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How can I always send a specific value for a given type in an ASP.NET Core app?

I'm loading some endpoints defined in external assemblies, into my web app on startup with:
// Add channel endpoints.
var endpointsFolder = Configuration.GetSection("EndpointsFolder").Get<string>();
foreach (var file in Directory.GetFiles(endpointsFolder))
services.AddMvc().AddApplicationPart(Assembly.LoadFrom(file));
All of the loaded endpoints derive from a custom class called SecureEndpoint which requires an interface ISecurityContext:
[ApiEndpoint]
public class SecureEndpoint : ControllerBase {
public SecureEndpoint(ISecurityContext securityContext) { ... }
}
So, for example:
[Route("test")]
public sealed class TestEndpoint : SecureEndpoint {
public TestEndpoint(ISecurityContext securityContext) : base(securityContext) { ... }
[HttpGet]
public string Get() {
return "This is a test.";
}
}
The problem I'm having is that when I invoke the endpoint, I get an error saying:
System.InvalidOperationException: Unable to resolve service for type Namespacing.ISecurityContext while attempting to activate Namespacing.TestEndpoint.
A few searches on the matter give a pretty simple solution:
services.AddScoped<ISecurityContext, SecurityContext>();
However, I have one problem; ISecurityContext is given to me in the form of the interface only. The value that is given to me, is the value I should use everywhere it's required. As a result, I need a way to say "if ISecurityContext is needed, use this value".
Is there a way to always send a specific value for a given type?
Edit: services.AddSingleton(...) did the trick, but I don't have time to type an answer up for it currently. I'll circle back later this afternoon.
If there are any compilation issues, they are only the result of typing this question.

WCF Services: Requests are limited to a single "Request" Paramater

I have a very strange and obscure issue with WCF services that I was hoping to get some insight on:
I am working a WCF service that we are building to replace one that we no longer have source code for. For some reason, in the new WCF service, everything is forced through a single paramater called "request". Using the WCF test client, this is what it looks like
On the "correct" service, this is what it looks like:
Is there any reason why this would be happening? I've defined all of the requests as follows:
[ServiceContract]
public interface IMyService
{
[OperationContract]
string SomeRequest();
}
Which seems correct, but there may be something I've overlooked that is causing this.

In your original WCF service, there is a request function parameter, and it has a definition similar to the following:
[ServiceContract]
public interface IMyService
{
[OperationContract]
Request SomeRequest(Request request);
}
[DataContract]
public class Request
{
string documentId;
[DataMember]
public string DocumentId
{
get { return documentId; }
set { documentId = value; }
}
}
In the new wcf service:
[ServiceContract]
public interface IMyService
{
[OperationContract]
string SomeRequest(string documentId);
}
So this is because the function parameters are different. Originally your parameter was class, but later changed to string, so the display in WCFTestClient is different.

Optional parameter of at UriTemplate causes twice invoces of AfterReceiveRequest - WCF - IDispatchMessageInspector

