Question

In WCF how to let user decide which service to request when you ask for two values and have ability to perform different calculations with those values.

For example you ask for value1 and value 2. And user have a choice to perform addition, subtraction and multiplication with those values.

How can you achieve that?

        [OperationContract]
    int GetTwoValues(int value1, int value2);

public int addition(int value1, int value2){
return value1+value2;
}

public int subtraction(int value1, int value2){
return value1-value2;
}

How to do some logic like

if user.request="addition"{
do addition
}
else if user.request="subtraction"{
do subtraction
}

i know its not a code that i have written but just trying to have you get some understanding of what i am saying. Any help will really be appreciated.

Answer 1

Not quite sure I understand the question

[OperationContract]
public int Subtraction(int value1, int value2)
{
    return value1 - value2;
}

[OperationContract]
public int Addition(int value1, int value2)
{
    return value1 + value2;
}

would work as would something like

[OperationContract]
public int Calculation(int value1, int value2, string calcType)
{
    switch (calcType)
    {
        case "addition":
            return value1 + value2;
        case "subtraction":
            return value1 - value2;
    }
    //return default or throw exception
}

Not that either is without drawbacks of course, but both meet your criteria.

edit: your comment raises the obvious point that the switch case allows the user to possibly supply a value that doesn’t map.

Yes it does and I wouldn’t use strings, that was your example!

Possible ways round it?

• Validate the user input – let them know when they provide something that isn’t valid
• Use a default
• Throw an exception
• Use an enum to force the user to select from a pre defined list
• Similarly use the first method

I think perhaps you need to explain more in your question about what you want to achieve.