Disable validation request for a single web method

See more:

VB

validation

webservice

.NET4.5

I created a SOAP webservice using VS 2010 and vb.net code. I wanted to send html tags in a single method that's why I added the validation mode to my web.config file:

<httpRuntime requestValidationMode="2.0" />
    <pages validateRequest ="false">

But the problem is that all methods are not secured anymore because validationrequest is set as false for the entire request.

What I have tried:

I made some searches and I found that in .NET 4.5 the ValidateRequestMode property was added, which allows excluding controls from the page global validation. but this property is used for check-boxes or controls ... how can I implement it in my webservice as we are invoking? If I cannot implement it, is there any solution to disable request validation only for one webmethod ?