Implementing data validation

Note: When validating HTTP parameter names and values using regular expression validator, the input string is canonicalized using ESAPI APIs. These APIs simplify the input string by performing every possible type of decoding that might result in modification of the input string (for example, the substring &or is translated to the logical 'OR' character v). If any such special strings are expected, the use of a Java validator is recommended because using a regular expression validator would modify the string.