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SIP Express Router (SER)

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SER Primer SER is an open-source, GPL-ed SIP server withSER is an open-source, GPL-ed SIP server with

High scalability (up to thousands of calls per second of transactional High scalability (up to thousands of calls per second of transactional throughput on a PC)throughput on a PC)

Effective application building (modules and FIFO/application interface)Effective application building (modules and FIFO/application interface) High flexibility (routing language)High flexibility (routing language)

Web address (download, documentation, etc.):Web address (download, documentation, etc.): www.iptel.org/ser/www.iptel.org/ser/

Some non-GPL features available too (LDAP, TLS, Some non-GPL features available too (LDAP, TLS, redundancy, …)redundancy, …)

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Linking Applications to SIP/SER To create rich services, one needs to link existing applications To create rich services, one needs to link existing applications

to SIP communication.to SIP communication. Design requirement: apply division principle and split SIP Design requirement: apply division principle and split SIP

infrastructure from applications cleanly.infrastructure from applications cleanly. I know, we are not the first to come up with the principle…I know, we are not the first to come up with the principle…

Divide and Conquer (“Divide et impera”, Caesar, 100BCE-44BCE)Divide and Conquer (“Divide et impera”, Caesar, 100BCE-44BCE) Labor Division (Adam Smith: The Wealth of Nations, 1776)Labor Division (Adam Smith: The Wealth of Nations, 1776)

““The greatest improvement in the productive powers of labour, and the The greatest improvement in the productive powers of labour, and the greater part of the skill, dexterity, and judgement with which it is any where greater part of the skill, dexterity, and judgement with which it is any where directed, or applied, seem to have been the effects of the division of labour.directed, or applied, seem to have been the effects of the division of labour.””

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Application Examples Web-applicationsWeb-applications

User manipulation of their contacts in user location databaseUser manipulation of their contacts in user location database Could not be done easily via a back-end database if cached by SIP serverCould not be done easily via a back-end database if cached by SIP server

““Send Instant Message” – initiate a SIP transactionSend Instant Message” – initiate a SIP transaction Monitoring of server healthMonitoring of server health

Management Applications (command-line or web)Management Applications (command-line or web) User administration (e.g., revoking user’s privileges)User administration (e.g., revoking user’s privileges) Run-time reconfiguration (e.g., introducing a new domain)Run-time reconfiguration (e.g., introducing a new domain)

Presence Applications:Presence Applications: Drive presence status displayed in SIP messengers.Drive presence status displayed in SIP messengers.

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On Windsurfing Jiri's hobby: windsurfing; cool but loading a van with gear, Jiri's hobby: windsurfing; cool but loading a van with gear,

traveling to a lake, setting up a sale and learning that the wind is traveling to a lake, setting up a sale and learning that the wind is gone is frustrating.gone is frustrating.

The application is out there: there are tons of software for The application is out there: there are tons of software for weather forecasts. The software can generate information that is weather forecasts. The software can generate information that is precisely needed.precisely needed.

Missing piece: link the applications to the SIP-based real-time Missing piece: link the applications to the SIP-based real-time communication infrastructure.communication infrastructure.

How to engineer that? Build in a door in SIP server that allows How to engineer that? Build in a door in SIP server that allows SIP-unaware applications to talk SIP.SIP-unaware applications to talk SIP.

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Our Proposal: Use ASCII InterfaceConnected via a FIFO Pipe

Design idea:Design idea: Export SIP logic to applications Export SIP logic to applications

through a textual request-through a textual request-response FIFO interface (named response FIFO interface (named pipes)pipes)

FIFO server propertiesFIFO server properties Server looks like a file to Server looks like a file to

application – any file-based application – any file-based application can use itapplication can use it

Excellent portabilityExcellent portability Simple and extensibleSimple and extensible Application isolationApplication isolation

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Example: Contact Maintenance

Web application can show, add and delete user contacts stored in server’s Web application can show, add and delete user contacts stored in server’s memory.memory.