers, the amount of code and effort required to actually build an app with WPF/Silverlight is absolutely less than Windows Forms or Web Forms - at least when using CSLA .NET.

I say this, because the exact same business objects and data access work in all those environments. So the business and data code is a wash - it is the same in all cases.

But the UI code for WPF/Silverlight is a tiny fraction of the code required for Windows Forms or Web Forms. XAML does require a learning curve, but once you get over that curve it is far more productive, even without good designer tooling.

Yes, I'm totally sold on the Silverlight/WPF/XAML UI future. Yes, there's a learning curve, and yes there's some initial pain. But once you get past that initial hurdle it is sooooo nice. You won't find me going back!

Thursday, October 23, 2008 10:50:46 PM (Central Standard Time, UTC-06:00)  #    Disclaimer
Thursday, October 23, 2008 7:10:47 PM (Central Standard Time, UTC-06:00)  #    Disclaimer
 Wednesday, October 22, 2008

Dunn Training is offering a CSLA .NET Master Class in November, located in Atlanta.

This is a full 5 day class covering CSLA .NET, and related technologies such as WPF, WCF, Web Forms and much more! Not only will this provide intensive coverage of CSLA .NET 3.6 (the latest version), but you'll learn an amazing amount about the application of important .NET technologies in the context of real-world business application development.

There is still time to register for this class, and you'll have a hard time finding training of this depth and breadth elsewhere!

Wednesday, October 22, 2008 11:44:16 AM (Central Standard Time, UTC-06:00)  #    Disclaimer
 Tuesday, October 21, 2008

I have released Beta 2 of CSLA .NET 3.6, with support for Windows (download) and Silverlight 2.0 (download).

This is an incremental release. Very few issues have been reported or found with Beta 1a, which gives me hope that we're still on track for a final release in the very near future. A lot of hard work by Sergey, Justin, Nermin and other Magenic colleagues have really paid off in the early stability of this version.

CSLA .NET for Silverlight does include one feature change. The Navigator control is now capable of handling a "cold start" scenario, where the user navigates directly to the Silverlight app, specifying a bookmark on the URL. The Navigator control will now immediately help your app navigate to the correct state so the user effectively returns to the page/control/view they'd bookmarked in the first place.

CSLA .NET for Windows also includes one feature change. Nermin is working hard on integrated Visual Studio file and project templates, and an installer project for the templates (and possibly all of CSLA .NET). This work is not yet complete, but Beta 2 has a much more complete set of behaviors than Beta 1.

We believe that this Beta 2 release is very stable. Please download and use it - on either Windows or Silverlight. If you have questions/comments or find issues, please post in the forum.

Also, check out my DotNet Rocks interview about CSLA .NET for Silverlight.

Finally, for those wondering about the status of the Expert C# 2008 Business Objects book, it is still on track for a December release. Watch www.apress.com, as they tell me that they'll be offering an "alpha release" program where you can pre-purchase the book and get early access to chapters in PDF form, and get the paper book when it comes out.

We are also on track for Expert VB 2008 Business Objects, probably in the February or March timeframe. This is dependent on the 3.6 VB conversion project, which has four volunteers and is moving along pretty well. I feel pretty confident that this will all come together so the framework and book will both be available to the VB community.

Code well, have fun!

Tuesday, October 21, 2008 7:29:29 PM (Central Standard Time, UTC-06:00)  #    Disclaimer
 Thursday, October 2, 2008

My schedule over the next few weeks in pretty busy.

Week of Where Why
Oct 6 San Francisco IASA Connections
Oct 11 Minneapolis (home) Twin Cities Codecamp
Oct 13 Las Vegas VS Live
Oct 27 Los Angeles PDC
Nov 3 Seattle/Redmond PnP Summit
Nov 10 Barcelona Tech Ed EMEA

While doing all this travel, I have to do second revisions on Chapters 9-21 as quickly as possible, still working toward a December release of the Expert C# 2008 Business Objects book. And of course finalizing CSLA .NET 3.6 for Windows and Silverlight.

Not that I'm complaining, I love speaking at (or attending) these conferences and getting a chance to talk to people about cool technology and interesting ideas and concepts!

