Most updates are updates (Posts, Puts or Deletes) to rows, processed per logic as shown in the example above.  Sometimes, however, transactions require arguments.  Consider giving an employee a raise, supplying the percent raise as a argument.

You can issue a POST like this:

https://MyServer/sample/v1/sample%3Aemployees/charlie?arg.RaisePercent=10


Which is handled by your logic like this, by reference to the Request Object: