I have Datamodel where I have used a DataSet as my data container.
I have a UI that is created in Silverlight.
I know that in SL 2 we cannot use Dataset. Can we use Dataset in Silverlight 4?
As far as I know, Dataset's aren't directly supported in Silverlight 4. Entity model allows for much more easier form of managing changes and it comes in in-build CRUD operations. Entities works flawlessly with silverlight controls.
Fortunately, there are many workarounds available in the internet for Datasets thought. Here's one of them.
Silverlight does not manage local databases/connections, so DataSet does not exist in Silverlight (including Silverlight 4).
The objects RIA services provide do a good job of manage changes so it would make sense to convert your app to use RIA Services and change your data model to use the RIA objects.
What feature of the DataSet do you require? If you can post a specific example of your data and how it is used we might be able to post a more detailed solution.
Related
I am planning an application which will have a web based component and a desktop client component. Basically I am planning to create the web based component using ASP.NET MVC3 & Entity Framework as a normal data driven website, however I am also planning to create a desktop client that will extend the functionality of the website, this is new territory for me and I am somewhat confused. I know that the best way to create an application that needs to access a central database is using WCF, however I have not used WCF before but have heard that it easily integrated with Entity Framework.
So I know that what I want to do is certainly possible I am just looking for some guidance for how the seperate components of this application should glue together, etc should I be working with WCF and Entity Framework first? Or should I complete the web based componenet before working with WCF?
Thanks,
Alex.
There are lots of ways to do this and all these ways have different level of complexities. For example, you could just build your web-application using Entity Framework, in the same web-application you expose an OData service (WCF Data Service) which provides a RESTful service that your WPF app can use to access the database. This is fairly easy, since WCF Data Services work really nicely with Entity Framework. This is basically a two-minute job (if you are not doing anything fancy). Your WPF application then has basically the same type of access to the database as your web-application does. In it's default configuration the WCF Data Service simply exposes a EF ObjectContext and allows the same type of operations on it. I would recommond you try this out and see for yourself if it fits your requirements.
But, this approach is basically a shortcut to allow a desktop application access to your database. Which in most cases, is perfectly fine. If you do want to put some effort into it, you could model a service-layer which either uses a Entity Framework data source or a OData data source. From here on in, it's all about design patterns. Which comes at a cost; separation of layers is a hard thing to do, if you want to do it right. Given that the .NET world as somewhat changed to "get the job done", it's fine to put those bits together and get a running app in no time.
You should also consider that the MVVM in WPF and MVC in a web-application have fundamental differences; where a MVC app just pulls a "snapshot" out of a database, a WPF application might need more effort and asynchronous programming to feel natural.
I can provide you with some guidance for specific tasks, like how to decouple the WCF Data Service and Entity Framework, but from my experience, the overhead of "doing it right" is enormous. If you are comfortible without a service-layer you will have a lovely experience working with EF and OData.
It is better you start with the web component first integrated with wcf, you can use entity framework, but i would recommend using T-Sql itself if you have a data heavy DB and it gives you lot of options for performance.
I would recommend you build the application model using MVP pattern as it makes it easy to switch from a desktop to web application and also inline with your requirements of extending it.
We're starting to develop a new Silverlight LOB application where the DataAccess will not be based on EF, rather our own DAL code (for legacy and other not related reasons).
We are currently debating whether to use RIA Services or simple WCF Services as the Silverlight's facade layer.
The options:
RIA Services and generated code: RIA Services will automagically create proxy classes of our Domain Model and DomainServices in our Silverlight project.
This will mean that our services will need to inherit from the DomainService class, and will require much work and workarounds to allow our custom model to be serialized normally (since we dont use EF)
WCF And shared libraries: We'll create a DomainModel library that will be shared between both Silverlight and our server code (as offered here) giving us more control as to how our domain classes look, and how they are seen on Silverlight, and our services would remain clean as WCF doesnt require us to use any base class and give us much more power over how our services are exposed.
So the question is - given that we dont use EF, what are the pro's to RIA Services, and what are the con's of using WCF and shared domain?
I have reasonable real-life experience with both technologies.
The main pros and cons in my perspective:
RIA Services
Pro: Development is (much) faster, even without using entity framework. You can create ViewModels, maybe mapping them with AutoMapper, and specify the attributes needed for validation / data entry / relationships. This is good practice even when using entity framework.
Con: A lot of overhead.
Con: Performance degrades when sending larger amounts of data (something like > 100 objects)
WCF and Shared Libraries
Pro: Performance is relatively excellent
Con: Development time / maintainability is not as good as RIA Services.
Con: Cannot use databinding as well without DomainDataSource (even when using MVVM).
Update
For the data-binding part: RIA Services allows for the DomainDataSource control in Silverlight. This enables easy (async) loading with bindable properties for its state (Busy etc.) which makes it easy to do loading animations and general improvements on user experience. This can of course be done without this control, but it helps.