I hope to see you at one of these events.

Thursday, October 2, 2008 10:36:41 PM (Central Standard Time, UTC-06:00)  #    Disclaimer

The next release of CSLA .NET for Silverlight will return to using the async WcfProxy in the data portal instead of the SynchronizedWcfProxy that restricts the data portal to allow only one concurrent call at a time. The WcfProxy allows parallel calls from the client to the server through the data portal. The change is already in svn for those that are using live code.

The reason we created SynchronizedWcfProxy originally was due to a bug in Silverlight 2.0 Beta 2, where in some cases you'd get a 404 error with overlapping WCF calls to the same server. This was wreaking havoc with our unit tests, which have a lot of parallel WCF calls.

It appears that the issue is resolved in Silverlight RC0, which is great news.

However, we didn't know right away, because we were still getting sporadic 404 errors. With some research, and help from Eugene Osovetsky and his colleagues at Microsoft, we figured out the remaining issue.

Part of the problem is described by Eugene's post on dealing with faults and exceptions in Silverlight. This was masking the underlying issue we faced.

The underlying issue is that we were testing using the ASP.NET Development Web server (often called Cassini). Cassini has some well-known limitations, among them that it doesn't work well when a custom .NET principal is used in your web server code. This particular issue appears as a SerializationException as Cassini attempts to transfer the principal from one thread to another. This issue doesn't occur with IIS, because IIS doesn't switch threads like Cassini does.

Several of our unit tests for CSLA use custom principals, because we have tests for the various authentication modes supported by CSLA .NET for Silverlight - including the use of a custom principal object. These tests would sporadically fail on Cassini, but only under load. Apparently the problem would only manifest if we were able to get Cassini to recycle an existing thread off the thread pool.

In Eugene's post he suggests that the solution to dealing with faults/exceptions is to wrap your code in a try..catch block and return any exception information as part of your service contract. The CSLA data portal has always done this, and so we were initially puzzled by the continuing 404 errors. However, it turns out that Cassini was failing before any of our code ran. Thanks to this, we couldn't wrap a try..catch around the code, because it wasn't our code...

This gave us another clue though. It turns out that the issue we faced was that a request would put a custom principal on the server thread. That principal was never removed from the thread, and if that thread got recycled (by random chance) we'd get the SerializationException. The solution is to ensure that the thread principal is set to null as each server request completes. That way a recycled thread never has a custom principal.

Again, not an issue that affects IIS, but by figuring this out we're now able to use Cassini too, which is far more convenient.

I post all this, because if you encounter 404 errors in Silverlight 2, you should first follow Eugene's advice and return error details as part of your service contract (which can really alter your service design!). And if you do that and still have trouble, look to deeper issues with the web host or network stack, they can be devious...

Thursday, October 2, 2008 6:16:01 PM (Central Standard Time, UTC-06:00)  #    Disclaimer
 Monday, September 29, 2008

Dunn Training is offering a CSLA .NET Master Class in November, located in Atlanta.

This is a full 5 day class covering CSLA .NET, and related technologies such as WPF, WCF, Web Forms and much more! Not only will this provide intensive coverage of CSLA .NET, but you'll learn an amazing amount about the application of important .NET technologies in the context of real-world business application development.

Monday, September 29, 2008 7:38:54 PM (Central Standard Time, UTC-06:00)  #    Disclaimer
 Friday, September 26, 2008

CSLA .NET version 3.6 is a framework for creating business applications using object-oriented design concepts, in a distributed computing environment. CSLA .NET for Windows and CSLA .NET for Silverlight share many common features and capabilities, though they support different platforms. The commonality between the two framework implementations allows sharing of business object code between .NET and Silverlight, while the differences allow you to exploit the power of the two different platforms.

CSLA .NET version 3.6 is the latest evolution in the CSLA .NET framework, which has been around since 2001. Over the past eight years the framework has grown and changed in many ways, and is now one of the most widely used open source development frameworks for the .NET platform.It is covered under a very liberal license and has a vibrant, helpful and friendly community.

