Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Keryx: Internet Notification Service for Dynamic Web Applications Søren Brandt Anders Kristensen

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Expanding the Scope of Push o Current push technologies notify users of Web- content updates o But notifications are potentially useful in a much wider context o The Internet would benefit from a general purpose Event Notification Service o Web content push is just one application of such a service

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Limitations of Current Push o Narrow focus on web content push o Location-centric channel concept o No standard filtering language defined o Closed architectures that do not support higher- order services o Bandwidth problems: m frequently changing information m index files (e.g., CDF) may become quite large

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol The Case for a Generic Notification Service o Standard would allow increased interoperation m between currently separated systems m intelligent devices can communicate with people m people can communicate with intelligent devices o Notifications can drive channel updates o A Nervous System for the Internet

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Elements of a Notification Standard o Format for describing structured data o Standard notification elements o Standard filtering language(s) o Schema language o Standard vocabularies o Transport protocols (?) expressive human-readable easy to generate must facilitate filtering

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Internet Notification Service o Any event can generate a notification: m WWW page update m stock price update m printer paper jam m telephone ringing m vehicle or domestic security m personal location update m package delivery m voic m travel documents ready o Existing Notification based systems: m Network Management (SNMP, GDMO) m Workflow m Communication services m PSTN, mobile, VOI m voic , pager, m Distributed games m Distributed Virtual Environments

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Example Service: Monitor Stock Prices NYSE Stock Price Service Publish Browser: Stock price monitor Event Routing Event Matching FTSE Stock Price Service Events Publish Events Subscribe

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Example: Spare Parts Shopping o Yesterdays scenario: check local weekly o Todays scenario: subscribe to Auto Parts channel m adds about unwanted car brands and parts m only information from anticipated source o Tomorrows scenario: subscribe to notifications about available 1984 VW Rabbit carburettors m only relevant notifications m notifications from unanticipated sources

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Keryx - Internet Notification Service o A light-weight, many-to-many communication service between applications or people o Publish and subscribe model o End-user defined filters o Decoupling of sources and sinks o Fine-grained information units o A nervous system for the Internet o Emergent services o Higher-order services Action Reaction

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Smart Seat Video Camera Web Client (Browser) Services written in Java Event Distributor Event Registration and Forwarding Service Web Server Services written in Java (e.g.) Active Badge Internet PBX Open Set of Devices Events Enterprise Telephony Events Electronic Mail WWW Site Watch Keryx Notification Architecture

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Internet Notification Service: Basic concepts o Publication m Declare an intention to send notifications m Describe notification types o Subscription m Register interest in receiving notifications m Register notification filter o Notifications m Fine-grained information packages m Describes an event m Suited for automatic processing m Undirected o Propagation m Supporting servers send notifications to end-users m Propagate only if interest exists (filters)

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Keryx Service Model o Service characteristics: m notification driven m sub-parts evolve independently o Service is a collection of small software elements m produce and consume events m need not be aware of other elements m located anywhere o Emergent services: not centrally planned m higher-order services

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Service Example: Event Correlation o Value-adding higher-order service m detects patterns in a low-level stream of notifications m generates derived higher-level notifications m reduces volume of traffic to event consumers o Example event correlation services: m personalised news m network management m personal location tracker m page-change digests m stock-change services

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Transfer Syntax { type (notify), content { type (stock-price price-change) stock-symbol HWP stock-price $65 exchange-name NYSE }, system { source quotes.nyse.com publication-id id://nyse/57 } o On-the-wire format o Structures m Maps: (name, value) m Lists: indexed o Atomics m Symbol, String, Number,... o Filter Language m Predicates on events o Human readable o Easy to generate

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Routing by Event Content o Distributor matches events to subscriptions m filtering based on event content o Events forwarded to interested subscribers m multicast or point-to-point event delivery o Events forwarded to other event distributors

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Keryx Reference Implementation o Notification Framework + APIs: Java and C o Event Distributor o Simple notification transport protocols (TCP and UDP) o Generic Notification Viewer m support for specialised plugins for specific event types o Rule-based notification rewriting service o Free for non-commercial use

Extended Enterprise Laboratory, Hewlett-Packard Laboratories, Bristol Conclusion o Expand scope of push technology discussions! o Base Web Content Push on Internet Notification standard! o Elements of a notification service: m notification language m filtering language m delivery component

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