I'm starting to jump in to WP7 development and I have a few questions. My current background/experience is with ASP.NET. I'm new to Silverlight as a whole, so I have some questions regarding the architectural design of the application. I don't have experience with MVC, and it appears that Silverlight is based off of it. Is that true? To my original question:
Once the new developer tools come out, the app will have a SQL CE back end that, as a future release, will sync with SQL Azure. I'd also like to provide a web based application that performs the same functions, and interacts with the Azure database. I'm wondering how I should structure the app to minimize any code duplication.
I was thinking of using a generic n-tier architecture. UI > Business Layer > DAL (LinqToSql) > Sql. These classes could get re-used on the web too.
Silverlight is not really based on MVC. In fact, you can implement any architectural pattern as long as you fully understand its functionality. Most people prefer MVVM, which is similar to MVC, the only main difference is that the controller is replaced by the ViewModel that plays the role of an intermediary data link between the model and the view.
With the release of Mango, you will indeed have access to SQLCE. In your case, since you are planning on using specific interoperability layers, I would recommend building both applications in Silverlight with an intermediary web service that will communicate with the data storage (in your case it will be Azure). You win in two points:
You are using Silverlight, which means that you can use a similar codebase (with platform adjustments, of course) to deliver the same functionality.
The web service is app-independent. Therefore if you ever decide to build, let's say, an iOS application, you will be able to use the same communication layer without major changes.
Related
I am currently developing an ERP solution for a company. The requirements are as below :
They need one winforms based application which will take care of modules like HR, BSC, Inventory etc.
A web based solution that needs all employees to get access to their personal data, apply for leave etc. This needs to be an internet based solution which can be accessed from anywhere.
In future they also want a document management system which will be web based.
Right now we are already through with some modules in winforms application as that was the urgent requirement. For winforms we have taken a horizontal approach for layered architecture. i.e. each module is one project with its own datalayer and businesslayer within project. Now I need to start working on the web solution. I am just wondering which approach will be best approach to share the datalayer and model layer between the winforms app and web app. Also the web app needs to have proper security in place as it will be sensitive data. I have thought about 2 approaches which may not cover all possibilities available.
The approaches I can think of are as below :
a. make a web service which will take care of datalayer and models. host it on the server and access it through winforms app and web app. For this I will need to change the coding that I have already done. But it is acceptable as it will require minimum efforts as its a layer architecture. here the only doubt I have is, for winforms app it will unnecessarily go through the web service layer and make it slower.
b. Convert the datalayer and models into dlls. Access these dlls in winforms and web app.
Also regarding the web app which will be the better approach :
a. Should I go for MVC3 based web app.
b. OR asp.net and WCF?
The situation is that I am working on this project along with a colleague and we are the team of just 2. So we are the ones taking decisions about everything.
I have fairly good experience in winforms but comparatively less experience in web based technologies. I will really appreciate your opinions on this.
If you want your model types to correspond closely to your database schema, you could create them using the Entity Framework designer and the Self-Tracking Entities template. This will allow them to be easily serialized with changes via WCF and persisted to and from the database. You then have the option of either creating a custom WCF service to deal with the entities or could exposing your Entity Framework context directly as a service using WCF Data Services (OData).
As far as the presentation layer goes, the two choices you listed are not mutually exclusive. You can have MVC with WCF, MVC without WCF, WebForms with WCF, WebForms without WCF... Since you are going to need to create the service anyway, and MVC seems like the way to go these days, I would probably recommend an MVC application that uses your WCF service to access the data.
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 are starting out with the development of a Silverlight app that will make use of Windows Workflow Foundation (WF4). Our workflows are long-running. We plan to use the tracking and persistence functionality of WF. We will probably need to also store data related to each workflow instance in another DB (I suspect running reporting against the workflow persistence store would be tricky). Our workflows may change with time so we would probably also need some strategy to implement versioning on them.
So specifically, are there any resources you can point me to or direction you can give me on where to start, taking into account that we need to implement tracking, persistence and versioning of workflows?
Based on your question, I'm assuming that you already have experience with WWF and are really just asking about how it interacts with Silverlight. The short answer is that it would not be noticeably different from how you would implement a WWF-enabled application in traditional ASP.NET. Remember that Silverlight is only a UI client that usually lives on top of a traditional ASP.NET web application. Your WWF-related logic and code would live in the ASP.NET layer -- not in Silverlight at all.
So if you already know how to make a WWF-enabled application in ASP.NET, all you really need to learn is how to wire up a shiny Silverlight interface to an ASP.NET web app. For that, you of course only need to hit up http://silverlight.net/, which you're probably already doing.
Good luck!
There seems to have a buzz around the Lightswitch application framework.
Reading some posts/forums/articles and listening to a video provdided some answers, but raised some others.
Extensibility?
Is there several hooks to override or extend features?
Modularity? Can MEF/Prism be integrated? Is there a concept of dynamic modules that can be loaded at runtime?
Localizable? Any special features about localization in different languages?
Versionnable? Any concept of version so simultaneous version can co-exist?
Abstraction? The connection to data source can be abstracted and replaced?
