Automatically call common method whenever request made for any method of that class
<p>I am working in maintenance for one ASP.net + c# [.net version 3.5] application. Requirement is, through out the application whatever string variable passed to the DAL layer must be checked for some specified words and symbols. </p>

<p>In this case I have to go on each method and then each string parameter to check specific words and symbol and this will take a lot of time. So I am thinking one approach which I don't know possible or not like </p>

<p>Whenever request made to call any method of DAL layer class from BLL layer, common method which defined under DAL layer must be call automatically with all arguments which were passing to actual DAL method
(This common method I supposed to resisted on constructor of DAL). 
In common method I supposed to check all string parameters and change their value if required and then after returning from this method actual method will call with changed value.</p>

<p>Please suggest me any other approach if this is not possible which has minimum effort.</p>
