I'm writing a progressive downloader as a Portable Class Library (Profile=24). It will support partial downloads of target files in chunks of bytes. HttpClient not being available, I'm going with HttpWebRequest, which has the AddRange method for partial downloads. But the method doesn't seem to be available from inside the PCL. So I set HttpWebRequest.Headers["Range"], but doing so throws the following ArgumentException:
"The 'Range' header must be modified using the appropriate property or method.\r\nParameter name: name"
That "appropriate property" seems to be HttpWebRequest.AddRange, but as I said it doesn't seem to be exposed from inside PCL. So I'm quite confused: what would be the right way of specifying the HttpWebRequest.Headers["Range"] in a PCL?
Thanks,
Simon
I didn't find the answer, but the following interface workaround worked for me:
Instead of creating the HttpWebRequest in my portable code, I defined the following custom interfaces:
public interface IMyRequest {
[...]
void AddRange(long from, long to);
}
public interface IMyRequestFactory {
IMyRequest Create(string url);
}
Then, in my non-portable code, I created classes that implemented those interfaces:
public class MyRequestImp : IMyRequest {
private readonly HttpWebRequest request;
public MyRequestImp (string url) {
request = (HttpWebRequest)WebRequest.Create(url);
}
[...]
public void AddRange(long from, long to) {
request.AddRange(from, to);
}
}
public class MyRequestFactoryImp: IMyRequestFactory {
public IMyRequest Create(string url) {
return new MyRequestImp(url);
}
}
At some point at initialization time, my non-portable code is passing a MyRequestFactoryImp object to my portable library through the IMyRequestFactory interface. Since the HttpWebRequest was created outside the PCL, you have access to the full functionalities of the class.
Related
The main WebServerExtension example from the JUnit5 manual is incomplete and it doesn't fully show how to properly store the configuration (e.g. enableSecurity, server url).
https://github.com/junit-team/junit5/blob/master/documentation/src/main/java/example/registration/WebServerExtension.java
The example ignores or hard codes the values. The manual (section 5.11. Keeping State in Extensions) implies that the "Store" should be used but the ExtensionContext is not yet available yet when the object is constructed -- its not clear how to handle migrating this data to the Store as the ExtensionContext is not yet available in the constructor.
Also its not clear to me that using the Store API for the WebServerExtension programmatic example is even desirable and perhaps it could work just using the internal state (e.g. this.serverUrl, this.enableSecurity, etc.).
Maybe the Store is more applicable to Extensions which don't use this "programmatic" style where multiple instances of the custom extension may exist (appropriately)? In other words its not clear to me from the guide if this a supported paradigm or not?
Other JUnit 5 extension examples online (e.g. org.junit.jupiter.engine.extension.TempDirectory) show how to leverage annotations to handle passing configuration info to the Store but it would be nice if there were a complete programmatic builder type example like WebServerExtension too.
Examples like TempDirectory clearly have access to the ExtensionContext from the beforeXXX() methods whereas the WebServerExtension example does not.
Using the following approach below seems to work fine but I wanted confirmation that this is a supported paradigm (i.e. using fields instead of Stores when using this programmatic approach).
public class WebServerExtension implements BeforeAllCallback {
private final boolean securityEnabled;
private final String serverUrl;
public WebServerExtension(Builder builder) {
this.securityEnabled = builder.enableSecurity;
this.serverUrl = build.serverUrl;
}
#Override
public void beforeAll(ExtensionContext context) {
// is it ok to use this.securityEnabled, this.serverUrl instead of Store API???
}
public String getServerUrl() {
return this.serverUrl;
}
public boolean isSecurityEnabled() {
return this.securityEnabled;
}
public static Builder builder() {
return new Builder();
}
public static class Builder {
private boolean enableSecurity;
private String serverUrl;
public Builder enableSecurity(boolean b) {
this.enableSecurity = b;
return this;
}
public Builder serverUrl(String url) {
this.serverUrl = url;
return this;
}
public WebServerExtension build() {
return new WebServerExtension(this);
}
}
}
Thanks!
