Multicast & Publish - Subscribe used to build Event Notification on IP How to make the Internet work better. John Mathon TIBCO Software Inc

Who is TIBCO? n Pioneer in Middleware, providing publish/subscribe technology since 1987 n 44th largest independent software company in 1995 Software Magazine “Software 100” n Market leader in industrial strength middleware for distributed computing n Proven in the largest deployments

The Active Enterprise Publish & Subscribe WAN Architecture Customers Sales NT Server ERP SAP Business Partners Inventory SAP Marketing Notes / DBMS Publisher Applications Databases Devices Publisher Applications Databases Devices Subscribers Browsers Applications Databases Devices Subscribers Browsers Applications Databases Devices

OS/400WindowsNTUnixOS/2VMSMVS The Information Bus® TIB Technologies Adapters Oracle Informix Sybase Ingres Java ActiveX CORBA COM Legacy Fax, , Pager ….. S.W.I.F.T. SAP EDIFACT Monitoring & Control Infrastructure

Information Bus n Subject Based - Highly Scalable n Location Transparency n Meta-Data - Model Driven - XML n Extensive Event Services - Routers, Initial Value, Historical Services, Entitlements, Accounting, Queuing, Load Balancing, Message Broker, Adapters, Application Monitoring, GUI Building Tools

6 The Tower of Middleware Reliable Multicast Messaging ORB Message Broker PUSH App. Management TP Monitor App. Integration Modulus, GlobalCast IBM, ISIS, Peerlogic Visigenic, Iona Neon, Mercator Backweb, Marimba CA, Tivoli Hitachi, BEA Crossroads, Constella Challenges n Integration n Scalability n Event-Driven n Ability to Change/ Flexibility n Open n Cost of Ownership n Ease of Implementation TIBCO’s Investment: $250M over 12 years Installed Base: $2B worth of Integrated Middleware TIBCO Enterprise Middleware

7 Representative Alliances TIB Microsoft, Pointcast, BackWeb, and 11 others Oracle, Informix Cisco, 3Com Hewlett Packard Database Desktop E-commerce Network Hardware Integrators VeriSign, CyberCash SUN IBM, PW, Andersen

Multicast Protocols n Unreliable Multicast - Available Today n Reliable Multicast (PGM) - Proposed to IETF n SBA - Subject Based Addressing - Available Today, not public domain. n Market Research/Voting - Theoretical.

Multicast Multicast Routing Protocol (among routers) Forms a loop-free set of trees to interconnect all members of a group Dynamically adjusts trees as hosts join and leave a group Use “tunnels” to circumvent non-multicast areas Internet Group Membership Protocol (routers and hosts) “Anybody Listening to Group XYZ”? “I’m Listening to Group XYZ”

Un-Reliable (Standard) Multicast n Optimistic - Needs applications which tolerate high error rates, high latency corrections n Problematic - At least 1% error rate in the best scenarios. n Error Correction Unsystematic - Proprietary Solutions n Uncontrolled streams of Data - High-Volume unsegmented bands of data. - Can overwhelm receiver. n Useful for Streaming Audio, Video, Radio/TV like Applications. n Difficult Addressing Content - Unclear Authority on Naming n No Security, I.e. Authentication of Publishers n No Guarantee of Order of messages

Reliable Multicast (PGM) n Good - Updates Thousands of Subscribers in a fraction of a second. n Good - Optimistic Algorithm - Proven in Industrial Environments. n Good - Useful for More Data Oriented Applications n Good - Guarantee of Order of messages from a single publisher n Bad - Increased Latency over Unreliable Multicast. n Bad - Uncontrolled streams of Data - High-Volume unsegmented bands of data. - Can overwhelm receiver.. n Bad - Difficult Addressing Content - Unclear Authority on Naming n Bad - No Security, I.e. Authentication of Publishers

Subject Based Addressing n Controlling Streams of Information - You don’t have to take the whole banana. Just have a bite! n More Efficient to User - Uses only the bandwidth required for what the user needs. n Creates a Taxonomy of Fine Grained Information - Provides a naming scheme for information that makes it easier for the user to find information. Better than Multicast numeric addresses. (I.e. Ala Internic) n Implements Authentication and Security n More efficient usage of Multicast addresses.

Reliable Multicast and SBA n Proven in Mission Critical Applications n Advantageous in almost all circumstances n Best for High Bandwidth / Large User Populations where “some” of the information is of interest to “some” of the users. I.e. N to N. n But is usually as good as 1 to N, or 1 to 1 or even N to 1 implemented with Point-to-point or pure broadcast protocols.

Cost/Benefit Tradeoffs n Where does multicast pay off vs repetitive polling or point-to-point push? n Where does SBA pay off vs repetitive polling? n Where does SBA/Multicast pay off vs repetitive polling?

Server Load n Point to Point Load Increases Geometrically with # of Publisher Messages and # of Receivers n Multicast load is linear with # of changes (Publishes) n Problem - What if everybody isn’t online at the time of the updates? n Problem - What if everybody isn’t interested in all the content being broadcast? n Advantage - Big Savings for many applications

One Message Updates Many Users, Caches, Proxies, and Search Engines User Cache/ Proxy Search Engine Content User Browser

Current New Approach n Caches periodically query servers for new updates. n Search Engines periodically go out and search and index new information. n Hidden Content Missing n Single Publish by Content source reaches all concerned caches and search engines. n Search Engines more up to date. n More efficient for publisher.

Flow Rates - Assume 1,000,000 sites changing on average of once a day. Using SBA and PGM. n Search Engines –1,000,000 messages a day which is about a tenth of what a typical trading room sees on a slow day. n Caches, Proxies –1,000 pages cached, then 1000 messages a day. Also Trivial. n Users Caches and Browsers. –A few messages a day, typically when viewing highly active sites with constantly changing content.

Advantages n Search Engines –No More Searching the Internet - or much more limited crawling and comparing. BIG WIN! –Content more up to date, more comprehensive. BIG WIN! n Proxies, Caches –No polling required, but need to process updates. n Users –UP TO DATE CURRENT CONTENT. WIN! n Content Providers –Reduced Load on Servers from Polls from Search Engines, Caches and Users. –BIG WIN!!! n Developers - Much simpler to build push applications.

One Message Queries Multiple Search Engines User Cache/ Proxy Hidden/Value Added content Search Engine(s) Search Engine(s) User Local Search Engine n Subscribe to all queries n Subscribe to limited set of topics n Publish Query n and topic

Simple Market Research Protocol (SMRP) n As Data is Broadcast, counts are kept and returned to distributor n Anonymity. Only counts are returned. n Advertisement is sent and an accurate count of number of impressions delivered n Proxies/caches can extend MRP protocol where cacheing is performed

Market Research User Cache/ Proxy Search Engine Content User Browser n Delivered 25 impressions n Delivered 4 impressions n Delivered 25 impressions n Delivered 1 impressions n Delivered 20 impressions

Lessons Learned n Everything is an Event - No special messages n Multicast and SBA are essential to make even small systems perform. n Internet Scale requires a “non- centralised” solution, I.e. TCP routing as an example. n Multicast and SBA really work.

Lessons Learned n Fine Tune the PGM algorithm and SBA algorithms. See how TCP routing has improved over the years. n Don’t just standardize the protocol but work on data representation issues as well. n Build assuming events are prolific and diverse.