09 Feb 09 Rock Solid Clouded Asterisk

This post is somewhat a combination of posts from previous posts, mainly, the posts about virtualization and my latest posts about the utilization of Amazon EC2. As some of you may know, a part of what I do at GreenfieldTech is develop various API’s for the Asterisk Open Source PBX systems. Two of these API’s are the IVR API and the Dialer API. This post if called “Rock Solid Clouded Asterisk” as it will describe the latest production environment that I’ve implemented, using these API’s and Amazon EC2 virtualization framework.

The network diagram

Our implementation consisted of the following general schematic:

The application logic was based upon a JAVA based web-service, implementing the XML-RPC server side of the IVR API, and a dialer management system that controlled the dialer API located on the remotely located dialers – hosted on Amazon EC2 instances. For simplicity, and we were very much aware this would reduce the overall capacity, we’ve located both the dialer framework and the IVR API execution on each of the servers, while allowing the server s to communicate internally.

Some constraints

As much as we wanted to run many Amazon AMI instances, we were limited to running 5 elastic IPs with a single Amazon AWS account. As a result, we’ve registered 5 accounts, and executed a total of 24 AMI instances with 24 elastic IP’s.

An additional constraint we had realised, but had no way of actually knowing its limitation was the actual number of concurrent calls per server. Initially, we’ve reached the following numbers and configuration on a physical server:

• Intel Quad Core XEON
• 2GB RAM
• 1GB Network Uplink
• CentOS 5.2 64bit
• Total capacity: 120 concurrent calls of Dialer+IVR on a single server

Per our theory, if we managed to reach a similar capacity using amazon c1.medium instances, we would be very happy.

The results

After conducting a test utilizing a single AMI instance, we’ve reached the following results:

• Dual Core instance (c1.medium)
• 180GB Disk Storage
• 8GB of RAM
• Fedora Core 8 32bit
• Total capacity: 80 concurrent calls of Dialer+IVR on a single instance

A decrease of 33% in comparison to the performance observed on a physical server. Ok, so we weren’t all that happy with these results, until we started doing the financial math, realising that using Amazon EC2 with that Dialer+IVR framework would yield a savings of almost 80% in operational costs.

Doing the math

The normal co-located option

Our aim was to reach a capacity of around 2800 concurrent channels. Per the normal physical setup, our hardware requirements would be to use at least 24 servers. At a price of 1500$ per server, that sums up to a total of 36,000$. Adding the time required to install 24 servers, the overall expense for 24 servers would be around the 42,000$ mark. To sustain a total of 2800 concurrent calls, using the g711 codec, we would be required to carry a total of 300Mbps internet uplink – basically talking about 10,000$ of bandwidth.

So, taking all of the above into consideration, we will need a total of 52,000$ just to maintain the hardware installation and operational cost. Taking into consideration that the system would be used at full for no more than a period of 30 hours, we end up with a total of: 1733$ per hour.

The Amazon EC2 option

Now, let’s calculate for Amazon EC2:

2800 concurrent channels translates into 35 instances. Price per c1.medium instance per hour is 0.2$. So, rack that up and you get: 210$ for operating 35 instances for 30 hours.

Elastic IP costs are 0.01$ per hour per server – a total of 10.5$ for 30 hours.

Bandwidth costs are 0.17 per each GB, so according to 300Mbps for 30 hours, with each call duration at 1 minute sums up to be: 5M of data per call. Calculating 2800 concurrent channels for 30 hours gives: 25,200,00 MB, or 25TB of traffic. According to Amazon, first 10TB are at 0.17$ per GB, and then the price goes down. So, let’s take a worst case of 0.17$ per GB. A total of 4284$ for operating 30 hours.

A total of: 4,468 US Dollars, Price per hours calculated at: 148$.

The savings

Per the task at hand, the utilization of Amazon EC2 yielded a savings of 92%

So, is Amazon EC2 good for any usage?

The answer is a definite NO! If your requirement is for a system that works 24×7, like a PBX system or a call center, then your utilization of Amazon EC2 would be identical to leasing a co-located server at any of the world wide co-location providers. If your application is of sporadic nature, or is utilized for short bursts of time, Amazon EC2 is a wonderful tool for lowering your overall expenses. Sure, it will require some work to get running, but the overall savings is more than worth-while.

Tags: Amazon, Amazon EC2, API, Asterisk, Cloud computing, Dialers, digium, Economics, GreenfieldTech, IVR

30 Jan 09 Asterisk 3rd Party API – and their importance

As some of may know, I spend most of my time working as an Asterisk Developer and Consultant in my own company – called Greenfield Technologies Ltd. - named GreenfieldTech for short. Since the day I started my company I knew a few facts and truths:

1. GreenfieldTech starts as a one man operation – thus, spending more than 15% of my day to day tasks on support issues will surely stress me out and drive my business to the ground.
2. I don’t really want to deal with PBX installations and various office telephony aspects of using Asterisk – simply because it requires to much of item 1.
3. I need a way to be able to provide a fast response to my customers, maintain a low support over head and make sure that what ever I do, it can be accounted for.

Hence the above, I understood that GreenfieldTech’s products are not really the various services it provides, but actually the products vary completely from what a product looks and feels like. I understood that in order to provide this fast development turn-around I needed my own development framework. Surely PHPAGI, Adhearsion and Asterisk-JAVA can easily provide for a development framework – but it still doesn’t help me one bit – I needed something different.

I then realized that GreenfieldTech’s products are the one product line that all developers and vendor steer away from: Programmatical API frameworks. The programmatic framework should provide the most basic feature set, allowing it to be extended and continued onwards at ease. Hence, the suite of GTx API frameworks were born. A set of 3 different APIs provide all the facilities required for building any of the below:

• Dynamic IVR structures – driven via web services
• Recording systems
• Pre-Paid/Post-paid solutions
• Inteligent Network (IN) services
• Automatic Dialers – Predictive, Power, Progressive, Preview
• Broadcasting systems
• and more …

The entire API suite is based upon XML-RPC based web services. When I introduced XML-RPC to one of my customers, he immediately indicated: “But, XML-RPC doesn’t really provide for session oriented persistency. Why are you using XML-RPC?” – The reason is simple – we don’t need session persistency in the API – Asterisk can provide all of that internally. Thanks to Asterisk’s channel oriented architecture, we can regard each of Channel thread in Asterisk as a seperated data container, capable of holding all your session information and persistency information at ease.

Recorder API – http://www.greenfieldtech.net/products/gtrapi
IVR API – http://www.greenfieldtech.net/products/gtvapi
Dialer API – http://www.greenfieldtech.net/products/gtdapi

The best thing about the GTx API suite is this – they are all interconnected. For example, call being handled by the Dialer API can be then handed over to the IVR API, operating within the same Asterisk server or a remotely located Asterisk server (via SIP/IAX2).

In the time to come, I’ll be showing you various XML-RPC structures and example of how to use the GTx API suite, and do all sorts of interesting IVR and Dialer structures.

Tags: Asterisk, dialer, digium, Greenfield Technologies, GreenfieldTech, Interactive Voice Response, IVR, Recorded

28 Oct 08 Hijacked by RTFM to la-la land

I keep a vigilant eye on Google Alerts. To be more exact, I’ve got a few alerts defined, in accordance to subjects that interest me. Two of these subjects are Asterisk and FreeSwitch. Recently, the following had been posted on a personal blog:

Our PBX/IVR web-based generator Telfa has been moved from Asterisk to Freeswitch. Why?