The primary goal of CSLA .NET is to enable you to build a rich, powerful and flexible business layer for your application.

image

This business layer is composed of business domain objects that encapsulate your business logic (calculations, algorithmic processing, validation and authorization). These objects should be designed based on the business use cases for your application domain. With some reasonable care, it is possible to create a single set of business objects that work within both the .NET and Silverlight environments.

In some cases your Silverlight business objects may contain the exact same object code used for CSLA .NET for Windows applications, though in most cases there will be some small variation of code. In most cases more than 90% of your object code will be shared between .NET and Silverlight, with less than 10% of the code being different. The differences are primarily due to the asynchronous nature of Silverlight programming, and the more synchronous nature of traditional .NET programming. If you are willing to apply the same asynchronous designs to your .NET implementation you can achieve 99% or 100% code sharing between the two platforms.

CSLA .NET Core Features

Regardless of platform, CSLA .NET is designed to do two things. First and foremost, it is designed to support you as you create a powerful business layer based on rich business domain objects. Second, it is designed to enable a distributed application architecture centered on a concept called mobile objects.

To support the creation of rich domain objects, CSLA .NET includes subsystems that supply commonly required functionality, including:

  • Full support for data binding (WPF, Silverlight, Windows Forms and Web Forms)
  • Object status tracking (is object new, changed, marked for deletion, etc.)
  • Standardized business and validation rule processing
  • Standardized authorization at the object and property levels
  • Integration with, and simplification of, standard .NET authentication models
  • Undo capabilities to support implementation of Cancel buttons and complex layered UIs
  • Standardized interaction with a data access layer or ORM
  • Enhanced support for LINQ queries against your business objects
  • Numerous general productivity features, useful in many business application scenarios
  • Asynchronous data access and asynchronous validation rules

My Expert 2008 Business Objects book (published by Apress) covers these subsystems in detail.

These subsystems are exposed through a set of base classes from which you inherit to create your business objects. These base classes enable a set of object stereotypes:

  • Editable root (single or collection) - an object that has read-write properties, and which can be directly retrieved and stored in a database
  • Editable child (single or collection) - an object that has read-write properties, and which is retrieved and stored in a database as part of some editable root
  • Dynamic list - a collection that contains editable root objects, integrating with data grid controls to auto-update each object when the user leaves a row in the grid (not applicable to ASP.NET interfaces)
  • Read-only root (single or collection) - an object that has read-only properties, and which can be directly retrieved from a database
  • Read-only child (single or collection) - an object that has read-only properties, and which is retrieved from a database as part of some read-only root
  • Name/value list - a read-only root collection that contains only name/value pairs for use in populating combobox or listbox controls
  • Command - an object that executes code on the client and/or the server; often used to execute database code or server-side workflows

The end result of building your business objects using CSLA .NET is that your objects are created in a consistent, standardized manner. So not only do your objects automatically gain substantial benefit from all of these subsystems, but your overall maintainability is radically improved thanks to the consistent architecture, design and coding of your application.

The concept of mobile objects is a technique that supports the use of rich business domain objects in distributed application environments. Specifically, the idea is that your business objects are mobile, able to move physically from one computer to another to take advantage of the resources available on each computer.

CSLA .NET includes a component called the data portal which is responsible for providing the mobile object functionality. Using the data portal, your business objects may come into existence on an application server so they can efficiently interact with your data access layer (and database). The objects may then physically move across the network to the client workstation (web server, Windows client or Silverlight client) where they can efficiently interact with the user by being data bound directly to the UI. Once the user is done interacting with the object, the object may then move back to the application server so it can interact with the data access layer to update the database.

Mobile objects are an incredibly powerful technique for exploiting the power of object-oriented design and programming in distributed environments. The CSLA .NET data portal abstracts the complexity of this concept. The result is that your application can switch between 1-tier, 2-tier, 3-tier and even 4-tier models with no change to code - the change is purely one of configuration.

CSLA .NET for Windows

CSLA .NET for Windows allows you to easily build WPF, ASP.NET (Web Forms, AJAX and MVC) and Windows Forms user interfaces on top of your business objects. It also supports WCF service, Windows Workflow and asmx web services interfaces. Technically you could create all of these interfaces on top of the same set of business objects, though most applications require only one or two types of interface (Web Forms and WCF services for example).

