Pardon if this is an obvious question but I don't see a way to get the IOC container in Nancy to provide a Singleton per Session. Obviously, I can check the Session for an item (a model in this case) that I've cached previously but that seems a bit heavy handed given the other niceties of the framework. Hosting in ASP.NET
Per session or per request? There's no way to maintain lifetime of an object for a session (that would be just plain weird), but you can do it per request by overriding ConfigureRequestContainer in the bootstrapper and registering it in there as a singleton like this:
https://github.com/NancyFx/Nancy/blob/master/src/Nancy.Demo.Hosting.Aspnet/DemoBootstrapper.cs#L35
Related
I am looking at building a class implementing the IdentityServer IResourceStore interface. My goal is to serve IdentityResource and ApiResource collections as defined in a custom repository.
Ideally, I will receive requests for these resources and respond with the subset relevant to the query. In short: You only get what you ask for.
The GetAllResources()method makes me leery: Is IdentityServer actually requiring that I pull the entire set of my Identity and API resources from my repository and make this available? At this point I have no idea how large those collections will grow, or the cost of pulling them from the repository.
What are the consequences of simply responding with a null or empty lists of resources?
-S
It's used in the GetAllEnabledResourcesAsync method in the IResourceStoreExtensions class, which in turn is used by the DiscoveryEndpoint. So, if you don't implement this method the Discovery endpoint will not be able to display any scopes or claims.
By don't implement I mean return some empty lists or something, not throw a NotImplementedException or return null... That would break everything.
I'm using RIA Services for Silverlight and I'm wondering if there's a way to get the service context an entity is attached to from the entity alone (on the client, ie with the RIA-Service domain context and entities!). This would help to implement functionality in them that need some context (the service context itself being one example) without relying on global (static) storage.
You can create many custom DomainContext instances, how you needed. You can cast it to base class (DomainContext) and store it in global storage for second use. In process of second use you should cast it to the custom DaomainContext class again. For example: ((CustomDomainContext)instance).Customers.SubmitChanges();
We need to get certain information from PortletRequest in our Portal application. We do that using a utility method inside our Portlet Application. In this Utility method we access FacesContext.getCurrentInstance().getRequest() to get the PortletRequest. We access this Utility method in our DAO layer. We do not have access to request parameter here.
It works sometimes, but at times it gives me NullPointerException. I found a similar thread which explains about this. They have mentioned, if it is part of the same request, then you should get the Context. For me, it is part of the same request, but I'm not getting the context. Can you please help me.
If you are getting a null FaceContext from FacesContext.getCurrentInstance() then no FacesContext has been constructed for this Thread/Request.
Are the failing requests coming through a non-faces entry point? Such as an Event or Resource portlet request? If so there will be no FacesContext created.
Rather than relying on static methods and thread local storage to access data in you DAO you should consider extracting what you need from the PortletRequest, and passing it down your stack. It is bad practice to mix presentation layer artefacts such as the FaceContext or a PortletRequest with your DAO layer.
If your application is deployed in separate WAR/JAR files, it is likely that different classloaders are used. I had a similar problem, when I tried to access the FacesContext inside an hibernate HAR archive on JBOSS5. I came up with a successfull solution using reflection API. Take a look at this.
If you bundle your whole application into one EAR, you might be able to force the use of one classloader for the whole ear, but AFAIK that is application server specific.
Regards
I am planning to use WCF (not ria) in conjunction with Entity Framework 4 and STE (Self tracking entitites). If I understand this correctly my WCF should return an entity or collection of entities (using LIST for example and not IQueryable) to the client (in my case Silverlight).
The client then can change the entity or update it. At this point I believe it is self tracking? This is where I sort of get a bit confused as there are a lot of reported problems with STEs not tracking.
Anyway, then to update I just need to send back the entity to my WCF service on another method to do the update. I should be creating a new OBJECTCONTEXT every time? In every method?
If I am creating a new objectcontext every time in every method on my WCF then don't I need to re-attach the STE to the objectcontext?
So basically this alone wouldn't work??
using(var ctx = new MyContext())
{
ctx.Orders.ApplyChanges(order);
ctx.SaveChanges();
}
Or should I be creating the object context once in the constructor of the WCF service so that 1 call and every additional call using the same WCF instance uses the same objectcontext?
