I'm on an MVC3 project and I am using snap structuremap for my dependecy injection. Everything was in-place, except when I started using SignalR where I can't seem to implement my DI like I have on my controllers. I've been googling about implementing structuremap DI on SignalR for days now, but haven't found a strong sample on how to do this. Seems like everyone that are using SignalR are using Ninject.
My goal is to have conditional statements (which requires me to inject services) inside my Hub before calling my client methods, but I had no success on this.
I didn't want this thing to delay my development so I researched for alternative ways, then I found out that I can actually call my client methods from my controllers using the following codes:
IConnectionManager connectionManager = AspNetHost.DependencyResolver.Resolve<IConnectionManager>();
dynamic clients = connectionManager.GetClients<MyHub>();
clients.myClientScript();
This works for me, but I'm not sure if this is a good approach - especially that I am using dependency injection.
So my question is: Is it ok to keep calling this inside my controller? Do you have a better approach?
Thanks
There is no reason you cannot send information to connected clients from your controller using SignalR however the current client will not see this information (due to not being connected during a post).
That said, getting Structuremap into SignalR is actually pretty easy. You can see exactly how to accomplish this in my answer here: https://stackoverflow.com/a/9866374/701062.
Related
I am currently studying Spring.
While reading a Spring book, I met a part regarding Event.
By using context.publishEvent(..), I could trigger the event.
But I don't know what It's exactly for.
I can use other Method instead of using complicated publishEvent.
Please, tell me. thank you.
Spring Events are used to implement publish-subscribe model (or observer pattern) where two not-related parts of code must be somehow connected.
Think of the analogy of web applications where servlet container creates http sessions and your code is informed about this using javax.servlet.http.HttpSessionListener.
Spring uses this mechanism internally. It's much more visible in Spring Security where several parts of the code are informed about e.g., successfull authentication.
After plenty of reading, I still don't understand Unity for MVC 3.
Specific points
Why use it? I can create a controller that in its constructor, it takes a new EF context for testing.
How? I keep seeing bits are parts, but is there an end to end walk through on implementing Unity on MVC 3 (Live)? There seem to be plenty on Beta and RC, but the code always seems to have a problem on live frameworks.
Currently this is not impacting my unit testing, since my controllers have overloaded constructors, as does my EF context.
If you have a small project, you may not benefit from IoC.
Lifetime management if a plus for me. I don't have to dispose a repository (or service layer) in every controller. It thins out my code and creates the object for me. In addition, I know I have a clean separation in case I ever need to change things. It almost forces me to. I use for example IRepository that is backed by entity framework. For testing I use a fake IRepository implementation. So sure, I could manually create it in my application but this leads to some bad practices in larger projects and I lose the benefits of having the interface.
I have a basic demo for a super short talk I did recently on this for (15 minutes) mvc and unity for dependency injection using the unity.mvc3 nuget package:
http://completedevelopment.blogspot.com/2011/12/using-dependency-injection-with-mvc.html
Btw. Dependency Injection in .Net - best book on the subject without a doubt.
It's very useful for wiring up all your dependencies, handling life cycle of your objects, error handling, transaction handling, testing purposes and ...
All of above point are advantages of using an IoC framework, but I strongly recommend using Ninject. it has a very friendly DSL for binding modules, has out of box library and extensions for ASP.NET MVC and is an open source lightweight DI framework.
It has also many extensions.
I wanted some tips regarding the following problem, from the Java experts in this forum:
I am currently working on a web application with lot of SQL transactions based on MVC architecture. Is is possible to have the view completely developed and hosted at the client side, with the controller and model at the server?
The idea is to represent data in a way desired by end users. So, the View is developed (adhering to some defined standards) by the end users itself, where the controller and model remains the same.
I think it is possible with the MVC Spring framework, but don't know how exactly.
Thanks.
Shaun
Is is possible to have the view completely developed and hosted at the client side, with the controller and model at the server?
What do you mean by this? Well, you may build HTML on client with Java Script by sending ajax requests for data to controller, but it's not the way Spring MVC designed for. For that you probably will need something like DWR
I am looking for some advice on the correct mechanism to use for getting a RavenDB IDocumentSession into my repositories in a true session-pr-request behaviour.