Background
I have a web api project which uses complex types for GET requests, here is an example of a controller method, and its associated complex type
[RoutePrefix("api")]
public class MyController : ApiController
{
[Route("Something")]
public IHttpActionResult GetSomething([FromUri]RequestObject request)
{
// do something to get "data"
return Ok(data);
}
}
// elsewhere
public class RequestObject
{
[Required]
public string SomeValue{get;set;}
}
This works with a url such as http://domain.com/api/Something?SomeValue=foo.
I would like to use alias' for these parameters, for which I will do some complex stuff (once I have this working) but effectively I have defined an attribute AliasAttribute.
[AttributeUsage(AttributeTargets.Property,AllowMultiple=true)]
public class AliasAttribute : Attribute
{
public string ParameterName { get; private set; }
public AliasAttribute(string parameterName)
{
this.ParameterName = parameterName;
}
}
Which I would like to adorn onto my request model like so:
// elsewhere
public class RequestObject
{
[Required,Alias("val")]
public string SomeValue{get;set;}
}
Allowing my url to shorten to http://domain.com/api/Something?val=foo. This is a contrived and simplified example, but hopefully demonstrates the background.
Problem
ModelBinding in web api has become very complex compared to Mvc model binding. I am getting twisted up between IModelBinder, IValueProvider, HttpParameterBinding et al.
I would like an example of where I should hook in to the model binding to allow me to write the value to my model from the querystring - note that I only use this aliasing behaviour when the route uses the FromUri attribute (see MyController.GetSomething above).
Question title: Support aliased arguments in get requests for web api. I think you are re-inventing a wheel here AliasAttribute , and have not given a really good reason why you don't want to use community ways of doing this.
I have done something similar with Newtonsoft.Json serializer. But if you want something ootb I'd have to google around.
public class RequestObject
{
[Required]
[JsonProperty("vla")]
public string SomeValue{get;set;}
}
Example SO that uses it: .Net NewtonSoft Json Deserialize map to a different property name
Here is a more agnostic way to do it.
[DataContract]
public class RequestObject
{
[DataMember(Name="val", IsRequired=true)]
public string SomeValue{get;set;}
}
I need to access the Server.MapPath(virtualPath) method in a controller in an MVC 4 ApiController.
The answer is usually to access it from ControllerContext.HttpContext.Server. However, unlike MvcControllers, the ControlerContext for an ApiController has no HttpContext.
The WebApiAppication that is instantiated in Global.asax.cs has an HttpContext element (Context). However, unlike MVC 3 and earlier, I can't find a way to access the WebApiApplication from a controller. (Earlier generations stored a reference to it in a static Instance variable. MVC 4 removes that.)
Also, I'm trying to find something that will also work without a ton of extra scaffolding when I call the controller methods from a unit Test. I think I could access it, even in a WebApi Controller, using HttpContext.Current (at least it compiles), but I can't mock that for testing. (I'm talking unit testing here, where you call directly to the Controller methods. I've seen some recent tutorials where you unit test with a thin HttpClient, and thus test the whole stack. That seems more like low-level integration testing to me.)
This doesn't seem like it should be that difficult, but I've spent several hours googling it and trying things, and my head's getting bloody from beating it against the wall.
I'd recommend you abstracting this functionality:
public interface IMyDependency
{
string MapPath(string path);
}
and then have an implementation:
public class MyConcreteDependency: IMyDependency
{
public string MapPath(string path)
{
return HostingEnvironment.MapPath(path);
}
}
and finally your ApiController is completely independent on all static method calls making it unit test friendly:
public class MyController: ApiController
{
private readonly IMyDependency dependency;
public MyController(IMyDependency dependency)
{
this.dependency = dependency;
}
public HttpResponseMessage Get()
{
var path = this.dependency.MapPath("~/App_Data");
...
}
}
For ApiControllers, build yourself a DelegatingHandler and push all of your goodies onto request.Properties. You can then retrieve them from your request whether you are testing or running live. The benefit is that you then have zero dependency on Session in your Controller.
MessageHandler
public class ContextHandler : DelegatingHandler
{
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
{
// get the goodies to add onto the request
var goodies = /* call to goodieGoodieYumYum */
// add our goodies onto the request
request.Properties.Add(Constants.RequestKey_Goodies, goodies);
// pass along to the next handler
return base.SendAsync(request, cancellationToken);
}
}
Controller Action
var goodies = (List<Goodie>)Request.Properties[Constants.RequestKey_Goodies];
Can you override the ToString function in a WCF DataContrat? Right now I have:
[DataContract]
public class Keyword
{
public int ID { get; set; }
public string Name { get; set; }
public override string ToString()
{
return Name;
}
}
But it doesn't seem to work. Anyway to get this working?