CSLA .NET includes some UI controls in each major UI technology. These controls help minimize UI code and maximize productivity.

In WPF the following controls are provided:

  • CslaDataProvider - a WPF data provider that enables the use of commanding to implement Save, Cancel, Add New and Remove Item functionality in the UI
  • PropertyStatus - like the Windows Forms ErrorProvider, but manages validation, authorization and busy notification for each control
  • ObjectStatus - enables data binding to the business object's status properties (IsValid, IsNew, etc.)
  • Authorizer - container-based implementation that enables/disables controls based on the business object's authorization rules

In Web Forms the following controls are provided:

  • CslaDataSource - a Web Forms data source control that supports data binding to business objects
  • DataMapper - a component that simplifies the copying of form post values into your business objects

In Windows Forms the following controls are provided:

  • BindingSourceRefresh - work around for a data binding refresh issue in Windows Forms
  • CslaActionExtender - automate object management behind buttons such as Save and Cancel
  • ReadWriteAuthorization - automatically enable/disable detail controls based on the object's authorization rules

CSLA .NET also includes functionality to assist in the creation of services and workflow activities.

For WCF and asmx services the following component is provided:

  • DataMapper - a component that simplifies the copying of data between your business objects and data contract objects

For WCF services, there is another component:

  • PrincipalCache - a component that temporarily caches .NET principal objects for use when implementing custom authentication/authorization in a WCF service

For Windows Workflow the following component is provided:

  • WorkflowManager - simplifies launching, suspending and resuming a workflow instance

CSLA .NET for Windows provides a great deal of flexibility in terms of data access. CSLA .NET is not a data access layer or an object-relational mapping (ORM) tool. However, CSLA .NET does provide a level of formalization around how your application interacts with your data access layer or ORM. This formalized flexibility allows you to use a wide range of data access technologies, including raw ADO.NET, DataSets, LINQ to SQL, ADO.NET Entity Framework, NHibernate, Paul Wilson's ORM mapper and many other technologies.

CSLA .NET for Silverlight

CSLA .NET for Silverlight allows you to easily build Silverlight 2.0 user interfaces on top of your business objects. By fully supporting Silverlight data binding, along with extra controls provided by CSLA .NET, you can create Silverlight forms with nearly no UI code. Just like with CSLA .NET for Windows, most of your code is encapsulated in your business objects, maintaining clean separation between the presentation and business behaviors.

Because Silverlight doesn't provide all the rich data binding features found in WPF or Windows Forms, CSLA .NET for Silverlight provides a set of Silverlight UI controls and features to provide a high level of parity with the functionality in WPF. Not only are you able to build a Silverlight interface on your business objects, but CSLA simplifies the creation of very rich, interactive business interfaces over those objects. For example, Silverlight doesn't include WPF commanding, and so CSLA .NET includes replacement functionality so you can hook up common UI functionality to your objects without resorting to code behind each form. The controls provided by CSLA .NET include:

  • CslaDataProvider - a Silverlight equivalent to the WPF data provider
  • InvokeMethod - a Silverlight equivalent to WPF commanding
  • PropertyStatus - a Silverlight equivalent to WPF validation or the Windows Forms ErrorProvider (though far superior to both)
  • ObjectStatus - a control that uses the visual state manager to automatically change the UI based on the state of your business object
  • BusyAnimation - a control that displays a busy animation; can be bound to your object to automatically show that your object is performing an asynchronous operation
  • Data grid columns - custom data grid column types that incorporate the PropertyStatus control to show validation, authorization and busy status for each cell

CSLA .NET for Silverlight enables a data access model where your business objects invoke remote services to retrieve or update data. You can use this model to implement client/server or service-oriented application designs. For example, you might use ADO.NET Data Services to expose data services from a server, and use CSLA .NET for Silverlight to create business objects and a Silverlight UI to interact with those data services.

