Windows Communication Foundation (WCF) is an SDK for developing and deploying
services on Windows. WCF provides a runtime environment for your services,
enabling you to expose CLR types as services, and to consume other services as
CLR types. In this article I am going to explain you how to implement restful
service API using WCF 4.0 . The Created API returns XML and JSON data using WCF
attribute.
Normally developer scared to use WCF because lot of confusing configuration. I
will try to use minimum configuration so that it will be easier to understand
for us. We will develop Restful WCS API in 6 steps. So let's start now.
What is REST?
Based on Roy Fielding
theory "Representational State Transfer (REST), attempts to codify the architectural
style and design constraints that make the Web what it is. REST emphasizes
things like separation of concerns and layers, statelessness, and caching,
which are common in many distributed architectures because of the benefits they
provide. These benefits include interoperability, independent evolution,
interception, improved scalability, efficiency, and overall performance."
Actually only the
difference is how clients access our service. Normally, a WCF service will use
SOAP, but if you build a REST service clients will be accessing your service
with a different architectural style (calls, serialization like JSON,
etc).
REST uses some common
HTTP methods to insert/delete/update/retrive infromation which is below:
a) GET - Requests a specific representation of a
resource
b) PUT - Create or update a resource with the supplied
representation
c) DELETE - Deletes the specified resource
d) POST - Submits data to be processed by the identified
resource
Why and where to use REST?Few days back i was writing a service
which was suppose to access by heterogeneous language/platform/system. It can
be used by iPhone, Android, Windows Mobile, .NET web application, JAVA or PHP.
Using web service it was bit complex for me to expose it to everyone using
uniform system. Then we decided to use REST, which was easily espoused over
cloud. This was a great example which shows the capability of SIMPLE RESTful
SERVICE :) . Below is some point which will help you
to understand why to use the RESTful services.
1) Less overhead (no
SOAP envelope to wrap every call in)
2) Less duplication
(HTTP already represents operations like DELETE, PUT, GET, etc. that have to
otherwise be represented in a SOAP envelope).
3) More standardized
- HTTP operations are well understood and operate consistently. Some SOAP
implementations can get finicky.
4) More human
readable and testable (harder to test SOAP with just a browser).
5) Don't need to use
XML (well you kind of don't have to for SOAP either but it hardly makes sense
since you're already doing parsing of the envelope).
6) Libraries have
made SOAP (kind of) easy. But you are abstracting away a lot of redundancy
underneath as I have noted. Yes in theory SOAP can go over other transports so
as to avoid riding atop a layer doing similar things, but in reality just about
all SOAP work you'll ever do is over HTTP.
Step by step guide
Generally developer
scared to use WCF because lot of confusing configuration. I will try to use
minimum configuration so that it will be easier to understand for us. We will
develop Restful WCS API in
6 steps. So let's start now.
Step 1. First of all launch Visual Studio 2010. Click
FILE->NEW->PROJECT. Create new "WCF
Service Application" .
Step 2. You can see in solution that By Default WCF service and interface
file is already created. Delete By default created file as we will create our
own interface and WCF service file.
Step 3. Now Right click on solution and create one new WCF service file.
I have given name to the service file as "RestServiceImpl.svc".
Step 4. as I explained in starting of the article that we will be writing
an API which can return data in XML and JSON format, here is the interface for
that. In IRestServiceImpl , add following code.
In above code, we can see two different method of IRestService which is XMLData
and JSONData. XMLData Returns result in XML whereas JSONData in JSON.
Step 5. Open the file RestServiceImpl.svc.cs and write following code
over there..
Implementation of the method is same for both function but the response format
would be different because of ResponseFormat of WCF 4.0 .
Step 6. Now let's move to configuration part which is the last one. There
will be two basic part of the configurations file which we must have to
understand...
A. <services>:
This part of the configuration file contains details about END POINT
B. <behaviors>:
This part contains details about service and endpoint behaviour details.
And that's it. Our Restful WCF service is ready for test purpose.
Now I launch the application in browser to see the result. I launch this service
in IE and my URL is now http://localhost:35798/RestServiceImpl.svc . Now if I
use http://localhost:35798/RestServiceImpl.svc/xml/123 URL, I get following
response on the browser which an XML format and that was my task to achieve.
Now if I use http://localhost:35798/RestServiceImpl.svc/json/123 URL, i get
following response on the browser which an XML format and that was my task to
achieve.
Comments, suggestions and criticisms are all welcome.
Thanks