Programmable End System Services Using SIP

1. Programmable End System Services Using SIP Xiaotao Wu, Henning Schulzrinne 2nd New York Metro Area Networking Workshop September 3rd, 2002

2. Today’s Endpoints • Processing ability • Graphical rendering • Storage capacity • Converged information • Varied platforms • Phones • PCs • PDAs

3. SIP promotes end system services • Two SIP UAs can talk to each other directly. • Service-related information is explicitly contained in SIP headers. • The simplicity of SIP makes it easier for end system to perform services.

4. SIP endpoints are more than IP-based POTS phones

5. SIP service interfaces <?xml version="1.0" ?> <!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd"> <cpl> <incoming> <address-switch field="origin" subfield="user"> <address is="anonymous"> <reject status="reject" reason="I don't accept anonymous calls" /> </address> </address-switch> </incoming> </cpl> @ECHO OFF IF %SIP_FROM%==sip:wxt@cs.columbia.edu GOTO BLOCK GOTO EXIT :BLOCK echo SIP/2.0 486 Busy :EXIT • CPL • SIP CGI • SIP Servlet public boolean doInvite(SipRequest req) { SipResponse res = req.createResponse(); res.setStatus(486); res.send(); return true; }

7. #! /usr/bin/env perl -w # Reject messages whose 'From:' matches 'sip:hgs@' by # responding with 486 Busy, redirect the others to voicemail print "SIP/2.0 100 Wait\n\n"; if (defined $ENV{SIP_FROM} && $ENV{SIP_FROM} =~ "sip:hgs@") { print "SIP/2.0 486 Don't disturb, I am working\n\n"; } else { print "SIP/2.0 302 Redirect\n"; print "Contact: sip:xiaotaow\@voicemail.cs.columbia.edu\n\n"; }

8. Describe end system services • Users pay for a bad service because they do not understand why it is not good • Techniques for network services are not good for end system services.

9. Network Services v.s. End System Services

10. Network Services v.s. End System Services End System Service Language

11. End system service languages • Simple and easy to understand by non-programmers • Platform neutral • Express user interactions • Control media and other end system applications • Extensible to accommodate new services • Restricted to certain class of services, not necessarily Turing-complete

12. Endpoint Service Markup Language (ESML) • XML based language • Platform and underlying programming language neutral • Readable by non-programmers • Defined as an XML schema • Derivation of new types • Pre-defined types • Tree-like structure • Use packages to group events and actions

13. ESML example • <esml name="online_call" • require="generic presence ui"> • <notification status="online" • priority="0.5"> • <address-switch field="origin"> • <address is="xyz@foo.com"> • <call /> • <alert sound=“foo.au" • text="Calling xyz@foo.com" /> • </address> • </address-switch> • </notifying> • </esml>

14. SIP user agent SIP Device agent Presence agent Basic user agent presence Generic Media UI x10 vcr ESML packages im email web calendar conference

15. Extend ‘general’ to ‘sip’ • <xs:schema targetNamespace="esml:sip" • xmlns:sip="esml:sip" • xmlns:generic="esml:generic" • .......... • <xs:complexType name="IncomingType"> • <xs:complexContent> • <xs:extension • base="generic:IncomingType"> • <xs:attribute name="priority" • type="PriorityType"/> • .......... • </xs:extension> • </xs:complexContent> • </xs:complexType>

16. ESML Service Creation

17. Compare to other languages • CPL • SCML • CCXML • CPML, TML, CallXML

18. Conclusion and future work • Service partition between end system services and network services • Feature interaction

19. Thank you! The End.