Book Image

Mastering FreeSWITCH

By : Russell Treleaven, Seven Du, Darren Schreiber, Ken Rice, Mike Jerris, Kalyani Kulkarni, Florent Krieg, Charles Bujold
4 (1)
Book Image

Mastering FreeSWITCH

4 (1)
By: Russell Treleaven, Seven Du, Darren Schreiber, Ken Rice, Mike Jerris, Kalyani Kulkarni, Florent Krieg, Charles Bujold

Overview of this book

FreeSWITCH is one of the best tools around if you’re looking for a modern method of managing communication protocols through a range of different media. From real-time browser communication with the WebRTC API to implementing VoIP (voice over internet protocol), with FreeSWITCH you’re in full control of your projects. This book shows you how to unlock its full potential – more than just a tutorial, it’s packed with plenty of tips and tricks to make it work for you. Written by members of the team who actually helped build FreeSWITCH, it will guide you through some of the newest features of version 1.6 including video transcoding and conferencing. Find out how FreeSWITCH interacts with other tools and APIs, learn how to tackle common (and not so common) challenges ranging from high availability to IVR development and programming advanced PBXs. Great communication functionality begins with FreeSWITCH – find out how and get your project up and running today.
Table of Contents (21 chapters)
Mastering FreeSWITCH
Credits
About the Authors
About the Reviewers
Contributors
www.PacktPub.com
Preface
7
WebRTC and Mod_Verto
Index

Utility functions


We've used a lot of self-written functions. It's time to have a look at them. Let's open the top half of the utils.lua file, in the preceding screenshot.

The first three functions serve mainly to build the fourth function, stamp(), that we use throughout our scripts to do structured logging.

shell() is an example of a typical Lua interaction with an operating system. It executes a command, and returns the output as a string. We use it in stamp() to obtain the result of the command date.

trim() uses Lua native string manipulation, and is equivalent to the chomp() command in Perl, and many similar others in different languages: it deletes the trailing newline in a string, if it exists, and returns the string without the newline.

whichline() comes from the debug package. It returns the current line number in the script, for example, like __line__ in C.

stamp() is our logging workhorse; it takes the string we want to log (our log message), a string (returned by whichline()) representing...