The OpenPhone Project—Internet Telephony for Everyone!
We envision a basic application that provides a framework for Internet telephony using plug-in modules to accomplish the various tasks to be performed. For example, one plug-in module would provide the signaling tasks, and another would provide the audio tasks (including use of RTP and jitter buffers). We envision an H.323 module, a SIP module and an MGCP module—the user could select which one to use based on the interoperability requirements. New modules could be plugged in as needed to evaluate different RTP/jitter buffer techniques. As improvements are made in signaling or audio-transport modules, all the user has to do is drop in the new module.
All that is needed to make this approach viable is a common API for applications to use to perform basic high-level functions. The modules would all provide those API functions; the appropriate module would be used to provide the actual functionality. Since many people refer to the signaling and audio code as a “stack”, we call this the Stack Adaption Layer (SAL). The SAL is a commonly defined and adopted API that will allow the application developer to focus on the functionality of the program, and the stack developers to focus on the detailed lower-level implementation.
To extend the concept down a layer and provide platform and hardware independence, we envision a Hardware Adaption Layer (HAL) that provides a set of common functions for controlling and using the hardware. This allows the signaling/audio stacks and the SAL to work seamlessly on top of the HAL code, regardless of which Internet telephony card is in use at the hardware level. This approach will allow us to realize the goal of true cross-platform multi-vendor interoperability.
Design specifications for the SAL and HAL layers are in active development as of this writing, and by the time of publication there should be several white papers and some reference code available on our web site. We encourage active participation and have started a mailing list devoted to the project. You can join this majordomo-hosted list by sending a “subscribe” message to email@example.com.
Internet telephony has many intricate pieces that work together to make it function well. There are programs available now that work—but not at a level that is truly useful. Most of these implementations fall short because they don't use modern compressed-codecs, or because they don't use something like RTP and good jitter-buffer techniques to control the audio stream. Most also lack a standardized signaling protocol that provides interoperability with other programs. The OpenPhone Project aims to provide a new, highly flexible framework that uses plug-in modules to provide the components discussed above. It will be based on inexpensive, easily available hardware that can be used in normal, commonly available computers. OpenPhone will use modern techniques to provide near-toll-quality calls between any two phone-enabled computers, and hopefully will foster growth and acceptance of Internet Telephony to the point that all computers are phone-capable.
Greg Herlein (firstname.lastname@example.org) has been using Linux since the early 1.0 series kernels. He's built and run systems on remote mountains, on research ships on the high seas and in corporate high-reliability settings. He's now a member of the technical staff at Quicknet Technologies, Inc. in San Francisco and is leading a team of developers to create the next generation of Linux-based IP telephony software.
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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- Stunnel Security for Oracle
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- Non-Linux FOSS: Caffeine!
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide