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mhupman_60939's avatar
mhupman_60939
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Nov 07, 2011

iRule Math - Square Root?

I hope I'm simply doing something wrong, but I cannot figure out how to calculate the square root of a number inside an iRule. I tried the sqrt() and pow() TCL functions, but it doesn't seem like th...
application delivery
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devops
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mhupman_60939's avatar
mhupman_60939
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Nov 08, 2011
O.K. I see. My point of view is: Even if it's possible to do a lot of things with an iRule (and I have done strange things to fix broken applications), there are very often better ways to do things offsite, by logging information to an internal system and implement all the required logic there, especially if it's about statistics and other performance data.

I agree, but it in this case I had a few hours to implement a status page for the Ops team to see who was making requests. It was much faster to use pure iRules then to attempt to integrate multiple systems.

 

 

 

O.K. I see. Is there any special reason for encoding the userid in that way? Sounds a bit like security by obscurity ;-))

 

 

 

The UserID in this case is just a unique identifier we use for tracing events. We take the original DB identity value and bitshift it and square it before handing it out to clients to use in their web calls. This is to prevent a typo or transcription error from mixing up two client's data (e.g. UserID's 143 and 144 might be represented as EncUserID 8347362 and 9234873 in the web call). It's not designed to be safe, but to prevent silly errors.

 

 

 

As much as I understand your demand, I also understand F5 if they just implement what's really needed. After all this is a load balancer with an included TCL interpreter and not a fully implemented TCL interpreter with some load balancing functionality ;-))

 

 

 

I guess we'll agree to disagree :).

 

 

 

You can use "sideband" connections to retrieve data from an external system with TCP or UDP (http://devcentral.f5.com/wiki/iRules.sideband.ashx).

 

 

 

As I mentioned above, I only had a short time period to implement this, so creating a decoding endpoint would have been impractical. However, I didn't know about the sideband connections, I'll read up on them. Thanks!