Asterisk just seems to come from a different world than what I am used to. Inflexible and problematic. Very long configuration files with ancient syntax. Now I’m far from pretending I’ve used Asterisk enough to understand it pros and cons well, but I have a decent software development experience and I can tell when something “smells.” I didn’t want to build our system (that I want to be flexible and scale well) on some old technology that is only living from its past.

And (most importantly) there are many people experienced with both Asterisk and Freeswitch favoring the latter: Anders Brownworth, Jonathan Palley (creator of Telegraph, a Rails plug-in that lets you talk to Freeswitch), or of course the creator of Freeswitch (and former Asterisk developer!) Anthony Minessale himself.

[Extract from: http://onruby.flempo.com/2008/10/28/chose-freeswitch-over-asterisk/#comment-58]

Reading the above simply flames me UP – WHAT A LOAD OF BULL!

The writer admits that: “Now I’m far from pretending I’ve used Asterisk enough to understand it pros and cons well, but I have a decent software development experience and I can tell when something “smells.”” – If he’s such a worthy developer, the above simply proves that he’s simply an RTFM!

Asterisk provides a multitude of methodologies for configuration management, dialplan logic programming, programmatic API structures – basically, all the tools you need to go about and create your application. While I admit that FreeSwitch is slightly better at the “Core Switching” environment, implementing a near true Soft Switching architecture – Asterisk is a totally different thing.

A while back I decided to develop a couple of my better systems on FreeSwitch, as a test of my abilities. To see if I can be as proficient with FreeSwitch as I am with Asterisk. I re-developed the applications on FreeSwitch from scratch, however, FreeSwitch’s somewhat annoying XML configuration structures made it a hell for me to develop something that I would ask my customers to put their money on.

I started working with Asterisk in 2002, and starting 2003 I tried to have people in Israel start using Asterisk. I can honestly say that the first ever true adaptation of Asterisk in Israel came about only late 2005, and even that wasn’t for mission critical applications. Asterisk had achieved a point in which it is now considered a valid replacement for classic IN and NGN applications and engines, such as SigValue. I suspect that FreeSwitch will become a more dominant contender in that part within a period of 18 to 24 months, as its developer community will grow – time will tell.

In my large installations, I like using Asterisk as my IVR/Application engine envrionment and using FreeSwitch as my routing and LCR environment, simply because it’s capable of handling slightly more SIP-to-SIP connections than Asterisk – but that is the only reason, all the rest is Asterisk.

Both projects are wonderful tools, each one with its own set of strengths and weaknesses. Learn how to balance the use of the two, utilize the best of both world – and stop being a bloody purist, that’s exactly what leads to poor technologies such as Microsoft and poor life practices, like wars and terror.

Tags: AdHearsion, Asterisk, DAHDI, digium, freeswitch, IVR, LCR, purist, pursits, Routing, Ruby, sangoma, VoIP

04 May 08 Asterisk powers Israel’s 60th independance day information service

Ok, the service is up and running, so now I can show it off. Israel’s 60th independance day parties information service is running of an Asterisk servers – how do I know that, you ask? simple, it’s my Asterisk server!

Well, actually, the service is being run by BeLowCall, an IVR and telecom services company, while the platform was developed by me. Essentially, the system is an Asterisk based application engine, that has a very minimalistic dialplan code and communicates with an SQL backoffice then instructs the Asterisk server what to do – in turn, turning the Asterisk server into a high scaleable state transition machine – capable of developing IVR system at any depth or as wide as you want.

If you want to feel the system, you are welcome to call +972-73-2126060. The entire application took about 4 hours to provision, including the database registration system and the recording – not bad, right?

Tags: Asterisk, independance day, IVR, open source

11 Nov 07 The annoyance of incompleteness

There is nothing more annoying than an incomplete specification design, brought to you as a design document. Why does every person that is capable of operating a word processor at a beginner level and operating Visio at a level of a child, believe that they are able to produce a proper design specification or ever a proper requirements document? (more…)

Tags: Apache, Asterisk, design, DTD, IVR, php, XML