For the RIA services performance, I cannot seem to find the example (someone here said they lost a few months of development time rewriting domain services to conventional WCF services because of the response time that could not be met).
One more note about a Silverlight (Business Application): try zooming your browser in to 110% or 90%, some arbitrary percentage. The fonts / components will get blurred because of way the rendering works. I have confirmed this on multiple machines/configurations and have not found a fix / work around for this. Snapping to device pixels does not help here at all.
Also before you make a decision, it's probably smart to also consider MVC3, with JQuery and HTML5 as an option for your solution. The HTML layout system might not be as good as Silverlight, but there are advantages like cross platform and mobile support.
How can I take advantage of EF Codefirst on a WCF app that being consumed in a WPF application. What I want is something closer to DbDomainService doing in the latest Silverlight RIA Services, but can I use that in a typical WPF app so that this DbDomainService take care of the EF changes back to the DB?
I am also seeing some hints on using WCF DataServices exposing DbContext.
http://blogs.msdn.com/b/adonet/archive/2011/03/21/using-wcf-data-services-with-entity-framework-4-1-and-code-first.aspx
But I couldnt locate any proper working sample or references.
You could create a third common assembly containing the body classes, then send them over the wire filled with data to be serialized.
Here is a good article regarding your topic.
I'm building a silverlight line of business application in silverlight 4 using RIA services currently and i'm finding RIA services to be more and more of a pain everyday..
A lot of the database interaction in this application doesn't follow the usual CRUD pattern and some of the data just doesn't "fit" with the RIA services style of doing things..
Even more importantly it doesn't fit the way my brain thinks about web services!
(I think that abstraction often gets in the way of the business problem you're trying to solve)
It's got to a point where a scary chunk of the code base is workarounds for the object context and spoofing ID's to create some kind of unique key etc..
I'd also like to swap out entity framework for rob conery's massive (he thinks the same way as me about abstraction, dynamic typing etc..)
Are there any alternatives which work using dynamic typing and JSON?
If not I may have to roll my own!
Have you looked at WCF Data Services?
http://msdn.microsoft.com/en-us/data/bb931106.aspx
You might also find that WCF Web APIs suits you better.
http://codebetter.com/glennblock/2010/11/01/wcf-web-apis-http-your-way/#0_undefined,0_
I'm confused about the architectures which we can use to develop a business application with WPF 4.0 and EF 4.0 technologies.
My first choice was a traditional N-tier architecture contains: UI, Business Logic Layer & Data Access Layer with a disconnected behavior.
In this way I create 3 project for each layer and another project for my Entities/DTOs (Each layer is an assembly). Each layer references only to it's upper and lower layers (That is: UI can see the BLL but can't see the DAL). But all layers have access to the Entity/DTOs assembly for communication purposes.
The problem starts when I want to create a simple CRUD form with a DataGrid for example. The BLL disposes the DataContext of the DAL when returns an Entity/DTO, this is the reason that forced me to use STEs. But yet there are several problems. For example I should call "StartTracking" method for each entity returned from BLL to the UI. In short, I don't sure about this pattern reliability or I think I have to forget about automatic handled CRUD forms.
I use the repository model in my DAL layer but when I search about the repository pattern I find it different. It seems that it's not bad to reference to both of the DAL/Repository and the BLL/Services(Not WCF nor WebServices) layers from the UI and thus we can have a connected environment (Without using STEs).
I see an example in which we can get a person from repository but do something on it using BLL or services:
UI CODE:
var person = new PersonRepository().GetPerson(10);
Bll.Salary.PaySalary(person);
-or-
var person = new PersonRepository().GetPerson(10);
Bll.Person.MarkAsAbsent(person);
Or something like that...
With this pattern we can send the Entities/DTOs to the UI in a connected way while the DataContext is alive.
I don't know if I understand the way of using the repository pattern in big projects. I think it's not clear to naming the BLL or services classes and methods in this way. More over the developers might be confused about where to use the repository methods or BLL/service methods or about where to create the methods (in repositories or BLL/service).
I prefer the N-Tier architecture using a good approach to track the Entities/DTOs changes automatically like STEs.
Would you please recommend the best pattern in such situations or/and reference me to some good books or documents about that.
I put together a sample app that may help with some of your questions. You can review the presentation notes and the sample via my blog post here:
http://blog.alner.net/archive/0001/01/01/wpf_ef_4_sig_presentation_2010.aspx
The sample shows using STEs and includes some helpers to make the Entity Framework STEs work better in a desktop client app.
Repositories are there to hide the details of how you get the data. The idea is that you could swap the implementation of a repository from one that uses a local database, to one that uses a remote web service without the upper layers knowing about it.
Maybe the article Architecture for WPF applications is any help for you.
You might have a look at the BookLibrary sample application of the WPF Application Framework (WAF) as well. It shows a WPF MVVM application together with the Entity Framework applying the described architecture.