I realize this is old but wanted to provide an answer since I just created a sample app for a coworker that used this idea. All of this work can be done on the consumer/test client side.
If you look at the code on the consumer/test client and, more specifically, the classes that are generated as part of the service reference, you will see the [DataContract] type you are interested in. In order to do this you should make sure that 'Show All Files' is selected. Drill down to the 'Reference.cs' class.
This is the top of my test class from Reference.cs:
namespace WebApplication1.UCCTestSvcRef {
using System.Runtime.Serialization;
using System;
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.CodeDom.Compiler.GeneratedCodeAttribute("System.Runtime.Serialization", "4.0.0.0")]
[System.Runtime.Serialization.DataContractAttribute(Name="UCCRecord", Namespace="http://schemas.datacontract.org/2004/07/UCCTest")]
[System.SerializableAttribute()]
public partial class UCCRecord : object, System.Runtime.Serialization.IExtensibleDataObject, System.ComponentModel.INotifyPropertyChanged {
The important bits that you will need to use are the namespace and the partial class. To make use of these you simply have to create a new class in your test client of the same type, in the same namespace, and override the ToString() method.
Here is an example of how to do that from the newly created UCCRecord.cs file on the consumer/test client.
namespace WebApplication1.UCCTestSvcRef
{
public partial class UCCRecord
{
public override string ToString()
{
return "Key: " + Key.ToString() + ", Time: " + Timestamp.ToString("d") + ", Value: " + Value;
}
}
}
Note that I can only reference Key and Timestamp and Value because they are [DataMember] values for the [DataContract].
This is relatively simple if you know what you are looking for. If anything here is not clear, please let me know and I will attempt to clarify.
Thanks
Where do you want to be able to invoke ToString()? Methods are not part of the DataContract so they won't be available when you create the proxy for the client.
Of course, nothing is stopping you from coding that method in the client's proxy yourself.
Remember too that if you own both the server and the client, that often you can use a shared library for data contracts rather than generating a client proxy. If you do that, then you can have the same method on both the server and client as they're exactly the same type.
I am researching Prism v2 by going thru the quickstarts. And I have created a WCF service with the following signature:
namespace HelloWorld.Silverlight.Web
{
[ServiceContract(Namespace = "http://helloworld.org/messaging")]
[AspNetCompatibilityRequirements(RequirementsMode =
AspNetCompatibilityRequirementsMode.Allowed)]
public class HelloWorldMessageService
{
private string message = "Hello from WCF";
[OperationContract]
public void UpdateMessage(string message)
{
this.message = message;
}
[OperationContract]
public string GetMessage()
{
return message;
}
}
}
When I add a service reference to this service in my silverlight project it generates an interface and a class:
[System.ServiceModel.ServiceContractAttribute
(Namespace="http://helloworld.org/messaging",
ConfigurationName="Web.Services.HelloWorldMessageService")]
public interface HelloWorldMessageService {
[System.ServiceModel.OperationContractAttribute
(AsyncPattern=true,
Action="http://helloworld.org/messaging/HelloWorldMessageService/UpdateMessage",
ReplyAction="http://helloworld.org/messaging/HelloWorldMessageService/UpdateMessageResponse")]
System.IAsyncResult BeginUpdateMessage(string message, System.AsyncCallback callback, object asyncState);
void EndUpdateMessage(System.IAsyncResult result);
[System.ServiceModel.OperationContractAttribute(AsyncPattern=true, Action="http://helloworld.org/messaging/HelloWorldMessageService/GetMessage", ReplyAction="http://helloworld.org/messaging/HelloWorldMessageService/GetMessageResponse")]
System.IAsyncResult BeginGetMessage(System.AsyncCallback callback, object asyncState);
string EndGetMessage(System.IAsyncResult result);
}
public partial class HelloWorldMessageServiceClient : System.ServiceModel.ClientBase<HelloWorld.Core.Web.Services.HelloWorldMessageService>, HelloWorld.Core.Web.Services.HelloWorldMessageService {
{
// implementation
}
I'm trying to decouple my application by passing around the interface instead of the concrete class. But I'm having difficulty finding examples of how to do this. When I try and call EndGetMessage and then update my UI I get an exception about updating the UI on the wrong thread. How can I update the UI from a background thread?