Testability? Are the different components unit testable in an automated way? Easy or difficult to achieve?
Cross-cutting / NFR ? Any hooks so we can plug NFR code? (logging, caching, audit, secuity )
Is this a solid framework to build some PAAS application over?
Let me give you my 2 cents based on an eval I just did:
Extensibility
You can of course add custom controls and apparently there will be a published extensability API.
Modularity
No. Lightswitch is not a code generator, it abstracts out implementation of the UI.
Localizable
Did not see anything, but I imagine this will occur in stages.
Versionnable?
You could TFS the Lightswitch project, but if you mean versioning from an execution standpoint ... it's as simple as deploying a new version of the app to the server. The client will check for updates on run and install as necessary from what I understand.
Abstraction
Yes, if you abstract it at the WCF RIA Services layer which is very easy to do.
Testability
Business rules can be implemented at the RIA Services layer so testing there should be a snap, but if you rely heavily on rules driven through the UI you will have to use another UI-based testing tool.
Cross-cutting / NFR
If you focus on getting the RIA Services tier of the app to be the central location for business rules and let the UI just focus on user experience you won't run into much overlap. I think Lightswitch is a good client for many solutions, but the core power of it is using it as a client for RIA Services which itself is not dependent on Lightswitch by any stretch.
I hope I at least provided some useful insight.
Extensibility? When the built-in LS controls don't allow you to do what you need, you can use just about any Silverlight control (including 3rd party controls), or create your own custom Silverlight controls. There is a little more work to do than using LS controls, because the LS controls have some extra "smarts" built into them, so you can just drop them on a screen, bind, & use them. There are also extensibility points built into the framework that allows you to create your own "extensions" (shells, controls, themes etc).
Modularity? LS already uses MEF under the covers, so it's quite possible that it may be able to be leveraged further in the future. LS does generate code, but for itself, not for external consumption. There is an excellent article, however, by Microsoft's Eric Erhardt
http://blogs.msdn.com/b/lightswitch/archive/2011/04/08/how-do-i-display-a-chart-built-on-aggregated-data-eric-erhardt.aspx
that shows how to reuse the data model that LS constructs (in Eric's case, he uses it to create a RIA service that aggregates data for presentation in a chart control).
Localizable? I don't believe there are currently any built-in localisation features.
Versionable? For a web-based app, if the data schema didn't change, I don't see why you couldn't publish separate versions, but desktop (OOB) apps are click-once apps & are therefore governed by that technology.
Abstraction? If you were to create a RIA service for your data source, you could abstract away the implementation details.
Testability? Unfortunately, V1 was not written with "testability" in mind. If you extract out your business logic into Silverlight class libraries (for use on the client, or full .NET class libraries for use on the server), you can unit test that logic, but the code that you write in an LS application itself is not really unit-testable at this point in time.
We are developing/mantaining an enterprise application which for historical reasons and development speedup it was targered for WinForms.
Now we are thinking that sooner or later (more sooner than later) that application will need to be Web based.
Thinking on the "to-Web" movement. Which are the most important things we have to consider? Something like, thing on MVP parading (or others), determine now the kind of platform/framework you are going to use, ...
Any experience on migration from winforms to web? Any suggestion to take care?
Aclaration: In our scenario the application would be nice NOW to be Web based but we are realistics. I agree that not all the applications have to be Web based (this is the main reason we developed with WinForms!). But sometimes the requirements changes and, in our scenario, we want to offer that application as SaaS.
The main thing is to completely separate the user interface from everything else. Once you've done that, you won't be rewriting the application in order to port it - you'll just be creating a web UI on top.
NESBAWA (Not Everything Should Be A Web App).
I worked for a company that went through a similar situation with their monolithic WinForms application. From that experience, there are two things to consider:
1] Decouple all data access logic (DAL) from the existing WinForms UI. You can start this process before any web development begins.
We did this refactoring in a series of 6 weekly sprints. Some parts of the app were easy to change - others were made of completely hellish spaghetti code that interwove DAL, inline SQL and UI code all in the code behind of the WinForm.
Once you have this separation in place, supporting two different UIs is easier.
2] Ignore ASP.Net MVC and target WebForms. WebForms was designed to make writing a web application close to the experience of writing traditional WinForms UI code (event driven, component based).
You need to understand the page lifecycle, and there are a few conceptual gotchas around dynamically generated controls that tend to trip up a lot of newcomers - but otherwise it's the most painless way to get a team of WinForms developers doing web stuff. MVC maybe very popular in web circles right now, and it provides a better separation of concerns (though you can achieve similar results with WebForms with a bit if diligence and strong design leadership) - but it requires a higher degree of knowledge. With MVC you're working closer to the metal of the HTTP request/response cycle. WebForms abstracts away a whole lot of that for you.
Best of luck in your endeavour!
John is right.
However, have you heard of the "Empty Client" approach? This is a fairly new approach to developing .NET WinForms applications that can also run as web applications on plain browsers. That approach would allow you to develop your WInForms application and put it on the web if and when you desire with no additional development or adjustments.
One framework that does it is Visual WebGui