Tips and Tricks

Leveraging the HTTP Header Location

There's more to RESTful services than just using the HTTP verbs. You should also be leveraging the Location header and status code, for example.

When REST was proposed as a way of leveraging the HTTP protocol, the idea was to do more than just take advantage of the HTTP verbs GET, POST, DELETE and so on -- the goal was to take advantage of all the features of HTTP. If you're creating RESTful services, you should be following that paradigm.

For example, HTTP headers can include a status code that indicates a new resource was created and a URL that points to that resource. In a RESTful application, if you add a new customer, then you should be sending the client a message with headers that include the HTTP Created status code and a Location set to the URL where the new customer could be retrieved. The code to create those headers would look something like this:

Public Function CreateCustomer(cust As Customer) As ActionResult
  Dim newCust As Customer
  '... code to add a customer with Id of 'A123'... 
  Response.StatusCode = HttpStatusCode.Created
  Dim hlpr As New UrlHelper(ControllerContext.RequestContext)
  Response.AppendHeader(
    "Location", hlpr.Action("GetCustomer", "Customer", New With {.id = "A123"}))     
End Function

The client can now check the HTTP status code and, when the client discovers that Created status, use the Location header to find the new resource. It's the RESTful way to do it.

About the Author

Peter Vogel is a system architect and principal in PH&V Information Services. PH&V provides full-stack consulting from UX design through object modeling to database design. Peter tweets about his VSM columns with the hashtag #vogelarticles. His blog posts on user experience design can be found at http://blog.learningtree.com/tag/ui/.

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