If you have a CSLA .NET for Windows server, you can take advantage of some advanced CSLA .NET capabilities. Specifically, your CSLA .NET for Silverlight application can interact with the CSLA .NET for Windows server, enabling 2-, 3- and 4-tier physical deployments of your application. In this model, your .NET business objects (perhaps already supporting a Web Forms UI) are effectively extended directly into the Silverlight client. The standard object persistence models supported by CSLA .NET are now automatically used to support the Silverlight client, providing an incredibly high level of code and functionality reuse across the .NET and Silverlight platforms.

CSLA .NET Deployment Models and Mobile Objects

The CSLA .NET data portal enables the use of mobile object concepts in your application. This is largely transparent to your code, and the code you do write to interact with the data portal is very standardized. The benefit of using the data portal is flexibility; you can switch your application from a physical 1-tier deployment to a 3-tier or even 4-tier deployment purely by changing configuration - no coding changes are required.

CSLA .NET for Windows supports 1-, 2- and 3-tier physical deployments.

image image image

Again, it is possible to switch between these physical models purely by changing configuration. Your UI code, business object code and data access code remains entirely intact across all three deployment models.

In the 3-tier model, the business logic layer (the assembly(ies) containing your business object code) is deployed to both the client and application server. Your business objects literally move between those two machines through the data portal.

The data portal uses standard .NET technologies such as WCF to manage the network communication. It is implemented using powerful design patterns such as channel adapter, provider and message router.

CSLA .NET for Silverlight supports 1-, 2-, 3- and 4-tier physical deployments. The 1-, 2- and 3-tier models employ the same architecture as CSLA .NET for Windows. The 4-tier model is a little different.

 image

In the case of CSLA .NET for Silverlight's 3- and 4-tier models, the data portal is more advanced because your business objects literally move between the Silverlight client and the .NET server(s). This means your objects are moving between different platforms, as well as different machines. This is usually entirely transparent to your code, so the resulting functionality and your code is the same as in a pure .NET application.

It is important to realize that in the 3- and 4-tier deployment models, for both .NET and Silverlight, your business code and business objects are fully functional on each machine. This means you have the flexibility to run logic on the client, the server or both as required to meet your applications needs.

Standardized Data Access

CSLA .NET is not a data access technology or an object-relational mapping (ORM) tool. However, the data portal (which implements the mobile object concept) does impose a level of standardization and structure around how your objects interact with your data access layer or ORM. This standardization remains very flexible, and you are free to use nearly any data access technology you choose, including (but not limited to):

  • Raw ADO.NET (connections, data readers, etc.)
  • DataSet and TableAdapter objects
  • LINQ to SQL
  • LINQ to XML
  • ADO.NET Entity Framework
  • NHibernate and other third-party ORM tools
  • Simple file I/O
  • Remote XML or JSON services

The data portal supports two models: data portal managed, and object factory.

In the data portal managed model, the data portal manages the creation and state of your business objects, and invokes methods on your object to perform persistence. So in this model, your business objects are responsible for interacting with your data access layer or ORM, and the data portal helps ensure your object state (new, dirty, etc.) is properly managed.

In the object factory model, the data portal creates a factory object that is responsible for the creation and state of your business objects. You must supply this factory object. The data portal invokes methods on your factory object to perform persistence. In this model your factory objects are responsible for interacting with (or implementing) your data access layer or ORM, and for managing your business object's state (new, dirty, etc).

The data portal managed model is ideal when using a data access layer built using raw ADO.NET, simple file I/O or other relatively direct techniques. It is the simpler of the models, because the data portal provides a lot of automatic management of your business objects.

The object factory model is ideal when using an ORM or a more sophisticated data access layer. It is more complex, and requires more coding on your part, but is far more flexible. It is also implementing using an open architecture, which enables some test driven development (TDD) scenarios that are (arguably) more difficult to achieve using the data portal managed model.

Summary

CSLA .NET is a powerful, time-tested framework that supports the creation of an object-oriented business layer for distributed application development. It helps you encapsulate your business logic in a set of rich business domain objects, and provides your objects with powerful features around data binding, business logic, validation and authorization.

Starting with version 3.6, CSLA .NET supports all common interface types on the .NET platform, and provides seamless support for the new Silverlight 2.0 platform as well.

Friday, September 26, 2008 10:47:15 PM (Central Standard Time, UTC-06:00)  #    Disclaimer