presence and im as sip services jonathan rosenberg chief scientist
TRANSCRIPT
Presence and IM as SIP Services
Jonathan RosenbergChief Scientist
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Presence as a Key Application Today, Presence is Just Online/Offline, Used for Instant
Messaging (IM)
Tomorrow, Will Describe Much More Than Online/Offline Status Presence is the dynamically changing set of means, willingness,
capabilities, characteristics and ability for users to communicate and interact with each other
The Means VoIP IM Mobile phone PSTN phone Email Games
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Presence Tomorrow continued
Willingness “Only if urgent” “Try mobile phone first, then business line” “Always send email”
Capabilities and Characteristics Voicemail available Voice or video Mobile or fixed Support for multiple languages Secretary available Geographic locale
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Presence: The Best Thing that Could Happen to Voice
Two Reasons Call completion Innovative services
Call Completion Problem A small fraction of calls result in useful conversations
Busy No Answer Voicemail Assistants “Call me back later”
Result is user frustration and no provider revenue
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Presence: The Best Thing that Could Happen to Voice
Solution Only call if I know where the called party is available, when they are
available, and how they are available Presence conveys exactly this information Result: successful call completion rates can skyrocket!
Services Presence is one of the key enablers Examples...
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Traffic Jam Alerts
Uses Geographic Locale as Presence Component Mobile phone site location GPS
Service Definition Turn on mobile phone in car As you drive, application server
monitors location As you approach traffic, service
will call you Voice response system reads
out alternate route
NOTIFY
INVITE
REGISTER
Application Server
Presence Server
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Auto Conference
Problem: Tough to Get Busy People Into a Conference Call
Solution: Use Presence to Create the Call When Everyone is Available!
Procedure Enter email addresses into a
web form (1) Application subscribes to users (2) When all online, application calls
each participant (3), calls a conference bridge (4), connects them together Presence
HTTPSIP Calls
Application Server
Conference Server
Presence Server
1
2
4
3
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
What Does Presence Have to Do With SIP? How to Deliver Presence
Need a network that can identify users independent of location
Need a way to forward subscription requests to server handling that user
Need a way for user to tell server its location and other presence data
Need a network which can forward notifications to subscribers
Needs to scale Needs to deliver messages in
real time
What Does a SIP Network Do? Identifies users independent of
location Forwards requests (INVITE or
otherwise) to server handling user REGISTER allows network to tell
server its location and other information
Can forward messages back to originators in reverse direction
Scales Delivers messages in real time
(call setup delays)
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Session Initiation and Presence/IM Share Other Requirements
Security Privacy Access controls Authentication
Carriage of MIME Data
Extensibility
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
SIP Already Provides Publication Capability REGISTER is a Publication Message
for Locations
Allows for SIP and Other URL Types
Multiple Entities Can Publish for the Same Address
SIP Caller Preferences Extension Allows for Attributes for Locations Mobile, landline Home, business Preferences Audio,video - MIME capability
Registrar
Registrar
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Advantages of Using SIP for Presence and IM
Unifies Major Communications Services Voice/video IM Presence
Shared Databases
Shared Proxies
Shared Servers
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Advantages of Using SIP For Presence and IM
Reduces Management Costs One infrastructure instead of two One NOC instead of two One set of managers instead of two
Enables New Combined Services Combined services integrate voice, video, IM, presence, web and email These new services will be a “killer app” for communications on
the Internet Delivery of combined services is greatly facilitated by alignment of
presence and communication signaling protocols
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
SIP Extension for Presence
New Entity: Presence Agent Purely logical entity Knows presence state of user Receives SUBSCRIBE requests Generates NOTIFY requests Co-located with proxy/registrar or User
Agent
Basic Operation Subscriber send SUBSCRIBE Routed to PA using normal SIP PA authorizes subscriber Acceptance contains presence state NOTIFY sent when state changes
Routed using SIP Record-Route
REGISTER
SUBSCRIBE
NOTIFY
Presence Agent +Proxy/Registrar = Presence Server
Proxy
Subscriber
Presentity
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Important Details
Subscriptions Refreshed Expires mechanism, same as
with REGISTER, determines lifetime
Subscription Has “INVITE” Semantics for Record-route/ Contact Processing SUBSCRIBE creates a
“session” Refreshes have same Call-ID,
as do Notifications Intermediate entities can
record-route
Body of NOTIFY Contains Presence Data
Authorization and Access Controls Are Orthogonal Presence agent sends 200 OK
if subscription is accepted How it determines whether to
accept? QAUTH DIAMETER Local policy database
configured via web CPL
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Features of SIP For Presence Extension
End Users Can Perform Notifications Scalability
Presence Agent Function Can Migrate Network provides service when user is offline When user is online, subscriptions migrate to user
Offline Subscriptions Handled
Authorization from User Can Be Obtained by Presence Server
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
Features of SIP For Presence Extension continued
Multiple Entities Can Generate Presence Information for One Presentity Mobile phone, PDA, laptop and desktop PC
Multiple Presence Clients Can Be Online at Once
Traditional SIP Proxies Route SUBSCRIBE and NOTIFY
Presence Data is Orthogonal
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
SIP Extension for Instant Messaging
Operation of Extension Messages carried in SIP messages New method - MESSAGE Routed to recipient using normal SIP techniques Simple extension
Features Associates an IM with an existing call Any MIME data can be sent TCP for large messages Routed by existing proxies and registrars Possible to have a different client for IM and communications
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
What Is Happening in the IETF? Instant Messaging and Presence Working Group (IMPP)
Could not come to consensus on a single proposal Chartered to develop CPIM – Common Presence and Instant
Messaging – common pieces across all protocols Presence data format Other groups will be chartered to do protocols
Application Exchange (APEX) Formerly IMXP Does IM and presence on top of a BEEP Mesh BEEP = Blocks Extensible Exchange Protocol
XML protocol for application frameworks
Presence and IM (PRIM) Not clear it will be chartered From scratch “TCP” protocol, much like SIP
SIMPLE
www.dynamicsoft.comSIP 2001 2.21Presence and IM as SIP Services
SIMPLE Group SIMPLE = SIP for Instant Messaging Leveraging Extensions
BoF Session Held at IETF 49 December 00 Chaired by Jon Peterson, Level(3) Clear consensus to move forward
IESG Officially Considering Charter at This Time
Charter Encompasses SIP for presence specification
Built off of CPIM and SIP event framework April 01
SIP for IM specification March 01
Information Resource Jonathan RosenbergChief Scientist+1 973.952.5060 [email protected]