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www.woomeravoip.org
WoomeraAccelerating access to VoIP
Cluecon 2009, 7 August 2009Craig Southeren
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Introduction
• Co-founder of OpenH323 project• Co-maintainer of Opal project• Post Increment– Consulting– Contracting– Open source development
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What problems are we trying to solve?
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Business Problems
• Create complex VoIP systems• Remote customers• Division of labour• Blame game• Scalability, redundancy, availability• Minimise duplicated code• Different programming languages
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Mix closed source and open source software, and incompatible open
source licenses
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Different operating systems in the same product
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We want simple and easy
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We don’t want lots of baggage
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The solution
• Socket-based protocol• Like HTTP or SMTP• Client-server architecture• Commands to make/hangup/answer calls• Not as complex as SIP!• TCP socket for multiple calls• MPL/GPL license
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Woomera
• Overriding principle: KISS• Use sockets to connect components• Text based protocol, not an API• Server/client architecture• Command/response for actions• Events for status changes• Not reinvention of SIP/MGCP/H.323
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One to one
• Driver abstraction
Server
Application
Client
VoIP protocol
Woomera
Woomera Server
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Many to one
• Application redundancy
Server
Application
Client
VoIP protocolWoo
mer
a
Woomera Server
Application
Client
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Server
One to many
• Load balancing
Server
Application
Client
VoIP protocol
Woo
mer
a
Woomera Server
Woomera Server VoIP protocol
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Server
Many to many
• Full redundancy
Server
Application
Client
Woo
mer
a
Woomera Server
Application
Client
Woomera Server
VoIP protocol
VoIP protocol
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Message flow
• Client sends command, server responds• Server can send events at any time• No overlapped commands/responses• Use of multiple sockets encouraged• TCP socket for commands• UDP socket for media• Extensible
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Message format
Same as SIP/HTTP/SMTP
command + argsMIME information<empty line>Optional body
• EventEVENT INCOMINGUnique-Call-Id: 20000000Protocol: sip<empty line>
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Command and media
• Commands sent over TCP• Audio media sent over UDP– PCM-16 / SLINEAR– uLaw/ALaw
• Audio can flow direct
• Audio can be proxied
Server ServerClient
media
cmds cmds
mediaServer Server
Client
media
cmds cmds
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Outgoing callClient Server
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Outgoing call
CALL sip:[email protected]: 12.3.4.5:1000<empty line>
Client Server
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Outgoing call
CALL sip:[email protected]: 12.3.4.5:1000<empty line>
Client Server
200 Call startedUnique-Call-Id: 10000000<empty line>
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Outgoing call
CALL sip:[email protected]: 12.3.4.5:1000<empty line>
Client Server
200 Call startedUnique-Call-Id: 10000000<empty line>
EVENT PROCEEDINGUnique-Call-Id: 10000000<empty line>
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Outgoing call
CALL sip:[email protected]: 12.3.4.5:1000<empty line>
Client Server
200 Call startedUnique-Call-Id: 10000000<empty line>
EVENT PROCEEDINGUnique-Call-Id: 10000000<empty line>
EVENT CONNECTUnique-Call-Id: 10000000Raw-Audio: 67.8.9.1<empty line>
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Incoming call (part 1)Client Server
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Incoming call (part 1)Client Server
LISTEN<empty line>
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Incoming call (part 1)Client Server
LISTEN<empty line>
200 Listen accepted<empty line>
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Incoming call (part 1)Client Server
LISTEN<empty line>
200 Listen accepted<empty line>
..... some time later .....
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Incoming call (part 1)Client Server
EVENT INCOMINGUnique-Call-Id: 10000000Local-Number: 1234Remote-Number: 5678Protocol: sip<empty line>
LISTEN<empty line>
200 Listen accepted<empty line>
..... some time later .....
