You use Microsoft Visual Studio 2010 and Microsoft .NET Framework 4 to create a Windows
Communication Foundation (WCF) Data Services service. You deploy the data service to the
following URL: http://contoso.com/Northwind.svc. You need to update the City property of the
Customer record that has its ID value as 123. You also need to preserve the current values of the
remaining properties. Which HTTP request should you use?
A.
PUT /Northwind.svc/Customers(123)
Host: contoso.com
Content-Type: application/json
{
City: ‘Seattle’
}
B.
PUT /Northwind.svc/Customers(123)
Host: contoso.com
Accept: application/json
{
City: ‘Seattle’
}
C.
MERGE /Northwind.svc/Customers(123)
Host: contoso.com
Content-Type: application/json
{
City: ‘Seattle’
}
D.
MERGE /Northwind.svc/Customers(123)
Host: contoso.com
Accept: application/json
{
City: ‘Seattle’
}
Explanation:
HTTP Actions
OData supports the following HTTP actions to perform create, read, update, and delete operations
on the entity data that the addressed resource represents:
HTTP GET – This is the default action when a resource is accessed from a browser. No payload is
supplied in the request message, and a response method with a payload that contains the requested
data is returned.
HTTP POST – Inserts new entity data into the supplied resource. Data to be inserted is supplied in the
payload of the request message.
The payload of the response message contains the data for the newly created entity. This includes
any autogenerated key values.
The header also contains the URI that addresses the new entity resource.
HTTP DELETE – Deletes the entity data that the specified resource represents. A payload is not
present in the request or response messages.
HTTP PUT – Replaces existing entity data at the requested resource with new data that is supplied in
the payload of the request message.
HTTP MERGE – Because of inefficiencies in executing a delete followed by an insert in the data source
just to change entity data, OData introduces a new HTTP MERGE action. The payload of the request
message contains the properties that must be changed on the addressed entity resource. Because
HTTP MERGE is not defined in the HTTP specification, it may require additional processing to route a
HTTP MERGE request through non-OData aware servers.
Accessing and Changing Data Using REST Semantics
(http://msdn.microsoft.com/en-us/library/dd728282.aspx)
HTTP header fields
(http://en.wikipedia.org/wiki/List_of_HTTP_header_fields)
Accept Content-Types that are acceptable
Content-Type The mime type of the body of the request (used with POST and PUT requests)
A Guide to Designing and Building RESTful WebServices with WCF 3.5
(http://msdn.microsoft.com/en-us/library/dd203052.aspx)