Recent Posts

  • Xamarin Evolve

    This past week I spent in Atlanta, Georgia, attending Xamarin Evolve and Atlanta Code Camp.  This was the second annual Evolve conference and attendance went from 600 the first year to 1200 this year.  This year’s event was an impressive affair. Continue reading...

  • RESTFest 2014

    Last week was RESTfest week.  RESTfest is an unusual little conference that happens in Greenville, South Carolina every September.  This is the fifth year it has run and this is my fourth time attending, and I learn a ton every time. Continue reading...

  • Vermont Code Camp

    This past weekend I had the opportunity to attend and speak at Vermont Code Camp.  Apart from being hosted at the beautiful University of Vermont, it was an event packed with excellent speakers. Continue reading...

  • Implementing Conditional Request Handling for your API

    In the previous post in this series on Conditional Requests I introduced the topic of validators, their purpose and how they can be constructed.  A large chunk of the work that needs to be done to support conditional requests is done by the origin server.  This blog post is about that role. Continue reading...

  • Code Camp NYC

    This weekend I had the opportunity to speak for the first time at the New York city Code Camp.  It was an excellent event with a huge turnout and an equivalently huge number of sessions. With fourteen different sessions happening simultaneously, attendees were spoiled for choice and I am quite sure there were plenty of people having to make difficult choices. Continue reading...

  • HTTP in depth

    Over the past few months I have written a number of posts relating to HTTP that have attempted to clarify some of the lesser understood areas of the HTTP specification and provide some practical guidance. Continue reading...

  • Using Etags and Last-modified headers to improve performance with HTTP conditional requests

    In the recent update of the HTTP specification, the details of conditional requests have been split out and given their whole own specification.  Most developers I talk to are familiar with the idea of 304 Not Modified response code, but whenever we start to dig deeper everyone, myself included, are missing pieces of the puzzle. This article is one of a series of blog posts that attempts to dig in to aspects of HTTP and provide practical guidance on their usage. Continue reading...

  • Caching resources with query strings

    This afternoon Scott Hanselman posted a fairly innocuous question on twitter.  However, the question involved versioning of a RESTful API, which is a subject that is sure to bring out lots of opinions.  This post is less about the versioning question and more about the commonly held belief that caches do things differently with URLs that have query strings. Continue reading...

  • A drive by review of the Uber API

    Uber recently announced the availability of a public API.  I decided to take it for a spin and provide some commentary.  The quick version is that it is a fairly standard HTTP API and that is both a good thing and a bad thing. Continue reading...

  • Centralized exception handling using a ASP.NET Web API MessageHandler

    ASP.NET Web API 2.1 introduced some significant improvements to the mechanisms that support global error handling. Before this release there were a number of different types of errors that would be handled directly by the runtime and there was no easy way to intercept these errors and add your own custom behavior.  The standard guidance suggests you register these new handlers as services, but I prefer a different approach that seems more natural to me. Continue reading...

  • These 8 lines of code can make debugging your ASP.Net Web API a little bit easier.

    I think most us ASP.Net Web API developers have, at some point, experienced the problem where their API is returning a 500 Internal Server Error, but tracing through with Visual Studio doesn't reveal any exceptions in our code.  This problem is often caused when a MediaTypeFormatter is unable to serialize an object.  This simple message handler can take away some of the pain of debugging these scenarios. Continue reading...

  • Everything you need to know about HTTP Header syntax but were afraid to ask

    If you use HTTP then the chances are good that you have to deal with HTTP headers.  The syntax of HTTP headers has a long and tortured history, originating from the syntax of email headers.  All too often I see headers that don't conform to the specifications.  This makes everyone's job a little bit harder.  The recent releases of the HTTP specifications have done a fair amount of clarification and consolidation to make getting the syntax right. Continue reading...

  • Hypermedia as the engine of application state, the client-server dance

    We are currently seeing a significant amount of discussion about building hypermedia APIs.  However, the server side only plays part of the role in a hypermedia driven system.  To take full advantage of the benefits of hypermedia, the client must allow the server to take the lead and drive the state of the client.  As I like to say, it takes two to Tango. Continue reading...

  • The Insanity of the Vary Header

    In my first deep dive into a HTTP header on the user-agent header I said that I would try and produce a series of posts going under the covers on certain HTTP headers.  This post is about the Vary header.  The Vary header both wonderful and sad at the same time.  I'll discuss how to make it work for you and where it fails miserably. Continue reading...

  • Composing API responses for maximum reuse with ASP.NET Web API

    In Web API 2.1 a new mechanism was introduced for returning HTTP messages that appeared to be a cross between HttpResponseMessage and the ActionResult mechanism from ASP.NET MVC.  At first I wasn't a fan of it at all.  It appeared to add little new value and just provide yet another alternative that would a be a source of confusion.  It wasn't until I saw an example produced by Brad Wilson that I was convinced that it had value. Continue reading...

  • An HTTP Resource is a lot simpler than you might think

    Unfortunately, I still regularly run into articles on the web that misunderstand the concept of an HTTP resource.  Considering it is a core piece of web architecture, having a clear understanding of what it means can make many other pieces of web architectural guidance considerably easier to understand. Continue reading...

  • Single purpose media types and reusability

    The one great thing about twitter is that you quickly find out what you failed to explain clearly :-)  My efforts in advocating for single purpose media types failed to clarify that by single purpose, I am not suggesting that these media types should not be re-usable.  Let me try and explain. Continue reading...

  • Single purpose media types and caching

    My recent post asking people to refrain from creating more generic hypermedia types sparked some good conversation on twitter between @mamund, @cometaj2, @mogsie, @inadarei and others.  Whilst thinking some more on the potential benefits of single purpose media types versus generic hypermedia types, realized there is a correlation between single purpose media types and representation lifetimes.  I thought it might be worth adding to the conversation, but there is no way I could fit it in 140 chars, so I’m posting it here. Continue reading...

  • XSLT is easy, even for transforming JSON!

    Most developers I talk to will cringe if they hear the acronym XSLT.  I suspect that reaction is derived from some past experience where they have seen some horrendously complex XML/XSLT combination.  There is certainly lots of that around. However, for certain types of document transformations, XSLT can be a very handy tool and with the right approach, and as long as you avoid edge cases, it can be fairly easy. Continue reading...

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