I just dived a little deeper into it and discovered new details.
Not the 'UriTemplate' in general causes the 2nd invocation of 'AfterReceiveRequest' but the optional parameter within!
If I call the method by
http:/ /myserver/result/val1
AfterReceiveRequest will be invoked twice.
If I pass all possible parameters like
http:/ /myserver/result/val1/val2/val3
there will be no useless invocation. Is that behavior as intended?
UriTemplate = "result/{para1=null}/{para2=null}/{para3=null}"
--- following the initial post, just for information ---
While implementing a WCF REST Service System I stuck on a problem with the http-headers.
In my ServiceContract there is a method with an UriTemplate definition at the WebGet attribute, so it can be called via
http://server/resource/val1/val2 ...
instead of
http://server/resource?para1=val1&para2=val2 ...
(I need this because of compatibility reasons.)
Also there is a significant value in the http-headers collection, that I need to read. Therefore I implement IDispatchMessageInspector and add this inspector to the EndpointDispatchers MessageInspectors collection. By that the AfterReceiveRequest will be invoked by WCF and I can access WebOperationContext.Current.IncomingRequest.Headers to read the desired Value.
The Problem: WCF solves the UriTemplate-mapping by generating a second request to the destination method, but does not pass the header entries from the original call to the generated second call. So AfterReceiveRequest (and of course BeforeSendReply, too) will be invoked twice, but the header-values from the real client call are only included in the first call.
Also I found no way to correlate the first and the second AfterReceiveRequest call, to implement a "special way" for passing the header-value from the first to the second call.
Is there a way to tell WCF to route the headers to the UriTemplate-redirected second call?
Here are some code fragments to make it clear:
[ServiceContract]
public interface IMyService
{
[WebGet(UriTemplate = "result/{para1=null}/{para2=null}/{para3=null}")]
bool MyMethod(string para1, string para2, string para3);
}
[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)]
[MyServiceInspectorBeavior]
public class MyService : IMyService
{
public bool MyMethod(string para1, string para2, string para3)
{
return DoTheWork();
}
//...
}
public class MyServiceInspectorBeavior : Attribute, IServiceBehavior
{
public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
{
foreach (EndpointDispatcher epDispatcher in serviceHostBase.ChannelDispatchers.OfType<ChannelDispatcher>().SelectMany(cDispatcher => cDispatcher.Endpoints))
{
epDispatcher.DispatchRuntime.MessageInspectors.Add(new MyInspector());
}
}
//...
}
public class MyInspector : IDispatchMessageInspector
{
//this is invoked twice for each client request,
//but only at the first call the header is present...
public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
{
WebHeaderCollection webOpContext =
WebOperationContext.Current.IncomingRequest.Headers;
string xForwardedIp = webOpContext["X-FORWARDED-IP"];
WriteLog(xForwardedIp);
return OperationContext.Current.IncomingMessageProperties["ActivityId"];
}
//...
}

WCF ServiceHosts, ServiceEndpoints and Bindings

I currently am running some WCF REST services in a Windows Service (not IIS), using the WebServiceHost. I have a separate interface and class defined for each service, but I'm having some issues understanding how WebServiceHost, ServiceEndpoint and ServiceContracts can be used together to create a selfhosted solution.
The way that I currently set things up is that I create a new WebServiceHost for each class which implements a service and use the name of the class as part of the URI but then define the rest of the URI in the interface.
[ServiceContract]
public interface IEventsService
{
[System.ServiceModel.OperationContract]
[System.ServiceModel.Web.WebGet(UriTemplate = "EventType", ResponseFormat=WebMessageFormat.Json)]
List<EventType> GetEventTypes();
[System.ServiceModel.OperationContract]
[System.ServiceModel.Web.WebGet(UriTemplate = "Event")]
System.IO.Stream GetEventsAsStream();
}
public class EventsService: IEventsService
{
public List<EventType> GetEventTypes() { //code in here }
public System.IO.Stream GetEventsAsStream() { // code in here }
}
The code to create the services looks like this:
Type t = typeof(EventService);
Type interface = typeof(IEventService);
Uri newUri = new Uri(baseUri, "Events");
WebServicesHost host = new WebServiceHost(t, newUri);
Binding binding = New WebHttpBinding();
ServiceEndpoint ep = host.AddServiceEndpoint(interface, binding, newUri);
This works well and the service endpoint for each service is created at an appropriate url.
http://XXX.YYY.ZZZ:portnum/Events/EventType
http://XXX.YYY.ZZZ:portnum/Events/Event
I then repeat for another service interface and service class. I would like to remove the Events in the Url though but if I do that and create multiple WebServiceHosts with the same base URL I get the error:
The ChannelDispatcher at 'http://localhost:8085/' with contract(s) '"IOtherService"' is unable to open its IChannelListener
with the internal Exception of:
"A registration already exists for URI 'http://localhost:8085/'."
I'm trying to understand how the WebServiceHost, ServiceEndpoint and ServiceContract work together to create the ChannelListener.
Do I need a separate WebServiceHost for each class which implements a service? I don't see a way to register multiple types with a single WebServiceHost
Secondly, I'm passing in the interface to the AddServceEndpoint method and I assume that method checks the object for all of the OperationContract members and adds them, the problem is how does the WebServiceHost know which class should map to which interface.
What I would love would be an example of creating a WCF self hosted service which runs multiple services while keeping the interface and the implementation classes separate.

