Browsing posts in: c#

ASP.NET Web API integration testing with in-memory hosting

In-memory hosting is one of the hidden gems of ASP.NET Web API. While the community, forums, bloggers have been buzzing about web-host and self-host capabilities of Web API, aside from the terrific post by Pedro Felix, very little has been said about in memory hosting.

Let me show you an example today, how a lightweight Web API server can be temporarily established in memory (without elevated priviliges, or cannibalizing ports like self host) and used to perform integration testing, allowing you to test almost the entire pipeline, from the request to the response.

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Control the execution order of your filters in ASP.NET Web API

One of the few minor annoyances in ASP.NET Web API is that you lack the ability to control the order in which the attributes/filters are executed. If you have several of those applied to one action, they will not run in the order they have been declared in the code, and that sometimes may cause a lot of problems.

In fact, as a member of the ASP.NET Web API Advisory Group I already brought that up during our meetings, not to mention it has already been submitted as an issue to the ASP.NET team on Codeplex. In the meantime, let’s tackle this problem and see how you can easily regain control over the execution order of the attributes.

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Extending your ASP.NET Web API responses with useful metadata

If you ever worked with any API, which, in this day of age, you must have, you surely noticed that in most situations the API response isn’t just the result (requested data), but also a set of helpful metadata, like “total Results”, “timestamp”, “status” and so on.

In Web API, by default, you just serialize your models (or DTO) and such information are not present. Let’s build something which will solve this problem and help you decorate your response with hepful information. This would make it very easy for the client to implement paging, auto-loading scenarios, caching (if you return last modified information) and a lot more.

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Implementing message handlers to track your ASP.NET Web API usage

Today’s focus is going to be on message handlers (or, to be precise, DelegatingHandlers) in ASP.NET Web API. If you are familiar with WCF you can surely recall them – used to be called DelegatingChannels at some point – but the purpose has been the same all along, to provide the first (or last, depending whether you look at requests or responses) extendibility point in your Web API applications. You stack up as many message handlers on top of each other as you wish, and the request will travel through all of them.

This, in turn, gives us developers a possibility to process/alter/modify/decline the incoming HTTP request before it reaches the HttpControllerDispatcher. Then, when the controller creates the response, it goes through the same chain of message handlers again, so we can tamper with the response. One example of the applicability of this is that message handlers are a perfect place to address security related matters i.e. integrating OAuth.

The plan for today is to show how DelegatingHandlers are used by building a functionality that checks for an API key on an incoming API request and then logs all requests and responses, thus allowing you to track the usage of your API.

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Output caching in ASP.NET Web API

Today we will continue with our favorite topic – ASP.NET Web API. I’ve heard folks asking about how you could easily cache the output of the API methods. Well, in ASP.NET MVC, that’s dead easy, just decorate the Action with [OutputCache] attribute and that’s it. Unfortunately, ASP.NET Web API doesn’t have a built-in support for this attribute.

Which doesn’t mean you can’t have it. Let’s build one

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Different MediaTypeFormatters for same MediaHeaderValue in ASP.NET Web API

Let’s say you have a model and want to serve it through a different MediaTypeFormatter from different controllers or routes or urls? You want same content type (MediaHeaderValue) request, to be formatted differently in different situations – how could you do that, if everything resides in GlobalConfiguration?

It would be perfect to be able to use per-controller configuration in ASP.NET Web API. Unfortunately, at this stage, this feature is not yet supported. Henrik mentioned that Mike Stall is currently working on this, and it will be supported in the full release on Web API (perhaps even earlier, on codeplex?).

Anyway, let’s take this idea for a spin and explore what we could do in beta version of ASP.NET Web API, because we could still vary our formatters and responses.

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RSS & Atom MediaTypeFormatter for ASP.NET WebAPI

Today we are going to build a custom formatter for ASP.NET WebAPI, deriving from MediaTypeFormatter class. It will return our model (or collection of models) in RSS or Atom format.
The Formatter is supposed to react to requests sent with request headers “Accept: application/atom+xml” and “Accept: application/rss+xml”.

Let’s get going.

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Fun with ASP.NET Web API – push-like messaging from one application to multiple subscriber applications

So last time around we built together a small p2p chat app using WPF and ASP.NET Web API. Today, we are continuing our experiments with ASP.NET Web API and setting up a simple push (or push-like) messaging system between different apps using self hosting.

In fact, we’ll use one app (“server”) to push out messages to a number of other apps (“clients” or “subscribers”). Even though we have the (in)glorious WCF callbacks at our disposal, I thought it might be fun to try it that way. Hopefully, that sounds interesting, or at least intruiging. In the process we’ll also serialize custom types to JSON using JSON.NET and pass them between self-hosting applications.

More after the jump.

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Build p2p chat application with WPF and ASP.NET Web API

Recently I’ve been really enjoying myself with ASP.NET Web API. It is a tremendous beast, and with it’s self-hosting capabilities, it’s suitable as an HTTP-channeled-communication not only for ASP.NET websites, but also for any other .NET applications. In this post, I’m gonna try to show you the outcome of my weekend mash up – a peer-to-peer WPF chat application (clients connect directly to each other), fueled by ASP.NET Web API.

More after the jump.

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Serializing Entity Framework objects to JSON in ASP.NET Web API

Recently, I’ve been playing a lot with ASP.NET Web API, as it is really an exciting technology. It works exceptionally well with JSON.NET (Henrik Nielsen wrote a great post on how to return JSON from ASP.NET Web API using JSON.NET).

However, as it’s been the case in the past with i.e. WCF, I’ve run into a issue with serializing Entity Framework object to JSON when returning them from the ApiController. This is not, by any means, an issue in ASP.NET Web API, as the problem in this case lies in the EF lazy loading, which causes circular reference between the objects. This then throws a corresponding error – “A circular reference was detected while serializing an object of type (…)” if you are using JavaScriptSerializer, “Self referencing loop detected for type (…)” if you are using JSON.NET and so on.

I thought it might be useful to remind about possible solutions to this. There is an easy workaround.

More after the jump.

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