how to use switch to match datagroup

in this case ,I can save the output of HTTP::path to a variable,right? because I run [HTTP::path] 3 times

 

hmm,I should use variable if one command run more than 1 time,right?

 

as i understand, even you call HTTP::path three times, you do not run function against it. so, no i do not think you should use variable.

hmm,can u show me in which case I should use variable to make it more efficent?

can u show me in which case I should use variable to make it more efficent?it is in 6 - Use Variables which you have mentioned.

 

 

uri variable is used instead of keep calling [string tolower [HTTP::uri]].

 

 

Ten Steps to iRules Optimization by Joe

 

http://devcentral.f5.com/Tutorials/TechTips/tabid/63/articleType/ArticleView/articleId/281/Ten-Steps-to-iRules-Optimization.aspx

in my case,it is like 6

 

why do u tell me it is better to use[HTTP::path] instead of variable

 

switch -glob [HTTP::path] {

 

"*gif" -

 

"*png" {

 

switch -glob [HTTP::path] {

 

"/static.*" -

 

"/s.*" {

 

switch -glob [HTTP::path] {

 

"*cswebtool*" -

 

"*cobrands*" {

 

persist none

 

pool SRWD52-STATIC

 

return

 

}

 

}

 

}

 

}

 

}

it is like 5 rather than 6.

hmm,I am a little confused

 

so if I use [string tolower [HTTP::uri]] many times,then,I need to use variable

 

but if I use [HTTP::uri] many times,then,I don't need to use variables,right?

 

 

oh

 

 

but u see Aaron's comment:

 

As you're only referencing HTTP::path once there isn't any reason to use a variable. If you were running an operation against a command multiple times you'd want to run it just once and then save the output to a variable. For example, if you were setting a URI to lower case and checking it multiple times, you'd want to save the lower case URI rather than running string tolower multiple times.

 

 

I do use [HTTP::path] many times

so if I use [string tolower [HTTP::uri]] many times,then,I need to use variable

 

but if I use [HTTP::uri] many times,then,I don't need to use variables,right?yes, that is what i understand.

 

 

If you were running an operation against a command multiple times you'd want to run it just once and then save the output to a variable.i understand operation means something such as string tolower ...

 

 

hope this helps.

The value for [HTTP::path] is cached in memory the first time the command is run. However, if you perform an operation on the path, like [string tolower [HTTP::path]] that output is not cached. So in your example, if you're running [HTTP::path] multiple times, it's better to not save the value to a variable.

If you were checking the path set to lower case in multiple locations in the iRule, it would be more efficient to save the value to a variable versus running string tolower more than once.

Here are examples of the two different scenarios. I hope this is clearer for you.

 Example using no variable as [HTTP::path] is cached:
switch -glob [HTTP::path] {
    "*gif" -
    "*png" {
        switch -glob [HTTP::path] {
            "/static.*" -
            "/s.*" {
                switch -glob [HTTP::path] {
                    "*cswebtool*" -
                    "*cobrands*" {
                        persist none
                        pool SRWD52-STATIC
                        return
                    }
                }
            }
        }
    }
}

Or

 Example using a variable as [string tolower [HTTP::path]] is not cached:
set path [string tolower [HTTP::path]]
switch -glob $path {
    "*gif" -
    "*png" {
        switch -glob $path {
            "/static.*" -
            "/s.*" {
                switch -glob $path {
                    "*cswebtool*" -
                    "*cobrands*" {
                        persist none
                        pool SRWD52-STATIC
                        return
                    }
                }
            }
        }
    }
}

Aaron

ahhhh

 

Aaron and Nitass,thank u very much

 

this time I understand this well

 

hahha

 

it is a depth explanation of this question.

Hi,Aaron

 

in this case

 

Example using no variable as [HTTP::path] is cached:

 

 

switch -glob [HTTP::path] {

 

"*gif" -

 

"*png" {

 

switch -glob [HTTP::path] {

 

"/static.*" -

 

"/s.*" {

 

switch -glob [HTTP::path] {

 

"*cswebtool*" -

 

"*cobrands*" {

 

persist none

 

pool SRWD52-STATIC

 

return

 

}

 

}

 

}

 

}

 

}

 

}

 

because [HTTP::path] is cached,so we don't need to set variable.

 

hmm,if I set uri [HTTP::path],it means every connection we have $uri and [HTTP::path] in memeory,right?(I am not sure this cached stuff can be used by other connection.)

 

 

so it is better not to use set uri [HTTP::path] to cache output of [HTTP::path] again,right?