I could create and destroy the WCF service in each method call from the client - hence creating in effect a new objectcontext each time.
I understand that it isn't a good idea to keep the objectcontext alive for very long.
You are asking several questions so I will try to answer them separately:
Returning IQueryable:
You can't return IQueryalbe. IQueryable describes query which should be executed. When you try to return IQueryable from service it is being executed during serialization of service response. It usually causes exception because ObjectContext is already closed.
Tracking on client:
Yes STEs can track changes on a client if client uses STEs! Assembly with STEs should be shared between service and client.
Sharing ObjectContext:
Never share ObjectContext in server environment which updates data. Always create new ObjectContext instance for every call. I described reasons here.
Attaching STE
You don't need to attach STE. ApplyChanges will do everything for you. Also if you want to returen order back from your service operation you should call AcceptChanges on it.
Creating object context in service constructor:
Be aware that WCF has its own rules how to work with service instances. These rules are based on InstanceContextMode and used binding (and you can implement your own rules by implement IInstanceProvider). For example if you use BasicHttpBinding, default instancing will be PerCall which means that WCF will create new service instance for each request. But if you use NetTcpBinding instead, default instancing will be PerSession and WCF will reuse single service instance for all request comming from single client (single client proxy instance).
Reusing service proxy on a client:
This also depends on used binding and service instancing. When session oriented binding is used client proxy is related to single service instance. Calling methods on that proxy will always execute operations on the same service instance so service instance can be stateful (can contains data shared among calls). This is not generally good idea but it is possible. When using session oriented connection you have to deal with several problems which can arise (it is more complex). BasicHttpBinding does not allow sessions so even with single client proxy, each call is processed by new service instance.
You can attach an entity to a new object context, see http://msdn.microsoft.com/en-us/library/bb896271.aspx.
But, it will then have the state unchanged.
The way I would do it is:
to requery the database for the information
compare it with the object being sent in
Update the entity from the database with the changes
Then do a normal save changes
Edit
The above was for POCO, as pointed out in the comment
For STE, you create a new context each time but use "ApplyChanges", see: http://msdn.microsoft.com/en-us/library/ee789839.aspx
How would you structure the code for calling a wcf service in silverlight application?
Using only-once instanciated wcf service-proxy (aka singleton) and using it across the whole SL app?
If so, how did you solve the unsubscribing controls from ws-call-completed event?
or
creating the wcf service-proxy for each ws-call? Where do you close the proxy then?
Here's the application structure I found workable:
Application is split into modules (Prism but can be anything) - module per vertical function.
Every module has its own set of service client classes (generated by slsvcutil)
For every service client partial class I have another generated partial class where for every service method I have a version that returns IObservable.
E.g. if my service client has a method GetAllMyDataAsync() and event GetAllMyDataCompleted the generated method signature will be IObservable<MyDataDto[]> GetMyData() This method will deal with subscribing/unsubscribing to an event, authentication, error handling, and other infrastructure issues.
This way web-service call becomes simply:
new MyServiceClient().GetAllMyData().Subscribe(DoSomethingWithAllMyData)
With this I can easily join data from multiple requests, e.g. (strictly for demonstration purposes, don't try this in real app):
var des = (from d in new MyServiceClient().GetMyDataItem()
from e in new MyServiceClient().GetDataItemEnrichment(d)
select new EnrichedData { Data = d, Enrichment = e});
des.Subscribe(DoSomethingWithEnrichedData);
Once application gets more complex (e.g. data is shared by multiple components, you add messaging that dynamically updates initially retrieved data, etc.) it's helpful to add another element in the stack - Model.
Therefore if I have a service MyDataService I'd have a model class called MyDataServiceModel. It will be registered in the container as singleton and it will be injected into viewmodels that needs it. Thus viewmodels talk to this class when they need data (so rather than calling MyServiceClient.GetAllMyData it would call MyDataServiceModel.GetAllMyData.
This way viewmodels are completely independent of WCF stack (easier to mock, easier to test) Additionally these model classes take care of:
data transformation from/to DTO
enriching and combining data (one model method may join data from more than one request)
handling issues like throttling (e.g. typical scenario, user selected something in a combobox, it caused a request to be sent to a server to retrieve a data for that selection, while that request is being exected user made another change, but for some reason responses came out of order), etc.
combining data pulled on initial load via WCF with data pushed by the service during the session