This is a greenfield MVC3 application, and I've gotten Ninject / Ninject.MVC3 using NuGet. RavenDB is running on an external server (i.e. non-embedded).
I've set up the Ninject module to return the right repositories, and also a session per request for them.
However - is it true that MVC3 will instantiate the controller for each action method? In that case, I can just allow MVC3/Ninject to inject my repositories and the sessions they need, no problem.
However, if a controller is reused across several requests, this might not work, as the repository hanging around from a previous request might now employ a session that is old and discarded.
I have looked at a few ways to do this - the above is the basic one. I have also tried to do something like an ActionFilterAttribute that gets a new session from the IoC container at the start of each request - but in that case, where should I put it?
Should my repository have a Session property it uses that actually gets the current session from the container each time? This would add coupling between the repository implementation and the IoC container, but otherwise should work I guess.
What is the proper way to do this? How are the cool kids doing it? Any help would be highly appreciated!
Unless you are doing something really funny with your controller factory, each controller instance will be used for a single requests.
Controllers are not thread safe and will not usually survive beyond a single request.
I've written a comprehensive blog post about using Ninject's InRequestScope so that IDocumentSession is injected once per request. Ninject is great at managing scope for you.
http://www.dalsoft.co.uk/blog/index.php/2012/04/12/mvc-get-ravendb-up-and-running-in-5-minutes-using-ninject/
I think that you should avoid going on with Controllers.
It may help sometime:
If session state is disabled we should no longer try to use the Session Property on the Controller as it will be null. Turning off session state and using the Session Property will give you the dreaded “object reference not set to an instance of object” error.
I googled but couldn't find any answer.
I am planning to use GWT. I want to know if I can use spring in my GWT code to use the dependency injection framework? I am not talking about GWT gui interaction with backend spring app.
The reason I am asking is the GWT code gets compiled to JavaScript and this is what gets executed in browser. If I am using spring code in that, then would it work or for that matter any other library like log4j, etc.?
Or the GUI code have to be pure GWT API only?
For example,
public class MyTable {
private Button myButton;
#Autowired
public MyTable(Button aMyButton) {
myButton = aMyButton;
}
}
Guice is supported on GWT using GIN. For Spring-like DI with GWT, check out GWT Toolbox or Rocket GWT.
I believe GIN is a more natural choice for GWT. Not because it's also made by Google, but because using XML for GWT configuration makes absolutely no sense. Everything gets statically compiled into JavaScript so there is no need for externalized configuration. Keep your refactoring tools happy; go for GIN.
To answer your other question, you will not find many SE frameworks that work on GWT. First and foremost, it has no support for reflection or bytecode manipulation (everything is JavaScript), which immediately rules out a lot of frameworks. Log4j, on the other hand, doesn't make sense because there is no file system accessible on the client side, but there are libraries available that do things differently.
The Spring libraries for GWT mentioned above are basically a rewrite of the Spring for GWT. They do not share any code with Spring simply because they can't. Those frameworks work by generating code ("factories") that wire up your components as if you were doing DI manually.
This is also how GIN works, it generates Java factories for your classes, and GWT compiles it into optimized JavaScript (meaning little performance overhead). GIN does use Guice behind the scenes though, to validate configuration at compile time and to inspect modules.
No, you won't be able to do that. The DI logic applies at runtime on the server side, and the GWT code is entirely client-side.
I thought it would be simpler to just create a Spring Controller that invoked the doPost method of the GWT RemoteServlet. A sample is provided here. I know this is a little round about. But this shields you from changes to the GWT implementation if any.. Hope it helps.
I wonder if Guice (the Google DI framework) is supported by GWT?
This might be an alternative.
You can implement a Servlet Service in the server side that retrive objects from a Spring ApplicationContext, rendering to JSon Objects (I did it with http://json-lib.sourceforge.net/apidocs/net/sf/json/JSONSerializer.html) by example.
Then you can have a Singleton Facade Service that make the request from the GWT-client side to our Servlet Service.
In this way you can get a runtime depency injection in the GWT-client side .
Spring ME is capable of helping you out here. Although I partly agree with some of the previous responses, it's nice to have the same programming (and plumbing) paradigm across your client and server code.