So I already have a working implementation of StructureMap with the WCF service (including custom instance provider, behaviors, etc.)
When I try to have an object that is instantiated only once per user request, I use the InstanceScope.HttpContext and it throws because the context is null.
Do anyone have a proper way of doing that?
On the server-side of the WCF service? By default, WCF has nothing to do with ASP.NET and thus all your HttpContext etc. aren't there.
By default, your WCF services will be called on a "per-call" basis, e.g. each request gets a brand-new, separate, totally isolated instance of your service class. Why not just put those things into the service class as internal fields??
Or you might want to check out this blog post on how to abstract request state and providing sample implementations for ASP.NET (using HttpContext.Items) and WCF.
Related
I would like my ASP.NET Core application to send messages to a Azure Service Bus.
In Microsoft's article Best Practices for performance improvements using Service Bus Messaging they argue that you should re-use instances of clients.
It is recommended that you do not close messaging factories or queue, topic, and subscription clients after you send a message, and then re-create them when you send the next message.
So I take that as I should not instantiate a new instance of the client (TopicClient or QueueClient) inside my controller using the new keyword.
I guess that I should use dependency injection in ASP.NET Core.
Should I directly inject a TopicClient/QueueClient or should I create an own class that wraps an instance of the client and expose a SendAsync method?
When registering the service with dependency injector should I register it as a singleton?
We did it with a wrapper class that is then returning the TopicClient/QueueClient and registered it as a singleton and found no big issues with this approach.
We based our approach on this example provided by Microsoft eshopOnContainers.
The example code for this functionality is found in this file. They than register this class as singleton in Startup.cs in the services where they require ServiceBus.
I have read about various implementations of authentication and authorization for WCF, starting from reusing some built in .NET and WCF features and ending with completely custom implementations.
But there are so many factors to take into account, so I'm confused about how to implement it for my intranet business application project.
Here is what I need:
- WCF .NET 4.5 services will be hosted in IIS 7 or newer.
Most probably, ASP.NET compatibility will be disabled.
Protocol will be HTTP with BasicHttpBinding, but it might need binary serialization to minimize traffic.
WCF method will receive a custom session ID which will be checked against a user session object in a database. No .NET sessions are allowed in this project.
After receiving the ID, the service will read the corresponding user data (including authorization flags to see if the user is allowed to execute the current operation) and validate it. If data is invalid, an exception will be thrown and the WCF operation won't be executed. If validation succeeds, the identity of the user will be stored in a current operation context (and also current thread principal) so it can be accessed by various components during the WCF operation execution.
All the authentication&authorization should be done transparently before the execution of the WCF operation - without additional efforts from programmers who will create the WCF methods.
I need access to the WCF operation name being executed, when I perform the auth validations, so I can throw an exception if the user does not have permissions to execute the operation.
testers will use SoapUI, so they'll need to be able to pass the session ID through standard SOAP or HTTP headers.
Which would be the most straightforward way to implement my auth routines? Should I use a custom binding? Custom behavior? Some kind of a built-in request event handler (which one exactly, and will they work if ASP.NET compatibility is disabled)? Authorization policy (seems a bit overkill because I won't be using most of its built-in features anyway)? Something else?
You can try making use of Message Inspectors. Your session ID can be passed like a token through SOAP or HTTP Headers and will be inspected by WCF through your defined behavior before it executes the actual service operation.
You can check the articles here and here, particularly focusing on the IDispatchMessageInspector interface which offers the "AfterReceiveRequest" and "BeforeReceiveReply" methods.
A little background info -
I'm trying to host a RESTful WCF service on Azure. As I understand, unless I have the ASP.NET type hosting on the role, I don't really need the global.asax class (which has the application_start method).
From basic prototyping, all I needed was the svc file and the implementation behind it and it automatically gets initialized on role startup (I mean, hosted up on IIS).This is great because I need no extra code other than web.config and my service is up and running. I don't need to create a new service host and start listening on it, etc. I'm able to deploy the role and POST messages to my service.
The problem -
I have custom logging and initialization classes implemented that I need to initialize when my service starts up. I configured my service to be a singleton and I'm not sure where I should put my custom initialization components.
Without an explicit application start method and my service configured as a singleton, can I assume that when the first request comes in, my service constructor gets called? (along with all my custom initialization?).
can I assume that when the first request comes in, my service constructor gets called?
Yes, but you should ask yourself whether you really want your service to run as a singleton. If you're happy with this then it will work fine; if you don't want it to run as a singleton then you should look into Russell's answer using a custom factory.
Look at Should WCF service typically be singleton or not? for some discussion about whether WCF services should be singletons. You need to decide for your situation, but generally WCF services are not singletons unless they need to be.
To implement a custom factory, see this MSDN link Extending Hosting Using ServiceHostFactory. As the link describes, extend the service host factory like so
public class DerivedFactory : ServiceHostFactory
{
public override ServiceHost CreateServiceHost( Type t, Uri[] baseAddresses )
{
return new ServiceHost(t, baseAddresses )
}
}
And then specify your factory in the ServiceHost directive
<% # ServiceHost
Service="MyNamespace.MyService"
Factory="MyNamespace.DerivedFactory" %>
You're looking for ServiceHostFactory. You can add a part to the SVC file to use a factory, where you can do any logging etc. you may need.
I have used this in the past to start a background worker to launch a separate thread for some background work.
http://msdn.microsoft.com/en-us/library/system.servicemodel.activation.servicehostfactory.aspx
Hope this helps you get where you need to be. :)
I have an existing WCF service.
Is it possible to add operation contract to the service interface and have the implementation in a workflow?
Or I absolutly need a seperate service interface for my workflow?
When you publish a WCF service you are publishing the interface and telling it what implementation to use. You can specify only one implementation, otherwise how would WCF know where to route which request. So in short you need to use a separate interface for your workflow services. That said, if you don't want to change your public facing API there is no reason you can't create a minimal implementation that just passes request on to your worklflow service.
If I have a client/server type of application built using both Prism and WCF, and I would like on the serverside to have the wcf service to be instatiated per call BUT I would like to use dependency injection (using the UnityContainer in Prism). How could I possibly do this? Should I have a single instance service it would be no problem, but are there any hooks in WCF to allow for a delegate to be called whenever a service is supposed to be instantiated and have this instance returned?
Any ideas?
Cheers!
It is possible! WCF provides a plugin to the WCF responsibility chain called an IInstanceProvider. This allows for you to replace the construction with your own.
Someone has implemented this as a service behavior and is available here:
http://code.msdn.microsoft.com/WCFResources/Release/ProjectReleases.aspx?ReleaseId=1252