Bryan Helmkamp

Presented by Jay Phillips

• Ruby is more than a language for building websites

Past & Today

• Started playing with extending Asterisk, ended up with Adhearsion
• Got into Rails, rewrote Adhearsion from scratch
• Released Adhearsion last Christmas
• Writing a section on Adhearsion for the next O’Reilly Asterisk book

Adhearsion in a nutshell

• More of a collaboration framework than an “Asterisk development framework”
• Asterisk is a good way to do VOIP
• Adhearsion is a good way to do Asterisk development
• Adhearsion is open source software
• Adhearsion attempts not to loose any Asterisk functionality

Why VoIP Rocks

• Being a hacker rocks… and you can hack VoIP
• VoIP can allow you to cut business expenses
• Now you can use Ruby!

Fun VoIP Projects

• Unlock your apartment door with your cell phone (with voice authentication)
• Control your hacked Xbox Media Center with a cell phone
• Rarely have to pay for a phone call
• Crazy phone-based reminder system
• Control anything with voice commands
• Phone-controlled Roomba

What is Asterisk?

• Open source phone call manager (PBX)
• Revolutionized the telecom world forever
• Makes hackers really happy
• Makes cash flow statements really happy
• Does everything you could want with a phone

Existing Asterisk Control Grammars Suck At…

• Conditional looping and branching
• Variables
• Complex data structures
• Database/LDAP integration
• etc.

Old Dialplan Example

• Looks like mutated BASIC and Perl hell
• GOTO statements FTW

Why use Adhearsion?

• Breaks down barrier of entry to Asterisk
• Grammar feels like assembler or Excel
• Adds many new features to your PBX
• Adhearsion dramatically improves Asterisk
• Database integration with ActiveRecord
• Integrate Rails and VoIP!

Other Aspects of Adhearsion

• Helper system for extending Asterisk framework
• One of the first times VoIP code can be traded
• Integrates with on-phone micro-browsers (via subframework Micromenus)
• Use other collaboration technologies together (AIM, email, SMS, etc.)
• Instant messaging, Growl, weather, reverse number lookup, etc.

Getting Started with Adhearsion

Asterisk?! Isn’t that hard to install?

• NO! Use Digium’s AsteriskNOW Linux distro
• Available on Live CD, VMWare and Xen
• Installed and running when booted
• Asterisk 1.4 has a web GUI
• Many good resources
• Works with Adhearsion

Installing Adhearsion

• gem install adhearsion

Writing Adhearsion Dialplans

• Dialplans – ways to process phone calls

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internal {
  loop { play 'hello-world' }
}

• Including other contexts:

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internal {
  +foo
}

foo {
  record {
    dial SIP/:out_trunk/1234
  }
}

• Above code is Ruby – overloading operators
• SIP is session initiating protocol – lets you make calls
• Another example:

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internal {
  play %w"a-connect-charge-of
          16 cents-per-minute
          will-apply"
}

• Adhearsion unifies API for playing numbers and other sounds

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internal {
  case extension
    when 10...100
      dial SIP/extension  # transfer
    when 6000...6820
      join extension      # join conf call
      
    when _"21XX"
      
      if Time.now.hour.between? 2, 10
        dial SIP/"berlin-office"/extension[2..4]
      else speak "It is not business hours now in Germany"
      end
}

• #_() is a method that converts String to Regex

Database-Driven Dialplans

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service {
  customer = Account.find_by_phone_number callerid
  usage = customer.usage_this_month
  
  if usage >= 100 then +beyond_limit
  else
    customer.usage_this_month += time do
      dial IAX2/"main-trunk"/extension
    end
  end
}

• #time method times execution of a block and returns the result

How Does Adhearsion Talk to Asterisk?

• Asterisk receives a call normally
• Asterisk connects to Adhearsion via socket and sends all call info
• Ashearsion evaluates dialplan, executes appropriate context

Things You Can Do From Rails

• Invoke virtually any PBX event with Adhearsion’s sexy syntax
  • Uses DRb
  • Start calls, view live channels, record channel
• Share Adhearsion’s ActiveRecord models
  • Manage users, groups, etc.
• Use your imagination!

What’s a helper?

• Code loaded when Adhearsion boots
• Introduce a technology to the framework
• Can do virtually everything
• Can be written in Ruby, C, Java (JRuby)

Micromenus

• Many modern phones have micro-browsers
• Use custom XML schema over HTTP
• Use a Ruby DSL to generate
• Mini-web app framework
• Also viewable in a web browser!

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item "Adhearsion Server Statistics" do
  item "View Registered SIP users" do
    PBX.sip_users.each do |u|
      item "SIP user #{u.uername} on IP #{u.ip}"
    end
  end
  
  item "View System Uptime" do
    item `uptime`
  end
  
  item "Network" do
    heading "Network Interface condig" do
      ...
    end
  end
end

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item "Call an Employee" do
  item "Select an employee below."
  User.find(:all).each do |user|
    ...
  end
end

...And then my laptop battery died…

Get Involved

• Contact Jay at jay AHT codemecca DOT com
• Adhearsion’s site: http://adhearsion.com/

Q & A

• Check out voip-info.org