I tried but I get UnauthorizedAccessException : Invalid cross-thread access.
string messageresult = _service.EndGetMessage(result);
Application.Current.RootVisual.Dispatcher.BeginInvoke(() => this.Message = messageresult );
The exception is thrown by Application.Current.RootVisual.
Here is something I like doing... The service proxy is generated with an interface
HelloWorldClient : IHelloWorld
But the problem is that IHelloWorld does not include the Async versions of the method. So, I create an async interface:
public interface IHelloWorldAsync : IHelloWorld
{
void HelloWorldAsync(...);
event System.EventHandler<HelloWorldEventRgs> HelloWorldCompleted;
}
Then, you can tell the service proxy to implement the interface via partial:
public partial class HelloWorldClient : IHelloWorldAsync {}
Because the HelloWorldClient does, indeed, implement those async methods, this works.
Then, I can just use IHelloWorldAsync everywhere and tell the UnityContainer to use HelloWorldClient for IHelloWorldAsync interfaces.
Ok, I have been messing with this all day and the solution is really much more simple than that. I originally wanted to call the methods on the interface instead of the concreate class. The interface generated by proxy class generator only includes the BeginXXX and EndXXX methods and I was getting an exception when I called EndXXX.
Well, I just finished reading up on System.Threading.Dispatcher and I finally understand how to use it. Dispatcher is a member of any class that inherits from DispatcherObject, which the UI elements do. The Dispatcher operates on the UI thread, which for most WPF applications there is only 1 UI thread. There are exceptions, but I believe you have to do this explicitly so you'll know if you're doing it. Otherwise, you've only got a single UI thread. So it is safe to store a reference to a Dispatcher for use in non-UI classes.
In my case I'm using Prism and my Presenter needs to update the UI (not directly, but it is firing IPropertyChanged.PropertyChanged events). So what I have done is in my Bootstrapper when I set the shell to Application.Current.RootVisual I also store a reference to the Dispatcher like this:
public class Bootstrapper : UnityBootstrapper
{
protected override IModuleCatalog GetModuleCatalog()
{
// setup module catalog
}
protected override DependencyObject CreateShell()
{
// calling Resolve instead of directly initing allows use of dependency injection
Shell shell = Container.Resolve<Shell>();
Application.Current.RootVisual = shell;
Container.RegisterInstance<Dispatcher>(shell.Dispatcher);
return shell;
}
}
Then my presenter has a ctor which accepts IUnityContainer as an argument (using DI) then I can do the following:
_service.BeginGetMessage(new AsyncCallback(GetMessageAsyncComplete), null);
private void GetMessageAsyncComplete(IAsyncResult result)
{
string output = _service.EndGetMessage(result);
Dispatcher dispatcher = _container.Resolve<Dispatcher>();
dispatcher.BeginInvoke(() => this.Message = output);
}
This is sooooo much simpler. I just didn't understand it before.
Ok, so my real problem was how to decouple my dependency upon the proxy class created by my service reference. I was trying to do that by using the interface generated along with the proxy class. Which could have worked fine, but then I would have also had to reference the project which owned the service reference and so it wouldn't be truly decoupled. So here's what I ended up doing. It's a bit of a hack, but it seems to be working, so far.