Sounds to me like the problem that you are having is you are trying to register more than one service on the same service URI. This will not work, as you have noticed, each service must have a unique endpoint.
Unique By
IP
Domain
Port Number
Full URL
Examples
http://someserver/foo -> IFoo Service
http://someserver/bar -> IBar Service
http://somedomain -> IFoo Service
http://someotherdomain -> IBar Service
http://somedomain:1 -> IFoo Service
http://somedomain:2 -> IBar Service
You get the idea.
So to directly address your question, if you want more than once service to be at the root url for you site, you will have to put them on different ports. So you could modify your code to be something like
public class PortNumberAttribute : Attribute
{
public int PortNumber { get; set; }
public PortNumberAttribute(int port)
{
PortNumber = port;
}
}
[PortNumber(8085)]
public interface IEventsService
{
//service methods etc
}
string baseUri = "http://foo.com:{0}";
Type iface = typeof(IEventsService);
PortNumberAttribute pNumber = (PortNumberAttribute)iface.GetCustomAttribute(typeof(PortNumberAttribute));
Uri newUri = new Uri(string.Format(baseUri, pNumber.PortNumber));
//create host and all that

I think it might be useful for you to re-think about your URI approach. Uri is a unique resource identifier.
Each your endpoint says that you try to expose outside a different kind of resource it's "Events" and "OtherResource". Thus you need to change your UriTemplates a bit.
I would make it so:
[ServiceContract]
public interface IEventTypesService
{
[OperationContract]
[WebGet(UriTemplate = "", ResponseFormat=WebMessageFormat.Json)]
IList<EventType> GetEventTypes();
[OperationContract]
[WebGet(UriTemplate = "{id}")]
EventType GetEventType(string id);
}
[ServiceContract]
public interface IEventsService
{
[OperationContract]
[WebGet(UriTemplate = "")]
Stream GetEventsAsStream();
[OperationContract]
[WebGet(UriTemplate = "{id}")]
Event GetEvent(string id);
}
public class EventsService: IEventsService, IEventTypesService
{
public IList<EventType> GetEventTypes() { //code in here }
public EventType GetEventType(string id) { //code in here }
public Stream GetEventsAsStream() { // code in here }
public EventType GetEventType(string id) { // code in here }
}
Type t = typeof(EventService);
Type interface1 = typeof(IEventsService);
Type interface2 = typeof(IEventTypesService);
var baseUri = new Uri("http://localhost");
Uri eventsUri= new Uri(baseUri, "Events");
Uri eventTypesUri= new Uri(baseUri, "EventTypes");
WebServicesHost host = new WebServiceHost(t, baseUri);
Binding binding = New WebHttpBinding();
host.AddServiceEndpoint(interface1, binding, eventsUri);
host.AddServiceEndpoint(interface2, binding, eventTypesUri);
And yes, you are right - you have to have different addresses, but it's really different resources. To understand it better you can refer: RESTful API Design, best-practices-for-a-pragmatic-restful-api
To finish, there is a way to use the same address, but the approach a bit weird:
Using the same address

The following solution:
allows a single object to handle a specific endpoint
no part of the path is in the URI template
uses the same port for all of the services
It does requires more than one WebServiceHost - one per object that handles requests. Another difficulty is that adding deeper endpoints (like /events/2014) means they either need to have unique parameters or the URI template must include part of the path, if you go convention over configuration that shouldn't be a problem.
A WebServiceHost can only host one thing (class) but that object can have multiple interfaces to handle multiple different types of requests on different URLs. How can different WebServiceHosts bind to the same domain:port? They can't so I guess WebServiceHost wraps an underlying static object that routes requests to the right object. This doesn't technically answer your question but I think this implementation allows you to do what you want right?
A console app that hosts the web services.
public class Program
{
static void Main (string[] args)
{
var venueHost = new WebServiceHost (typeof (Venues));
venueHost.AddServiceEndpoint (typeof (IVenues), new WebHttpBinding (), "http://localhost:12345/venues");
venueHost.Open ();
var eventHost = new WebServiceHost (typeof (Events));
eventHost.AddServiceEndpoint (typeof (IEvents), new WebHttpBinding (), "http://localhost:12345/events");
eventHost.Open ();
while (true)
{
var k = Console.ReadKey ();
if (k.KeyChar == 'q' || k.KeyChar == 'Q')
break;
}
}
}
The Venues class implements IVenues and handles any requests to http://localhost:12345/venues/
[ServiceContract]
public interface IVenues
{
[WebInvoke (Method = "GET", UriTemplate = "?id={id}")]
string GetVenues (string id);
}
public class Venues : IVenues
{
public string GetVenues (string id)
{
return "This would contain venue data.";
}
}
The Events class implements IEvents and handles any requests to http://localhost:12345/events/
[ServiceContract]
public interface IEvents
{
[WebInvoke (Method = "GET", UriTemplate = "?venue={venue}")]
string GetEvents (string venue);
}
public class Events : IEvents
{
public string GetEvents (string venue)
{
return "This would contain event data.";
}
}