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Incoming call (part 2)Client Server
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Incoming call (part 2)Client Server
ACCEPTUnique-Call-Id: 10000000
Raw-Audio: 12.3.4.5:1000<empty line>
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Incoming call (part 2)Client Server
ACCEPTUnique-Call-Id: 10000000
Raw-Audio: 12.3.4.5:1000<empty line>
200 Call acceptedUnique-Call-Id: 10000000Raw-Audio: 67.8.9.1<empty line>
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Incoming call (part 2)
ANSWERUnique-Call-Id: 10000000
<empty line>
Client Server
ACCEPTUnique-Call-Id: 10000000
Raw-Audio: 12.3.4.5:1000<empty line>
200 Call acceptedUnique-Call-Id: 10000000Raw-Audio: 67.8.9.1<empty line>
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Incoming call (part 2)
ANSWERUnique-Call-Id: 10000000
<empty line>
Client Server
200 Call answeredUnique-Call-Id: 10000000<empty line>
ACCEPTUnique-Call-Id: 10000000
Raw-Audio: 12.3.4.5:1000<empty line>
200 Call acceptedUnique-Call-Id: 10000000Raw-Audio: 67.8.9.1<empty line>
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Local call hangupClient Server
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Local call hangupClient Server
HANGUPUnique-Call-Id: 10000000
<empty line>
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Local call hangupClient Server
HANGUPUnique-Call-Id: 10000000
<empty line>
200 Call hungupUnique-Call-Id: 10000000<empty line>
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Remote call hangupClient Server
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Remote call hangupClient Server
EVENT HANGUPUnique-Call-Id: 10000000<empty line>
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Remote call hangupClient Server
EVENT HANGUPUnique-Call-Id: 10000000<empty line>
HANGUPUnique-Call-Id: 10000000
<empty line>
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Remote call hangupClient Server
EVENT HANGUPUnique-Call-Id: 10000000<empty line>
HANGUPUnique-Call-Id: 10000000
<empty line>
200 Call hungupUnique-Call-Id: 10000000<empty line>
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DTMFClient Server
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DTMFClient Server
DTMFUnique-Call-Id: 10000000Content-Length: 11<empty line>14157773456
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DTMFClient Server
DTMFUnique-Call-Id: 10000000Content-Length: 11<empty line>14157773456
200 DTMF acceptedUnique-Call-Id: 10000000<empty line>
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DTMFClient Server
EVENT DTMFUnique-Call-Id: 10000000Content-Length: 11<empty line>14157773456
DTMFUnique-Call-Id: 10000000Content-Length: 11<empty line>14157773456
200 DTMF acceptedUnique-Call-Id: 10000000<empty line>
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H.323 and Woomera
CALL
Command H.323 PDU
H.225 SETUP
H.225 PROCEEDINGPROCEEDING
Event
H.225 CONNECTCONNECT
HANGUP H.225 RELEASE COMPLETE
H.225 RELEASECOMPLETE HANGUP
DTMF H.245 UI/RFC 2833
H.245 UI/RFC 2833 DTMF
INCOMING
ACCEPT H.225 ALERTING
ANSWER H.225 CONNECT
H.225 SETUP
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SIP and Woomera
CALL
Command SIP PDU
INVITE
180 RingingPROCEEDING
Event
200 OKCONNECT
HANGUP HANGUP
HANGUPHANGUP
DTMF INFO/RFC 2833
INFO/RFC 2833 DTMF
INCOMING
ACCEPT 180 RINGING
ANSWER 200 OK
INVITE
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Real-world example #1
Asterisk
chan_woomera
WoomeraOpal
H.323
H.323 for Asterisk
Woomera
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Real-world example #2
Jabber-based collaboration server
WOpenMCU
WoomeraOpal
Audio-conferencing for collaboration
WoomeraRTP
Jabber clients (2000+) WoomeraWoomera
Jabber
RTP
CLI
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Real-world example #3
WoomeraOpal
Multi-protocol router
Woomera
Inco
min
g le
g
Out
boun
d le
g
SIP, H.323 etc SIP, H.323 etc
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Real-world example #4
Control software
WOpenMCU
WoomeraOpal
Dealer trading room system
SIP gateway
Woomera
CLI
SIP handsets
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Libwoomera
• “C” interface• Single threaded• Triple license : GPL/LGPL/MPL• Server and client• Windows and Unix• Self-proxy• Auto-discovery of servers
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Clients
• WOpenMCU – audio MCU• Wproxy – back to back proxy• chan_woomera – asterisk channel• Sangoma Media Gateway
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Servers
• WoomeraOPAL – SIP, H.323, IAX, ivr, fax• WoomeraRTP – raw RTP and SRTP• WoomeraPRI – E1/T1 over Sangoma PRI• Sangoma – BRI and SS7
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Future work
• Draft RFC• Video support• Hold and transfer• Server limits and soft
shutdown• Secure command
channel• Secure media
• Different raw media types
• Call bridging• Libwoomera
enhancements