First here's my interface definition and an adapter class for the custom event handler args generated with my proxy:
using System.ComponentModel;
namespace HelloWorld.Interfaces.Services
{
public class GetMessageCompletedEventArgsAdapter : System.ComponentModel.AsyncCompletedEventArgs
{
private object[] results;
public GetMessageCompletedEventArgsAdapter(object[] results, System.Exception exception, bool cancelled, object userState) :
base(exception, cancelled, userState)
{
this.results = results;
}
public string Result
{
get
{
base.RaiseExceptionIfNecessary();
return ((string)(this.results[0]));
}
}
}
/// <summary>
/// Create a partial class file for the service reference (reference.cs) that assigns
/// this interface to the class - then you can use this reference instead of the
/// one that isn't working
/// </summary>
public interface IMessageServiceClient
{
event System.EventHandler<GetMessageCompletedEventArgsAdapter> GetMessageCompleted;
event System.EventHandler<AsyncCompletedEventArgs> UpdateMessageCompleted;
void GetMessageAsync();
void GetMessageAsync(object userState);
void UpdateMessageAsync(string message);
void UpdateMessageAsync(string message, object userState);
}
}
Then I just needed to create a partial class which extends the proxy class generated by the service reference:
using System;
using HelloWorld.Interfaces.Services;
using System.Collections.Generic;
namespace HelloWorld.Core.Web.Services
{
public partial class HelloWorldMessageServiceClient : IMessageServiceClient
{
#region IMessageServiceClient Members
private event EventHandler<GetMessageCompletedEventArgsAdapter> handler;
private Dictionary<EventHandler<GetMessageCompletedEventArgsAdapter>, EventHandler<GetMessageCompletedEventArgs>> handlerDictionary
= new Dictionary<EventHandler<GetMessageCompletedEventArgsAdapter>, EventHandler<GetMessageCompletedEventArgs>>();
/// <remarks>
/// This is an adapter event which allows us to apply the IMessageServiceClient
/// interface to our MessageServiceClient. This way we can decouple our modules
/// from the implementation
/// </remarks>
event EventHandler<GetMessageCompletedEventArgsAdapter> IMessageServiceClient.GetMessageCompleted
{
add
{
handler += value;
EventHandler<GetMessageCompletedEventArgs> linkedhandler = new EventHandler<GetMessageCompletedEventArgs>(HelloWorldMessageServiceClient_GetMessageCompleted);
this.GetMessageCompleted += linkedhandler;
handlerDictionary.Add(value, linkedhandler);
}
remove
{
handler -= value;
EventHandler<GetMessageCompletedEventArgs> linkedhandler = handlerDictionary[value];
this.GetMessageCompleted -= linkedhandler;
handlerDictionary.Remove(value);
}
}
void HelloWorldMessageServiceClient_GetMessageCompleted(object sender, GetMessageCompletedEventArgs e)
{
if (this.handler == null)
return;
this.handler(sender, new GetMessageCompletedEventArgsAdapter(new object[] { e.Result }, e.Error, e.Cancelled, e.UserState));
}
#endregion
}
}
This is an explicit implementation of the event handler so I can chain together the events. When user registers for my adapter event, I register for the actual event fired. When the event fires I fire my adapter event. So far this "Works On My Machine".
Passing around the interface (once you have instantiated the client) should be as simply as using HelloWorldMessageService instead of the HelloWorldMessageServiceClient class.
In order to update the UI you need to use the Dispatcher object. This lets you provide a delegate that is invoked in the context of the UI thread. See this blog post for some details.
You can make this much simpler still.
The reason the proxy works and your copy of the contract does not is because WCF generates the proxy with code that "Posts" the callback back on the calling thread rather than making the callback on the thread that is executing when the service call returns.
A much simplified, untested, partial implementation to give you the idea of how WCF proxies work looks something like:
{
var state = new
{
CallingThread = SynchronizationContext.Current,
Callback = yourCallback
EndYourMethod = // assign delegate
};
yourService.BeginYourMethod(yourParams, WcfCallback, state);
}
private void WcfCallback(IAsyncResult asyncResult)
{
// Read the result object data to get state
// Call EndYourMethod and block until the finished
state.Context.Post(state.YourCallback, endYourMethodResultValue);
}
The key is the storing of the syncronizationContext and calling the Post method. This will get the callback to occur on the same thread as Begin was called on. It will always work without involving the Dispatcher object provided you call Begin from your UI thread. If you don't then you are back to square one with using the Dispatcher, but the same problem will occur with a WCF proxy.
This link does a good job of explaining how to do this manually:
http://msdn.microsoft.com/en-us/library/dd744834(VS.95).aspx
Just revisiting old posts left unanswered where I finally found an answer. Here's a post I recently wrote that goes into detail about how I finally handled all this:
http://www.developmentalmadness.com/archive/2009/11/04/mvvm-with-prism-101-ndash-part-6-commands.aspx