The Double Whammy of Scripting

Many of you are very familiar with iRules, our Tool Command Language (Tcl) based scripter. It’s a powerful application delivery tool to have a programmable proxy that allows you to manipulate – in real time - any network traffic passing through the BIG-IP. Many BIG-IP fans have used it to address their specific needs and some iRules have even been productized as features. For example, the cool ASM Data Mask feature that blocks sensitive info like SSN or credit card numbers from leaking out was once an iRule. Aw, our baby made it to the BIGs.

And by now you may have heard the trumpets about iRules LX, available in our most recent BIG-IP v12.1 release. So I was wondering if you were wondering what’s the difference between iRules and iRules LX? Why would you use one or the other?

iRules is based on Tcl and is an extremely stable and well-documented solution. We introduced it in BIG-IP v9.0 and we continue ongoing feature development for it. iRules Language eXtensions (where the LX comes from) is the next-generation of network programmability based on JavaScript. IRules LX is not intended to replace or antiquate Tcl, but provide additional functionality in certain situations.

Say you are writing a rule in Tcl that looks for some piece of data. When you find that data, you then need to make a database call to verify the parameters. That could get messy with many lines of code. You may even say to yourself, ‘Geeze, this would be a whole lot easier if I had a parser…wouldn’t that be nice.’ This is where IRules LX can be handy. Toss it over to a Node.js extension and let it do the work. With the proper node package manger (npm), of which there are some 280,000 (and counting), iRules LX will process and send back to Tcl so you can go on your merry way.

Essentially, that last 10% is 90% of the work so why not have a proper engine run it.

iRules LX is a simple way to solve tough challenges…another tool to use when you need it. Granted, it is not necessarily a hammer but that particular hex tool for precise jobs. It also bridges into the new world of programming. Tcl is still very relevant yet Node.js a popular, cutting edge language that the development community has eaten up. It offers more flexibility when you need it and a new tool in your arsenal of application delivery solutions.

You should also check out Eric Flores' Getting Started with iRules LX series which covers some concepts, use cases, configurations and workflows.

Published Jun 07, 2016

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