WCF self hosting can be done in many ways like Console application hosting, Windows service hosting, etc.
I had tried to host two services using a single console application. The structure of the services was similar to what you mentioned, that is, separate classes and interfaces for both the services.
You might want to have a look at this link:
Hosting two WCf services using one console app

WCF OperationContract property forgets value

recently have been successful getting my IIS hosted WCF service to work with basic authentication.
Since successfully implementing that. I have noticed that property values are not remembered.
Here is some code:
[ServiceContract]
public interface IEcho
{
string Message { [OperationContract]get; [OperationContract]set; }
[OperationContract]
string SendEcho();
}
public class EchoProxy : IEcho
{
public string Message { get; set; }
public string SendEcho()
{
return string.Concat("You said: ", Message);
}
}
public class EchoService : System.ServiceModel.ClientBase<IEcho>, IEcho
{
//-- ..... CONSTRUCTORS OMITTED ....
public string Message
{
get { return base.Channel.Message; }
set { base.Channel.Message = value; }
}
public string SendEcho()
{
return base.Channel.SendEcho();
}
}
Here is the console and the result:
EchoService client = new EchoService("SecureEndpoint");
client.ClientCredentials.UserName.UserName = "test";
client.ClientCredentials.UserName.Password = "P#ssword1";
client.Message = "Hello World";
Console.WriteLine(client.SendEcho());
Expected Result: You said: Hello World
Actual Result: You said:
I have Uploaded the sandbox project to my skydrive. I have included a SETUP.txt in the API project.
Click here to download.
How can I get properties to work?
thank you

I have never seen WCF contract used with a property to transfer data. i.e. the Message property. AFAIK its just not possible.
My recommendation would be to keep the concerns that are part of the contract separate, i.e. Operation and Data.
[ServiceContract]
public interface IEcho
{
[OperationContract]
string SendEcho(string Message);
}
Or
[ServiceContract]
public interface IEcho
{
[OperationContract]
string SendEcho(Message message);
}
[DataContract]
public class Message
{
[DataMember]
public string Message {get; set;}
}
At some later point you may wish to change the Message Object.
[DataContract]
public class MessageV2 : Message
{
[DataMember]
public DateTime Sent {get; set;}
}
While this changes the contract, changes like this can be backwardly compatible if managed carefully.

To understand what's happening, you need to know how the lifetime of the service object you're connecting to is configured. A good starting point is the MSDN article on Sessions, Instancing, and Concurrency.
For example, with InstanceContextMode.PerCall, a new service object will be created for each call, so no properties of the service object will be remembered between calls.
At the other end of the scale, InstanceContextMode.Single means a single instance handles all client requests for the lifetime of the application. In this case properties set by one client will be visible to all clients, not usually desirable.
In general, I would recommend using a stateless service object. But if you want a stateful service object (e.g. one with properties), you should use InstanceContextMode.PerSession, and (important) use a binding that supports sessions.
While I agree with #JTew that you shouldn't generally expose operations as properties, you will have the same problem if you try to use an object that stores state between calls in another way (such as a private field). I.e. the following would have exactly the same problem:
[ServiceContract]
public interface IEcho
{
[OperationContract]
void SetMessage(string message);
[OperationContract]
string GetMessage();
... etc ...
}