HMR and RegEx

How much RegEx do you need to understand to create HMRs that work the way you want? The easy answer is that it depends (on the complexity of the manipulations you want to perform). This article uses posts from HMR experts to be more helpful than that.

 

Regular Expressions—or familiarly, RegEx—are a flexible way in computing to specify and recognize text strings. For HMRs, using RegEx allows you to match and manipulate certain strings in SIP messages so you can control traffic in a way that suits your network’s demands. The Net-Net SBC supports POSIX Extended Regular Expressions, a dialect different from the RegEx used by PERL. Acme Packet has made some additions to the POSIX ERE that have been part of HMR’s capabilities from its beginning. RegEx can be complicated stuff—and when you’re deleting and replacing SIP header information, it’s pretty important to get it right.