irule to replace any .asp to be .aspx in uri

switch matching is not sub-string matching. Indeed, by default, it is absolute matching. Thus, if I did something like this:

switch $x {
    "fo"  { ... }
    "bar" { ... }
    "foo" { ... }
}

If $x is the value "foot", none of the cases would match. If, instead, $x is "foo", only the last case would match.

The -glob flag to switch changes the matching style to "glob". With this style, any instance of an asterisk (*) matches zero or more characters, a question-mark (?) matches exactly (any) one character, and characters in square-braces ([...]) form a character class (e.g., "[adgk]" would match a single character if and only if that character is a, d, g or k).

Putting this together, in this example:

switch $x {
    "foo" { ... }
    "*foo" { ... }
    "foo*" { ... }
    "*foo*" { ... }
}

Case 1 will match if and only if $x is exactly the string "foo". Case 2 will match if $x ends with the string "foo". Case 3 will match if $x starts with the string "foo". Case 4 will match if $x contains the string "foo".

In my code:

switch -glob "[HTTP::path]" {
   "*.asp"  {...}
   "*.aspx" {...}

the first case will match if HTTP::path ends with the string ".asp". The second case will match if HTTP::path ends with the string ".aspx".